Problem when using Rinter = 0.01 - 0.05

Question

Greeting for everyone, 
 
 I use Plaxis 3D to simulate deep excavation using Butress wall and Cross wall. However, when I activate interface in the early phase (using very small Rinter value), the severe divergence occurs in the output results. Is there any ways to encounter this problem? Thanks in advanced.

Dennis Waterman · Accepted Answer

Hi, 
 Please note that when using Rinter, this will reduce the strength of the interface with Rinter, but the stiffness of the interface will be reduced with (Rinter)^2. So when using Rinter = 0.01 you will actually reduce your interface stiffness with 0.0001 .... And this is probably the cause of your problems. The solution is to create a separate material set for your interfaces in which you either 
 
 manually specify c, phi and stiffness and keep Rinter = 1, 
 specify Rinter = 0.01 and c and phi as in the soil, but increase the stiffness with a factor 100 or 1000 or so to compensate for the quadratic reduction due to Rinter. 
 
 With kind regards, 
 Dennis Waterman

Ari Surya Abdi · Answer

You can try to simplify the model (either geometry or soil cluster) to check if the problem is due to the complex model. 
 Moreover, since you are modeling the retaining wall, butress wall, and cross wall using plate element, you might need to select &ldquo;prevent punching&rdquo; t o provide some vertical end bearing (tip resistance) to encounter the problem when activating the interfaces with low Rinter value. For further information regarding this option, you can read though Reference manual.

Problem when using Rinter = 0.01 - 0.05

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