浅埋偏压隧道稳定性分析及其可靠度研究

发布时间：2018-05-20 10:49

本文选题：浅埋偏压隧道 + 稳定性分析　；参考：《中南大学》2014年博士论文

【摘要】：随着我国经济发展对综合交通网络和现代化城市建设的依赖性日益增强,浅埋隧道工程作为一种重要的交通构筑物型式,在丘陵山区斜坡地段公路、铁路建设和城市地下空间开发利用过程中往往不可避免,而浅埋隧道开挖引起的围岩应力、位移变化较之深埋隧道更为复杂,研究浅埋隧道稳定性和形变问题对于隧道设计、施工和理论研究具有重要意义。学术界和工程界普遍认为：企图采用一种理论,彻底解决各种不同地质条件下和不同使用目的的隧道工程的难题是不现实的,必须综合利用多种理论研究手段才可获得最佳效果。因此,有必要丰富、完善和拓展经典理论在浅埋隧道工程之中的应用,以期为浅埋隧道工程设计和施工提供科学理论指导。本文的主要研究内容如下： (1)基于极限分析上限定理和“切线法”非线性破坏准则,构建了考虑地表倾斜和隧底隆起的浅埋隧道围岩破坏机制,进而推导浅埋隧道极限围岩压力计算表达式,并运用非线性规划优化方法对目标函数进行优化求解。对典型影响因素的敏感性进行算例分析,探讨了斜坡坡脚开挖对围岩稳定性的影响。结合c、φ值分别取不同折减系数的综合强度折减技术,为浅埋隧道围岩稳定性评价提供一种新的思路和方法。 (2)依托湖南省永吉高速公路龙潭坪隧道工程实例,以塑性区贯通为失稳判据,结合数值模拟方法和正交试验原理,辨明影响浅埋隧道围岩稳定性的主控因素。将浅埋隧道围岩稳定性极限上限分析方法、综合强度折减技术和可靠度理论有机结合,运用蒙特卡罗法计算浅埋隧道围岩的失效概率和可靠度指标,同时分析了c、φ值不同概率分布形式以及参数间相关性对隧道工程可靠度的影响。 (3)基于极限分析上限定理,结合Hoek-Brown破坏准则和非关联流动法则,构建浅埋隧道掌子面三维多滑块型破坏机制,推导浅埋隧道掌子面支护反力计算式。运用非线性优化方法对目标函数进行优化求解,进而分析不同参数对浅埋隧道掌子面支护反力的影响规律,并对管棚注浆预支护条件下的浅埋隧道开挖掌子面稳定性进行拓展研究。 (4)基于经典弹塑性理论,考虑岩土介质的应变软化效应,采用岩石材料的三线性应力-应变软化(弹性-塑性软化-塑性残余)模型和虎克-布朗(Hoek-Brown)强度准则,运用逐步求解法获得非对称荷载下圆形隧洞围岩弹性区、塑性软化区和塑性残余区的应力场、位移场和塑性区半径的近似解析解。 (5)针对边坡开挖和隧道掘进共存的特殊工况,以经典弹塑性理论解析计算所得的围岩径向位移为最大隧洞收敛的初值,构建山体斜坡和椭圆形隧道非均匀收敛的随机介质理论分析模型,推导出边坡开挖和隧道掘进引起地表移动与变形的计算公式,并结合现场监测数据对计算结果进行验证,拓宽了随机介质理论的工程应用领域。
[Abstract]:With the increasing dependence of economic development on the comprehensive traffic network and the construction of modern cities, shallow tunnel engineering, as an important type of traffic structure, is located on slopes in hilly and mountainous areas. In the process of railway construction and urban underground space development and utilization, it is inevitable that the surrounding rock stress and displacement change caused by shallow tunnel excavation is more complicated than that of deep buried tunnel. The study on the stability and deformation of shallow buried tunnel is of great importance to tunnel design. Construction and theoretical research are of great significance. The academic and engineering circles generally believe that it is unrealistic to attempt to adopt a theory to solve the problem of tunnel engineering under various geological conditions and for different purposes. It is necessary to make comprehensive use of various theoretical research methods in order to obtain the best results. Therefore, it is necessary to enrich, perfect and expand the application of classical theory in shallow tunnel engineering, in order to provide scientific theoretical guidance for the design and construction of shallow tunnel engineering. The main contents of this paper are as follows: 1) based on the upper limit theorem of limit analysis and the nonlinear failure criterion of "tangent method", the failure mechanism of shallow tunnel surrounding rock considering surface tilt and tunnel bottom uplift is constructed, and the calculating expression of surrounding rock pressure of shallow buried tunnel is deduced. The objective function is solved by nonlinear programming optimization method. The sensitivity of typical influencing factors is analyzed and the influence of slope foot excavation on the stability of surrounding rock is discussed. Combined with the comprehensive strength reduction technique with different reduction coefficients, a new idea and method are provided for the stability evaluation of shallow tunnel surrounding rock. Based on the example of Longtan Ping Tunnel of Yongji Expressway in Hunan Province, the main controlling factors affecting the stability of surrounding rock of shallow buried tunnel are identified by taking the transfixion of plastic zone as the criterion of instability, combined with the numerical simulation method and the principle of orthogonal test. The upper limit analysis method of surrounding rock stability of shallow tunnel is combined with comprehensive strength reduction technique and reliability theory. The failure probability and reliability index of surrounding rock of shallow buried tunnel are calculated by Monte Carlo method. At the same time, the influences of different probability distribution forms of c and 蠁 values and the correlation between parameters on the reliability of tunnel engineering are analyzed. 3) based on the upper limit theorem of limit analysis, combined with Hoek-Brown failure criterion and non-associated flow rule, the three-dimensional multi-slide failure mechanism of shallow tunnel face is constructed, and the formula of supporting reaction force of shallow buried tunnel face is deduced. The nonlinear optimization method is used to solve the objective function, and the influence of different parameters on the supporting reaction force of shallow tunnel face is analyzed. The stability of the face of shallow tunnel excavation under the condition of pipe-shed grouting pre-supporting is studied. Based on the classical elastic-plastic theory and considering the strain softening effect of rock and soil media, the trilinear stress-strain softening (elastic-plastic softening plastic residual) model and Hoek-Brown strength criterion of rock materials are adopted. The approximate analytical solutions of stress field displacement field and radius of plastic zone in elastic zone plastic softening zone and plastic residual zone of circular tunnel under asymmetric load are obtained by using the stepwise solution method. In view of the special conditions of the coexistence of slope excavation and tunnel excavation, the radial displacement of surrounding rock calculated by classical elastic-plastic theory is the initial value of maximum tunnel convergence. A stochastic medium theoretical analysis model of non-uniform convergence of mountain slopes and elliptical tunnels is constructed, and the calculation formulas of surface movement and deformation caused by slope excavation and tunnel excavation are derived, and the results are verified by field monitoring data. The field of engineering application of stochastic medium theory is widened.
【学位授予单位】：中南大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U451

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