Practical design procedures of different types of retaining walls against high seismic loads

为了建立实用的设计方法来评价不同挡土墙在高地震荷载作用下的抗震稳定性，对6种不同挡土墙模型进行了一系列不规则振动试验，试验结果表明，在回填土中形成第一破坏面后，在高地震荷载作用下形成第二破坏面.这可以通过考虑回填土中应变局部化的影响以及沿着先前形成的破坏平面从峰值到剩余值的剪切阻力的相关峰后降低来解释。在以往的倾斜试验和正弦振动试验中，与传统的重力式、倾斜式和倾斜式挡土墙模型相比，具有刚性全高面板的加筋土挡土墙模型表现出延性特性。当模型墙开始倾斜时，地基反力集中在传统类型挡土墙的趾部，导致局部失效，由于承载能力的损失。另一方面，在类似的条件下，加筋土挡土墙的拉力可以有效地调动抵抗倾斜位移。此外，挡土墙在1999年集集地震的性能进行了调查。据估计，传统类型挡土墙的损坏是由地面永久位移沿着表面断层、大规模的斜坡移动、底土承载力的损失、墙体惯性力过大和/或回填土压实不足造成的。研究还表明，在其他类似条件下，使用楔石作为饰面的加筋土挡土墙的损坏程度受钢筋垂直间距的影响。

In order to establish practical design procedures to evaluate seismic stability of different types of retaining walls against high seismic loads, a series of irregular shaking tests was conducted on retaining wall models consisting of six different types.In some tests, after the first failure plane was formed in the backfill, the second failure place was formed at higher seismic loads. This can be explained by considering 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. Such behavior has not been observed in the tilting tests and the sinusoidal shaking tests that were conducted on the same models in the previous study.In these tests, reinforced-soil retaining wall models with a rigid full-height facing exhibited a ductile behavior compared to conventional type retaining wall models such as gravity-type, leaning-type and cantilever-type ones. When the model walls started to tilt, concentration of subgrade reactions at the toe of conventional type retaining walls resulted in local failure due to loss of bearing capacity. On the other hand, under similar conditions, tensile force in the reinforcements of the reinforced-soil retaining walls could be mobilized effectively to resist against the tilting displacement.In addition, performance of retaining walls during the 1999 Chi-Chi earthquake was investigated. It was estimated that damage to conventional type retaining walls was caused by permanent ground displacement along surface faults, large-scale slope movement, loss of bearing capacity in the subsoils, excessive inertia force of the wall, and/or insufficient compaction of the backfill. It was also shown that extent of damage to reinforced-soil retaining walls using keystones as a facing was affected by the amount of vertical spacing of the reinforcements under otherwise similar conditions.