1) The document discusses numerical modelling of boulderly soil, which contains rocks and gravel within a clay matrix, using finite element analysis to determine soil parameters for slope stability analysis. 2) It describes conducting triaxial simulation tests in finite element models to observe how the shear strength of boulderly soil increases as the rock and gravel content rises. 3) The results from the numerical modelling are then used to calculate cohesion and friction angle values under the Mohr-Coulomb model and analyze the stability of boulderly soil slopes, finding that realistic rock modelling shows non-circular sliding planes compared to using combined parameters.

1. NUMERICAL MODELLING OF BOULDERLY SOIL USING FINITE ELEMENT
FOR SLOPE STABILITY ANALYSIS
Sugianto, A.1
, Rahardjo, P.P.2
ABSTRACT: Slope stability in common practice is conducted in homogenous soil or rock material, especially in
Indonesia. For homogenous soil, design parameters are obtained by soil investigation and laboratory test. In case
the materials are dominantly consists of heterogenous material which is defined as boulderly soil, the soil
sampling will be difficult. Finite element modelling is powerful to determine characteristic of boulderly soil by
making triaxial simulation test with incremental rock/gravel toward clay. It is found that shear strength of
boulderly soil will higher along with increasing of rock/gravel content. From the numerical results, it will serve
stress-strain characteristic of boulderly soil then calculate the cohesion and friction angle under Mohr-Coulomb
model by GTS Midas. As a result, the strength parameters are implemented to analyze the slope stability in
boulderly soil slope cutting. Sliding plane are compared between boulderly soil with combination parameters
which is obtained from numerical modelling with realistic rock modelling in Plaxis 2D. Realistic rock modelling
shows sliding plane is influenced by rock material and not defined as circular sliding plane which is shown when
using combination parameters from numerical simulations.
Keywords: Slope stability, Boulderly soil, Triaxial simulation test, Mohr-Coulomb Model, Sliding plane
1
PT. GEC, Bandung, currently M.T. student at Parahyangan Catholic University, email: andysugianto.sorong@gmail.com
2
Professor, Parahyangan Catholic University, Jl. Ciumbuleuit No. 94, Bandung, Indonesia