隧道盾构法掘进触发二次地应力分布规律研究

以拟建哈尔滨市松花江隧道为例 ,采用因子对目标函数影响的优化分析思想 ,直接针对隧道施工过程 ,在各种不同工况下 ,建立尽可能逼近实际问题的有限元数值计算模型 ,通过大量的反复数值模拟实验 ,研究因盾构掘进在土体中触发二次地应力的分布规律 ,总结各单项因子对土体变形力学性状的影响特性 ,预估隧道周围土体最危险破坏点位置 。

盾构掘进法开挖隧道对地表沉降影响的预估

盾构掘进法开挖隧道引起的地表沉降对地面建筑物影响在地下工程施工中越来越受到人们的关注,而这个问题的关键是要对地表沉降进行预估。总结了国内外对盾构掘进法开挖隧道引起地表沉降进行预估的常用计算方法,如Peck横向沉降槽经验公式及修正公式、数值分析法、模型试验法和智能决策理论方法。最后就目前国内外盾构掘进法施工隧道对地表沉降影响研究中存在的问题进行了探讨,并提出了一些实质性的建议。

地铁盾构法遇不良地质施工技术研究——以福州地铁2号线为例

以福州地铁2号线福州大学站至董屿站区间盾构掘进时遇到孤石与基岩凸起等不良地质施工为例,探析了该区段采用微动探测、密集钻孔破碎处理、盾构改造及优化掘进调整等主要处理工艺,并基此提出在市区内处理该类不良地层的施工技术及控制要点。

多条盾构隧道穿越既有桥基的三维有限元分析

城市建设和地下轨道交通的飞速发展给地铁施工带来了全新的挑战,施工环境的日益复杂多变使得城市地铁施工难度不断加大.结合天津某地铁线路工程实例,利用三维有限元软件PLAXIS 3D2012分析了四线同时穿越既有桥基时,盾构穿越对桥基变形受力性状的影响及对周边环境土体变形的影响.计算结果显示:隧道掘进可引起桩基础产生上部沉降、下部隆起的变形,以及较小的水平位移;四线盾构掘进后,土体产生的累积沉降形状为"U"型;四线穿越后的桥基群桩的桩侧总摩阻力基本不变;计算得到的相应控制指标均处在变形控制标准以内,工程安全可行.

Settlement characteristics of large-diameter shield excavation below existing subway in close vicinity

A case of Qinghuayuan tunnel excavation below the existing Beijing Subway Line 10 is presented.The new Qinghuayuan tunnel,part of the Beijing-Zhangjiakou High-speed Railway,was excavated by a shield machine with an outer diameter of 12.2 m.The existing subway was excavated by shallow tunnelling method.The project layout,geological conditions,reinforcement measures,operational parameters of shield machine and monitoring results of the project are introduced.During the Qinghuayuan tunnel excavation below the existing subway,total thrust,shield driving speed,cutterhead rotation speed and torque were manually controlled below the average values obtained from the previous monitoring of this project,which could effectively reduce the disturbance of the surrounding soil induced by shield excavation.The Gaussian fitting function can appropriately fit both the ground and the existing subway settlements.The trough width is influenced not only by the excavation overburden depth,but also by the forepoling reinforcement and tail void grouting measures.

Modeling approaches to pressure balance dynamic system in shield tunneling

In order to deal with modeling problem of a pressure balance system with time-delay, nonlinear, time-varying and uncertain characteristics, an intelligent modeling procedure is proposed, which is based on artificial neural network(ANN) and input-output data of the system during shield tunneling and can overcome the precision problem in mechanistic modeling(MM) approach. The computational results show that the training algorithm with Gauss-Newton optimization has fast convergent speed. The experimental investigation indicates that, compared with mechanistic modeling approach, intelligent modeling procedure can obviously increase the precision in both soil pressure fitting and forecasting period. The effectiveness and accuracy of proposed intelligent modeling procedure are verified in laboratory tests.

Parameter identification and pressure control of dynamic system in shield tunneling using least squares method

An estimation approach using least squares method was presented for identificationof model parameters of pressure control in shield tunneling.The state equation ofthe pressure control system for shield tunneling was analytically derived based on themass equilibrium principle that the entry mass of the pressure chamber from cutting headwas equal to excluding mass from the screw conveyor.The randomly observed noise wasnumerically simulated and mixed to simulated observation values of system responses.The numerical simulation shows that the state equation of the pressure control system forshield tunneling is reasonable and the proposed estimation approach is effective even ifthe random observation noise exists.The robustness of the controlling procedure is validatedby numerical simulation results.

我国矩形掘进机隧道施工技术发展与应用

1概述 1825年，英国伦敦泰晤士河下首次采用盾构法掘进道路隧道，断面为11．6m×6．4m的矩形。但由于圆形断面具有结构受力好、易拼装、施工方便等优点，以后的盾构法隧道99％采用圆形。近20年来，日本在矩形、椭圆形、马蹄形等异形盾构隧道技术上开发应用了许多新工法。