复杂应力路径下堆石料的颗粒破碎特性研究

Particle breakage characteristics of rockfills under complex stress paths

针对堆石料进行了一系列等向压缩、常规三轴和复杂应力路径试验,采用相对颗粒破碎率为度量研究了多种应力路径条件下堆石料的颗粒破碎特性。对不同应力路径下试验过程中的塑性功进行了对比,分析了颗粒破碎与平均应力p、广义剪应力q所做塑性功之间的关系,研究了不同应力路径下三轴试验颗粒破碎的差异和原因。结果表明：模拟心墙土石坝填筑和蓄水应力路径下的颗粒破碎远小于常规三轴试验。多种应力路径下塑性功与相对颗粒破碎率之间存在明显的相关性,并可用幂函数较好拟合。不同应力路径下塑性功分量之间差异明显。常规三轴试验中广义剪应力q所做功占总塑性功的主要部分,不同复杂应力路径试验p,q所做塑性功占比差异较大。

A series of conventional triaxial tests, isotropic compression tests and complex stress path triaxial tests are conducted to investigate the particle breakage characteristics of rockfills, which are evaluated quantitatively by using the relative breakage Br. The plastic work in the progress of triaxial tests under different stress paths is compared. The relationship between particle breakage and plastic work done by the mean stress p or generalized shear stress q under different stress paths is analyzed. The results show that the particle breakage of triaxial tests under complex stress paths which simulate the stress paths of rockfills during the progress of construction and impoundment of earth-rockfill dams is much less than that of the conventional triaxial tests. The relationship between plastic work and relative breakage under different stress paths tends to show a unique curve, which can be well fitted by the power function. The plastic work done by the generalized shear stress q accounts for a dominant proportion of all work in the conventional triaxial tests. And in the complex stress path triaxial tests, the proportion of plastic work done by the mean stress p to that done by the generalized shear stress q is different from case to case.