非饱和花岗岩残积土动力变形特性试验研究

为了探究某高速公路工程中非饱和花岗岩残积土动力荷载作用下的变形特性,以衡阳非饱和花岗岩残积土为研究对象,采用美国GCTS公司的USTX-2000非饱和土/饱和土动静三轴试验系统进行了非饱和动三轴试验,并利用Janbu公式进行了拟合。分析了吸力、净围压等对非饱和花岗岩残积土的变形特性的影响,并对其相应的本构关系及模型参数进行了探讨。结果表明:在吸力一定情况下,动应力应变骨干曲线呈双曲线型,骨干曲线随着净围压增大向上移动,不同净围压情况下,其与吸力未呈明显的相关关系;净围压相同时,非饱和花岗岩残积土的最大动弹性模量随动应变增大而减小;吸力一定条件下,最大动弹性模量随着净围压的增大近似线性增加;相同净围压下,阻尼比随动应变的增大而增大。研究成果为工程地质问题治理提供理论依据。

Experimental study on dynamic deformation characteristics of unsaturated granite residual soils

In order to explore the deformation characteristics of the unsaturated granite residual soils under dynamic load in a highway project，an unsaturated dynamic triaxial test is carried out with GCTS USTX － 2000 static and dynamic triaxial test system for unsaturated and saturated soils by taking the unsaturated residual granite soils in Hengyang as the study object，for which relevant fitting curves is made with Janbu formula. The effects of suction and net confining pressure on the deformation characteristics of unsaturated granite residual soil are analyzed，and the corresponding constitutive relationship and model parameters are discussed as well. The result shows that under the condition of certain suction，the dynamic stress-strain backbone curve exhibits a shape of hyperbolic curve，while the backbone curve moves upward along with the increase of the net confining pressure and it does not present an obvious correlativity with suction with different net confining pressure. When the net confining pressure is kept samely，the maximum dynamic elastic modulus of the unsaturated granite residual soil decreases along with increase of dynamic strain. Under a certain suction，the maximum dynamic elastic modulus approximately exhibits a linear increase along with increase of net confining pressure. With same net confining pressure，damping ratio increases along with increase of dynamic strain. This study result provides a theoretical basis for treatment of engineering geological problems concerned.