基于局部变形测量的粉质黏土变形参数

摘要

In order to investigate the influence of deformation measurement methods on the deformation parameters of undisturbed silty clay,triaxial consolidated-drained shear tests equipped with local deformation measurement transducers were carried out to analyze the behaviors of strain-stress,shearstrength parameters and the characteristics of Poisson's ratio and stiffness under small strain.The results show that the effective internal friction angle by using the local deformation measurement,compared with by using the full deformation measurement,decreases about 4.5％ to 6.0％,while the effective cohesion increases about 5.7％ to 14.0％.The volumetric strains obtained by different measurements are similar before the contraction peak value,after that,the volumetric strain gained by the local deformation measurement is the biggest,followed by the ones via the full deformation measurement and the water measurement.The stiffness gained by the local deformation measurement is twice larger than that based on the full deformation measurement under small strain.When axial strain is smaller than 0.2％,Poisson's ratio increases rapidly with the increase of axial strain in the initial stage,then slows down and becomes stable gradually.%为考察测量方法对原状粉质黏土变形参数的影响,用配置局部位移传感器的三轴测试系统,进行了多组固结排水剪切试验,分析了测量方法对应力-应变关系、抗剪强度的影响,研究了小应变范围内泊松比和刚度的变化特征.结果表明:局部变形测量的有效内摩擦角比整体变形测量减小4.5％ ～6.0％,有效粘聚力提高5.7％～14.0％；剪缩峰值之前,局部变形测量、整体变形测量及进排水量法的体应变基本相同,峰值之后局部变形测量的体应变最大,进排水量法最小；小应变范围内局部变形测量的刚度值高于整体变形测量,二者约相差1倍；轴向应变小于0.2％时,加载初期泊松比随轴向应变增大而增大较快,后期减缓并渐趋稳定.