【作者】 郭小红；

【导师】 王梦恕；

【作者基本信息】 北京交通大学 ， 地下工程， 2011， 博士

【摘要】 本文以厦门翔安海底隧道风化槽衬砌的设计与施工为背景,围绕海域风化深槽围岩力学特性、隧道施工工法和长期稳定性及可靠性等关键技术难点,开展系统的室内应力渗流耦合三轴试验、应力渗流耦合流变试验,研究风化槽围岩的非线性力学特性和流变机理,建立适合厦门翔安海底隧道风化槽围岩特征的本构模型,并开展风化槽段隧道的合理施工工法及防排水方案研究、围岩变形现场监控量测及反演分析研究。在上述研究基础上,建立三维计算模型,对风化槽段隧道衬砌结构的长期稳定性及可靠性进行了计算和评价。论文的主要研究成果如下：(1)强风化花岗岩渗流应力耦合特性研究。通过风化槽段强风化花岗岩渗流应力耦合的三轴试验,对厦门海底隧道海域风化深槽的围岩力学特性开展系统的研究,建立应变硬化的风化槽围岩力学模型；通过强风化花岗岩渗流应力耦合的三轴流变试验,建立蠕变损伤力学模型,该模型能很好地反映不同应力水平下蠕变速率的变化趋势。(2)海底隧道风化槽段的合理施工工法及衬砌结构受力特征研究。应用建立的风化槽围岩力学模型,数值仿真全断面帷幕注浆、超前管棚、小导管支护和台阶法、CRD工法及双侧壁导坑工法开挖下隧道围岩的稳定性,通过对比研究提出CRD工法是风化槽隧道施工最优工法；研究风化槽段在不同防排水方案下隧道衬砌的外水压力特征；研究渗流应力耦合作用下潮汐荷载对隧道衬砌和围岩稳定性的影响；应用荷载结构法理论研究海底隧道在不利荷载组合作用下的轴力、弯矩和偏心距特征,并对不同衬砌厚度条件下的衬砌结构的安全性进行校核,提出工程可行的最优衬砌厚度。(3)厦门翔安海底隧道围岩变形的监控量测、反馈分析及长期稳定性预测。根据风化槽围岩现场位移监控量测的研究成果,采用Nelder-Mead法与有限元联合反演法,反演风化槽围岩的力学参数,结合流变力学试验成果,通过三维数值仿真对海底隧道围岩和衬砌结构的长期稳定性进行预测。(4)厦门翔安海底隧道地下结构支护可靠性研究。在改进的蒙特卡罗法的基础上,采用能明显节省样本数量,并能产生任意大小维数的分层—拉丁超立方复合抽样方法,自行编制了基于改进的蒙特卡罗法的Matlab-Abaqus联合实现的有限元可靠度计算程序；应用荷载结构法和连续介质力学方法,对厦门海底隧道衬砌支护的长期可靠性进行计算分析。计算结果表明：翔安海底隧道的衬砌结构设计安全可靠。更多还原

【Abstract】 Combining with design and construction of xiang’an subsea tunnel in Xiamen, focusing on the key technology of mechanical properties of surrounding rock in the strongly weathered strata, tunnel construction consequences, its long-term stability and reliability, a series of laboratory tests including hydro-mechanical coupled triaxial tests and hydro-mechanical coupled creep tests have been carried out. On the basis of above coupled tests, nonlinear mechanical properties and rheology mechanism has been studied and coupled constitutive model for strongly weathered rock mass has been developed correspondingly. In addition, the suitable construction method and different water-proofing and discharge methods aiming to the tunnel in weathered trough are conducted as well as field-monitoring and inversion analysis. Finally, the large-scale three-dimensional calculation model is established to analyze the long-term stability and reliability of tunnel lining in weathered trough. The main achievements includes:1. Laboratory tests to study hydro-mechanical coupling characteristics of the weathered strata.With the help of hydro-mechanical coupling triaxial test machine, tests on the mechanical characteristic of host rock in the weathered strata in Xiamen has been carried out, including conventional triaxial compression test and creep test for a long time. Basing on the tests results, a strain hardening mechanical model and a creep damage model which considered creep stress and time for host rock in weathered strata has been established. It is indicated that the creep model can reflect changing trend of creep rate very well under different stress levels.2. Study on the reasonable construction methods of tunnel and stress characteristics of lining in the weathered strataWith the new developed mechanical model of weathered granite, numerical simulations have been done to simulate stability of tunnel by full-face curtain grouting, advanced tune shed, small pipe supporting and bench method, CRD method or two side-wall pilot tunnel excavation method respectively. By comparison, the numerical results show that CRD method is the best for Xiamen subsea tunnel in weathered strata. The characteristics of external water pressure of tunnel in weathered strata with different water-proofing and discharge methods are studied, Considering the hydro-mechanical coupling, the effect of tidal cyclic loading on stability of tunnel lining and surrounding rock is studied. With the load structure method, the axial force, bending moment and eccentricity of subsea tunnel under unfavorable combined loading are calculated. The optimized lining depth is evaluated by a comparative study of the safety of lining structure with different lining depths.3. Back analysis of field measurements and its long-term stability prediction on Xiamen xiang’an subsea tunnelBased on field measurements of displacements in weathered strata, a methodology of back analysis combing the Nelder-Mead algorithm and finite element method is proposed, mechanical parameters of surrounding rock in weathered strata is studied. Based on mechanical model of weathered strata and results of back analysis, the long-term stability of surrounding rock and supporting structure in tunnel construction is predicted4. Reliability theory of underground structure and its application at Xiamen xiang’an subsea tunnelBased on the improved Monte Carlo method, using the latin hypercube sampling method which has the advantage of reducing sample size obviously and produce arbitrary dimensions, a finite element reliability program based on Improved Monte Carlo method using Matlab and Abaqus combinablenably is developed, then reliability of Xiamen Under sea tunnel lining and supporting is analyzed. The results demonstrate that the supporting design is safe and reliable.更多还原