【作者】 边亦海；

【导师】 黄宏伟；

【作者基本信息】 同济大学 ， 结构工程， 2006， 博士

【摘要】 近几年，对主要建筑项目的环境影响评估已经逐渐开始成为了一种趋势。城市深基坑工程由于其事故的多发性以及后果的严重性，越来越成为关注的热点。因此，如何尽可能减小深基坑工程施工中的事故发生率以及灾害损失，已经成为了一个迫切需要重视的课题。风险分析理论为此提供一条可行的途径。总体来讲，本文的研究主要分为三大部分。 第一部分，以深基坑工程事故统计资料为研究对象，根据勘察失误、设计失误、施工失误、监理失误、监测失误、业主单位的管理失误等六个方面分析了深基坑工程失事的原因。然后，根据收集得到的342个基坑工程事故，不同的事故责任人，不同的支护结构形式、不同的开挖深度对事故案例进行了统计分析，得到了各种不同情况下，失事基坑的频率分布和统计规律。 第二部分是深基坑支护结构本身的风险分析。首先根据深基坑工程事故资料分析结果，编制了失事频率较大的钻孔灌注桩、SMW工法桩、土钉支护、水泥土墙(深层搅拌桩)、地下连续墙的事故树，并以SMW工法桩，地下连续墙、钻孔灌注桩为例，引入模糊集概念，以模糊失效概率代替基本事件的失效概率，用三角形模糊数代替确定性发生概率，然后进行模糊数的运算，得到顶事件的模糊失效概率，并进行基本事件的重要度分析，确定减小深基坑工程支护事故发生可能性的措施。 其次，在大量的文献研究基础上，对深基坑支护结构的基于变形的稳定性进行了定量的可靠度分析，分析其基于支护结构变形的破坏模式并建立了相应的极限状态方程和可靠度模型。对模型中可能的影响参数，包括粘聚力、内摩擦角、土的重度、地面附加荷载，计算模式不定性以及外荷载，几何尺寸和材料性能指标等的变异性进行了分析，采用蒙特卡罗有限元方法计算深基坑支护结构的失效概率，并对支护结构变形失效的损失进行分析，最终得到深基坑开挖中支护结构的时变风险并结合一个实例给出了整个分析过程。 第三部分：是深基坑工程施工的环境影响风险分析。首先，根据地层损失法，时空效应法等方法对深基坑开挖引起的地表沉降进行了分析。在地表沉降分析的基础上，按照建筑物上部结构形式的不同，将建筑物分为砖混结构和框架结构两大类，采用裂缝宽度作为建筑物破坏的评价标准来计算建筑物的损失，并更多还原

【Abstract】 In recent years, it’s a trend to assess environmental impact of main building project. There has been an increasing concern on deep excavations in urban area because of it’s frequent accidents and huge losses. As a consequence, how to reduce the accidents and losses of deep excavations has become an important task. Risk analysis theory maybe a feasible way. In general, this paper includes three parts.In the first part, based on the statistical data of deep excavations accidents, accidents cause of deep excavations are analyzed by survey error, design error, construction error, monitor error, supervisor error and owner error. According to 342 deep excavations accidents, statistical analysis is done through different accident responsibler, different retaining structures, different excavation depth. Frequency distribution and statistical law of failure deep excavations is obtained in different situation.The second part is risk analysis of retaining structures of deep excavations. Firstly, according to the analysis result of deep excavations accidents, fault tree of drilled piles, soil mixing wall, composite soil nailing, cement-soil retaining wall and diaphragm wall are established. As a example, a triangular fuzzy number is introduced to represent the failure probability of a basic event. The fuzzy failure probability of SMW retaining structures in deep excavations is calculated by a fuzzy fault tree. Main basic events affecting the occurrence probability of the top event are verified by a sensitivity analysis, which can be applied in the risk analysis of SMW retaining structures in deep excavations.Secondly, based on deformation of retaining structures in deep excavations, failure mode is analyzed, and corresponding limit state equation and reliability model is established. Variability of affecting parameters, including cohesion, internal friction angle, soil gravity, extra load, calculation mode uncertainty, external load, physical dimension, material performance are analyzed. Failure probability of retaining structures in deep excavations is calculated by Monte-carlo FEM and failure loss of retaining structures is analyzed. Finally, time-dependent risk of retaining structures in deep excavations is obtained and the whole analysis procedure is presented with a example.The third part is environmental impact risk analysis of deep excavations更多还原