【作者】 李鹏飞；

【导师】 王梦恕； 张顶立；

【作者基本信息】 北京交通大学 ， 桥梁与隧道工程， 2011， 博士

【摘要】 随着我国交通事业的大发展,将有大批量的越江跨海通道投入建设,水下隧道已受到越来越多的关注。与山岭隧道相比,跨海隧道通常具有地质勘探困难、单口连续掘进距离较长、衬砌结构受长期的动静水压力作用、防排水难度大、围岩成拱作用较低、不良地质体段易发生涌水事故等特点,因此在海底隧道衬砌结构的设计和分析计算方面,将具有与一般隧道不尽相同的关键技术问题,亟待在设计中着重反映。论文研究以我国目前蓬勃发展的海底隧道为背景,以富水条件下隧道围岩稳定性及其控制技术为研究重点,综合采用理论解析、数值模拟、室内模型试验和现场监测等多种研究手段,主要开展了以下方面的研究工作：(1)基于弹性力学中厚壁圆筒承受均布压力的拉梅解答和Mohr-Coulomb屈服条件,推导了考虑渗流场和围岩超前位移释放的含衬砌海底圆形隧洞的弹塑性解析公式。根据本文推导过程,可推演满足其它屈服条件和流动法则的隧道围岩应力与位移的弹塑性解答。同时结合一座海底隧道的工程实例,本文采用解析公式对围岩塑性区范围、应力场、位移场和渗流场的分布进行了理论分析,得到了各场的分布规律和演化特点,并讨论了海底隧道顶板厚度、海水深度、内水水头、衬砌围岩物理力学参数及其渗透性关系等因素的影响规律。(2)基于前人研究成果,针对暗挖海底隧道开挖面围岩稳定性问题,总结了极限分析上限法、楔形体模型、二维对数螺旋线模型,以及条分法模型等4种理论分析模型,并考虑了开挖面滑移体上部地层压力等因素,对理论解析公式进行了修正。结合海底隧道工程实例,采用数值模拟方法,与理论解析方法进行了对比分析,并讨论了围岩粘聚力、摩擦角、海水水位、超前注浆等因素的影响。(3)依托厦门翔安海底隧道,对穿越陆域全、强风化花岗岩段的地层变形进行了现场监测,指出了产生地层大变形的力学机制,总结了拱顶沉降、海床沉降、地层水平变形、海床开裂随隧道施工过程的发生、发展规律,并建立了它们之间的关系,提出通过易于监测的隧道拱顶下沉量及收敛值判断海床地层的完整性,实现对海床状态的信息化控制。(4)采用FLAC3D有限差分软件模拟分析翔安隧道穿越海域F1风化深槽段的围岩稳定性,指出地下水的渗流作用对海底隧道的围岩变形影响较大,由渗流引起的隧道围岩变形在向上传递过程中折减较小,且超前导洞开挖对围岩渗流场的影响作用最为直接和明显,而相应的超前预支护、预注浆技术则是改善围岩强度、刚度、渗透性的核心技术。(5)采用理论分析方法,建立了综合考虑围岩、注浆加固圈、初期支护和二次衬砌的海底隧道渗流场计算模型。依托厦门翔安海底隧道和青岛胶州湾海底隧道,采用理论分析、数值模拟、室内模型试验和现场监测等多种研究手段,分析了隧道衬砌外水压力的分布规律,并指出海底隧道注浆圈设计存在相对经济合理的参数值,给出了海底隧道合理注浆圈参数的确定程序。(6)采用荷载—结构模型讨论了海底隧道衬砌结构断面形状设计参数对衬砌结构受力特点的影响,并对青岛胶州湾海底隧道衬砌结构的断面形状进行了优化分析,得到了以衬砌结构断面安全系数为目标函数的最优断面。更多还原

【Abstract】 With the great development of transport, large quantities of river crossing channels will be invested into construction. And the underwater tunnel has been paid more and more attention. Compared with the mountain tunnel, subsea tunnels often have the characteristics of difficulties in geological exploration, long distance single-port continuous excavation, long-term static and dynamic water pressure acting on the lining structure, difficulties in waterproof and drainage, low arching effect, gushing water likely to happen when passing through unfavorable geologic bodies and so on. Therefore, there are many different key technical issues in design and analysis of the lining structure for the subsea tunnel compared with the mountain tunnel, which are urgent to be solved in design. In this paper, taking booming subsea tunnels in China as project background and stability of surrounding rock and its control technologies in rich water condition as the research focus, the following six aspects are carried out by using theoretical analysis, numerical simulation, indoor model test and field measurement methods.(1) Based on the Lame solution to thick cylinder under uniform pressure in elastic mechanic and Mohr-Coulomb yield condition, the subsea circular tunnel with liner is simplified as axially symmetrical and the effect of seepage field is simplified as seepage volume force acting on the stress fields. Elastic-plastic analytical solutions of stress and displacement are obtained respectively with considering the release of the displacement ahead of the cutting face. Other elastic-plastic analytical solutions which satisfy other yield conditions and flow rules can be deduced, according to this derivation. Combined with the results of a practical example, the deformation of host rock around the tunnel, the range of the plastic zone of rock, and the stress field and characteristic of seepage field in the rock around the tunnel have been analysed using the analytical formula, and the distruction law as well as the evolution features of these fields are obtained. Besides, the influence on seepage field and displacement of surrounding rock by some factors such as seawater tables, rock cover thickness, inside water head in tunnel, the mechanical parameters of the lining and the surrounding rock and the penetration relation between them have been discussed.(2) Based on previous research results, four models including upper bound solution, wedge analysis, two-dimensional logarithmic spiral model and slice method for estimating the support pressure required for the face stability were derived by utilizing upper bound theorem and limit equilibrium method. With considering of the pressure of overlying strata, theoretical analysis formulas have been modified. The existence of groundwater may seriously affect the face stability. Under the steady-state groundwater flow condition, most part of the total support pressure is owing to the seepage pressure acting on the tunnel face. Also, the coupled numerical analysis has been performed and the proposed estimation methods to obtain the support pressure have been verified. Combined with the results of a practical example, the results of the numerical simulation and the analytical formulas are comparied and analyzed. Meanwhile, influencing factors such as cohesion and friction angle of surrounding rock, advanced Injection, sea water level and depth have been discussed.(3) Taking Xiamen Xiang’an subsea tunnel as project background, by using in-situ measured data when passing through the completely weathered granite, the mechanism of integral deformation of upper strata due to tunnel excavation has been then expounded. It is shown by the in-situ deformation monitoring that how the settlement of crown and seabed, horizontal ground deformation and surface crack have distributed and developed with time and space. The relation between surface crack space and strata displacement is presented to offer guidelines to water inflow prediction.(4) Based on the coupled fluid-solid theory, numerical analysis is made to study the stability of surrounding rock during Xiamen Xiang’an subsea tunnel passing through the weathered slot under the sea. The distribution principle of displacement field and seepage field of surrounding rock, as well as the mechanical characters of lining structure are studied in various construction stages of subsea tunnel. The seepage of groundwater has great influence on deformation of surrounding rock, causing a large range of sea-bed subsidence. The excavation of pilot heading has the most direct and obvious influence on seepage field of surrounding rock, and the attenuation of surrounding rock deformation induced by seepage is small in its transfer process from surrounding rock to sea-bed. The surrounding rock deformation and sea-bed subsidence mainly concentrate on the excavation of both sides of pilot heading and the upper rock of the central core; And the advanced support and pre-grouting are the key technologies for improving the strength, stifness and the permeability of the surronding rock.(5) By using theory of analytical method, calculation model for subsea tunnel seepage field has been established with considering of the surrounding rock, grouting circle, primary liner and second liner. Taking Xiamen Xiang’an subsea tunnel and Qingdao Jiaozhou Bay subsea tunnel as project background, by using in-situ measured data, numerical simulation, indoor model test and theoretical analysis method, the basic regulations of the effects of grouting circle on tunnel gushing water and external water pressure on lining are studied. And it is potined out that there is an appropriate and economical parameter when designing the grouting circle. Based on the above-mentioned research results, the method and program for choosing appropriate parameters of grouting circle are proposed.(6) Based on load-structure model, the influence of the structural cross-section shape and design parameters on the stress characteristics of the lining structure are discussed. The lining structure section shape optimization calculation of Qingdao Jiaozhou Bay subsea tunnel water section is made. And taken the safety factor of the lining structural cross-section as the objective function, the optimum section is obtained.更多还原