浅埋暗挖地铁隧道开挖砂土地层稳定性研究

发布时间：2018-01-22 00:10

本文关键词： 砂土地层地铁区间隧道浅埋暗挖地层变形坍塌风险　出处：《山东大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文基于青岛地铁一期工程(3号线)河西站-河东站区间工程实际,采用理论分析、数值计算、现场监测相结合的方式分析了砂土地层浅埋暗挖地铁隧道开挖地层变形规律以及围岩稳定性,并对施工风险进行了评价、预测,对隧道坍塌机理进行了研究。(1)本文从经验法、解析法、数值分析法以及模型试验法四个方面系统总结了浅埋暗挖地铁隧道施工诱发地层变形规律的国内外研究现状与研究进展,通过对地铁建设期安全事故统计分析得出坍塌是地铁建设安全事故的主要类型,进而引出对隧道开挖诱发地层变形规律以及地层稳定性研究的必要性、重要性和迫切性。(2)简要介绍了青岛地铁的发展历程、各线路规划,并详细介绍了青岛地铁3号线河河区间的工程地质、水文地质情况,基于层次分析法对施工风险进行分析,指出地质情况和复杂的周边环境是最需注意的风险因素。基于特尔菲-理想点法选取纵波波速、埋深、跨度、地下水、周边环境以及施工单位管理水平六个方面作为影响因素,建立坍塌预测模型,分析坍塌风险,进而提出了一套浅埋暗挖隧道坍塌风险预测评价体系并对河河区间坍塌风险进行预测,以一起典型坍塌案例对预测结果进行了验证。(3)阐述PECK公式与随机介质理论的适用性,基于现场监测数据,选取典型断面,利用PECK公式对监测数据进行拟合分析,探讨PECK公式在砂土地层浅埋暗挖地铁隧道的适用性,针对当前随机介质理论极坐标解法的不足提出了直角坐标解法及其详细步骤。(4)利用FLAC3D有限差分软件对砂土地层浅埋暗挖隧道施工诱发地层变形进行计算分析,计算结果表明该地层地表沉降横向影响范围约为2～2.5倍洞径,地表沉降纵向影响范围约为2倍洞径,地表最大沉降出现于隧道中线正上方。拱顶沉降变化趋势与地表沉降变化趋势整体一致,但数值与地表沉降相比较大。针对不同核心土长度工况分析其对隧道开挖地层稳定性的影响。(5)基于现场监测数据,将监测数据与数值计算结果相对比,分析隧道开挖横向影响范围,对地表沉降与拱顶沉降进行对比分析,指出拱顶沉降监测中不可避免的弊端,即监测的滞后性导致了拱顶沉降的监测数据仅为实际沉降量的40%左右,进而提出了拱顶沉降预测理论,并基于粒子群算法对拱顶沉降进行拟合分析,做出拱顶沉降位移全过程曲线。(6)对砂土地层浅埋暗挖地铁隧道地层坍塌类型进行分类,按照坍塌位置进行划分,地层坍塌包括掌子面失稳和地表塌陷两类,同时地层坍塌亦包括开挖面土体超出以及小范围的地表沉陷；按照坍塌时间进行分类,地层坍塌包括掌子面失稳与地表塌陷同时发生和地表塌陷滞后于隧道开挖两大类。从砂土本身物理力学性能、施工措施以及隧道埋深三个方面分析坍塌的成因,基于改进的楔形体理论探讨了隧道坍塌的力学机理,并选用PFC2D软件模拟计算了地层坍塌失稳过程,对地层水平位移、竖向位移按照不同横断面、纵断面进行分析。
[Abstract]:In this paper, based on a project of Qingdao subway station (line 3) - east west station interval engineering practice, using theoretical analysis, numerical simulation, field monitoring combination of sand soil layer of Shallow Metro tunnel deformation regularity and stability of surrounding rock excavation, and the construction risk evaluation, prediction of tunnel collapse mechanism is studied. (1) this paper from the empirical method, analytical method, numerical analysis and model test method four aspects summarized current situation and research progress of Shallow Metro Tunnel induced ground deformation law at home and abroad, based on the statistical analysis of subway construction safety accident collapse the main types of safety accidents in subway construction, which leads to the excavation induced deformation regularity and the necessity of research on tunnel ground stability, importance and urgency. (2) a brief introduction of the Qingdao subway The development process of the line planning, and introduces the engineering geology of Qingdao Metro Line 3 river range, hydrogeological conditions, the level of construction risk analysis method based on the geological conditions and points out the complicated surrounding environment is the need to pay attention to the risk factors. The Delphi ideal point method based on wave velocity. Depth, span, groundwater, surrounding environment and the management level of construction units in six aspects as influence factors, the establishment of collapse prediction model, analysis of collapse risk, and proposes a set of shallow buried tunnel collapse risk prediction evaluation system and forecast the river interval risk collapse, with a typical case to predict the result of collapse verified. (3) describes the applicability of PECK equation with stochastic medium theory, based on the monitoring data, selecting the typical section, fitting analysis of monitoring data by using the PECK formula, discuss The applicability of PECK formula in sand soil layer of Shallow Metro tunnel, in view of the current lack of polar coordinate method of stochastic medium theory put forward the Cartesian coordinate solution and detailed steps. (4) by using the FLAC3D finite difference software on sand soil layer in shallow strata induced by tunnel construction deformation were analyzed and calculated, the calculation results show that the formation of surface settlement lateral influence range is about 2 ~ 2.5 times the diameter, the surface subsidence vertical influence range is about 2 times the diameter of the tunnel, the maximum surface subsidence appears in the midline of the tunnel. Just above the vault settlement and ground settlement trend of the overall trend is consistent, but the value and settlement phase for different core soil is relatively large. The length of working conditions and analyses the effect of tunnel excavation formation stability. (5) based on the monitoring data, the monitoring data and numerical comparison, transverse influenced range analysis of tunnel excavation. Compared with the settlement of vault settlement, crown settlement monitoring pointed out shortcomings inevitably, which leads to the lag of monitoring crown settlement monitoring data is only about the actual settlement of the 40%, and then put forward the prediction theory and the settlement of vault crown settlement, particle swarm optimization algorithm based on fitting analysis, make the whole process of settlement curve vault. (6) of sand soil layer of Shallow Metro Tunnel Collapse types are classified, divided according to the collapsed position, including collapse instability of tunnel face and surface collapse in two categories, at the same time also includes the collapse layer beyond the soil of excavation face and surface subsidence range; in accordance with the classification of collapse time. Including the formation collapse instability of tunnel face and surface subsidence and surface subsidence occurred at the same time lag in the tunnel excavation in two categories. From the soil physical and mechanical properties, construction measures to Analysis of collapse of the three aspects and causes of deep tunnel, the improved wedge theory based on the mechanical mechanism of tunnel collapse, and simulate the collapse instability process with PFC2D software, the displacement on the stratigraphic level, vertical displacement according to the different cross-sectional profile were analyzed.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U231.3;U452.1

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