摘要
土石混合体-基岩接触面是下伏基岩堆积体边坡稳定性的主要控制面,基覆面形态特征是重要的设计内容。为此,开展了不同基覆面形态参数条件下接触面室内大型直剪试验,研究了基覆面形态参数对接触面剪切力学特性的影响,探讨了接触面土石颗粒运动概化模式,建立了接触面剪切简化的复合幂-指数模型(composite power exponential model,CPE模型)。结果表明:随着粗糙度的增加,接触面抗剪强度不断增大,表观内摩擦角和表观黏聚力分别呈非线性上凸增长和似线性增长趋势,随着锯齿高度的增加,接触面抗剪强度先增大后减小,增加锯齿高度对表观黏聚力的影响较为明显;接触面剪应力-剪切相对位移关系曲线基本呈弱硬化型,土石颗粒骨架密实度随粗糙度的增大而减小,但随锯齿高度的增大呈先增大后减小,接触面土石颗粒运动主要表现为咬合、翻转和滑移,较高法向应力时会发生颗粒破碎和基岩尖端剪切破坏;模型参数k、b和n与无量纲化法向应力σ_(n)/Pa存在线性关系(σ_(n)为法向应力,P_(a)为标准大气压),拟合系数α_(i)(i=1,2)不受基覆面形态参数的影响,拟合系数βi和i分别与粗糙度R和锯齿高度D存在线性关系;简化CPE模型能够很好地模拟出不同基覆面形态参数条件下土石混合体-基岩接触面剪切变形全过程,模型适用性良好,参数的确定方法合理且可行。
The soil-rock mixture-bedrock contact surface represents as the primary control interface for the stability of accumulated landslides,and the morphological characteristics of bedrock interface represent a pivotal element of the design.Large-scale direct shear tests were conducted on the contact surface under varying morphological parameters of the bedrock interface.The objective of these tests was to investigate the influence of the aforementioned parameters on the shear mechanical properties of the contact surface.A generalized model was developed to describe the movement of soil and rock particles at the contact surface.A simplified composite power exponential(CPE)model was established to describe the shear behavior of the contact surface.Results show that as the roughness of the contact surface increases,the shear strength of the contact surface progressively enhances.This is accompanied by a nonlinear upward convex growth trend in the apparent internal friction angle and a quasi-linear increase in the apparent cohesion.As the sawtooth height increases,the shear strength of the contact surface initially rises and subsequently declines.The impact on apparent cohesion is more pronounced when sawtooth height increases.The relationship curve between shear stress and shear relative displacement at the contact surface generally exhibits a weak hardening pattern.The compactness of the soil-rock particle skeleton is observed to decrease with increasing roughness,but to increase initially and then decrease with the elevation of sawtooth height.The movement of soil-rock particles at the contact surface is primarily characterized by interlocking,rolling and slipping,while particle fragmentation and shear failure at the bedrock tips occur under conditions of higher normal stress.The model parameters k,b,and n are found to exhibit a linear relationship with the dimensionless normal stressσ_(n)/P_(a).σn is normal stress,and P_(a) is standard atmospheric pressure.The fitting coefficient α_(i)(i=1,2)remains unaffected by the morphological parameters of the bedrock interface.Moreover,fitting coefficients β_(i) and γ_(i) demonstrate a linear relationship with roughness R and sawtooth height D,respectively.The simplified CPE model effectively simulates the entire process of shear deformation at the soil-rock mixture-bedrock contact surface under varying morphological parameters of the bedrock interface.The model demonstrates good applicability,and the method for determining the parameters is both reasonable and feasible.
作者
侯克鹏
江帆
张超
龚晶汉
HOU Ke-peng;JIANG Fan;ZHANG Chao;GONG Jing-han(School of Land Resources Engineering,Kunming University of Science and Technology,Kunming,Yunnan 650093,China;Yunnan Key Laboratory of Sino-German Blue Mining and Utilization of Special Underground Space,Kunming University of Science and Technology,Kunming,Yunnan 650093,China;Hunan Provincial Key Laboratory of Geotechnical Engineering for Stability Control and Health Monitoring,Hunan University of Science and Technology,Xiangtan,Hunan 411201,China)
出处
《岩土力学》
北大核心
2025年第S1期271-284,共14页
Rock and Soil Mechanics
基金
中国博士后科学基金(No.2023MD744275)
岩土工程稳定控制与健康监测湖南省重点实验室开放基金(No.E22308)
关键词
土石混合体
基岩界面
形态参数
剪切特性
本构模型
soil rock mixtures
bedrock interface
morphological parameters
shear characteristic
constitutive model
