Probabilistic Analyses of a Post-Grouted Anchor–Soil Bond Friction Performance Considering the Geological Origin and the SPT-N Tendency with Depth

Abstract

This paper presents a probabilistic study of anchor–soil bond stress performance in a post-grouted anchor wall. The variability of geotechnical shear strength parameters will be described by a probability density function (PDF) and as a linear and squared shear strength function with depth based on widely available standard penetration test (SPT) data on two geologies (mudflows and residual soils). Monte Carlo simulation was carried out to evaluate the mean and standard deviation of ultimate anchor strength. The study allows the factor of safety (FS) to be determined to achieve a target probability of failure (pf). The first analyses consist of a probabilistic analysis without considering the shear strength varying with depth (SSVD), while the second one includes SSVD. Probabilistic analyses (without SSVD) show that a reduction of the pf depends only on the design FS. The probabilistic SSVD analyses showed that the N-value at the surface (N0), and the function gradient (ρ) had an important influence on the anchor pf. It is shown that the use of an overall FS can be considered as a high-risk design for soils with a high N0 variability and low ρ. Therefore, the target pf shows that the top anchors are the most critical, so higher FS values are required (FS > 2.5), especially for mudflow soils.