考虑支护—围岩相互作用的隧道开挖可靠度分析与设计优化

发布时间：2018-03-17 14:25

本文选题：隧道工程　切入点：收敛约束法　出处：《浙江大学》2017年博士论文　论文类型：学位论文

【摘要】：随着国民经济持续快速发展,各种重大基础设施建设迫切需要新建大量隧道、地下硐室等岩石地下工程。地下岩体工程因其所处环境的复杂性且受各种因素的影响,使其存在极大的不确定性和变异性。基于概率统计的可靠度方法因其可以定量的考虑各种不确定性因素及岩土体力学参数、实际荷载及支护结构等变异性的影响,在隧道等地下工程领域日益得到重视和关注。为此,本文针对地下工程围岩变形与稳定可靠性分析与评价,建立了考虑支护与围岩相互作用的隧道多重失效模式及其对应的功能函数;提出了基于移动最小二乘法的隧道可靠度分析的一阶可靠度法和二阶可靠度法;发展了基于条件概率和Excel电子表格的隧道系统可靠度分析方法;建立了考虑岩体参数空间变异性的隧道可靠度分析方法;构建了基于响应面法的隧道开挖概率设计优化模型。通过以上研究,获得了以下主要成果和认识:(1)利用收敛约束法,阐述了隧道开挖过程中围岩与支护的相互作用机理,并建立了考虑支护与围岩相互作用的隧道开挖稳定可靠性分析的多种功能函数。(2)结合均匀设计,提出了基于移动最小二乘法的隧道可靠度分析新算法。通过均匀设计取样,在U空间(标准正态空间)中构建移动最小二乘响应面,并利用迭代算法不断更新响应面从而获得准确的可靠度结果。与其他响应面模型相比,新算法不仅具有较高的计算精度,且计算量小、内部参数简单,使得可靠度分析简便容易。(3)针对具有多个相关失效模式的隧道问题,提出了基于条件概率的系统失效概率计算方法。通过引入“DS类模型”,实现了“共同来源随机变量”的识别与定义,将相关失效模式事件转换成条件独立失效模式事件。通过条件概率,将系统可靠度分析转换成单失效模式可靠度分析,并建立了基于Excel电子表格的简单、方便且透明的系统失效概率计算程序。(4)利用插值自相关和响应面法,提出了考虑岩体参数空间变异性的可靠度分析新算法。通过插值自相关,将随机场离散为一系列控制点处的随机变量,并结合响应面,利用一阶可靠度法进行随机可靠度分析,揭示了岩体参数空间变异性对隧道变形失效概率的影响规律,研究了岩体参数波动范围对隧道变形失效概率的影响,探讨了插值自相关中控制点间距对结果的影响。(5)针对具有多个失效模式的隧道支护系统,提出了基于可靠度的概率设计优化模型。利用响应面,分别通过可靠指标法和功能度量法进行概率设计优化的求解,并比较了两种方法的效率和准确性。讨论了岩体质量、设计变量变异系数和目标可靠度指标等因素对概率设计优化的影响。
[Abstract]:With the sustained and rapid development of the national economy, a large number of underground rock projects, such as tunnels and underground chambers, are urgently needed for the construction of major infrastructure facilities. The underground rock mass engineering is affected by various factors because of the complexity of the environment in which it is located. The reliability method based on probability and statistics can take into account all kinds of uncertainty factors, physical parameters of rock and soil, actual load and support structure, etc. More and more attention has been paid to underground engineering fields such as tunnels. Therefore, this paper analyzes and evaluates the reliability of surrounding rock deformation and stability of underground engineering. The multi-failure mode of tunnel considering the interaction between support and surrounding rock and its corresponding function function are established, and the first-order and second-order reliability methods of tunnel reliability analysis based on moving least square method are proposed. The reliability analysis method of tunnel system based on conditional probability and Excel spreadsheet is developed, and the tunnel reliability analysis method considering the spatial variability of rock mass parameters is established. The optimization model of tunnel excavation probability design based on response surface method is constructed. Through the above research, the following main achievements and understandings are obtained. By using the convergence constraint method, the interaction mechanism between surrounding rock and support during tunnel excavation is expounded. A new algorithm of tunnel reliability analysis based on moving least square method is proposed, which considers the interaction between support and surrounding rock, and combines with uniform design. Sampling through uniform design is carried out. The moving least square response surface is constructed in the U space (standard normal space), and the response surface is continuously updated by iterative algorithm to obtain accurate reliability results. Compared with other response surface models, The new algorithm not only has high calculation accuracy, but also has a small amount of calculation and simple internal parameters, which makes reliability analysis simple and easy. This paper presents a method for calculating system failure probability based on conditional probability. By introducing "DS class model", the identification and definition of "common source random variable" are realized. The correlation failure mode event is transformed into conditional independent failure mode event. Through conditional probability, the system reliability analysis is transformed into single failure mode reliability analysis, and a simple method based on Excel spreadsheet is established. By using interpolation autocorrelation and response surface method, a new reliability analysis algorithm considering spatial variability of rock mass parameters is proposed. The random field is discretized into a series of random variables at the control points. Combining with the response surface, the random reliability analysis is carried out by using the first-order reliability method. The influence of the spatial variability of rock mass parameters on the failure probability of tunnel deformation is revealed. The influence of rock parameter fluctuation range on the failure probability of tunnel deformation is studied, and the influence of control point spacing in interpolating autocorrelation on the result is discussed. The probabilistic design optimization model based on reliability is put forward. The reliability index method and function measure method are used to solve the probabilistic design optimization by using response surface, and the efficiency and accuracy of the two methods are compared, and the quality of rock mass is discussed. The influence of variable coefficient of variation and target reliability index on probability design optimization.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U455

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