Influence of groundwater level changes on the seismic response of geosynthetic-reinforced soil retaining walls

Abstract

Geosynthetic-reinforced soil retaining walls (GSRWs) have been widely used in civil engineering projects. However, as the climate changes, extreme weather conditions and natural hazards are likely to become more frequent or intense, posing a huge threat to the stability of GSRWs. In this paper, the effect of groundwater level fluctuations on the seismic response of GSRWs is investigated. First, a dynamic numerical model was established and validated through centrifugal shaking-table test results. Using the established numerical model, the seismic response of GSRWs under four different groundwater level conditions was then investigated, i.e., an earthquake occurring at a low groundwater level (Case LW), an earthquake occurring when the groundwater level rises (Case RW), an earthquake occurring at a high groundwater level (Case HW), and an earthquake occurring when the groundwater level drops (Case DW). The results show that the GSRW in Case DW has the worst seismic stability because of the drag forces generated by the water flowing to the outside of the GSRW. For Case RW, deformation of the GSRW under earthquake forces was prevented by the drag forces generated by the water flowing to the inside of the GSRW and the water pressure acting on the outside of the facing, giving the GSRW the best seismic stability in this case. Compared with Case LW, the seismic stability of a GSRW in Case HW is worse, because the high groundwater level will generate excess pore-water pressure during an earthquake. On this basis, we provide engineering design suggestions to be considered by practitioners.

摘要

目的

土工合成材料加筋土挡墙（GSRW）已被广泛应用于各类工程。然而，近年来受气候变化的影响，极端天气和自然灾害频发，这对加筋土挡墙的稳定性造成了较大的危害。本文主要研究了地下水位变化对加筋土挡墙动力稳定性的影响。首先，通过离心振动台试验结果对数值方法进行了验证。然后，利用建立的数值模型，对四种不同的工况下的加筋土挡墙稳定性进行了探究。分别为：在低地下水位条件下发生地震(Case LW)、在地下水位上升的条件下发生地震(Case RW)、在高地下水位条件下发生地震 (Case HW)，以及在地下水位下降的条件下发生地震 (Case DW)。结果表明，加筋土挡墙在Case DW工况中的稳定性最差，这是由于水位下降时，地下水会从挡墙内部向外部渗流，此时的渗流力会加剧挡墙失稳破坏。相反，地下水位上升过程中，渗流力表现为抵抗加筋土挡墙变形的阻力，因此加筋土挡墙在Case RW工况中的变形并不明显。此外，受超孔隙水压力的影响，加筋土挡墙在地下水位较高情况下 (Case HW) 的稳定性要小于地下水位较低的情况(Case LW)。本研究可以为工程实际提供参考和借鉴，因此具有一定的实际意义。

创新点

1.基于离心振动台试验结果建立了可用于水位变动情况下加筋土挡墙地震响应的数值解析方法；2. 基于建立的数值解析方法，系统揭示了不同地下水位工况下加筋土挡墙抗震稳定性和变形破坏规律。

方法

1. 利用离心振动台试验结果验证了数值方法的合理性；2. 通过建立加筋土挡墙数值模型，系统考虑了低水位、上升水位、高水位和下降水位四组地下水位条件；3. 通过对不同地下水位条件下的加筋土挡墙施加地震荷载，探讨了地下水位变化对加筋土挡墙抗震稳定性的影响。

结论

1.加筋土挡墙在地下水位下降情况下的动稳定性最差；2.地下水位上升可有效降低地震作用下加筋土挡墙的向外变形；3.加筋土挡墙在较高地下水位情况下的抗震稳定性要小于地下水位较低的情况。