【作者】 陈炜韬；

【导师】 王明年；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2009， 博士

【摘要】 近年来,随着我国城市基础建设的需要和地下工程修建技术的发展,大量隧道及地下工程全部或部分修建于软弱的土质围岩中。厦门海底隧道是我国规划建设的第一条海底隧道,全长约30%修建于第四系沉积或风化成因的软弱土质围岩中,因此施工中保证两端陆域段土质围岩稳定对整个隧道建设和展示我国隧道修建技术有重要意义。目前国内对土质围岩稳定性评价指标和方法与岩质围岩相同,没有体现土质围岩的特点;同时,对土质围岩稳定性判定和预加固措施及参数的选择仍以经验为主。因此,提出明确的、能较全面反映土质围岩稳定性且易于操作的稳定性评价指标及方法,并提出相应的施工方法及预加固措施,是土质隧道施工中迫切需要解决的问题。本文针对厦门海底隧道陆域段土质围岩施工中亟待解决的几个重点问题,对土质围岩的稳定性及预加固进行了系统的研究,其工作具体体现在以下几个方面:1.结合现场监测和调研资料,对陆域段土质围岩进行地质分段,然后通过室内试验获得各段的物理力学参数,并对两端土质围岩进行遇水崩解试验;以实测数据分析各段土质围岩开挖变形和破坏特征,并以此验证地质分段的正确性,同时对土质围岩段设计和施工存在的问题进行了分析。2.针对厦门海底隧道陆域段粘质土围岩和砂质土围岩,运用调研资料和理论分析方法,提出了粘质土围岩和砂质土围岩稳定性的评价指标体系;基于土工试验和调研资料,以强度值比对粘质土和砂质土围岩稳定性指标值进行组合分组,并通过模型试验和数值计算获得了各组合的自稳跨度;根据围岩自稳跨度,建立土质围岩亚级分级方法并对厦门海底隧道陆域段土质围岩进行亚级分级。3.根据调研资料和模型试验,总结和定义土质围岩的破坏模式的同时,分析了土质围岩破坏模式的影响因素;运用临界尺度分析破坏模式的形成、转化和统一机理,在此基础上,提出了发生各破坏模式的理论条件并加以验证;运用该理论条件获得了陆域段各亚级土质围岩可能的破坏模式。4.在分析施工跨度、开挖进尺、初支封闭时间和距离及台阶长度对围岩稳定性影响基础之上,结合自稳跨度研究结果,提出土质围岩施工方法、预加固水平及施工参数的确定原则;根据此原则,研究了双车道、三车道土质隧道的施工工法及预加固水平和厦门海底隧道陆域段土质围岩的施工方法及相关施工参数。5.根据小导管、注浆和正面锚杆的预加固机理,分析它们各自及其组合加固措施与围岩类型和破坏模式的适应性;在适应性分析基础上,通过模型试验分析了它们的预加固效果;根据预加固措施的适应性和加固效果,提出了预加固措施选择原则,并根据此原则获得厦门海底隧道陆域段土质围岩预加固措施。在利用双参数地基模型求解了小导管加固时的扰度及内力后,分析了小导管加固后掌子面的稳定性;以小导管扰度和内力满足设计要求且最优和预加固后掌子面稳定为原则,建立了小导管预加固参数的设计方法,并以此确定了厦门海底隧道各亚级的小导管预加固参数。更多还原

【Abstract】 In recent decades, with the need of city basic construction and the construction technology development of underground project, most of tunnels and underground engineering are constructed completely or partially in weak soil surrounding rock. Xiamen subsea tunnel is the first subsea tunnel to be planned and constructed in our country. Almost thirty percent of its length is located in soil surrounding rock formed by the Quaternary sedimentation or weathering, so it is important to ensure the soil surrounding rock stability of land segment in excavation for itself construction and the display of our construction technology. Now the stability indexes and evaluation methods of soil surrounding rock are the same with the rocky surrounding rock methods in domestic, which don’t reflect the characteristics of soil surrounding rock. In addition, the experience is the major way to estimate soil surrounding rock stability and select the pre-reinforcement measure and parameters. Thereby, it is in an urgent need to propose an explicit and user- friendly the stability indexes and evaluation methods, which can comprehensively show the stability of soil surrounding rock, and the excavation method and pre-reinforcement measure. Aiming at the solution of major problems of soil surrounding rock in Xiamen subsea tunnel, this thesis makes a systemic research on rock mass classification of sandy tunnel and arrives at conclusions as follows:1. The physical and mechanical parameters of each geological subsection in land segment of Xiamen subsea tunnel, divided by testing and investigation , are obtained, and the disintegration of soil surrounding rock in land segment is tested. The deformation and failure of surrounding rock which are analyzed according to monitoring data are used for verifying the validity of geological subsection. The problems in the design and construction are also analyzed.2. Aiming at clayey surrounding rock and sandy surrounding rock in this tunnel, a new evaluation index system of stability is established by geotechnical test, investigation materials and theory analysis. The values of stability index are grouped, and the basic steady excavated span of each group is studied through model test, numerical simulation. The sub-classification method of soil surrounding rock is established according to the basic steady excavated span, and then the sub-classification of soil surrounding rock in land segment is divided.3. Based on the results of investigation materials and model test, the failure mode of soil surrounding rock is summarized and defined, and the influence factors of surrounding rock failure is discussed. The mechanism of failure modes is analyzed by critical measure, including occurring, transforming and unifying. The possible failure mode of all levels of soil surrounding rock in land segment of Xiamen subsea tunnel, using theory failure condition which is developed according to the failure mechanism, can be obtained.4. Depending on the influence on stability of soil surrounding rock from construction span, excavated length, closing time and distance of primary support and the length of bench, and combining with the research of self-stability span, this paper proposes the determination principle of construction method and parameters and pre-reinforcement level, which is applied in double lane and three lane soil tunnel and in land segment of Xiamen subsea tunnel to determine construction method and parameters.5. According to the pre-reinforcement mechanism of small pipe, grouting and frontal blot, the adaptability of their single or combination reinforcement measures and surrounding rock type and failure mode are analyzed. Their pre-reinforcement effect is contrasted through the results of model test on the base of adaptability analysis. The select principle of pre-reinforcement measures, developed based on the analysis of adaptability and reinforcement effect, is used for determining pre-reinforcement measures of soil surrounding rock in land segment of Xiamen subsea tunnel. Utilizing double-parameter model of foundation, the deflection and internal force of small pipe were deduced, and tunnel face stability is also analyzed after pre-reinforcing. Taking the deflection, internal force of small pipe meeting the design requirements that is optimum, and stability of tunnel face after pre-reinforcing as a principle, the design method of small pipe pre-reinforcing parameters is generated. Pre-reinforcing parameters of small pipe of each sub-grade of soil surrounding rock in land segment of Xiamen subsea tunnel are ascertained.更多还原