【作者】 徐兴良；

【导师】 孙春岩；

【作者基本信息】 中国地质大学（北京） ， 地质工程， 2014， 博士

【摘要】 近几年，随着城市建设的快速发展，特别是在一线大城市，高层建筑的迅速发展和地下空间的充分利用促进了深基础的发展，这必然带来大量深基坑的开挖与支护。目前，深基坑工程已逐渐呈现出“数量越来越多、规模越来越大、深度越来越深、难度越来越大”的特点。从目前情况看，错综复杂的地层构造，高度不确定的土体性质，加上设计的不合理性，施工管理的不完善等原因，深基坑边坡不稳定是经常发生的深基坑事故，这种坍塌事故比较严重的时候将会造成较大的经济损失和严重的社会影响。因此，对深基坑边坡稳定性进行研究具有重要的现实意义。文章首先论述了选题的意义及国内外研究现状，接着阐述了目前桩锚围护结构的构造类型、护坡原理及设计计算原则。其次，介绍了依据不同标准及不同规范对深基坑安全性的等级划分，对比分析了目前深基坑边坡稳定性的评估方法，并提出了利用测斜仪对桩体变形监测位移数据的信息，根据实测数据，利用差分法计算分析围护桩弯矩，阐明了该方法评价深基坑边坡稳定性的理论依据和优势，详细分析了其计算原理、计算步骤及适用性。再次，文章详细分析了基于测斜数据的围护桩弯矩计算的影响因素，主要包括测量误差、基坑设计方案和计算方法参数选择等三个方面，阐述了误差产生的原因，并提出了相应的解决办法。文章最后以广安门医院扩建门诊楼项目深基坑工程为例，通过在施工过程中对现场实际数据的监测，采用FLAC‐3D软件对基坑开挖和支护进行了模拟分析，得到基坑及支护结构的变形和受力数据。并将上述数值分析成果和实际的基坑监测成果进行了对比分析，验证了数值分析的可靠性。同时，依据前文所述的基于差分法分析计算桩弯矩的方法，采用测斜数据计算得到了实际的桩的弯矩值，并将其与采用弹性法计算得到的弯矩进行了比较，得到了桩弯矩的发挥程度。再根据现行规范对于基坑变形和支撑内力发挥程度的规定，结合基坑实际情况，确定了基坑变形和桩弯矩发挥程度报警值，并将基坑监测数据进行分析，最终得到了基坑安全状态，验证了通过围护桩弯矩判定基坑安全状态的方法的可行性。更多还原

【Abstract】 With the rapid development of city construction, the high-rise buildings and thefull use of underground space promote the development of deep foundation pit, whichleads to a large number of deep foundation excavations. At present, the deepfoundation pit engineering has been gradually showing the characteristic of increasingnumber, larger scale, deeper and more difficult in technology. Because of perplexinggeological structure, uncertainty of soil properties and lack of effective design andconstruction management, collapse of deep foundation pit slope occurs frequently.Serious collapse will lead to great economic loss and bad social influence. So it hasimportant practical significance to study the stability of deep foundation pit.Firstly, this dissertation discusses the significance of the topic and the status offoundation pit research at home and abroad. After that, the structure type, slopeprotection principle and design calculation principle of pile-anchor supportingstructure are presented.Secondly, the classification of safety level of deep foundation pit is introducedaccording to different standards. The comparative analysis is done for someevaluation methods of the deep foundation pit slope stability. A new method has beenpresented, which uses the central difference method to analyze the pile bendingmoment according to the data of pile deformation which is monitored by inclinometer.The theory basis and the advantage of the evaluation method are explained. There is adetailed analysis of the calculation principle, calculation steps and applicability in thisdissertation.Thirdly, the factors affecting the calculation results are analyzed according toinclinometer data. These factors mainly include measurement error, design scheme offoundation pit and the parameters selected for calculation. At the same time, thecorresponding solutions are put forward.Finally, the deep foundation pit project in Guang’anmen hospital is taken as anexample. The excavation and support are analyzed by FLAC-3D software through theactual monitoring data which is monitored during the construction process. The comparative analysis of monitoring results and the numerical simulation results isdone and the reliability of numerical simulation analysis is verified. At the same time,on the basis of the central difference method mentioned above, the monitor data iscompared with the elastic method. According to the standards for foundation pitdeformation and internal force of supporting structures, the alarm value ofdeformation and moment are confirmed. The method of determining the safetysituation of foundation pit by the moment of supporting structures is feasible.更多还原