Estimating the properties of weathered bedrock and pilerock interaction from the geological strength index

Abstract

The effect of variable rock mass properties on pile-rock interaction poses a great challenge to the design of stabilizing piles and numerical analysis of pile-rock interaction. The paper presents a novel method to estimate the properties of weathered bedrock, which can be applied to routine design of landslide-stabilizing piles for collivial landslides. The Ercengyan landslide located in the Three Gorges Reservoir, China, is the area of interest for this study. A geological investigation and triaxial tests were conducted to estimate the basic parameters, including Geological Strength Index (GSI), uniaxial compressive strength sigma(ci) and Hoek-Brown constant m (i) of intact bedrock in the study area. Hoek-Brown criterion was used to estimate mechanical properties of the weathered rock, including elastic modulus E (m) , cohesion c, friction angle I broken vertical bar, and normal ultimate lateral resistance p (max) . A parametric study was performed to evaluate the effect of parameterizations of GSI, sigma(ci) and m (i) on the bedrock properties and p-y curves. The estimated rock mass properties were used with PLAXIS 2D software to simulate pile-rock interaction. Effect of GSI on stress at the pile-rock interface and in the rock, pile bending moment, pile shear force, and p-y curve were analysed.