【作者】 李英华；

【导师】 张明媛；

【作者基本信息】 大连理工大学 ， 工程管理， 2017， 硕士

【摘要】 随着我国国民经济以及城市建设的快速发展,城市空间也变得日益紧缺。城市地下空间的开发和利用有效缓解了城市住房紧张和交通拥挤状况。随着地下室、地下停车场、地下铁道等大量的出现,深基坑工程应运而生。深基坑工程是一项复杂且重要的工程,它的稳定与否不仅关系自身的安全,而且还会对周边建筑物的变形造成影响,所以预防深基坑边坡失稳十分重要。基坑边坡稳定性分析是基坑工程顺利开展的前提和依据,要想真实地反映和分析基坑边坡的稳定性,首先要查清基坑工程地质条件及其相关土体参数,并找到众多因素中影响基坑边坡稳定性的主次关系,其次又要有科学合理的分析方法,抓住问题的关键因素。通过对监测数据分析,能揭示深基坑的外部变形状态,掌握建筑物沉降变形的原因及趋势,提出风险管理建议。除此之外,在实测资料的基础上采用科学有效的方法对深基坑的变形趋势进行预测和控制能有效预防深基坑事故的发生。为了研究不同影响因素对基坑边坡失稳的贡献程度,将某大学文化中心的基坑边坡作为实例研究,把基坑土体的粘聚力、重度、内摩擦角、坡度、坡高5个影响因素作为研究对象,研究其对基坑边坡稳定的敏感性。在常规正交试验设计分析的基础上,借助MATLAB软件进行编程,计算瑞典条分法和毕晓普法的安全系数,并依据实例数据分别计算出边坡安全系数,通过应用四种分析方法,包括极差分析、方差分析、因素间交互作用影响分析以及安全系数变化率趋势分析,将不同因素的敏感程度转化为数值变化,定量的得出在这五个敏感性因素中,哪些是相对主要因素和哪些是相对次要因素。通过多种试验的综合分析,结果表明:土体的粘聚力,重度和坡高为相对主要因素,内摩擦角与坡度为相对次要因素。分析结果符合工程实践经验,能为日后类似工程提供借鉴。分析是前提,监测是手段,预测是目的。为明确深基坑开挖引起的地表沉降变形规律,对大连市Z地铁站的第29-48期深基坑沉降监测数据结合施工过程进行分析,找到深基坑地面沉降变形的普遍规律和特点,并提出风险管理建议。同时,结合C#软件对灰色GM(1,1)模型进行建模预测,预测时考虑不同施工阶段对实测数据的影响,对两个变化类型不同的沉降点沉降变化进行预测。结果显示,在应用灰色GM(1,1)模型对深基坑的沉降进行预测时,考虑施工过程的影响更加可靠。可见,深基坑的沉降变形与开挖施工过程紧密相关。该研究得出的结论能为日后深基坑沉降实测数据资料的分析与预测提供参考。更多还原

【Abstract】 The contradiction between the increasing construction demand and the limited urban space has become more and more obvious with the rapid growth of national economy and urban construction,while the development and use of urban underground space effectively help relieve urban disease such as housing shortage and traffic congestion.The requirement of solving analytical problems existed in the underground construction project urged the emerge of deep excavation engineering,which has for a long time played an important role in structural safety as its stability not only decides its own safety,but also influences the structural distortion of the buildings surrounded.Stability analysis of foundation pit slope is the primary basis of deep excavation construction,and a framework of analytical process was constructed in the paper so as to reveal slope stability correctly.The engineering geology conditions of the foundation pit project and its relative soil parameters must be mastered at first in order to distinguish the main as well as the subordinate factors influencing slope stability,and the scientific analytical method was used to extract the most critical ones.The dynamical slope deformation was revealed through the analysis of monitoring data,which helped explain reason and tendency for building settlement deformation as well as provide suggestion for the risk management.In addition,taking reasonable forecast and control measures in line with the slope deformation tendency can effectively help prevent accidents related to deep foundation pits.In order to study the factors affecting the degree of contribution to the foundation pit slope instability.Taking the foundation slope of a university culture center as an example,the sensitivity analysis of the factors which influence the slope stability of the foundation pit including foundation soil cohesive force,internal friction angle,weight,height and slope was done.The quantitative evaluation of sensitive factors was done based on the combination of conventional orthogonal experiment,the calculation of soil mechanics safety coefficient by Sweden Circle and Bishop methods were done by Matlab software.The slope safety coefficient was calculated according to instance data,quantitative evaluation of the sensitivity of the factors was done by range analysis,variance analysis,interactive analysis and variation trend analysis of safety coefficient in order to find the main and secondary factors influencing the stability of foundation pit.The results obtained through the comprehensive analysis of a series of experiments,which were in accordance with engineering practice,showed that soil cohesive force,weight and height should be taken as the main factors whereas internal friction angle and slope as the secondary ones and could provide guidance for similar projects in the future.Analysis is the premise,monitoring is a means,forecasting is purpose.In order to define settlement deformation feature of ground surface caused by deep pit excavation of subway,refering to the construction process,data monitored of deep pit in Dalian city subway station is analyzed.It is concluded that common ground subsidence deformation characteristics of deep foundation pit,and put forward the risk management advice.At the same time,in order to forecast the settlement of two typical points of monitoring data,we used the grey GM(1,1)model which combined with C# software according to different construction stages.Prediction results show that the gray GM(1,1)model is reliable in the prediction of deep foundation pit settlement and the prediction in stages has higher reliability.It can be seen that the deformation of deep foundation pit is closely related to the excavation and construction,which can improve the forecast precision by combining with the construction schedule.It can provide reference for the analysis and forecast of the settlement monitoring data of Metro deep foundation pit in future.更多还原