中文摘要：

城市地区密集的基坑群施工中,有时会遇上两个甚至多个基坑在同一时期进行开挖施工的情况。相邻基坑开挖的失效机理、破坏模式与基坑单独开挖存在较大的差异,目前尚缺乏考虑相邻基坑开挖的基坑失效机理和破坏模式研究。以某实际相邻双基坑工程为原型,利用Rockscience Phase2有限元软件建立相邻基坑开挖的二维模型,采用应变剪切带判别基坑破坏模式,采用强度折减法分析基坑稳定性,探讨影响相邻基坑稳定性的主要因素。结果表明：相邻基坑破坏模式主要表现为上部倾覆破坏或下部滑移破坏或两者组合破坏形式。开挖深度、基坑间距、锚杆长度、支护桩嵌固深度、土体强度、支护方式和软土层厚度等对相邻基坑破坏模式产生明显的影响。

英文摘要：

It was inevitable to excavate two or more ajacent foundation pits at the same time because of the construction of a group of intensive foundation pits caused by high density of high-rise buildings.The failure mechanism and failure mode of twin ajacent excavations were quite different from those of single excavation.Current researches seldom touched on the issue of the failure mechanism and failure mode of adjacent excavations.A twodimensional finite element model for the actual twin adjacent foundation pits was established by Rockscience Phase2 software,in which the reduced shear strength method was used to evaluate the stability of excavations.The criteria of the strain-based shear zone to determine the failure mode of excavations were presented.Then,the impact factors of the stability of twin ajacent excavations were investigated.The results indicated that the overturning failure of the upper excavations or slip failure of the base of excavations or the combination of the two failure modes were the main failure modes of ajacent twin excavations.All of the excavation depth,the distance between adjacent excavations,the length of anchors,the embedded depth of piles,the shear strength of soil,the type of supporting structures and the thickness of soft soil layer had significant influences on the failure mode of the adjacent excavation.