Hi all and Dennis Waterman Rushan Gizzatullin
For the embedded beam row, we have provided skin resistance value in the material data set as kN/m based on the length of the pile. Embedded beam row is connected with soil using springs with axial, lateral and base resistance factors.
I have provided linear start 0 and 200 kN/m at then end for the skin resistance with zero weight of the pile and out plane spacing is 1.5m , i got max skin as 133.3 kN/m/m ( which is 133.3*1.5 => nearly 200 kN.m)
Let's consider the case this pile in cohesionless soil with length less than the critical depth of the pile, we have used A ks σv tan(δ) to calculate the skin friction where A is the surface area, ks is the factor depending on pile material , σv is the average vertical stress and tanδ is the friction angle between soil and pile. In plaxis 2D skin resistance is kN/m (per length) so we need to multiply only by the perimeter in that equation and provide the value.
My question is here we have ks and tan(δ) value which is depend on the soil pile interaction so if we provide the value for skin resistance P δv in the above equation (where P is the perimeter) is correct or do we need to multiply by ks and tan(δ) and then provide the value? i thought since there is the interaction factor between pile and soil this value would be covered by that factor.
I hope you understand my question. If so plz reply.
Thanks.
You can set beam resistance with subsoil conditions where soil strength and Rinter at the interface are already defined in. Because embedded beam is superimposed in the mesh, you need to multiply by ks, tan when setting the resistance manually. I think so.
Mr. Vu,
Thanks for the reply, we can provide the ks as it varies with the material which the software not know. but resistance can be calculated by the program am i correct ?
Yes, skin resistance is to define vertical spring of the beam. One paper from WB was validated for bored pile response well in vertical, but there’s still some limitations of embedded beam row for a particular case..
Can you please tell how do you calculate the resistance (skin and base) and input in plaxis 2D beam embedded row ?
Dear Mr. Vu Ngo,
This ks tan values are depend on the input option we have used in embedded beam. There are 3 input options for shaft resistance namely linear , multi-linear and layer dependent. First 2 cases we need to input the values by multiplying ks tan whatever, no need to consider about the interface values as it depend on the deformation of the pile until soil reach the shear strength (did some analyses by changing the interface values and results showed that vast change in the deformation).
in the third case (layer dependent) option when selecting the resistance ks and other values need to be considered because Rinter (of the soil) going to influence in the shaft resistance of the embedded beam row. Here i don't understand why Rinter is used out of the tan term in reduced friction angle as we normally using reduced friction angle and taking tan of it.
correct me if i'm wrong.
your comment please.