【作者】 乔金丽；

【导师】 张义同；

【作者基本信息】 天津大学 ， 工程分析与计算力学， 2009， 博士

【摘要】 盾构隧道技术己成为近年来城市地下工程施工对周围地层扰动最小的施工方法,但由于地质条件和施工工艺的限制,很难避免盾构推进对周围环境的扰动,当隧道开挖面失稳破坏时,导致地面塌陷,给周边的环境带来了很大的破坏,造成巨大的经济损失,同时也妨碍了交通的正常运行,极其严重地影响了人们的生活。因此,盾构隧道开挖面稳定性成为该领域的重要课题,对其研究相对紧迫。然而,国内盾构隧道开挖面支持力的确定仍然处于过分依赖工程经验的阶段,对盾构施工开挖面稳定性研究在国内相对较少。本文针对以上所述,主要研究内容如下:(1)根据稳定性理论,确定开挖面支护压力在进行微小变化时,中心点水平位移发生突变时的支护压力为极限支护压力。通过盾构掘进原理分析及实际工程实测资料,并针对至今国内外还没有一个系统、简单而又直接地对渗流作用时复杂地质条件下盾构开挖隧道开挖面上极限支护压力的模拟预测,通过VB6.0与FLAC3D混合编程的接口实现方法,建立了对复杂地质条件下盾构隧道开挖面稳定时确定极限支护压力的集成可视化计算系统,简化了软件的可操作性和盾构施工力学建模,使一般工程技术人员能够方便地应用本软件对开挖面稳定进行模拟;(2)针对渗流作用时盾构穿越多层土开挖隧道时,开挖面支护压力施加在理论方面还不太完善,通过假定开挖面滑动块形状为一个梯形楔型体,采用太沙基有效松动土压力理论,利用极限分析上限法推导了渗流作用下盾构穿越多层土开挖面极限支护压力的计算分析公式,为开挖面支护压力的施加提供了依据;(3)将强度折减法应用于盾构隧道开挖面稳定性评价,建立了开挖面稳定安全系数的概念,并对影响开挖面稳定安全系数的隧道所在土层参数及开挖面支护压力、地下水位等进行了分析,为设计和施工时分析影响隧道开挖面稳定性主要因素提供依据;(4)运用遗传规划理论,选取盾构隧道开挖引起地表沉降的主要影响因素,如隧道埋深、盾构直径、盾构掘进时推力、盾构推进速率、注浆填充率、注浆压力、地层的粘聚力、摩擦角、压缩模量等,用地表最大沉降实测数据对网络进行训练,建立确定盾构隧道开挖引起地表最大沉降的遗传规划模型,为盾构隧道开挖引起地表最大沉降的预测开辟了一条新的途径。更多还原

【Abstract】 Shield tunneling method is becoming the most primary method in underground excavation with the minimum soil disturbance, but because of the limit of geology conditions and construction technique, it is inevitable that shield constructions disturb circumjacent environment. Tunnel face instability leads to the surface collapse that destroys the surrounding environment badly, causes huge economic losses, hinders the normal operation of the traffic, and seriously affects people’s lives, so shield tunnel face stability is key point and becoming an important task. However shield tunnel face pressure depends on engineering experience mostly at present in native, the study of face tunneling shields is relatively less.The paper developed the following work and research according to the related circs:(1) According to the stability theory, the limit face pressure is that when face pressure is changed very small, displacement of the center at tunnel face increases large suddenly. Through the principle of shiled progress and the datums of measurement, and so far, there is no simple and direct software in simulating and forecasting the limit support pressure of shield tunnel face stability at home and abroad. By means of VB6.0 and FLAC3D, software analysis integration system about the face limit support pressure is founded under complex geology conditions, the calculations that simplify operation of software and modeling of tunnel construction mechanics are simple and convenient, ecumenical engineers simulate and predict tunnel face stability expediently using the system.(2) On the assumption that the shape of sliding block is a trapezoid wedge and introducing the Terzaghi’s effective relaxed soil pressure theory, limit support pressure of tunnel face under seepage by upper theorem are deduced. It is providing a basis for the setting of tunnel face pressure.(3) Strength reduction method is used in stability analysis of shield tunnel face and the face safety factor is defined. And the effect of soil parameters, the support pressure and ground water level on face safety factor is analyzed,all these can provide useful reference to the setting of tunnel face support pressure in design and construction. (4) Using the genetic programming method and selecting the main influencing factors of the surface settlement by shield tunneling, including tunnel overburden, shield diameter, the thrust of shield tunneling, advancement rate of shield, fill factor of grouting, cohesive, friction angle and compression modulus of the soil et al. GP program is trained using practical maximum surface settlement data, and then the maximum surface settlement model of GP is set up, a new method of prediction of the maximum surface settlement by shield tunneling is provided.更多还原