汕头市花岗岩残积土的工程特性及路堑边坡稳定分析

花岗岩残积土在汕头市分布广泛,具有不均匀性及各向异性、扰动性、软化特性和崩解性。在天然状态下它们具有较低的压缩性、较高的承载力和较大的抗剪强度,但遇水后力学性质显著降低。花岗岩残积土的扰动性通常导致室内试验指标失真,使压缩模量低于变形模量,因此,花岗岩残积土的变形模量和地基承载力应通过原位测试(主要是标准贯入试验)来确定,并为此建立了本区花岗岩残积土地基容许承载力与标准贯入击数的对应关系。同时对汕头市花岗岩残积土路堑边坡失稳的原因进行分析并提出切实可行的防护办法。

Engineering characteristic of granite residual soil and stability analysis of cut slope in Shantou City

Granite residual soil is widely distributed in Shantou City,Possessing properties of inhomogeneity,anisotropy,disturbance,softening and disintegration.Under the natural condition,the granite residual soil is low in compressibility but bears high weight and strong shear strength.When it encountered water,its mechanic characteristic decreased obviously.The property of its disturbance usually resulted in distorting indoor experimental index,which caused compress modulus is under deformation modulus.Therefore,the granite residual soil' s distortion modulus and foundation bearing capacity should be defined by in-site measurement(mainly for standard injection test).The correspondence relation between available foundation bearing capacity and standard injection base is established accordingly for the granite residual soil within certain area.The authors also made analysis on the reasons of side slope instability in Shantou City, and proposes practical preventive solutions as well.