滑带土含水率与力学参数关系试验研究

Experimental Study on the Relation Between Water Content and Mechanical Properties of Soils in Sliding-Zone

为研究降雨型滑坡滑带土力学性质的变化规律,通过三轴剪切试验,在不同含水率下对某滑坡滑带土的应力-应变关系、抗剪强度与变形模量以及强度指标进行了初步研究。研究表明,含水率对滑带应力-应变关系发展模式影响显著。当含水率小于塑限时,应力-应变关系的发展模式为弹性变形→应变硬化→出现峰值→应变软化,出现剪切破坏面;而当含水率大于塑限时,应力-应变关系发展模式基本上是应变硬化,出现鼓胀破坏。随含水率增大,滑带土抗剪强度降低,可分为3个阶段:塑限含水率以前,抗剪强度变化不明显;塑限含水率至17%(液限与塑限含水率的平均值附近)时,抗剪强度下降速率最大;随后变缓。随含水率增大,滑带土黏聚力降低,近似符合双线性关系。

To research the mechanical properties of soil in the sliding-zone of rainfall-induced landslide,we investigated the stress-strain relation,shear strength index and initial deformation modulus by triaxial shear tests.The results indicated that the water content has remarkable impact on the development mode of stress-strain relations.When the water content is smaller than the plastic limit,the stress-strain relation experienced a process from elastic deformation to strain hardening,to peak value emergence,then to strain softening,and finally to shear failure surface;while when the water content is larger than the plastic limit,the mode of strain-stress relations generally developed from strain hardening swell at the bottom of the sample.With the increase of water content,the shear strength decreases,which can be divided into three phases： when the water content is smaller than the plastic limit,the variation of shear strength is not obvious;when the plastic limit is 17%（in the vicinity of the average value of liquid limit and plastic limit）,the shear strength reduces most rapidly;and afterwards,the decrease of shear strength slows down.With the increase of water content,the cohesion decreases in an approximate bilinear relation.