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通过室内模型试验研究了卸荷尺度及孔隙率对砂性土成拱应力释放特性的影响,并应用离散元分析软件PFC2D进一步对颗粒摩擦性质影响、成拱后应力场以及位移场变化规律和应力释放分区进行了细观研究。研究发现:(1)数值模拟对卸荷尺度影响因素的研究结果与室内试验一致,应用PFC2D研究砂性土应力释放特性是可行的。(2)应力释放区内竖向应力释放大于应力加载区,而水平应力释放小于应力加载区;侧压力系数在应力释放区内距离卸荷位置越近增量越大,而在应力加载区距离卸荷位置越近增量越小。(3)砂性土摩擦性质会减小土体成拱对应力释放以及侧压力系数变化的影响。(4)应力释放随着卸荷尺度及孔隙率的增大而增大;对于侧压力系数,在应力释放区内随着卸荷尺度或孔隙率的增大而增大,而在应力加载区随着卸荷尺度或孔隙率的增大而减小。
The influence of unloading scale and porosity on the stress release characteristics of sandy soil was studied by indoor model test. The effect of PFC2D on the friction properties of the granule, the change law of the stress field after displacement and the displacement field and stress Release the partition for a detailed study. The results show that: (1) The results of numerical simulation on the influencing factors of unloading scale are consistent with those of indoor tests. It is feasible to study the stress release characteristics of sandy soil by PFC2D. (2) The release of vertical stress in the stress relief zone is larger than that in the stress loading zone, but the horizontal stress release is smaller than that in the stress loading zone. The increase of the lateral pressure coefficient in the stress releasing zone closer to the unloading position is greater, The closer the unloading position is, the smaller the increment. (3) The frictional properties of sandy soil will reduce the influence of soil arching on stress release and lateral pressure coefficient. (4) The stress release increases with the increase of the unloading scale and the porosity. For the lateral pressure coefficient, it increases with the increase of the unloading scale or porosity in the stress releasing zone, As the unloading scale or porosity decreases.