为解决非对称基坑环梁支护体系局部失效导致基坑发生连续破坏问题，依托北京某基坑工程，通过三维有限元模拟结合现场实测，研究地表沉降、地下连续墙水平位移以及支撑结构内力（弯矩、轴力）的演化规律，数值模拟结果与现场监测结果具有很好的一致性； 针对环形支撑不同角撑方案，利用“拆除杆件法”分析非对称双环梁支撑结构的抗倒塌能力； 最后，采用冗余度理论计算得到各方案各支撑的强度冗余度和刚度冗余度。研究表明： 1）基坑呈阶梯状开挖坑中坑时，处于中间高度的地表沉降受到两侧土体高度和边界距离的共同影响，距离越近影响越大； 2）地下连续墙水平位移随基坑开挖深度呈“弓”形分布，在支撑位置处发生突变，位移变化速度受两侧基坑深度及支撑体系共同影响； 3）非对称基坑大环梁各部位轴力及弯矩随开挖步序离散程度逐渐增大，环梁各部位杆件冗余度离散程度同样升高； 4）支撑内力离散程度与基坑跨度及开挖深度呈正相关，增加传力路径可有效缓解内力离散，但当传力路径增大到一定程度缓解效果减弱； 5）角撑位置对整体支撑体系内力分配影响较大，中间角撑失效时强度冗余度绝对值趋近于1； 6）中间位置角撑对结构倒塌的抵御能力影响最大，最短角撑失效对结构刚度影响最小。

A case study is conducted on a foundation pit project in Beijing, China, to address the continuous failure caused by partial failure of ring beam support system in asymmetric foundation pit. Further, the evolution law of surface settlement, horizontal displacement of diaphragm wall and internal forces (bending moment and axial force) of supporting structure is investigated using threedimensional finite element simulation and field monitoring methods. The numerical simulation results are in good agreement with the field monitoring results. The collapse resistance of asymmetric doublering beam supported structure is analyzed using the method of "removing the rod" for different Angle bracing schemes. Finally, the strength redundancy and stiffness redundancy of each support are calculated using redundancy theory. The results show the following: (1) The surface settlement at the middle height is affected by both soil height and boundary distance, and the closer the distance, the greater is the influence. (2) With the excavation depth of foundation pit, the horizontal displacement of diaphragm wall presents a bow shape distribution, and suddenly changes at the supporting position. The displacement change speed is affected by the depth of foundation pit on both sides and the supporting system. (3) The axial force and bending moment of each part of the large ring beam in asymmetric foundation pit gradually increase with the dispersion degree of the excavation sequence, and the dispersion degree of the member redundancy of each part of the ring beam also increases. (4) The dispersion degree of bracing internal forces positively correlates with the span and excavation depth of the foundation pit. Increasing the transmission path can effectively alleviate the dispersion of internal forces. However, when the transmission path increases to a certain extent, the relief effect weakens. (5) The position of the Angle braces has a great influence on the internal force distribution of the entire support system, and the absolute value of the strength redundancy tends to 1 when the middle Angle braces fail. (6) The middle Angle brace has the greatest effect on the collapse resistance, while the shortest Angle brace has the least effect on the stiffness.