崩岗侵蚀区非饱和花岗岩残积土强度特性试验研究

Experimental Study of Strength Characteristics of Unsaturated Granite Residual Soil in Collapsing Erosion Area

以崩岗侵蚀区花岗岩残积土为研究对象,应用非饱和土三轴仪对重塑花岗岩残积土进行强度特性试验,研究干密度、净围压和基质吸力对应力-应变关系和强度的影响规律,并分析重塑非饱和花岗岩残积土在控制吸力条件下的抗剪强度特性。结果表明,非饱和花岗岩残积土的应力-应变关系均呈硬化型;在干密度相同时,非饱和土强度随着基质吸力和净围压的增大而增大;在净围压相同条件下,非饱和土强度随着基质吸力和干密度的增大而增大;基质吸力对粘聚力影响较大,基本上呈线性增长关系,而有效内摩擦角受基质吸力的影响较小,几乎可以不计;非饱和重塑花岗岩残积土的强度随着基质吸力和干密度增大而增大,与基质吸力相关的摩擦角较大。

The strength characteristics of unsaturated granite residual soil in collapsing erosion area are investigated by a series of triaxial tests with suction-controlled conditions. The influences of different initial dry density,net confining pressure and suction on stress-strain relationship and strength of unsaturated residual soils are studied and the shear strength characteristics of remolded unsaturated granite residual soil under suction-controlled conditions are analyzed. The results show that,( a) the stress-strain relationship of unsaturated granite residual soil exhibits a characteristics of strain-hardening;( b) under the condition of same dry density,the peak strength increases with the increase of suction and net confining pressure;( c) under same net confining pressure,the peak strength increases with the increase of suction and dry density;( d) the cohesion increases greatly with the increasing of suction with a linear growth to suction,but the suction has smaller effect on friction angle which can be nearly ignored;and( e) the increases of suction and dry densities have a positive effect on the strength of residual soil,and the triaxial shear coefficient is larger.