考虑固结路径影响的花岗岩残积土 不排水剪切试验研究

针对常规的等向固结剪切试验不能反映实际工程中复杂应力路径对土体力学特性的影响,采用GDS应力路径三轴仪,对华南地区广泛分布的花岗岩残积土进行了不同固结条件下的不排水剪切试验,探讨不同初始平均有效主应力p′_c与初始应力比η_c对其不排水特性的影响。结果表明在初始应力比相同的情况下,初始平均有效主应力越大,花岗岩残积土的不排水剪切强度越大,破坏时的孔压也越大;在初始平均有效主应力相同的情况下,初始应力比越大,花岗岩残积土的不排水剪切强度越大,而破坏时的孔压越小。然而,e-p′-q三维空间中的临界状态线是唯一的,不受初始平均有效主应力和初始应力比影响。

Experimental Study on Undrained Shear Behavior of Granite Residual Soil under Various Consolidation Stress Paths

In engineering practice, conventional triaxial tests under isotropically consolidated conditions cannot reflect the effects of various stress paths on the mechanical behavior of granite residual soil which is widely distributed in south China. To investigate the influence of the initial mean effective stress p′_c and the initial stress ratio η_c on the undrained shear behavior of reconstituted granite residual soil, a series of triaxial tests under different consolidated conditions were conducted on the GDS triaxial apparatus. The test results revealed that both the initial mean effective stress and the initial stress ratio have effects on the undrained shear behavior. It was found that, for the granite residual soil in this study, under the same initial stress ratio, there would be an increase of undrained shear strength and excess pore water pressure with a higher initial mean effective stress. Besides, under the same initial mean effective stress, the higher the initial stress ratio is, the higher the undrained shear strength and the lower the excess pore water pressure would be. However, a unique critical state line can be postulated in e-p′-q space, regardless of the various initial mean effective stress and initial stress ratio.