绕墙底转动模式下装配式挡土墙土压力研究

Earth Pressure of Assembled Retaining Wall with DisplacementMode of Rotating around the Base

墙背土压力分布及大小是装配式挡土墙设计的关键依据。设计并开展新型装配式混凝土挡土墙现场试验,研究挡土墙在加载条件下的位移模式和土压力分布规律。以现场试验为原型,建立无黏性填土、墙背倾斜且粗糙的挡土墙理论计算模型,同时考虑挡土墙位移模式与大小、土拱效应和土层间剪应力的影响,采用水平层分析法推导了绕墙底转动(RB)模式下挡土墙的土压力计算公式。结果表明:①该装配式挡土墙整体性能良好,绕墙底刚性转动。在RB模式下,墙顶处土体最先达到主动极限状态,土体从上至下逐渐达到极限状态;任意深度处的土体位移S_(c)达到7 mm时将达到极限状态,即S_(c)=0.16%H(H为墙高)。②本文理论解与试验值吻合较好,计算公式可用于求解挡土墙绕墙底转动过程中的土压力分布及大小。③随着挡土墙转动幅度的增大,土压力分布曲线凹向逐渐明显,土压力合力作用点高度呈现先降低后回升的现象;挡土墙转动角度η=0.007 rad为挡土墙达到主动状态的临界值。

The distribution and magnitude of earth pressure behind wall is the key basis for the design of assembled retaining wall.We investigated the displacement patterns and soil pressure distribution of retaining walls under loading conditions via designing and conducting field tests of a new type of assembled concrete retaining wall.Based on the field tests,we established the theoretical computational model of retaining wall with sloping and rough wall backs yet with no cohesive fill.In consideration of factors such as displacement pattern and magnitude,soil arching effect,and interlayer shear stress,we adopted the horizontal layer analysis method to derive an earth pressure formula for retaining wall rotating around the base(RB),defined as an RB displacement mode.Results indicate a sound overall performance of the retaining wall,rigidly rotating around the base.Under the RB mode,soils at the top of the wall reach the active limit state first,progressively followed by lower depths.Limit state will be reached when soil displacement S_(c) reaches 7 mm at any depth,corresponding to S_(c)=0.16%H(H is the wall height).The theoretical value closely matches test value,demonstrating the applicability of our derived formula in predicting the distribution and magnitude of earth pressure during the retaining wall’s rotation around the base.Furthermore,as the rotation intensifies,the concavity of the earth pressure distribution curve becomes more pronounced,and the height of the resultant soil pressure force point initially decreases and then recovers.A rotation angleη=0.007 rad is identified as the critical threshold for the retaining wall to reach its active limit state.