三峡库区巴东组岩-土接触面抗剪强度特性研究

Shear Strength Characteristics of Rock-soil Interface in Badong Formation in the Three Gorges Reservoir of China

以三峡库区巴东组岩-土接触面为研究对象,设计了三种碎石含量(20%、50%和80%)、三种不同基岩(T12b、T22b、T32b)在室内进行了大型直剪试验,研究了碎石土-基岩接触面抗剪强度特性。试验结果表明:碎石土-基岩接触面τ-σ关系曲线分为应变硬化型和应变软化型;碎石土-基岩接触面剪切过程中碎石土中含有的孤石会随着剪切面的起伏发生摩擦、翻滚、平移等物理形态变化,剪切后在剪切面上留下深坑;碎石土-基岩接触面抗剪强度指标c、值与碎石土中碎石含量有关,其内聚力c随碎石含量的增加呈现先递增后递减的趋势,内摩擦角随碎石含量的增加总体呈现递增的趋势;碎石土-基岩接触面抗剪强度指标c、值与选材的地质代表性也有关系,T22b层的紫红色砂岩相对于T12b层和T32b层的灰岩来说具有内聚力c高,内摩擦角低的特点。

Taking the rock-soil interface in Badong formation in the Three Gorges reservoir of China as the research object,this paper explores the shear strength characteristics of gravel-bedrock interface through carrying out the large-scale direct shear tests indoors using the three kinds of designed gravel content（20%,50% and 80%）and three different bedrocks（T12b、T22b、T32b）.The test results show that the relationship curves betweenτ-σof gravel-bedrock interface are divided into strain hardening and strain softening;in the gravel-bedrock interface shearing process,boulders in gravel soil may experience the physical and morphologic changes such as shear friction,rolling and translation,leaving pit at the shear plane after shear;the gravel-bedrock interface shear strength parameters c andvalues are related to the gravel soil content,the cohesive force c exhibits a trend of first increasing and then decreasing with the increasing of gravel content,and the internal friction angleshows an overall increasing trend with the increasing of gravel content;the gravel-bedrock interface shear strength parameters c andvalues are also related to the geological representativeness of the rock,the cohesive force c of the purple red sandstone of the T22 blayer is higher than that of T12 b and T32 blimestone,while the internal friction angleis lower than that of the latter.