不同加载速率对磷块岩破坏特性的影响研究

Study on the effect of loading rates on the failure characteristics of phosphate rock

为了探究磷块岩受力后的动态响应规律,开展了不同加载速率作用下的磷块岩单轴压缩试验,并结合PFC3D颗粒流软件,对加载速率与峰值应力、破坏形态、裂纹扩展数量及位移变化的对应关系进行分析。室内试验结果表明:不同加载速率下磷块岩单轴压缩过程均经历了压密、弹性变形、塑性变形、峰后破坏等4个阶段;随着加载速率的增大,试件峰值应力及其应变增大,弹性模量增幅显著,峰后破坏愈加剧烈。PFC^(3D)数值模拟结果表明:随着加载速率的增大,模型裂纹数量增多;模型由局部破坏转为剧烈的全局破坏。磷块岩强度随着加载速率的增大而增大,试件内部孔隙在较大加载速率作用下闭合不充分,各向异性较强,形成的宏观破裂面更明显,破坏范围更大。

In order to find the dynamic response law of phosphate rock under stress,uniaxial compression tests of phosphate rock at different loading rates were carried out.The corresponding relationship between loading rate and peak stress,failure form,crack growth and displacement changes was studied by using PFC 3D particle flow software.The results from indoor tests show that at different loading rates,the uniaxial compression of phosphate rock was proceed in four stages:compaction,elastic deformation,plastic deformation and post-peak failure.With the rising of loading rate,the peak stress and strain increased,the elastic modulus increased significantly,and the post-peak failure became more badly.The numerical simulation results from PFC^(3D) show that the number of cracks grown with the increase of loading rate.The model presented changes from local failure to whole bad failure.The strength of phosphate rock increased as the loading rate went up.The internal holes of the testing sample were not closed completely with strong anisotropy at a high loading rate,resulting in the obvious and wide failure eventually.