郑 刚 ,赵璟璋 ,程雪松,俞丹瑶 ,王若展,朱晓蔚 ,衣 凡

AuthorsHTML:郑 刚 ^1,2，赵璟璋² ，程雪松 ^{1, 2}，俞丹瑶 ² ，王若展 ² ，朱晓蔚 ² ，衣 凡 ²

AuthorsListE:Zheng Gang,Zhao Jingzhang,Cheng Xuesong,Yu Danyao, Wang Ruozhan,Zhu Xiaowe,Yi Fan
AuthorsHTMLE:Zheng Gang^{1, 2}，Zhao Jingzhang²，Cheng Xuesong^{1, 2}，Yu Danyao²， Wang Ruozhan²，Zhu Xiaoweⁱ²，Yi Fan²
Unit:1. 滨海土木工程结构与安全教育部重点实验室(天津大学)，天津 300072；
2. 天津大学建筑工程学院，天津 300072

Unit_EngLish:1. Key Laboratory of Coastal Civil Structure Safety of Ministry of Education(Tianjin University)，Tianjin 300072， China；
2. School of Civil Engineering，Tianjin University，Tianjin 300072，China

Abstract_Chinese:近年来，关于基坑连续破坏的研究已经取得了一定的进展，但对于内支撑式基坑局部破坏引发沿竖向连续 破坏的发展规律及其控制措施目前仍缺乏系统研究，而实际工程中竖向连续破坏的案例却经常出现．本文依托新加 坡地铁 Nicoll Highway 事故案例，建立了有限差分法数值模型，探究了不同构件极限承载力情况下基坑支护体系由 初始破坏引发的连续破坏过程，以及不同初始破坏程度下的支撑体系竖向荷载传递规律，进而提出了多道内支撑式 基坑在竖向上的连续破坏控制方案．研究结果表明，支撑初始破坏后的荷载转移主要作用于紧邻层支撑，导致其轴 力迅速大幅度增加，而其余远处支撑所受影响甚微，因此初始破坏极易引发紧邻层支撑后续破坏，且后续破坏更易 向上发展；支撑竖向连续破坏过程中，当下部支撑破坏范围较大时，由于地下连续墙墙顶向坑外挠曲，首道支撑常 会出现拉力导致支撑掉落；当支撑失效超过一定数目时，地连墙最大弯矩超出受弯极限承载力而折断破坏，进而引 发基坑整体垮塌．依据不同初始局部破坏情况下的荷载传递规律，在保证所有钢支撑与地连墙节点连接抗拉强度的 前提下，通过加强关键部位钢支撑(例如第 1 道及倒数第 2 道等)，可有效控制支撑体系沿竖向的连续破坏，增强整 个支护体系的整体安全性．
Abstract_English:In recent years，several researchers have investigated the progressive collapse of deep excavation. How ever，the process and control measures of the vertical progressive collapse caused by the local failure of excavations retained by a propped retaining system have not been investigated，although many vertical progressive collapse cases have been recorded. Based on the Nicoll Highway accident in Singapore，numerical simulations using the finite difmethod were conducted to explore the vertical progressive collapse process caused by the initial local failure in deep retaining structures with different ultimate bearing capacities and to investigate the load transfer law in the verti\u0002 cal direction of the strutting system under different initial local failure degrees. Then，a method to control the vertical progressive failure was proposed. The simulation results show that the load transfer after the initial local failure mainly acts on the adjacent layer，causing its forces to increase rapidly and significantly，which subsequently leads to failure，particularly those developing upwards. Meanwhile，the rest of the distant struts are minimally affected. Dur\u0002 ing the vertical progressive collapse，if the damage range of the lower struts is large enough，the struts in the first layer are subject to tensile force and subsequently fall because the top of the diaphragm wall deflects toward the outside of the pit. When the failed struts exceed a certain number，the diaphragm wall will break because the maximum bending moment exceeds the ultimate bending capacity，causing the overall collapse of the excavation. According to the load transfer law under different initial local failure cases，by strengthening the key parts of the steel struts(such as the first and penultimate layers)，the vertical progressive collapse of the strutting system can be effectively controlled，and the safety of the entire retaining system can be enhanced under the premise of ensuring the tensile strength of the connection between all of the steel struts and the diaphragm wall.
Keyword_Chinese:基坑；内支撑；有限差分法；连续破坏
Keywords_English:excavation；strutting system；finite difference method；progressive collapse

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