加筋重力式挡土墙主动土压力的上限分析方法

Upper Bound Limit Analysis for Active Earth Pressure of Gravity Retaining Wall with Geogrids Support

基于极限分析理论的上限法,考虑平面滑动的破坏模式,将加筋重力式挡土墙拉筋破坏分为拉断和拔出2种模式,分别计算其能量耗散功率,取二者的小值作为拉筋在极限状态下的能耗功率,进而求得作用于墙背的主动土压力。以衢宁(衢州—宁德)铁路路基加筋重力式挡土墙为例,采用本文方法、数值模拟及规范方法分别计算墙背主动土压力。结果表明:本文方法与数值模拟结果吻合较好,比后者偏大15%以内;所建立的方法能充分反映墙后填土的黏聚力、内摩擦角、拉筋极限拉力、拉筋长度、间距、墙高、墙背倾角、地面倾角等重要参数对土压力的影响特征,并可用于拉筋间距及长度的优化设计。

Based on the upper bound limit analysis and considering the failure mode of plane sliding,the geogrid failure modes of the gravity retaining wall with geogrids are categorized into tensile fracture and pull out.The energy dissipation power of the two modes is determined individually and the lower value is adopted as the energy dissipation power of the geogrid at the limit state.And furthermore,the active earth pressure at the back of retaining wall is derived.A gravity retaining wall with geogrids of Q uzhou-Ningde Railway subgrade is taken for case study.The active earth pressure at the back of retaining wall is calculated in three different ways including the proposed method,the numerical simulation and the specif ication method.The results show that the result using the proposed method is in good agreement with numerical simulation result,and the former is larger than the latter within 15 %.With the proposed method,the effects of backf ill cohesion,internal friction angle,ultimate tension of geogrid,geogrid spacing,wall height,slope of wall back and slope of ground on earth pressure were revealed,which may be used for the optimization of the spacing and length of the geogrid.