考虑填土强度的加筋土挡墙动位移计算

加筋土挡墙在地震荷载作用下的位移大小对结构的抗震性能影响显著。为了计算地震荷载作用下加筋土挡墙的位移，Newmark滑块法通常被用于设计中。由于传统的Newmark滑块法在计算中忽略了填土强度的变化，因而采用单一峰值或残余强度的计算将可能导致计算得到的位移小于或大于实际位移值。在二楔块破坏模式的假定条件下，根据楔块的力学平衡条件，建立了加筋土挡墙滑动安全系数计算式，同时通过引入位移阈值考虑了填土的应变软化特点。通过将计算结果与模型试验结果对比，得到以下结论：相较于单楔块法，二楔块法更能真实地反映出墙体的实际破坏模式，且计算得到的屈服加速度系数更接近试验值；相较于采用单一峰值或残余强度计算的位移，考虑填土应变软化的计算解更接近于模型测试值。

Calculation of seismic displacement of reinforced soil retaining walls considering backfill strength

The displacements of reinforced soil retaining walls under seismic loads have a significant influence on their seismic performances. In order to calculate the displacements under earthquakes, Newmark’s sliding block method is usually used in design. As the traditional Newmark’s sliding block method neglects changes of soil strength, so the peak or residual strength is used in calculation, which lead to the calculated values being smaller or bigger than the actual values. Under the assumption of a two- wedge failure mechanism, sliding safety coefficient of reinforced earth retaining walls is obtained using the mechanical equilibrium equations of wedges. At the same time, the strain softening characteristic of backfills is considered by introducing thresholds of displacements. The following conclusions have been obtained by comparing the calculated values with the model tests. Compared with the single wedge method, the two-wedge method can better describe the actual failure mode of model walls and the calculated yield acceleration coefficient is closer to the test values. Compared with the calculated displacements by using the peak or residual strength, the calculated values from the proposed method where strain softening is considered is closer to the model test values.