【作者】 孔恒；

【导师】 王梦恕；

【作者基本信息】 北京交通大学 ， 桥梁与隧道工程， 2003， 博士

【摘要】 基于大量的文献和广泛的实践，籍助深圳地铁实测资料，利用现场试验、理论分析、数值模拟和实验室物性参数试验等多种研究手段，对城市地铁浅埋暗挖法地层预加固机理进行了全面而系统的深入研究，并结合实际工程对本文的研究思想进行了应用研究，取得了一系列有益于理论和实践的研究结果。 (1)通过对现场试验研究内容的精心设计，系统研究了浅埋暗挖法隧道工作面在开挖通过观测主断面前、通过中、通过后地层的响应规律。全面分析了围岩的应力与变形的分布特征及其变化规律，阐明了地层变位以及应力与地层参数、支护参数的相互关系；揭示了隧道上覆地层的区域性及结构性特点。提出了隧道工作面上覆地层沿工作面推进方向可分三个区①超前变形影响区；②松弛变形区；③滞后变形稳定区，而沿地层垂直剖面又可分为五带Ⅰ弯曲下沉带、Ⅱ压密带、Ⅲ松弛带、Ⅳ工作面影响带、Ⅴ基底影响带。 (2)建立了分析隧道上覆地层稳定的地层结构模型，给出了维持隧道工作面上覆地层结构稳定的水平推力计算公式；提出了隧道工作面上覆地层结构失稳坍落的椭球体概念，分析了工作面上覆地层结构失稳的演变形态及其内在作用机制；揭示了隧道工作面无支护空间范围是影响隧道上覆地层结构稳定与否的关键区域；论证了地层预加固结构系统的概念，建立了反映地层预加固系统4个主要单元的串并联模型，提出了地层预加固作用机理的4个效应：即地层拱的稳定促成效应、梁拱效应、拉杆效应和挡土墙效应。 (3)建立了反映隧道工作面超前预加固结构力学行为的工作面超前预加固结构力学模型；提出了基于塑性极限理论的工作面土体稳定性分析的上限解模型；论证了拱部与正面土体预加固的力学效果；揭示了工作面土体失稳的渐进破坏概念；说明了特殊地层条件下，工作面正面预支护的必要性。 (4)通过建立的一系列工作面地层预加固力学行为模型的数值解，以及有限元数值模拟的结果，对浅埋暗挖法地铁隧道工作面地层预加固参数的设计与选择进行了探索。全面分析了影响工作面超前预加固参数的因素；揭示了拱部超前预加固参数与地层参数、隧道开挖与支护参数等的内在联系；论证了地层预加固参数的最佳值概念；给出了确定超前预加固结构作用荷载的半拱法、全拱法和全土柱法理论计算公式；建立了隧道工作面上覆地层稳定性判别的准则；提出了工作面地层预加固参数设计与选择的5个指导原则；最后给出了一整套确定浅埋暗挖法隧道工作面地层预加固参数的动态设计方法。 (5)针对深圳地铁一期工程，重点围绕双线隧道6标段和单洞重叠线隧道3A标段的地层预加固详细介绍了本论文的研究思想和成果在工程实践中的具体应用。实践表明：本论文的研究思想和成果能成功地指导地层预加固的参数设计；而针对不同的地层条件，适时进行地层预加固参数的动态设计是值得推行的一种有效设计方法。更多还原

【Abstract】 Based on vast literatures and extensive practices, the mechanism of earth pre-reinforced by shallow tunnel construction method (STCM) in urban subway was investigated, by local experimentation, theory analysis, numerical simulation and parameters test at laboratory. Its application was carried throughout, and a series of results were obtained.Firstly, by a series of sites test, the earth responded law which tunneling face of SCTM passed through observation main-transect during its frontage, backside and same position were studied systematically. Distribution characters of the soil stress and its distortion were analyzed. The interaction relation among the character, and earth parameters and timbering parameters were clarified, and properties of region and structure of overlay soil for tunneling face was posted. Its three distortion areas: frontage effect, loosing and backside distortion stability were given along head face advancing, and its five distortion belts: bend subsidence, pressing dense, loosing, face and tunnel floor effect were given along its vertical section too.Secondly, the stratum structure model for analyzing overlay soil stability of tunneling was founded, and its formula for calculating level thrust force was given. To analysis its instability, a ellipsoid concept was put forward, which could interpret its structure evolvement shape and its mechanism. That non-support space was a key factor resulting in instability was posted. The concept of big structure for stratum and small structure for pre-reinforcement was demonstrated. Four effects reflecting pre-reinforcement mechanism: earth-arch stability, girder-arch, pull pole and retaining wall were given.Thirdly, the structure mechanics model for pre-reinforcement of heading were founded, and the upper limit solution model analyzing soil stability by the plastic limit theory were erected. Based on the above-mentioned models, the soil pre-reinforcement effects for the arch and frontispiece part of tunnel heading, and a gradually instability concept of face was explained. It was necessary that the frontispiece of face was pre-supported in the especial stratum.Fourthly, by the model analytic value and the FEM numerical simulation, the advance reinforcement parameters were analyzed roundly, and its results explained that the parameters had optimal values. A series of formulations conforming loads bom up for pre-reinforcement structure were given, and five rules for its design and choice were put forward. Finally, a dynamic design method confirming the stratum pre-reinforcement parameters of the STCM face was established.Finally, to aim at Shenzhen subway engineering, the results of paper have been applied at the 6 and the 3A sections. The application indicated its fruits could supervise successfully the design of pre-reinforcement parameters, and the method was good for dynamic design of the pre-reinforcement.更多还原