临近地下室外墙影响下的挡土墙空间土压力研究

目前关于临近地下室外墙影响的挡土墙空间土压力的计算理论的研究还比较少，原有的平面应变条件下的理论不能满足挡土墙的长高比B/H较小时的挡土墙土压力计算要求。通过将土拱效应原理引入顾慰慈[8]建立的空间土压力计算模型，建立了考虑土拱效应的临近地下室外墙影响的空间土压力计算模型，根据挡土墙和地下室外墙的间距与土体破裂面状态的关系将该模型分为3种情况，并将各模型划分为Ⅰ、Ⅱ、Ⅲ、Ⅳ四个区域，通过在各个区域内取水平微分单元体，建立各微分单元体的水平和竖向静力平衡方程，推导出了各区相应的挡土墙空间主动土压力计算公式，该公式可以计算出墙背任意位置的主动土压力；并提出了空间土压力合力及其合力作用点的计算方法。通过算例计算可以直观地看出挡土墙后主动土压力的空间分布，由此可以看出，当空间效应存在时，考虑土拱效应的挡土墙主动土压力沿墙长的分布与平面应变条件时有很大的不同，此时挡土墙两端附近区域的主动土压力远小于平面应变条件下计算出的主动土压力，同时可以看出，考虑空间效应的挡土墙主动土压力合力作用点要比平面应变条件下的位置要高，挡土墙长高比B/H越小，空间效应对主动土压力沿墙长的分布和主动土压力合力作用点位置的影响越大。

Research on space earth pressure behind retaining wall adjacent to existing basements exterior wall

Currently the less effort of research on the theory of space earth pressure behind retaining wall adjacent to existing basements exterior wall has been made. the existing plane strain state theories can’t satisfy the calculation requirement of the earth pressure behind retaining wall adjacent to existing basements exterior wall when the length height ratio B/H of retaining wall is smaller. In this paper, soil arching effects principle is introduced into the space earth pressure calculation model built by GU[8] and a model for calculating space earth pressure is developed considering soil arching effect and existing basements exterior wall. Based on the relationship between the failure space and the distance of two walls, the soil between the retaining wall and the existing basement exterior wall is divided into four districts, I, II, III, IV. Formulas for calculating the space active earth pressure in every district behind the retaining wall are derived by establishing horizontal and vertical static equilibrium differential equation of the horizontal differential element taken from every district. The Formulas can be applied to calculate the active earth pressure wherever behind the retaining wall. Furthermore, the method of resultant force of the space active earth pressure and its position are also put forward. The spatial distribution of active earth pressure behind the retaining wall can be seen visually through the calculation of the numerical examples. Two conclusions can be drawn as follows: When the spatial effect exists, the active earth pressure distribution considering the soil arching effect along the retaining wall is quite different from that when the retaining wall is in the plane strain state; that is, the active earth pressures behind both ends of the retaining wall are much smaller than that in the plane strain state. The position of the active earth pressure resultant force point considering spatial effect is higher than that in plane strain state; and when the B/H gets smaller，the influence of spatial effect on the distribution of active earth pressure along the retaining wall and the position of the resultant force point will increase.