摘要
土石混合体作为一种典型的浅表层堆积体,常引发不同规模的滑坡灾害。本文通过对比土石混合体在室内大型直剪和离散元(PFC2D)数值模拟直剪条件下剪切带厚度随含石量和上覆压力的变化特征,以期进一步揭示影响土石混合体剪切带厚度的主要控制因素。试验结果显示,室内试验中土石混合体的剪切带厚度主要受含石量的影响,其次为上覆压力,受块石尺寸的影响不明显。剪切带厚度随含石量从0增加到50%时表现为增大的趋势,随含石量的继续增大而表现为减小的趋势。但上覆应力小于200 kPa时,剪切带厚度随上覆应力的增大表现为增大的趋势,但上覆应力超过200 kPa时,其值表现为减小的趋势。然而,在数值模拟计算中,考虑块石不可破碎的情况下剪切带裂纹区域的宽度随含石量和上覆压力的增大表现为持续增大的趋势特征。分析认为,土石混合体剪切中大块石之间咬合后的齿轮带动效应是促使剪切带厚度增大的重要原因,而骨架结构含石量以及高垂直应力下块石咬合部位因高度的应力集中,随后导致的咬合棱角破碎,块石变形被限制在一定的区域内,却抑制了剪切带厚度的进一步增大。相反,在块石不可破碎的数值模拟计算中,高含石量试样内块石可持续的咬合滚动,促使周围的块石也发生变形,进而增大了剪切带的厚度。研究结果有利于揭示土石混合体的剪切变形破坏机制。
Soil-rock mixture(S-RM),as a typical surface sediment on slopes,frequenly causes landslides of dif-ferent scales.This study aims to further reveal the influence of rock content and normal pressure on the thickness of the shear band of S-RM through large scale direct shear testing and numerical stimulation testing using the Particle Flow Code in Two Dimensions(PFC2D).The experimental results indicate that the thickness of S-RM is signifcant-ly afcted by the rock content,fllowed by the normal pressure,and is minimally infuenced by the rock block size.The thickness of the shear band increases with an increase in rock content from 0 to 50%.The thick ness of the shear band also increases with an increase in normal stress;however,a deereasing trend is observed after the nor-mal stress exeeds 200kPa.The nommal stress before the formation of the S-RM skeleton presents a deereasing trend.Nevetheless,the thickness of the shear band maintains a continuous increasing trend in numerical analysis samples with unbreakable rock blocks.The main reason for the increment in the thickness of the shear band is the gear efeet caused by the occlusion of large blocks.Stress concentration at the interlocking contact position with a high rock block propotion and high normal stress contributes to the breakage of interlocking edges,inhibiting the further increase of shear zone thickness.Conversely,in the numerical simulation testing of S-RM with a high rock proportion,continuously interlock ing rotation for unbreakable rock blocks was observed,resuling in the deforma tion of the surrounding soil and rock blocks and enhancing the thickness of the shear band.The resuls presented in this paper could provide essential insights into S-RM deformation.
作者
胡峰
祝诗逸
王颂
朱益军
吕庆
李志清
HU Feng;ZHU Shiyi;WANG Song;ZHU Yijun;LV Qing;LI Zhiqing(Zhejiang Insitute of Communications Co.,.Itd,Hangzhou 310030,China;College of Ciril Enginering and Architeture,Zhejang Uniersity,Hangzhou 310058,China;Key laboratory of Shale Gas and Geninering,Isitute of Gedogy and Geophysics,Chinese Academy of Sciences,Bejing 100029,China)
出处
《工程地质学报》
CSCD
北大核心
2024年第1期39-51,共13页
Journal of Engineering Geology
基金
自然灾害防治技术、装备研发和应用示范——交通基础设施全生命周期地质灾害预警与防治技术装备研发(资助号:2021KCKT2011)
第2次青藏高原综合科学考察(资助号:2019QZKK0904)
浙江省重点研发计划项目(资助号:2021C03159)
自然资源部浙江地质灾害野外观测开放基金项目(资助号:ZJDZGCZ-2021)。
关键词
土石混合体
剪切带厚度
含石量
大型直剪
PFC2D
Soil-rock mixture
Thickness of shear band
Rock content
Large-scale direct shear test
PFCZ
