深基坑土钉支护结构稳定问题的可靠度与模糊可靠度研究

发布时间：2018-10-22 09:05

【摘要】：基坑工程在岩土工程建设中占据着十分重要的地位,它影响着建筑物的整体稳定性。目前对于基坑支护稳定性的评价方法仍然是以基于极限平衡理论的安全系数法,对于其可靠度及模糊可靠度方面的评价体系尚未规范化。在基坑支护中,土钉支护结构是目前在我国得到广泛应用的基坑支护形式之一,具有成本低、施工简单、操作方便及安全可靠等优点,并取得了良好的经济效益及社会效益。本文分析了基于多种失效模式的土钉支护结构的可靠性、模糊可靠性分析和有限元数值模拟。研究了经典可靠度、模糊随机可靠度的计算方法,并结合工程实例通过编写MATLAB程序计算得到可靠指标、模糊可靠指标,并与传统安全系数相比较,得出了相关结论。在此基础上选用ABAQUS有限元软件创建土钉支护结构的二维及三维有限元模型,进行了基坑开挖过程、土体变形与土钉轴力的模拟计算,主要研究内容如下:1、基于可靠度理论,详细阐述了多元破坏模式下的可靠指标、模糊可靠指标的计算方法,并将各种可靠指标的计算步骤通过计算框图的形式列举出来,同时概括了各种计算方法的优缺点,并选取适宜的方法运用到后续的工程实例中。2、运用JC法与模糊随机可靠度法分别对深基坑土钉支护结构的稳定可靠性、模糊可靠性进行验算,包括整体抗滑移稳定性、整体抗倾覆稳定性、土钉整体抗拔出稳定性、抗楔体滑落稳定性以及土钉单根抗拔稳定性,并结合典型工程实例,通过改变土钉长度L、内摩擦角?、黏聚力c及界面粘结强度?等参数来分析它们对土钉支护结构的土钉整体抗拔出稳定可靠性的影响。3、利用ABAQUS软件对典型工程实例进行二维及三维有限元数值模拟,并分析基坑开挖过程、边坡土体变形以及土钉所受轴力情况,结合稳定可靠度理论总结相关结论,并对理论及实际工程提出有一定价值的建议。
[Abstract]:Foundation pit engineering plays an important role in geotechnical engineering construction, which affects the overall stability of buildings. At present, the safety factor method based on limit equilibrium theory is still used to evaluate the stability of foundation pit support, and the evaluation system of reliability and fuzzy reliability has not been standardized. In the foundation pit support, soil nailing support structure is one of the widely used foundation pit support forms in our country at present. It has the advantages of low cost, simple construction, convenient operation, safe and reliable, and has obtained good economic and social benefits. In this paper, the reliability, fuzzy reliability analysis and finite element numerical simulation of soil nailing support structure based on multiple failure modes are analyzed. The calculation method of classical reliability and fuzzy random reliability is studied. The reliability index and fuzzy reliability index are obtained by compiling MATLAB program combined with an engineering example, and compared with the traditional safety factor, the relevant conclusions are obtained. On this basis, the 2D and 3D finite element models of soil nailing support structure are established by using ABAQUS finite element software. The foundation pit excavation process, soil deformation and axial force of soil nailing are simulated and calculated. The main research contents are as follows: 1, based on reliability theory, The calculation methods of reliability index and fuzzy reliability index under multivariate failure mode are expounded in detail. The calculation steps of various reliability indexes are listed through the form of calculation block diagram, and the advantages and disadvantages of various calculation methods are summarized. The appropriate methods are selected to be applied to the subsequent engineering examples. 2. The JC method and the fuzzy random reliability method are used to check the stability and fuzzy reliability of the deep foundation pit soil nail support structure, including the overall anti-slip stability. Overall anti-overturning stability, overall anti-pull-out stability of soil nailing, anti-wedge sliding stability and single root anti-pull-out stability of soil nailing, and combined with typical engineering examples, by changing the length of soil nailing L, internal friction angle, cohesion C and interfacial bond strength? The influence of the same parameters on the stability and reliability of the soil nailing system is analyzed. 3. The typical engineering cases are simulated by using ABAQUS software, and the excavation process of foundation pit is analyzed. The deformation of slope soil and the axial force of soil nailing combined with the theory of stability reliability are summarized and some valuable suggestions are put forward for theoretical and practical engineering.
【学位授予单位】：苏州科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.2

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