石笼挡土墙的颗粒离散元细观力学模拟研究

针对在施工过程中，石笼挡土墙墙面位移的发展、墙背填土中土应力的变化的问题，从细观层面，采用基于离散单元法的颗粒流程序，通过多组试件的模拟压缩试验，确定了填土、填石、石笼等材料合理的力学参数值，以工程中的实体石笼挡土墙为原型，建立了墙背阶梯式石笼挡土墙数值模拟模型。通过在填土表面施加均布荷载，研究了挡土墙的力学行为。模拟结果显示：填土中的水平应力随深度的增加对均布荷载的敏感性降低，填土深度越浅，应力值越早得到增加，增加幅度越大，这主要是由于石笼挡土墙上部发生了较大的位移，均布荷载的作用大部分消耗在上层填土中，仅有小部分能量传递到较深填土；石笼挡土墙变形主要发生在填土阶段，应加强石笼挡土墙填土阶段的施工管理；无论是在填土阶段，还是均布荷载作用阶段，石笼挡土墙墙面的位移值均是中上部较大，下部较小。由此可推断，墙背阶梯式石笼挡土墙的破坏形式为倾覆式。

Mesomechanical research on gabion retaining wall with particle flow code

The wall surface displacement growth and the stress change in the filling of gabion retaining wall during construction process are researched. Based on the theory of particle flow code (PFC), one of the discrete element methods, a series of numerical compression tests are simulated to establish the proper mechanical parameter values for filling, filling stone, gabion. The real gabion retaining wall being prototype, the model of gabion retaining wall of back ladder model is constituted. The mechanical behavior of retaining wall is studied during the uniform load acting on the surface of filling. The simulation results show that: (a)The sensibility of horizontal stress to uniform load decreases with the increase of depth in the filling; and the stress increases earlier and more in the lower filling depth. This is because that the upper layer filling consumes mostly energy of uniform load; and the lower layer filling absorbs a small quantity of energy when macro displacement occurs in the upper layer of the gabion retaining wall.(b) The most displacement of retaining wall occurs in the filling stage. Construction management of gabion retaining wall should be emphasized. (c) The displacement is comparatively large in the upper, lesser in the lower layers not only in the filling stage but also in the concentrated uniform load; from this, it can be seen that the destruction form for gabion retaining wall of back ladder is overturning. The results provide a foundation for studying the active earth pressure of this gabion retaining wall.