交通动载下砾性土动三轴试验分析

Dynamic triaxial test analysis of gravel soil under traffic dynamic load

为了探讨交通动载下砾性土的动力特性,采用GDS高级动态三轴测试系统,对级配良好的砾性土进行了大尺寸动态三轴试验,分析砾性土的应力应变及动模量等参数的变化规律.试验结果表明:循环荷载作用下,砾性土的应力应变关系整体上呈递增的趋势,动应变ε_d≤2.36%时,砾性土动应变随动应力呈线弹性增长;ε_d>2.36%后,土体出现塑性变形,砾性土动应变呈非线性加速发展趋势.砾性土轴向动应变随振动次数逐渐增大,动应变增长率随振次增加而增大.砾性土动弹性模量随着动应变增加整体呈现骤减→略增→减小的趋势,其中在1%<ε_d<3%范围时动弹模出现小幅增长.密实的饱和砾性土在多级短时荷载作用下,产生剪胀变形,对应动孔压随动应变呈局部振荡整体递减的趋势.

In order to investigate the dynamic characteristics of gravel soil under traffic load, GDS advanced dynamic triaxial test system was used to carry out large-scale dynamic triaxial test on well-graded gravel soil. The test results show that under cyclic loading, the stress and strain relation of gravel soil is increasing on the whole. When the dynamic strain is less than or equal to 2.36%, the dynamic strain of gravel soil increases linearly with the dynamic stress. After the dynamic strain was greater than 2.36%, the soil body appeared plastic deformation, and the dynamic strain of gravel soil presented a trend of non-linear acceleration. The axial dynamic strain of gravel soil increases with the number of vibration and the growth rate of dynamic strain increases with the number of vibration. As the dynamic strain increases, the dynamic elastic modulus of the gravel soil shows a tendency of sharp decrease, slight increase and decrease. Under the action of multi-stage and short-term loads, the compacted gravel soil produces shear expansion deformation, and the dynamic strain of the dynamic pore pressure shows an overall decreasing trend of local oscillation.