不同含水率原状黄土的强度与变形特性试验研究

Experimental study on strength and deformation characteristics of intact loess with different water contents

为研究含水率的变化对黄土强度与变形特性的影响规律,通过FSY30型应变控制式非饱和土三轴仪,进行了5种不同含水率下原状Q_(3)黄土的各向等压固结试验和三轴剪切试验.研究结果表明:由原状黄土各向等压固结试验e-lnp曲线确定的结构强度p_(s)随初始含水率w的增大而连续降低,两者之间的关系可用幂函数p_(s)=Aw^(λ)来描述;由三轴剪切试验得到的(σ_(1)-σ_(3))-ε_(1)关系曲线在固结围压(σ_(3)-u_(a))=50 kPa时呈现为弱硬化型,在固结围压(σ_(3)-u_(a))=200 kPa、300 kPa时呈现为强硬化型;由三轴剪切试验得到的ε_(v)-ε_(1)关系曲线在w=9.0%,(σ_(3)-u_(a))=50 kPa、100 kPa时呈现弱软化型,其余试验条件下均为强硬化型;原状黄土的黏聚力c及固结后的初始基质吸力(u_(w)-u_(a))均随着初始含水率w的增加而迅速减小.

In order to study the strength and deformation characteristics of intact loess with different water contents,the isotropic consolidation compression tests and triaxial shear tests are performed by using FSY30 unsaturated soil strain-controlled triaxial apparatus.The research results are summarized as follows:The structural strength p_(s) decreases continuously when the initial water content increases,and their relationship could be described by the power function p_(s)=Aw^(λ);(σ_(1)-σ_(3))-ε_(1)curves from triaxial shear tests are the weak hardening when the confining pressure(σ_(3)-u_(a))is 50 kPa,but they show the strong hardening when the confining pressure(σ_(3)-u_(a))is 200 kPa or 300 kPa;The ε_(v)-ε_(1)curves from samples with water content of 9.0%are the weak softening when the confining pressure(σ_(3)-u_(a))is 50 kPa or 100 kPa,but they show strong hardening type in other test conditions;The cohesion c and the initial suction(u_(w)-u_(a))after consolidation decrease rapidly with the increase of initial water contents.