碎石料应力路径大型三轴试验的离散元模拟研究

碎石料在高填方工程中得到广泛应用。由于其粒径较大,对碎石料力学特性的研究通常需要大型的试验设备。该文探索通过离散元数值模拟方法研究碎石料的应力路径相关力学特性。离散元程序可以将若干球形单元粘结成一个捆绑单元,从而模拟可破碎的碎石颗粒。该文首先简要介绍了离散元的计算原理、特点和模拟过程,并建立碎石料试件的离散元模型。通过对比一组恒定围压下的大型三轴试验,确定了各参数,对所建模型进行了标定。进而通过该模型独立预测碎石料试件在三种不同应力路径加载时的应力-应变关系及体变特性,并与相应的应力路径大型三轴试验结果进行对比,验证了离散元方法可以较为准确地计算碎石料沿不同应力路径加载时的力学特性,同时还讨论了碎石料的小应变刚度特性。

STUDY OF STRESS-PATH-DEPENDENT BEHAVIOR OF ROCKFILLS USING DISCRETE ELEMENT METHOD

Rockfills have been widely used in high-fill projects. The study of the mechanical properties of rockfills usually requires large-scale test equipment because of large particle size. This paper explores to study the stress-path-dependent behavior of rockfills using a Discrete-Element numerical-simulation Method (DEM). A number of spherical units can be bonded into a cluster in DEM to simulate a crushable rockfills particle. This paper briefly introduces the calculation principles and characteristics of the discrete element method as well as its simulation process, and builds up a discrete model of rockfills specimen. Model parameters were determined and the model was calibrated according to a set of large scale conventional triaxial tests of rockfills under different confining pressures. Using the model with same parameters, the stress-strain relationship and volumetric strain characteristics of rockfills along different stress loading paths were predicted. By contrasting the simulation results with the large scale stress-path triaxial testing data, the discrete element model was verified to simulate the mechanical properties of rockfills under different loading paths accurately, meanwhile the small strain stiffness characteristics of rockfills was discussed.