Study on rational procedures to evaluate seismic stability of retaining walls

为了建立合理的挡土墙抗震稳定性评价方法，对1995年兵库县南部地震中受损的铁路路基挡土墙进行了反分析，对各种挡土墙进行了振动台和倾斜台模型试验，反分析结果表明，设计水平与实际水平存在较大差距挡土墙当前拟静力抗震设计方法中使用的系数，以及峰值地面加速度除以1995年兵库县南部地震期间许多RW所经历的重力加速度。在倾斜台试验中，无论墙的类型，一个或一组破坏面发展在回填土中与主动破坏回填土，随后的最终破坏或倒塌的墙只有在稍大的倾斜角。另一方面，在振动台试验中，墙的最终破坏或倒塌发生在很晚的阶段，与相对较大的变形和位移发生在第一个主动破坏面在回填土中发展。虽然它是类似的Mononobe-Okabe方法，所提出的方法考虑了应变局部化的影响，在回填土和相关的峰后减少的抗剪强度从峰值到剩余值沿着先前形成的故障平面。

In order to establish rational procedures to evaluate seismic stability of retaining walls, back analyzes of retaining walls for railway embankments damaged by the 1995 Hyogoken-nanbu earthquake, shaking and tilt table model tests on a variety of retaining walls, and investigations to evaluate active earth pressures at high seismic load levels were conducted.The back analyzes revealed that there exists a big gap between the design horizontal coefficients used in the current pseudo-static seismic design approaches for retaining walls and the peak ground acceleration divided by the gravitational acceleration experienced by a number of RWs during the 1995 Hyogo-ken-nambu Earthquake. In the tilt table tests, irrespective of wall type, a failure plane or a set of failure planes developed in the backfill associated with the active failure in the backfill, followed by the ultimate failure or collapse of wall only at a slightly larger tilting angle. On the other hand, in the shaking table tests, the ultimate failure or collapse of wall occurred at a much later stage associated with relative large deformation and displacement of wall occurring after the first active failure plane developed in the backfill.Based on the above results, a modified pseudo-static and limit-equilibrium approach to evaluate active earth pressure at high seismic load levels is proposed. Although it is similar to the Mononobe-Okabe method, the proposed method considers the effects of strain localization in the backfill soil and associated post-peak reduction in the shear resistance from peak to residual values along a previously formed failure plane.