摘要
土石混合体介质具有高度非均质性、显著的结构效应与尺寸效应等特点,这使其物理力学特性及其复杂。本文针对土石混合体在剪切过程中剪切带的变形性状与影响因素,采用自主研发的RSM–1000型电机伺服控制大型土工抗剪强度试验系统,考虑不同含石量(0,30%,50%,70%)、上覆压力(50,200,300,400 k Pa)、块石尺寸(L1,L2,L3)3个主要结构控制因素,进行土石混合体剪切变形试验,通过在试样内部钻孔设置铝丝与干灰的方法,监测剪切带特征变化规律。研究结果表明:当含石量小于30%时,块石对试样的变形影响较小,强度主要依赖于砂土强度;当含石量达到50%时,试样内已形成骨架结构,变形受块石的影响突显,强度由块石和砂土共同作用;当含石量达到70%时,试样内已形成块石架空结构。在高含石量与大粒径块石条件下,含贯穿剪切面的块石试样随剪切变形发展,块石发生挤压、翻转现象;剪切面附近分布块石的试样,随剪切变形发展,块石以剪胀作用为主,块石发生挤压、棱角剪断与错动重分布。试样的剪切变形现象可类比由后向前变形的推移式滑坡或由前后向中间变形的复合式滑坡的破坏特征,即后缘坡顶在主动土压力作用下产生裂隙,随之下沉挤密、失稳起滑;前缘坡脚蠕滑变形推移;坡中岩土体发生剪切错动至滑动面渐进扩展破坏,最终剪切面贯通,形成整体破坏。该研究成果对揭示土石混合体滑坡剪切带形成演化规律、破坏模式及土石混合体滑坡的防灾减灾具有重要意义。
Soil-rock mixture has the characteristics of distinct heterogeneity,obvious structural and size effects,and thus has the complex mechanical properties. In this research,the deformation properties and the influencing factors of shear band of soil-rock mixture during the shearing process were investigated with the servo motor controlled system of geotechnical experiment developed in-house（RSM-1000）. The shear band deformation tests on soil-rock mixture were conducted considering the effects of different rock contents（0,30%,50%,70%）,normal pressures（50,200,300,400 k Pa） and rock sizes（L1,L2,L3） respectively. The deformation characteristics of shear band were monitored by putting the aluminum wires and dry ash into the hole inside the samples. The results show that when the rock content is less than 30%,rocks have little effect on the deformation of samples,and that the mechanical strengths of samples mainly depend on the sand. When the rock content reaches 50%,samples are transformed into a skeleton structure,rocks have obvious effects on deformations and the mechanical strengths of samples are affected by rocks and sand simultaneously. When the rock content reaches 70%,samples are transformed into the rock structure with empty space. Under the condition of high rock content and rock particles of large diameter,the rocks through the shear surface tend to extrude and roll during the shear process. The rocks around the shear surface are mainly affected by dilation,and present extrusion,particle breakage and redistribution. The shearing deformations of the samples are comprised of three distinct stages and can be depicted as the failure of thrust landslide with the deformation from back to front or compound landslide with the deformation from two slides to the middle. At the first stage,the cracks were generated on the top of the backward slope under the effect of active soil pressure,which leads to the sink,compaction and instability of the top of backward slope. Then,the front edge of the slope begins to deform and move forward. Finally,the shearing dislocation of the soil-rock mass and the progressive expansion failure of the sliding face result in the cut-through of shearing plane and the whole destruction of the slope.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2018年第3期766-778,共13页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(41330643)
中国科学院青年创新促进会项目(2017092)
云南省科技厅科技计划项目(2017ZE020)~~
关键词
土力学
土石混合体滑坡
滑带
剪切带
结构效应
尺寸效应
大型直剪试验
soil mechanics
soil-rock mixture（SRM） landslide
sliding zone
shear band
structure effect
sizeeffect
large scale direct shear test
作者简介
胡峰（1991-），男，2015年毕业于中国地质大学（北京）地质工程专业，现为博士研究生，主要从事岩土工程等方面的研究工作。E-mail：18810550150@163.com。
