软弱层对层状复合泥岩体力学特性影响研究

Influence of weak layer on the mechanical properties of stratified composite mudstone mass

为研究软弱层对层状复合泥岩体力学性质的影响规律,有效提高层状复合泥岩体力学参数的可靠性,考虑到现场很难完整取得含软弱层的层状泥岩体试件,采取室内压制办法制作具有规则层状特征的泥岩试样,然后对其进行单轴和三轴压缩试验,对比分析各试样的强度、变形特性。试验结果表明:当软弱层厚度比变化时,层状复合泥岩体的强度、变形、弹性模量均随之发生规律性变化;上软下硬型层状泥岩与含软弱夹层层状泥岩试样的单轴抗压强度和弹性模量均随软弱层厚度的增加而非线性降低;轴向应力损失率分析表明,软弱层显著降低了硬层泥岩强度,降幅达70%以上;在三轴压缩试验条件下,层状泥岩的承载能力均有不同程度的提高。层状泥岩的粘聚力和内摩擦角随夹层厚度的增加而减小。试验结果对区域性软岩地基的设计和施工具有一定指导意义。

In order to study the influence of weak layer on the mechanical properties of stratified composite mudstone mass,and improve the reliability of the mechanical parameters of stratified composite mudstone effectively,considering the samples are not easy to be obtained by coring in field,the regularly stratified mudstone was made by pressing,and the uniaxial and triaxial compression tests were carried out in order to analyze the strength and deformation of samples. The test results show that the strength,deformation and elastic modulus of stratified composite mudstone mass changes regularly with the change of the thickness ratio of the weak layer. The uniaxial compressive strength and elastic modulus declines in nonlinear with the increase in the soft thickness ratio of upper-soft and lower-hard stratified mudstone samples. The analysis of the axial stress loss rate shows that the soft layer weakens the strength of the hard mudstone significantly. The strength decreases by more than 70%. The bearing capacity of mudstone with weak layers will be improved more or less in triaxial compression test. The cohesion and internal friction angle of stratified mudstone with weak interlayer decrease with the increase of the thickness of weak interlayer. The results could be referred for the design and construction in the soft rock area.