拉筋带对地震作用下土工格室挡墙力学性能的影响

Influence of tensile strip on mechanical properties of geocell retainingwall under earthquake

为研究地震作用下不同位置和数量的拉筋带对土工格室挡墙稳定性的影响,借助FLAC~(3D)软件,建立土工格室挡墙支护边坡数值模型,并采用振动台试验结果对数值模型进行验证,采用标定后的数值模型,系统研究了不同位置和数量的拉筋带对于边坡动力响应的影响。研究结果表明:不同布设方案下,格室约束围压沿墙高表现为“增加-减小”的两段形态;拉筋带布设位置不同,位移沿墙高分布形态不同;水平峰值加速度沿墙高呈“增加-减小-增加”的三段形态,最大值出现在坡顶处;坡顶沉降自坡肩向坡体深处呈先增加后减小的“V”型分布,最大值出现在墙体与坡面交界处;布设两层、3层和4层拉筋带时,其最优位置依次为(H/3,H)、(0,H/3,H)、(0,H/3,H/4,H);随着拉筋带数量的增加,边坡塑性区增大,但墙面永久水平位移、水平峰值加速度和坡顶沉降逐渐减小;拉筋带位置处格室约束围压和水平峰值加速度,自墙面向坡体延伸均呈先增大后减小的“人”字形分布,最大值出现在墙体与坡体交界处,墙面加速度小于墙体加速度,格室及其填料对于加速度的传播具有一定的衰减作用。该研究结果对于地震作用下土工格室柔性挡墙的抗震设计具有一定的指导作用。

In order to study the effect of different positions and quantities of tension bands on the stability of geocell retaining wall upder earthquake action,a numerical model of geocellular retaining wall supporting slope was established with the help of FLAC 3D software,and the results of shaking table test were used to verify the numerical model.The calibrated numerical model was used to systematically study the influence of different positions and quantities of tensile strip on the dynamic response of slope.The results show that under different layout schemes,the confining pressure presents a two-stage pattern of“increase-decrease”along the wall height.The displacement distribution pattern along the wall height varies with the location of the stretching belt.The horizontal peak acceleration presents a three-stage pattern of“increase-decrease-increase”along the wall height,and the maximum value appears at the top of the slope.From the slope shoulder to the depth of the slope,the settlement of the slope top increases first and then decreases in a“V”shape,and the maximum value appears at the junction of the wall and the slope.When two,three and four layers of reinforcement tape are laid,the optimal positions are(H/3,H),(0,H/3,H),(0,H/3,3 H/4,H);The plastic zone of the slope increases with the increase of the number of reinforcement zones,but the permanent horizontal displacement of the wall,the horizontal peak acceleration and the settlement of the slope top decrease gradually.The constrained confining pressure and horizontal peak acceleration of the cell at the position of the reinforcement strip increase first and then decrease from the wall to the slope.The maximum value appears at the junction of the wall and slope,and the acceleration of the wall is less than that of the wall.The cell and its packing have a certain attenuation effect on the propagation of acceleration.The results can be used to guide the seismic design of geocell flexible retaining wall under earthquake.