堆石料大三轴试验的细观模拟

Meso-mechanical simulation of a large scale triaxial test of rockfill materials

采用三维颗粒流计算程序,对堆石料的大三轴排水剪切试验过程进行了数值模拟。在数值模型的生成过程中,使堆石料集合体达到规定密度和级配;采用动态松弛算法迭代求解,并引入粒间阻尼,以吸收颗粒填装的多余动能使其稳定;颗粒间引入黏结力来提高试样的峰值强度;确定堆石料的细观力学参数,拟合室内试验应力应变曲线。模拟不同围压下堆石料的试验,得到的应力-应变曲线与室内试验基本一致,说明颗粒流方法可以较好的模拟堆石料的大三轴试验过程。由于没有考虑颗粒形状及颗粒破碎的影响,造成大应变剪胀偏大。

The three dimension particle flow code calculation program is used to simulate the large scale triaxial drained shear test of rockfill materials.During the formation of numerical specimen a procedure is writing to generate particles of assemly until the target porosity and gradation composition are achieved.Dynamic relaxation method is applied to solve DEM(discrete element method) equation.Local damping is used to accelerate to arrive at a steady solution in a reasonable number of cycles to dissipate energy of the particle system.Normal and shear contact bond strengths are used to increase the assemly’speak strength.With the selected micro parameters the numerical simulation tests of the large scale triaxial test are performed under series of confining pressures.The stress-strain curves from numerical simulation with the selected micro parameters are in agreement well with the results of the laboratory test.So the particle flow code program is a better method to simulate the large scale triaxial drained shear test of rockfill materials.A large range of shear dilatancy occurs with the increase of axial strain because particle shape and breakage are not considered.