G technical analysis, a Lexus. To determine the factors of safety. Babylon rope pack and. Can you hear me? Can you hear me now I re enabled this sound? Yes, we can hear you Michelle now OK perfect so let's start over. Sorry for that just getting to start with the new system. I think it's a very nice system. But here we still have to get the. First steps with this so today, we're doing the special interest group workshop for detecting analysis in Bentley Systems. And we're going to talk about pressures today how to determine your factors of safety. Are. Ben legit technical analysis special interest group today will take about 45 to 60 minutes, it will be recorded. And it will be available through your personal link. You should be receiving one personal development hour, it will be applied to your Bentley transcript if you have registered. Ann. Actually problems with that, please contact bentley.insteadmainly.com if you have issues with this. And, of course, our six are complementary. We only need you to register online and then you're able to watch it now. Or later on the month. The nice thing of course, if you watch it life. You can also ask questions during the session. Topics for today, 1st I'm going to talk a bit about the factor of safety an how to apply safety analysis within flexes. And I'm doing a few examples here today life. We do a natural slope actual notes on the calculations and I'm going to apply some reinforcements. How to increase the factor of safety so we have a higher stability factor we and also some closing notes on? What safety analysis and informations? How they're related? What how you should be applying your undrained analysis? And what are the benefits of the file download method for determining factor of safety because we can also. Use for instance, limit equilibrium analysis like using EFI slow. Which of course also gives you quickly your factor of safety but there are some benefits using it in? Together with finite element calculations and I'm going to do a summary. Note everything that we talk about applies both Reflections 2D in Plex is 3D in the demos away. Access to D because the calculations are much, much faster and that will fit in the. Current time that we have today. So the factor safety if we look at the we have different types of slopes. And that we want to calculate the slope stability for you can think about. Ann. Yeah, so on the right hand side you will see a typical case where you want to assess the. A slope stability for instance, for River embankment in which you have a higher water level at one side. A lower water level and lower. Show surfers even which is difficult case for instance in. The Netherlands for instance, to where we have a fairly low short surface and the River is actually higher. So we can think of those kind of situations where you want to. Calculate the slip servers ancestor slope stability wants the smallest factor of safety and you can think about the also the. Calculation using Bishop methods. All the methods, but today, we talk about finite element calculations. So how do we? Determining factor of safety up there are many possible definitions that we can apply if we think about the case that we see here. We have failed. Load acting on the soil body. And you can think about different definitions of applying the order of Terminator factor of safety. You can think about how we can have. A maximum load that we can apply on the social services until their failure and we have working load. We can take this ratio. This gives us truth factor uhm we can also. See what kind of mobilized source strength. We have so the current choice strength and how much is still available so. That's a different ratio for the same case it is might give different factors so make sure that you understand which. Type of factors Tracy you actually going to need for your analysis in this case plexus full determined the factor. And safety factor based on troll strength this nicely complies with. Conventional methods in slope stability analysis in which we apply? Also a Resistance factor based on the available source strengthened immobilized or straight. Soon, as safety analysis in plexus, we determine is what we call at 5C reduction or shear strength. Reduction. Basically, it's a reduction of the strength parameters until we have failure in the model. And it's not that we Just get on one point failure, but we have to really develop a full failure slip servers. And until that time, the calculation cannot reduce the strength anymore. So if using effective Frank for instance, where the parameters Sigma images. Or some MSF which is basically the strength reduction factor. And we're going to reduce the this in new calculation and we do this gradually app. LEXIS calculates incrementally so we use a lot of steps and we try to reduce the strength. In every step just a little bit more until we reached this failure state. What we do we reduce the tangent of the friction angle? And we reduce the cohesion, we reduce them at the same rate? Now you can see this on the. Right hand side of the image. As we see that they were starting with the red line. Which is the original strength of the applied theory in the model then we're going to reduce this? Until we reach the more column circle for the current state and when that happens, we try to reduce it more. See redistribution of stresses her because then we get the stress it invalid state, which means we have to. Previously, which dresses and then based on that you can see dishes. Development of Haislip servers. If we using undrained shear strength for instance, yeah, using hundreds. Beorn brains, she will also going to reduce the strength. And it will be just the. As you fired by the SU reduced this gives us the strength reduction factor. Just having the strength reduction factor. Is not necessarily the factor of safety? I'll come back to that later? So how do we determine a factor of safety within Plex is now of course we need a safety face so. Which. We shut the calculation type to a safe type of calculation. Actually, we, we diverted through and uh. A face where we calculate this the state and then we're going to add a new safety face. So we create a new safety phase that starts from the stress state, which you want to analyze the factor of safety for. Delivery inputs by default, setting, incremental multipliers. The incremental value for MSF but this is the strength reduction that we want to. Additionally, for every step, it set by default 2.1 and the first calculation step, it will attempt to increase this. Somehow, Jeff from one which is the default value that always wear the color starts from it, who wants to. Increase it from one to one point 1. Anne for any subsequent calculation steps that come after this initial step. There's an automatic step of procedure so if it's. Easy to do to reduce the strength. We're going to keep the same factor or maybe even make the. Make this factor, larger, but usually you see this process, the development and then actually this step. There's someone who's F. Will be made smaller every step? Then you just said the calculate button. Then. Is that 3 we carefully have to examine this summer? Jeff value first displacement 3 mega curve in Plex? Is output? So we have to make sure that actually the final failure. State has been reached. It could be that it's not fully developed yet, but we just. Uh with the number of steps that we set the calculation. Has reduced the strength, but it's not really at the ultimate level yet? So we have to make sure that that happens, I will show. Later, how it works. If we are the state. Are a summer Jeff value or shear strength reduction factor? At this at this failure state that is what we assume to be the factor of safety on martial strength. So. Just running calculation getting summer value is not enough, you have to make sure that you reach a fully developed. I'm also going to show you this later in the demonstration. So I'm going to hear show this. I'm going to have a slope with a steep angle. So I'm going to share my screen with you. I'm going to go to screen #2. Here we are. Should be able to see my screen right now? Alright let's show area and I'm going to load the more that I already prepared for you so here we have a model. Here we have the slope where we want to calculate the factor of safety for without open Liberty or database. I have here he in this case, we use a simplified more column training material simply because we would just want to. Just the slope stability as I was just interested in strength today. We're not interested. Yet in deformations. The parameters and you can see we have a friction angle of 30 degrees. Show I'm going to generate a mesh footage and we're going to use a fine mesh. In the stage construction will start here by activating the Polygon here, so this is the soil block. I want to. Analyze the different boundary conditions here, you can see this here. These are. Correctly applied already so we don't have to do anything about that. The thing is because we using a non. Horizontal. Soul surface. In order to soil layers. I'm going to use the gravity, loading here, so we're going to use the gravity loading. So that we get a correct stretch tight with rotated stresses. Anna said before now on to assess the factor safety for this. State. An I'm going to hear. Is called? Factor of Safety. I'm going to start Hey safety calculation here. And you can see it's automatically started to incremental multipliers damage first point one. Some other settings here. But I'm going to do everything by default here, then we're going to calculate. Ahs maybe want to select some points for curves. As I said before this is important. And I'll show you later. Why this is important, but I'm going to ignore it for now. And we're going to run the calculation you can see the calculation starting. And we get a failure here. Initial face fills here, so we're going to open here phase window and here you can see what happens. Goat sounds with procedure. Phil error codes will not treat now if you have worse our previous special interest group. Video that we did in December. We talked about the error codes and how we can expect them so in this case. We're going to open the output program. So here we have the output program and we have to assess why the calculation filled. The calculation here, so we have to check of course, I default mesh maybe we also want to see. Incremental displacements here, so the agreement of displacements are to display things that happened in the last calculation step. Usually, when you are doing a plastic consultation type or dynamic type of calculation and interested in what kind of. Classic behavior you want to have seen in the last step usually that gives you a good indication or the failure. We can see here that we have a shallow slip surface. Also, if I look at the incremental strange here that the incremental shear strains in this case. You can see also here. Dagit develop ship service San Juan we look at the. Plastic points and we can also see, there's a lot of plasticity and even tension could've points so this gives a good indication where the ship services. Question is why this is it did it happen. So if we look at the interior parameters, so look at the material information for the more clump and we know that we have a? Friction angle of 30 degrees. Now, with this sleep steps surface actually what we're going to do, we're going to hear measure the? Slip service to see if we can find something here, so we just measured the. To wear so I just started here. This tool the ruler. Or the distance measurement tool actually you can click 2 points. Which I just did. Discuss window actual repeated again. So we just clicked this is measurement, which collect 2. Notes so he would do the one letter. Crashed and one here at 2. And actually what we see here is that from the original orientation. It's at 45 degrees and of course, when we use the friction angle of 30 degrees. Which will not? Well, not. Yep, this will not be a stable situation so we cannot calculate encryption for this so there's also one of the things that we cannot do with find elements. Because finally elements must. In order to have a converse calculation, we must have equilibrium in the calculation. So that's that is not something that we can do with find elements. We cannot calculate a factor of safety. Golden one. So, in this case with a steep slope we actually got failure with effective safety, which is blue one. How much how far below 1 we're not sure because we just cannot reach a converse calculation with the current star state. So we have to adjust the model if you want to calculate R factor of safety for this case. So, in this case, I'm going to adjust the model later with. And I'm going to double click here on the. As we want to adjust the pool and pool again just double click on the. Falling in the air and this point, I will move here from 2522. 1520. So here we are afternoon. Geometry of the calculation. Um. I'm also going to calculate here in the mesh generated mesh. Get about 4:00 and elements. And then we're going to run the calculation. And you can see here it's already quickly gives us like. Green check mark, which means digital first calculation now we can see the shade calculation running. And we also get a green check mark so let's go through the output and see what we can. Find out. And you can see, there's a different stressed out here. Let's go look at the incremental displacements. And you can see here we get. A nice sleep surface. Also looking at the incremental shear strength. We also gives us this. Ship service. Looking at plastic points you can see, there's a lot of plasticity even more than in the previous case. But you can see that there's a lot of plasticity developed here in the analysis. Because then we want to reduce this country reduce the strengthening calculation and then we're going to determine the. I'm just trying to Duction Factor. Then comes the problem how we're going to define the. How are you going to define the factor safety? First from notes before going to. Move on. Anne she hears the so we just did the natural slope. I would change the angle of slopes to calculate a factor. So if we want to do a calculation. We have to make sure that we choose control points inside the failure area. And with that, we can make sure that this point control points that we do that. They have a lot of deformation during the? Analysis such that we can see, there's uh. That. Development of our. Displacements. You can see here. On the left side we do not have enough load steps. We can see the line for the Displacement. First there's some MSF parameter. This is on the vertical axis so the strange reduction factor if it's still increasing while having deformations with means that we're not. Reach the complete Philly Management. If you look at the right hand side we have to add more load steps. And actually here, you can see, there's a fully developed. I'm fairly sure fish. An it goes we have a stable value for the stoners. FY ongoing deformations, which is a bit through definition. For a list of closest E. Then, some results in Czech we can use different Postal check the filling mechanism increment displacements, both in Irosin shadings. Our shelter shading so I'm going to show you the arrows. And also the incremental shares trains and also for that we can use shadings so it gives a good indication for the. So yeah, so back to the. Analysis that we did. I didn't select any control points. So 1st I'm going to do that, and then I'm going to read around the calculation. Had to start output using the select point for curves option here. And since I know that the slope here is going to move. I'm just going to deform I'm going to select for instance, here. Point on the Crest and maybe somewhere along the line for the slope. Choose update now let's run the calculation. You can see it's relatively quick quick quick, which is just about 1:50 elements. Johansson indication of the factor of safety and bought 1.5. So let's again go to the calculation results. Let's go half the incremental. Display Asians and I'm also showed him continue to shadings, but also can use the arrows. I can see the errors here. That there are actually. Move in a logical manner, so the arrows here, pointing downwards downwards slope, which is actually something that we would expect so that's That's a good thing looking at shadings. We have a better idea of the overall shape behavior, but with the errors. Cancel it a good indication of the direction. They should be 4 how to assess the final factor of safety. Let's start the curse manager. Go to start with their new curve. And for the X axis I'm going to use a? Friends are there? Crest of the slope using the. Total displacements and on the vertical axis from the project. I will choose the multiplier that some amaseffer so this is our. Strength reduction factor. I click OK and we can see a graph here. And you can see here we give them lots of deformations. I will come back what the absolute value of the deformation mean? Usually, we just interested in the incremental form of the displacements in a safety analysis. And we can see here is that we have. A plateau of our strength reduction factor and which is located around that way. If I hover over the points I can see it. It's 1.57 and if I go here it's 1.572. And there is 1.573 OR factor of safety in this case will be 1.57. 1.573 or 1.573, so this tour of the stable failure here. And actually here with the Orange. And the struggles the points with the Orange Circle around it deep is our maximum in the analysis. Which gives us here 1.573? So effective safety for this slope with this angle and this string parameters of the shore model gives us. Shows factor of safety. Of 1.573. So back to our presentation. Let's go to the. Next one. So we can also of course, improve our slope. In this case, I'm going to add a retaining wall first. We're going to do an elastic case for the analysis. Um so I just using elastic inelastic plate element. So I'm going to go back to my input program again. Here we are. And actually have to go back to structures mode. An let's draw, a new plate element, so here we have the plate element. And we're going to add here at halfway my slope just going to add a sheep wool. Um. At this location here in 2515. Then I'm going to make it. 10 meter, she bought 1 just is an example of how we can reinforce your. Slope I'm going to head. Interface around my plate elements. Of course I need to assign a material to my play times already prepared. A material data material set for my plate. Going to use the shower elastic so we have these parameters, it's elastic material. Uh with a Yi value here. EA value in EI value such that will give me a. The proper behavior for my she Powell. Show I'm going to apply it here. And you can see here we have a nice color. If I look at this selection Explorer. You can see it's being applied. Great one. Elastic material, the interfaces will take the. Strength brothers from the surrounding soil, which is the default setting. So let's again. That generate A mesh. So the calculation psychologist user medium mesh Oh it's a bit faster. Standing good stage construction. In this case, we started with the natural slope, but we have not installed. She thought well, yet so I'm going to insert this face and I'm going to call it install. She fell. OK. Should she fell over here? I'm going to activate it here. Together with the interfaces. And then I'm going to determine the fact of safety for this one since we regenerate the mesh. I also have to. Reselect my point for curves. I'm going to select altered. 2 point here. And I also want to select. Note here at the Top. It's update this one. And let's hit the calculate button. And you can see we get it already bit higher, effective safety is for every one point. 7. During calculation, which only let's go to the output program to see what we can learn from this analysis. You would expect we get a higher effective safety because also we put the shipper wall. Hum right through the uh original slip surface. Now, if we look at the default mesh you can see. Natural stuff going on, but it's killed up 5 times, so that still might be a bit over generated. So let's look at the incremental displacements. And you can see that the. Slip server is not. Along the entire length of the slope will just up until the part that we have the. Cheap bowl Also, if we look at the incremental strange. Incremental share strange we can also see this. Behavior Mikulski this might be some indication of a deeper slip surface, but it's not developed in the one here it's more critical and. That's what you get with him. Find the element. Shear strength reduction, you will get the most critical slip surface. So we took out through the plastic points. You can see, there's a lot of plasticity, but where we get the most deformations where we get the? Incremental displacements and we look at the arrows. We can see this behavior, so if you want to assess the. Hum. The graph we have to select the point here at the Crest. Simply because we get the most movements here. Let's make an you graph X axis we should. Select it. Crash point through this one is 1520. And we want to get the total deformations and here I got this project. Multiplier shop images. And you can see here we get also this behavior, but there's some more asymptotic as the one before this one was. Much clearer, but you can see here at the end, we will reach this stable value. Maximum indicates here it's located at one. For hover over it, it's just 1.877. So this is effective safety compared to our 1.57 from our. Case without the reinforcement. So if we look at the factor of safety if we go back to my presentation. And the screen share. So if we look at the factor of safety. The influence of all material behaviors, mostly for structural elements. We've done now, inelastic calculation. For the elastic. Uh played elements actually these effective safety is only based on the source strength, but as I will show you also here. Very excessive high structural forces. You might want to switch to an elastic plastic material. And here you might also see uh. Early structural failure. Which might even give you a lower factor of safety because we also going to limit the maximum? Force that can develop in our plate elements, so that means. More has to be taken by the disorder, which is not possible because it's in a failure state so it gives us? Lower factor of safety. Optionally, we can also reduce the strength over plates angers NGO grits by activating them from the. 40 safety reduction for strength reduction method. Will not do this in this example. I'll show you where you can do it at first go back to the. Analysis here. And I'm going to share my screen again. And here we are so this was the model that we had. So let's just. Select. Here are played elements I used to like structures. Double clicking on the plate element. It loads and you. Analysis an let's go look at the M can look at that information plus where the forces. We can see here are actual forces. They aren't that big it's My Internet really killed it in for meter. But if I look at the bending moments, we can see here we have 260 Q Newton. Need a permit out of plane. That might be too much depending on the cheaper award that you use? Ann. In this case. I have assumed that my sheep our maximum capacity will be around 155 kilometer. And you can see it overshoots this capacity, which might give a bit. A2 optimistic factor of safety because she clearly overshoot the capacity of the. She bowl So how can we do that, then outlook and we can we take that into account? So for that I created the shame cheaper war. Played data set but instead of having it. Elastic I changed it to elastic plastic. And in this case, I said here in the uh. Plastic bending moment, so this is the maximum bending moment, it can have. Uh. And also here we can do a? Actual force. Here we're going to limit that one. And well we can run the calculation of course, we have to change the material but in order to compare. I'm going to install. I'm going to add a new fail. Item here and let's call it install cheaper war elastic plastic. So I'll just search for my initial phase. So let's just activate everything here. And I'm also going to from the plate. I want to change the material so I can right click here. Change it here. Should I get my cheaper wall elastic plastic with my maximum plastic bending moment to Arthur 50 units medium? Let's change that one country, the color has changed. Anne also have to add a gnu. So let's call it factor of safety. A list of Classic. EP. And change it here to safety. Now I already selected my point recurs I didn't regenerate the mesh. I still have the same points. So we can just run the calculation for these additional. Phases. OK, I'm sort of calculation is done. Let's go to the output program. I have to select of course, the face on here. Few calculation results. Output programmers launched and here we can see. The results was interesting to see here we have a small. Bent in the She bought all the allocated for more rotating entirely, but here it looks to be. Having some kind of. National bending discrete bending air happening. So if we look at the deformation pattern. Look for incremental displacements and you can see here again. Finger shouldn't service bit up, but they also you can see, there's something happening here. If you look at the incremental shear strength. We can see also that we have more two of the two mechanisms, which are bit competing with each other. And if we look at the incremental displacements with the arrows. Conceded this ones who? Hum. The form in this direction, but also on the lower level, we can see also a bit higher deformation is happening. Looking at the plastic points. We can also see and we can still have a fully plastic zone around our she power. So, in this case the. The real slip sources in less it less clear. But you can see it's having. A deeper. Deeper slip surface happening in if we look at the plastic. And the plate deformations, and also also the actual force now, which is. As in the same range as the previous one bit lower actually but the bending moment there are different. You can see here, the maximum here is blower. Plastic maximum. Plastic bending moment are actually it's it's limited here at around the 55K Newton meters should actually you can see here. Now you can see here that this whole this area is in a plastic state. So you can see it reaches the maximum that we have here. Showed it also in the gifts is a plastic hinge basically in the analysis. I know if we look at the different eh. Factor of safety development, so let's select the same point again. Let's just deformations. Hence, some image F. And you can see we have. Basically took girls because we feel like this, it selects all my face. Uh Oh my calculation results for all my faces. So what I'm going to do here. I'm going to double click on the ledge and I'm going to. Change the curve here, I will do. Flight. Elastic and I'm going to select just the face to face select phases. I'm just going to select the. Tractor safety that we calculated for the elastic plate. Say OK. And I'm going to add a curve from the current project. An I'm going to select everything the same same point, saying some Amazon value on the vertical axis. But I'm going to select different phase so I'm going to disconnect everything just a factor shade for the elastic plate. Of course we have to rename this one, so we know what we're looking at so we call it. It left a plastic. Will apply but we can see? In the elastic case, we have a lot of deformations in the elastic plastic plate case, we have less deformations. And that's uh so we want to make sure that we can see everything clearly so I'm going to change the? Version 2X axis scaling. And I'm going to check the maximum 2 or what we say here. This is 5, so let's check. Like that one meter. Apply. And you can see here that's open tools shouldn't point to factor safety valve is the same as 'cause we didn't reach. Any persist in the blade yet, but from that point on, we can see here it gets from maximum. Of this in this case, the blue line indicates are elastic so it reached this higher value to 1.87. Well looking at the elastic plastic plate we can see that it, it gives a maximum of one point. So you can see, there's a clear difference when using when you overshooting your maximum capacity off your plate elements. That, it can make a difference in your factor of safety if you come too. Limit the maximum bending moment that you can develop in New York late elements. So that's one way to. To increase your soaps ability, but of course, we can also look and also do is that we use a different type of reinforcement. Rush loop going to back to the input program. And in this case, I'm going to remove all my. Phases. And I'm going to. Go at Show your nails. I'd go with the structures mode. I'm going to remove my plate element. And in this case what I want to do I just want to get the factor safety, but I'm going to use? In this case what I'm going to do, I'm going to stand by Dean Rd? And I'm going to add this here. Dish location here until 11. So here we have one then going to bed. Next one make sure that you want to make sure that you're actually on the edge of your Polygon. You can see it's all highlighting when you want to draw it. Did you hear shaped object is activated? But if I don't do it, you can see. I'm not sure exactly where I am it's snap to the grid that might also work should have to object. Indicates clearly that you. Control. Exactly snap on adjacent element. Discussion going to add it here at. 2714. And with the same angle and then I will get it. 17 nine So the user gives you my 2 embedded beam row elements, but you see here is that. Both of these developments that rigidly connected with the soil power if you do not apply any this is there. Richly connected with the end of the show, which is a bit if you just have so here without. Any special connection with there's not a structural element. In reality of course, yeah, you just have granular material, maybe around the end of your? Show new show, you might not want to connect it originally with you. Surrounding but in this case, we're going to send it to A. 3 connection type so. He also see it changes the. Icon for the connection point here, so we don't have any. Connection point here. How's it going to assign a material in this case to soil nails. If we look at the material properties. It gives us here. Uh stiffness parameter an? A weight in this case, I'm going to have steal soil nails with a. Diameter of 3.2 centimeters. How do we spaced? 1 meter Fortunately not out of plane direction. There will be space for me to report. In this case, I'm going to do the actual skin resistance with the linear this is just an upper limit. Of our shell shell nails. 'Cause I don't want to have the? Skin resistance be a limiting factor of the analysis. I just want to have the overall slope stability in this case. So let's go to the mesh. Generate the mesh. Generate the mesh here also going to select points for curves. Again, I'm going to select it. The point here, Anna Point along with slope depending on where we get the most information at the end. I'm going to select this. I'm going to install mine sure nails. OK. And activate them here, let's just simple's death. And the Next One I'm going to run a safety analysis, so I gotta go. Sexy with nails. Calculator diapers changed their safety and I'm going to leave the default settings here in this case. I watch the green ice. Let's compare the case also. Solar nails show him do Justin natural slope. It will strike from our initial stage retrieves gravity loading. And I'm going to use also in this case safety calculation. Now you can see we do 2 type of calculations taken after the initial fish they can re run independently. To make the cargo ship, it faster hold change the Microsoft course to 2, I have 6 cores in my machine. So that means. Once the initial phase is done their phase one and Phase 3 can start simultaneously so that will speed up the calculation in a little bit. So just hit calculating the calculation will start you can see here. Safety with nails and the natural slope. You can see, there done at the same time, so this one we limited number of course, we can. Have this inference. OK, so let's go look at the output safety, with nails. And you can see here our information pattern, and you can see that clearly, the soil, not have an influence in the? Department of there. Slip surface so let's look at the incremental displacements. And you can see here that the limited and you can see the limiting. Analysis is done here also have a look at the incremental shear strength. We're going to see here that the critical slip services here located at the bottom point. So if you want to maybe increase it. You might want to change the location of the showing nails a little bit. Maybe a bit good place, the bit lower along the slope and it will maybe improve this so we can also play with with. Optimizing the location of the solar nails. So let's look at the uh. Our curve developments show. Good thing I selected the? Points in the middle of along the slope so not check also. Deformations here and use the multiplier something Jeff. So we should have 2 lines. Well, you can see here this line here and also wanna hear the Top which has a very low. Information but you can see the one here is very, very large. So I'm going to do here just E. Safety with nails. So let's see. Quit nails. And I'm going to add the same curve. Amplichip default select the previous selected one so that's easy you can just had one change the faces I'm going to. So this one. Say OK. And I say without nails. Go to chart an change again, the scaling here so that maybe 2. 2. Let's see how it looks like maybe should be sure to 5 is here. It's still with increasing in this direction. I said the five apply OK. And you can see here is that without nails, which the UM. The red line here. It gives us our 1.54. Value while the other one here, which way to nails gives us a much higher value still relegated one point. 8 eight 1.87. So you can see that then I don't even have my transmitter reached so we might want to. Set the match made tell me to see in this case. And you can see here that having a Family, which fluctuates around this 1.888 point, 1.89 this will be our value, you might want to. Add more calculation steps here to make sure we get the fully stable for stable. Value for our effective safety. So this would give us another option to reinforce harsh are slope, so get a higher factor safety by. Applying reinforcements. And so that's what I've done it's done showed you improve the slope so we can add retaining wall to do. Elastic plastic with these Elasto plastic material, which you see that you get a lower factor of safety. If the failure surface influence is influenced by the maximum. Allowable force in or Please element. Or if we can apply soil nailing of course, which also gives us a quick we can also influence the slip surface so make sure that you. Apply your nails that go through your sleep shifts otherwise of course, they don't have any there's no meaning. I said something about the safety Oz Anarde formations. If you look at the safety analysis, the absolute deformation do not have a real physical, meaning an we. Artificially reduce the strength to get a sense of what's the factor shady force or strength. A look at the absolute information they don't have any physical, meaning were more interested in the incremental deformations an incremental shear strength. In the final step when we reach a stable summer Jeff. Because this will indicate are likely filling mechanism. So if you look at the stretch point level, so this is the. But where we calculated stresses and strains for every stress point in the analysis. And we might be at this state actually yeah, you can see will reach the maximum strength for this. For the stress point and actually we what we want to do, we want to. Produce the strength that we do apply strength reduction. Which means it has to follow this blue line? And also this means we've lowered the we have to readjust the stretches because we it's not allowed to have a stress that which is? Outside the maximum capacity of the soil, so we have to reduce the stress and distress point by doing so, we have to redistribute stresses. Over 2 adjacent stretch points. But if we look at just this point this is what's happening there. In the next step. We want to do string conduction, even more answer. It means we increase the some Amazon value. And we get the screen line. And you can see also we get a bit more of the. A bit more of strange just by reducing the strength because we have to. Adjust the distressed state spend whether we should we have to reduce to stress is and by doing so. We get strange. And this and this leads to deformations in the model. And we're going to try to reduce the strength even more. We might even see more and more strains, so that means we have the ability to through. We get more and more information and that's why absolute. The information do not have a physical meaning in your safety analysis. Not only mark when using underlying type of laundry and type of calculation if you use undrained behavior that means using 108? Or we can develop accessport pressures. And by default, the safety now is will generate accessport pressures. So that means when we get a deformation behavior to the underlying behavior we generate accessport questions. If you do not want to include that and it's up to you to decide if you want to include. The additional development of the untrained show behavior. We can use the option choose ignorant behavior to avoid this. And in typical cases, but it's not always the case when you use ignore under behavior. If you have a loading tab from friends embankment or the slope it. We show this in this case, we get a higher factor of safety. If we're going to ignore Andre behavior. If you have unloading that from she could think of an excavation mate only problem maybe. If you do and. If you're going to ignore additional undrained behavior so no additional. Accessible pressure developments, we get the lower factor of safety. Hum. Traditional duplication in general, if you're not sure I would recommend just run. Both you can run them relatively quickly. Quickly, in this case, we run to safety analysis in less than a minute. So. You can quickly run both cases to see which one is critical in which you think is most valid for the. Did they announce that you're doing right now? One important note here. If you have the latency in your model this could lead to very high factor safety. If you do and undrained calculation. Ann you're going to allow the development access for pressures and you have the latency in your model. Please set them to 0 just for the safety analysis make a copy of the material. Uh. Apply a 0 delay to see angle and then apply Dustin in the safety analysis. To make sure that you do not have an overestimate because ever going to share the model with the latency. It will make the volume change the volume changed not allowed when you have ignore everyone have under control behavior should it means you are. Your answer for British growth change and usually it needs to add in order to hold it together, it will develop. Access point tension and that will lead to higher. Affective stretches and of course, when you have a friction angle whenever higher stresses you also have higher strength. So, in that case, it will lead to very high factor safety so do try to avoid not to let. What are the benefits of using fired element compared to automatics? If usually you start with the formation analysis and this gives us already a stress distribution. This is the one we used. Strength reduction methadone. So. It covered which states construction it gives us our historical stress path so that the mission would not have. Maybe of the conversation into account, but also we can include the behavior of time dependent process like consultation. Mention groundwater flow in which the slash path is also changed by in time. So I think I'll collision gives us the most critical failure mechanism, so you do not have to choose your. Great and radius 40 for maybe shirtless lip service flexible just give the most critical failure mechanism and it could be circular. But if you have, maybe some weekly Asian between it might find a sleep shirt, which has also ellipsoid. Type of shape or different type of shape and. Non circle shape could also happen just gives you the most critical failure mechanism. Now, if we look beyond the safety analysis safety houses only giving us an evaluation of the ultimate strength. It doesn't include any performance criteria of the Geo structure. We saw that we get a lot of deformations. Using these the Safety analysis. I am because you don't have an absolute meaning. But you might have performance criteria for you, you cheer structure. If using design approaches that you can apply partial factor so you can use for instance. Eurocat Chevron withdrawn approach 3, we can apply partial factors and based on the partial facts we can also. See in the output limit state what the performance of it, you structure shaded you have building on Top of our slope. We might have you might want to see what the rotation of the building will be when you apply the? Ultimately, which state so we can also do that usually find out method, we can. Apply partial factors we get deformation based criteria for your safety assessment and it's not safety analysis, but these are safeties freshmans based. So should we limit state in hard limit state. And we can chat using design approaches. So summarizing the Presentation here today after that, we can go to the questions already a few questions so that's good. The factor safety in Plex. This is fashion factor of safety of source strength. Uh so this might be different. Bit different from might be different with your local practice make sure that you use the same types definition for safety. When you run a calculation make sure you sufficient number of load steps. Please make a curve in output do not just read value, but pretty. Read the curve from some MSF urges displacements that will give you good indication if you get a fully developed. So mechanism and then you can say it's a factor of safety. Also highlighted a bit the influence of the under in behavior and also the structural behavior. If you have to choose elastic way. Let's do plastic. So if you're up slip service influenced by your structure elements make sure that you do not overshoot. The capacity of your structure elements. That can have magnificent influence on your factor of safety in this case simplified case that we have here we went from 1.87 to 1.8. Depending on The UM criteria for the factor safety this might be critical for analysis. An R safety calculation will find the most critical failure mechanism, so that's one of the benefits using fine. Forgot to questions here watching references you should also find them in the resources attached to this. Is a webinar? So we have to the original paper on the only fire damage analysis of safety factors. It's paper from. Brinkley Van Barker. You can find it here on R Bentley Geotechnical Bentley communities wiki and you can find the link here. It'll ruin your resources. There are also other wiki resources, so safety, Nelson displacements safety analysis in 100 and behavior. Uh if you updated mesh how does it influence your safety analysis? We can also go clear say things up onto a target value so you might not want to get the ultimate. Effective safety, but they want to assess the model when you for instance, reduce strength with a factor of 1.2. We can set the target value if you also use that one. And some notes on selecting point for cursor? How does implies? How does it work out so bunch of hints are? In this article. Interested in more. And the month, we have our standard course on computational geotechnics, so we go into plexus. The backgrounds of taxes and how you can. Uh. Use. You're just taking knowledge into using file down calculation numerical methods using plexus. Uh next month, will do another shake onshore parameters how we can use or lab testing in practice. To enter February, also have a workshop on fight and an automation for blacklist. And in March with the advanced course fold by a special course, so we have a two day. Dynamics in seismic geotechnical engineering workshop. I'll show all local here, Nedlands John to register for this, if you go to plex.com/events. You can have the? Uh the question workshop for any online events. Please refer to the Bentley pages or if you signed up for the newsletter. You also receive it in my email. So it's time for questions if you're interested in getting more information or see what you can do with. Flexus, please indicate that you want to be contacted with. One of our sales representatives. So let's go to the question and there are a bunch of questions here. About the sound so I'm going to. She does want here. Eugenia is the question uhm. He mentioned it to the original's natural slope that we calculated that he gets the factor safety without design combination. Indeed, it's just. The raw input that we did on the material. Without any uhm. Without any design combination or design approach or your code 7. It's just the the input params that we told to date with krstic failures. So we didn't apply any partial factors from that one. So I hope that answers that question. Sharon asked questions his remark the filters changed side of the ship was installed in the upper part of the slope. I'm so let's go back to the model. I think I've shaved it. Travel mentioned it. In touch with. Here and then I'll make it tomorrow. So this is the model that we had before. So struggle measure if we move this point here to let's say. To hear that. This location, which is. 2117 trucks change it to 2117. I should say. 1720. Hello. I should change it as share my screen so you can also see what I'm doing. So the question was if I change. This location and maybe I change location here to this location, which is located at. 2117. So I change the first point here chains X2 twenty one and the white 17. Of course, also need to change this location to 27. And do it, too. 721 is the location of course, drinking. So again with vertical wall. Let's run around it. Mesh. Sage construction and Let's calculated. Honda after question where we can find this recording the recording if you have the email. It will available through your personal link. So we can just uh recording would probably online later today but for sure. Tomorrow then you can just. Via your link you can just assess this one. Directly. So let's see. Adele collision results in indeed if so in the previous case, we had to slip surface. And the upper part of the slope, but you can see here looking at the incremental share strange. Or my English displacements. 30. Slip surface has changed locations now at the lower part so you can hear with this influence this result. Also, when we don't have any point selected. Hello. Let's look at. In theory, information, we just get a look at the calculation results. In my shaman Jeff here at the final 1.7. 1. Which is a bit lower than the one that we had before which will triplicate on .8? But it might be that we do not have enough load steps here, so I cannot really say what the final factor. But you can see that the factor of safety slip service here is changing from the upper lip service. The lower lip service. That's the question from Sherman. Why you so are the question why? Is there an interface for the soil nail now if we look at? The definition of the MLB MRO embedded beam rule has an implicit definition of the interface so with the. Hum. With the interface we can clearly see that the. So we've been rolled there's an implicit definition of the. Interface so there's no need to add an additional individuals have 2 interfaces. Which of course not realistic, so far. Embedded beam rush there's an implicit definition of the. It was definitely interface you can assess the results by using at the skin friction in the final results because there we go collect the maximum skin resistance. And maximum skin friction along the embedded beam rule. So I hope that answers there. Question. Uh my tablet after question for the first example instead of gravity, which came up with some additional steps do, we have same factor safety? That's a very good question. Somebody asked OK if we do first day, not procedure and then we do a. Plastic new step. To get the care they corrected. Stress state do we also get the same factor of safety for the slope so let's? To that I'm going through? Remove this one. And uh in this case, it's Delete this one slipped and. Delete. There's an initial face an effective safety first used gravity loading in Spanish. This one crafty loading. Let's calculate this one. So the question is Why? When should you do this. This is very good question because. You must make sure that always you, however, correct stress state when you slide your analysis, he usually not procedure. When you have not heard of the short layers and the cleanup procedure just looks at vertical the weight of soil. Vertically above stretch point and then applies today, not procedure so you just get Sigma One, an SQL 2R. Aligned with the Cartesian Axis while in reality, if you have a slope you will have rotated stresses there. Um. This was the selected point for curves of course, which I forgot. Let's quickly that and the one is located here. Re run the calculation. Answer 1.56 for this match configuration. Just look at the results. Let's go get this they will factor of safety. Around. Curse. Another new chart uh that's cool. Deformation OFT. Crash point and some Jeff. When you can see it gives factor of one point. 56 show, let's do the one with the suggested with a K not procedure have to. Include this one. I do a initial face. OK, not procedure, I entered a new phase here in between. Which is to face one and then we'll say? I just called the new step basically we don't do anything but we just make sure that. Uh the whole model gets calculated equilibrium, it means if you have a slope. It it will have a stress redistribution. How much will show you that in the results? And then we calculate effective safety. Let's go play this one. OK, we are. And let's look at the calculation results. Used output program. And because you have the same slip surface here and if we look at. Deformation. God deformations. Jeff. And you can see here it's 1.56. So this is the same value as we get with the gravity loading. One issue do you use? What that depends a bit on the configuration that you have if you need to take into account? Mace Oracle data fringe of consolidation ratio cannot procedure. Can can deal with consolidation ratios so you can input OCR or TRP to calculate your free consultation stretch? The user gravity, lowering it will always be in a normal solid state in this case you use the? We used the more color model, so it doesn't really make a difference. Because it doesn't take any of conservation into account. Uh and something I said about. Stress state so if we look at the effective principles stresses. And let's go to the. Initial face. You can see that there. We just have a signal one is look at his oriented vertically and horizontally we have. Shake my tree or check my jacks, but you can see it is also the case around sold servers will actually would. Expect the rotate it stresses. Should we go to go little step were actually recalculate equilibrium you can see, there's a stress rotation here? So again stress rotation. Based on the highest dresses here on the left side compared to the right side. So this gives us the same value when used more column and you just use the the the. But you just use the crafty loading or just the natural slopes only calculate the factor safety without any. Additional analysis if you do something else make sure that you start from an equilibrium state so if you cannot procedure. With this kind of situation run the plastic nail step and check your stresses after this note that 'cause That's essential. In this case make sure that that is what you expect. So I hope this answers your question. We have here a question from Sherborn regarding the latency. It would be nice for the user to choose to ignore it when performing safety analysis. Uh that's a very good point that you would be a nice way to automatically ignore it, so it will be. Is it too? She wrote, I will write it down that might be a good conditional improvements for the future. Picture. Ignore. The latency. Angle. When running. Safety analysis. Not sure how feasible disease, but I will make sure that it will be added auto on the wish list. Question here how to model solo as attention only member so if you want to only include tension in the model. Um let's go here. Trying this case. When you use a bed, bro? Fresh ideas. We have interaction with the surrounding soil completely. So it also have a sheer resistance if you do not want to have that. Yeah, you might want to include a? Delta knows anchorhead alternate anchor his just he taken just have tension along here without any shear. Um. But of course, we might get a point of singularity here any as well so that might not be the best option you might want to limit the? Maximum lateral 40 or maybe um. Yeah, it's been. Limiting their natural skin resistance to a very low values that will only be on tension. Have you got any ask the question is it disco only possible for more column or going to be used for an art. The safety analysis method is going to use for any type of material that we have in the plastic. Azure Standard Lexus showing model. So we can use it for more column of course, we cannot use it for linear lastic because does. It doesn't have any strength criteria between usually for more column pilings or a small software social creep. Concrete you push and so with all these methods. We can calculate this, who Brown. Even so, the loop around doesn't use the? Friction angle cohesion as strengthened area, but we have a special implementation at all says reduced the strength of the hook. Joseph Canfield ask questions for the for the safety analysis, using his strength reduction factor? Why are cohesion and? Angle friction reduced at the same rate? Um. Very valid question it was chosen to use. This at the reduced at the same rate so we just have the go back to the slides. Let's see if I can still find here. So if you look at the safety analysis in plexus what we do by reducing the cohesion, an friction angle. Attention of the fictional at the same rate actually we will keep the apex point at the same location. So that's the reason why this is done so we just do a rotation off. Of this line. Search that it will be reduced. Should we don't change this apex plantation? We don't change that so that's the reason why it's? Ram reduced at the same rate? OK, back to the questions. Why you should ask question but the push factors in your question for giant poach one? She wanted and which ones. He threw his ultimate limited with respect, said it should be sure stability limit state. This is how you apply your factor safety so how you assess the safety. Nelson should make sure that you put in a consistent manner. What I've shown here is just based on the karasick values we see what the factor safety is if you also have to apply according to a design approach. Um. And you want to apply partial factors. Dairy uhm this is not exactly the same as using a safety analysis safety analysis is just a measure. Of the German factor of safety for your soil so you have to make sure that you put in it. Right in the correct concept also may be on there. And our website. There's a link out fine it here for you. Here is Vapor. Where we get more in detail of using the design approaches? Everybody should find the link here in the link to the paper. So that should help you get that done. Does the mesh course find verifying affect effectively? Yes. So somebody else here if the mass size has an influence? Yes, as anything in our find element calculation if you choose the mesh to be too coarse. Actually, uh you cannot sort of really capture the all the stress gradients that you have in the model. Junk food that we have to make sure that we have the. Do you have a sufficiently fine mesh so we've done a few studies on measurements there so we reach? We can reach a? Um. I should amount off. Effective safety and when we refine it, it might be a bit lower, so if you have a 2 course it might. Predict the factor of safety, sometimes just have to see if I come to change this a little bit. Does it matter? And if not, then you're good if it changes a lot then you have to refine it, a bit more. And make sure that you refine it, in the area where you see this lip service happening now. You don't have to refund the entire model. Otherwise, the calculation time will probably increase. A lot, but you can also just refine the zone where the fact where the slip shows happening in that will help you too. Get a better and more accurate answer. Or some other ask the question can, we model using limit equilibrium methods. Nothing flexes we'd find download methods. We cannot include their limited limited, if we do have a Corporation with another Bentley Product, which is actually slope. Just roll vision as we slow. Where we can calculate limit equilibrium at it's an working on making full integration in our latest version way? Import already. Uh actually slope models into plexus with working on better and better integration so we can also use flexes. To use it as a basis for Linda equilibrium methods. You do need ask the question sometimes disarms FL is less than one? What does it mean if the? Someone had failures less than one in your final in safety analysis, it means that probably. This state this the face before your safety analysis. It has a such a It's so close to failure what might be just on the edge of failure. Should you have a unstable equilibrium? And that means that with when you just construct the safety answers, then factor is less than 1 doesn't happen that often. It could happen, but it means that your face before is already very close to failure for that you can finish look at the. Uh the current status parameters. CHP parameter value that is probably also very low incomes look at incremental. Deformations inventor share strange to see what the factors are the scriptures is already happening it could be that it just. Gets into an unstable. Equilibrium. Comfort and ask the question is there anyway for safety answer for seismic case that's a very tricky case. If you do a seismic analysis if you serve static analysis. Yes, we can definitely do that, if you do seismic. Analysis in which we have baby ski applier fully dynamic calculation using earthquake signal with. Death we have stretches that vary in time. But we also philosophers and accelerations. The fact of safety crap. Circulation that we do is a static calculation, so we do not include inertia floors next generations in equilibrium state. For a safety analysis, so it cannot be directly be done using this type of answers for fully dynamic. Using static analysis, yes, we can do that. Uh share and ask the question regarding the Delage and could be a work around to use design approach. Introduce it almost legitimate forming safety analysis. Yes, you can do that, so the question is using design approaches. Can reduce it to nearly 0 such that it doesn't have any influence on the safety analysis? Yes, you can do that, but I'm not sure uhm. Yeah, it's a work around probably it's still simply to make a quick copy of the of the material. Apply. A0 deleted the ankle in a copy of the material. But it can be done. Uh. Groups would ask the question will the wiki on Bentley side replace an old based on the plexus website. Yes, we're working on a full migration of all the knowledge that we have from our lectures website and apply. Content it will all go into the Bentley communities wiki. Uh. Currently we are making copies of all the material and think 99% is already done so we can find them both locations. Updates on all content will be done on Bentley communities so please look at Bentley communities for any updates on materials. Also, if you look at the still sharing my screen. Also, if you look at the NYU. Layout of the latest patches version and we can see the familiar options as the Start Options, an recent projects. We added here and there. Our view of all our licenses, so if there blue their lives are activated if there read the latest are disabled. After the also gives you a good indication, which places are enabled on your system. But we also edit here a new item so if we update anything on our Bentley communities wiki you should see update here. In the news item. Yeah, we can see the release notes and also we published a paper on a new new technology preview feature. In our latest edition, which is the Westergaard added Marsh, so we can also include initial for water bodies. Into your Fully dynamic case. I'm at ask the question has the choice of the location at that point for safety graph effect on value for. Safety factor. Um so if we go back to the. Audience here. So here we have the uh. Screen for which control points to choose make sure that you select the control point inside the. Slip sure because there we can see, there, we have significant displacements, which help you to assess the factor of safety. In the graph. However, the factor of safety is a model factor so all materials and if you include the structure elements. All of those structural materials those for those strength will be reduced. Showed the final factor safety will not be influenced by your control point and of course, choosing appointed monitor should not. Influenced result so this over the case here, but only a session related results in the graph will be more difficult. Show me ask the question how does strange addiction routine work with the concrete model compared to a more common model? So what happens there are a few string theory in the concrete model. We will apply to save reduction factor on those strength catiria. Richard can ask the question is platters good to model sliding along a plane so rock joints, yeah, we've done. Few studies here with discrete rock joints. And we can use interface elements for those an with interface elements. You apply their strength that you want to have. In your rock joint and then you have fewer than you can just have your own joint there. If for instance, you have not so unique. Rock joint in model you can information also use the joint Brock model, then we can also. For every sliding plane direction, we can also have the strength reduced. So we can also use that one, yeah, you're right. And so I wanna ask the question for phase with a factory Florida. One is it a permanent permanent approach to reduce the incremental. Sean Jeff from .1, two .01. Um effective safety get slower than one so you summers ever again slower than one, yeah, you can try to. Change this parameter from incremental value from .1 to .01. But from my own experience. Most of the Times the. The face before. The from the nerves that you for setting answers. That's already just on the edge of. A failure such that it. This doesn't really make much difference. Um. Sometimes it helps to actually do plastic nails that before your. For your safety analysis, so and so we insert the face just before you safety answers through plastic nail step. Because sometimes there's still some out of balance left there because we can split error of 1%. It could be that if there's some kind of very small local inaccuracy that this has an influence, but Most of the Times doesn't really help, and usually you're looking for a factor of safety for 1.2. This doesn't really make much difference. OK, I think I have seen all questions and all the questions are. Answered um so I want to thank you for your time here. The recording should be available through your personal link in. Later today at least lay this week, it will be for sure available, so he can then you can watch it on the month. And then I want to thank you for your time and I hope to see you in one of our next special interest group workshops. So thank you and goodbye.

This Geotechnical Analysis Special Interest Group virtual workshop guides engineering professionals in the use of PLAXIS, and the strength reduction method (or phi/c reduction method), to calculate factors of safety which determine soil strength as well as stability of slopes and embankments.

You will learn how to:

- Use the Safety analysis with the phi/c reduction method
- Assess the Factors of Safety
- Inspect the failure mechanism in PLAXIS Output

***The webcast will be streamed through your computer, so there is no dial-in number. Please make sure your computer speakers (or headset) are turned on and the volume is set to an audible level so you can hear the presenters. #EVENTHELPURL#*