地震作用下刚性挡土墙发生转动时动主动土压力计算

Calculation of dynamic active earth pressure of rigid retaining walls when rotation mode in earthquakes

为研究地震作用下成层土主动土压力、墙后土坡及墙体位移模式对主动土压力的影响,本文采用水平层分析法,考虑滑动土楔体内水平土层间的平均剪应力,对不同位移模式下水平微分单元进行了受力分析,得到了地震作用下主动土压力的表达式;并进行了土层间等效内摩擦角、墙背摩擦角及土坡角对主动土压力的影响研究。研究结果表明:墙后填土由于为成层土,土体物理特性不同,导致土压力强度在土层间位置会发生突变;在两种位移模式下,土压力强度均呈非线性分布;随着坡角和地震系数的增大,动主动土压力合力增大,并且合力作用点的位置也在提高,RT模式下作用点高度明显大于RB模式。

In this study, the dynamic active earth pressure of layered soil is investigated using the horizontal slicemethod with the average shear stress between horizontal soil layers in the sliding wedge is taken into account. The expression of active earth pressure under earthquakes is obtained by analyzing the force acting on horizontal micro-elements, and the effects of internal friction angle, wall friction angle and slope angle on the active earth pressure are verified. Results obtained show that due to the different physical properties of layered soils, the earth pressure intensity changes abruptly at the interface of different soil layers. In both displacement modes, the earth pressure strength is nonlinearly distributed. With the increase of the slope angle, the active earth pressure is increasing and the position of the resultant force point is also increased under different slope angles. As the seismic coefficient increases, the combined force of the active earth pressure increases, and the position of the resultant force point also increases. By comparing the two displacement modes, it is found that the position of the action point in the RT mode is significantly higher than the position of the action point in the RB mode.