基于SRM法的直剪作用下不同随机节理倾角岩体尺寸效应研究

Study of the size effect of rock mass with different random joint dip angles under direct shear based on the SRM method

摘要

【目的】旨在揭示不同倾角区间的随机节理对岩体破坏特征、抗剪强度和剪切模量尺寸效应的影响规律。【方法】利用PFC^2D离散元软件的SRM技术，结合分形理论和Monte Carlo方法，对不同尺寸、内嵌随机节理的类岩体进行数值模拟直剪试验。【结果】结果表明：(1)岩体抗剪强度随内嵌随机节理倾角区间的增大均呈现“S”型非线性特征，且最小值多出现在15°~30°区间，最大值均在60°~75°区间。(2)不同尺寸的内嵌随机节理倾角区间变化对岩体破坏影响效果相似。低倾角区间出现明显的优势破坏面和次优势破坏面，随着倾角区间增大，其应力集中发生向节理中部转移，两优势破坏面的优势发生转换。(3)随机节理倾角区间变化显著影响岩体抗剪强度和剪切模量的尺寸效应，且对岩体抗剪强度尺寸效应的影响大于对剪切模量尺寸效应的影响。【结论】研究了相同尺寸条件下内嵌随机节理倾角区间变化对节理岩体抗剪强度及破坏特征的影响和不同尺寸条件下内嵌随机节理倾角区间变化对节理岩体抗剪强度和剪切模量尺寸效应的影响，为岩体力学性质的预测和工程应用提供了重要的参考价值。

Abstract

[Objective] Aiming at revealing the patterns of influence that random joints within different dip angle intervals have on the failure characteristics, shear strength, and size effect of the shear modulus of rock masses, [Methods] the SRM technology in PFC^2D discrete element software is used combined with fractal theory and the Monte Carlo method, and numerical simulation of direct shear tests is conducted on rock-like materials of various sizes with embedded random joints.[Results] The result indicate that:(1) The shear strength of the rock body shows “S”-type nonlinear characteristics with the increase of the inclination angle of embedded random joints, and the minimum value mostly occurs in the interval of 15°~30°, and the maximum value is in the interval of 60°~75°.(2) Different sizes of embedded random joints have similar effects on the damage of the rock mass by the change of inclination intervals. The low inclination interval shows obvious dominant and subdominant damage surfaces, and as the inclination interval increases, the stress concentration is shifted to the middle of the joints, and the dominance of the two dominant damage surfaces is switched.(3) The variation of random joint dip intervals significantly affects the size effects of rock shear strength and shear modulus, and the effect on the size effect of rock shear strength is greater than the effect on the size effect of shear modulus.[Conclusion] The study investigates the impact of variations in the embedded random joint dip angle intervals on the shear strength and failure characteristics of jointed rock masses under the same size conditions, as well as the influence of variations in the embedded random joint dip angle intervals on the shear strength and the size effect of the shear modulus of jointed rock masses under different size conditions. It provides significant reference value for the prediction of rock mechanical properties and their engineering applications.

关键词

SRM法 / PFC / 随机节理 / 直剪试验 / 尺寸效应 / 抗剪强度 / 力学性能

Key words

SRM method / PFC(Particle Flow Code) / random joints / direct shear test / size effect / shear strength / mechanical property

基金资助

国家自然科学基金项目(52064008)

贵州省科学技术基金(黔科合基础-ZK[2022]一般082)

贵阳城市轨道交通科研项目(GD3-FW-YJ-05-2020-13-ZB)