【作者】 黄园园；

【导师】 漆泰岳；

【作者基本信息】 西南交通大学 ， 桥梁与隧道工程， 2013， 硕士

【摘要】 成都地区的砂卵石地层,具有以下几个特点：结构松散,自稳性差；卵石含量高、粒径大；均一性差,并随机分布透镜体砂层。成都地质的这些特点,极为特殊,施工技术难点多。地铁2号线在百草路上交叉换边,区间左右线隧道上下重叠,盾构重叠施工相互影响大,盾构施工控制难度大。此外,地铁周围的工程环境复杂,临近的建筑物、地下管线多,环境保护要求高。提高砂卵石地层交叉重叠隧道的盾构施工掘进效率,安全快速地完成施工,可以为今后类似的工程提供借鉴。本文基于以上问题,以成都地铁2号线交叉重叠隧道为背景,主要完成了以下工作：1.针对砂卵石地层的特殊性,进行交叉重叠隧道的施工优化控制。分析了砂卵石地层的地层空洞和滞后沉降特性,以及并行隧道、重叠重叠的应力应变,从开挖面土压平衡、地层沉降构成、地层注浆加固措施方面论述了盾构施工的改良和优化,掘进参数控制等。2.采用数值模型对交叉重叠隧道的全过程进行施工力学研究,根据不同施工的顺序对比,分析了“先下洞后上洞”施工顺序的合理性；分析了先后修建隧道情况下,隧道结构和地层的应力应变规律,对比分析了不同空间位置中,两隧道施工的相互影响；并结合工程实际,模拟了地层的空洞效应和滞后沉降效果。主要得出以下结论：下洞施工后,主要起到对地层的扰动作用,使上洞所在处土体变松动,自稳定性变差；上洞施工后,松动的地层容易发生失稳破坏,造成盾构超挖,形成空洞,造成过大沉降；上洞施工后,下洞隧道结构有向上洞开挖后形成的空洞内移动的趋势,地层沉降主要发生在上洞上部,下洞所在地层有隆起的趋势,上下洞之间的地层有隆起也有沉降。3.根据交叉重叠隧道的地表沉降、隧洞洞内收敛变形以及临近的工程环境等监测数据以及盾构施工记录表等现场原始数据,结合数值模拟进行对比分析,不仅对盾构施工起到了很好的预测指导,还可以针对施工中出现的异常情况进行模拟分析,并提出合理的注浆加固措施,抑制地层变形,保证施工安全。更多还原

【Abstract】 The character of sandy cobble stratum of Chengdu is, loosen structure and poor stability, rich in cobble content and big size grain, nonuniform in distribution and random in filling of lens sand. This makes the sandy cobble stratum of Chengdu particular and causes lots of construction techniques. The both tunnels of Metro Line2intercross underneath the Baicao Road, overlaps with each other, makes strong influence between each other, and great difficulty in controlling the tunneling construction. In addition, the project environment around the metro line is complicated, with lots of buildings and underground pipelines, and needs very strict environmental protection requirements. Improving the shield tunneling efficiency of the overlapped tunnels of the sandy cobble stratum, finishing the construction safely and rapidly, can offer successful experiences to the similar construction in the future. With these problems, this thesis is based on the construction of Metro Line2of Chengdu, the following researching work is completed:1. According to the specificity of the sandy cobble stratum, optimize the construction control of the overlapped tunnels. The hole effect and the lagged ground collapse behavior are analyzed, combined with the strain and stress state of parallel tunnels and overlapped tunnels, discussed the improvement and the optimization of the shield construction, the control of the tunneling parameters from the aspect of the earth pressure balance of the excavation face, the composition of the subsidence of the ground, and the grouting and reinforcement measures.2. Study the whole shield tunneling construction mechanics by the numerical simulation, according to the comparison with different tunneling sequences, analysis the rationality of the "down to upper" tunneling sequence, the stress-strain characteristics of the tunnel structure and the ground in the condition of build the tunnel by sequence, the influence of both tunnels during tunneling by comparison of different location, the hole effect and the lagged ground collapse behavior is also simulated. The main conclusions are:the disturbance effect is formed after the down tunnel excavated, which makes the surrounding of the upper tunnel loose, its stability weaken. The loosen surrounding is easy to lose stability and destroyed, which causes over excavation of the shield tunneling, bring about big subsidence. The down tunnel will move toward to the hole after the upper tunnel excavated, the subsidence is mainly happened to the above of the upper tunnel, the surrounding of the down tunnel will heave while the ground between the tunnels some subsides and others heaves.3. Make comparative analysis according to the field monitor data of the subsidence of the surface, the deformation and constringency of the tunnel structure, and the nearby project environment, combined with the shield construction records, and the numeral simulation, which can not only predict and guide for the shield construction, but also can make analysis and simulation according to the abnormal situation during tunneling, and give reasonable advice for grouting measures, which can restrain the ground deformation to ensure the tunneling safety.更多还原