基坑工程中常采用土体加固措施来减少围护结构的侧移。为了探讨坑中坑土体加固对悬臂式围护结构的影响规律,利用ABAQUS有限元软件,建立坑中坑土体加固的弹塑性计算模型,讨论加固深宽、宽度、加固刚度、加固体位置、加固体尺寸对内外坑围护结构的影响。计算结果表明:被动区加固宽度、深度、刚度都存在一个最优范围,超过该范围之后,对基坑围护结构加固效果不再明显;在坑中坑类型的基坑中,外坑被动区阶梯型加固能达到全尺寸加固的效果,因此经济上更加合理;当各阶梯加固的深度和宽度相等时,加固效果较好。研究结果可为坑中坑围护结构实际工程的应用提供参考。

Soil reinforcement is often used to reduce the lateral deformation of retaining structure in foundation pit projects. In order to study the influence of pit-in-pit soil reinforcement on cantilever retaining structure, we established an elasticity-plasticity calculation model for soil reinforcement of pit-in-pit by using ABAQUS and discussed the effects of depth, width, stiffness, location and size of reinforcement body on retaining structures of inner pit and outer pit. Calculated results show that 1) there is an optimum interval for the values of depth, width, and stiffness of passive reinforcement zone respectively, beyond which the reinforcement effect on retaining structure of pit will be not obvious;2)for pit-in-pit, the effect of stepped reinforcement in the passive zone of outer pit could reach that of full-size soil reinforcement, hence is more economic;3)when reinforcement width and reinforcement depth of each step are approximately equal, the reinforcement effect is good. Finally, the research results can be taken as reference for pit-in-pit retaining structure in actual projects.