云南山区岩堆体公路隧道施工参数优化研究

发布时间：2018-04-05 03:24

本文选题：岩堆体隧道　切入点：理论分析　出处：《昆明理工大学》2015年硕士论文

【摘要】：云南山区岩堆体分布广泛,在隧道建设中常遇到岩堆体这种不良地质,给隧道施工带来了诸多困难,如引起隧道坍方、衬砌开裂、地表变形及滑坡等,影响施工进度和安全。随着西部山区公路建设的快速发展,穿越岩堆体隧道日益增多,亟待解决和岩堆相关的工程地质问题,以实现岩堆体隧道的快速、安全施工。本文依托麻昭高速公路沿线岩堆体隧道工程,在总结岩堆体工程特性的基础上,采用理论分析、数值计算和现场实测相结合的方法,对岩堆体隧道洞口段的开挖进尺、三台阶七步工法中的台阶长度、锁脚锚杆长度与斜插角度等施工参数进行了研究分析,给出了岩堆体隧道洞口浅埋段的较优施工参数。主要研究内容及成果如下：(1)结合麻柳湾-昭通高速公路沿线的岩堆体情况,分析了岩堆体特征、形成条件及工程特性,总结了国内典型岩堆体隧道的施工参数和施工控制措施。(2)基于弹性地基梁理论、太沙基理论及筒仓理论,提出了岩堆体隧道洞口浅埋段优化开挖进尺的计算模型,进行了不同情况下隧道洞口段的施工进尺的优化分析。结果表明在采用管棚支护下,合理开挖进尺为1.0m左右。(3)采用Midas-NX有限元软件,建立了岩堆体隧道洞口浅埋段的多工况三维数值计算模型,完成了岩堆体隧道洞口浅埋段三台阶七步法施工过程的三维仿真计算,系统分析了不同施工参数下隧道围岩及支护结构的受力变形规律,并与现场测试结果进行了比较。结果表明：1)随着台阶长度的增加,隧道围岩竖向位移以及水平收敛值均随之变大,而钢拱架承受的轴力和弯矩值均逐渐减小,喷射混凝土层承受的拉应力也随之减小。综合围岩变形和支护结构受力情况,岩堆体隧道洞口浅埋段台阶长度宜取4m左右。2)随着锁脚锚杆插入角度的增大,不同部位的水平位移变化规律相当,上台阶水平位移呈逐渐减小趋势,中、下台阶水平位移呈先减小后增大趋势。锁脚锚杆的斜插角度均宜取20°-30°。3)随着锁脚锚杆长度的增加,拱脚和边墙以及墙脚处的水平位移随之减小,当锚杆长度超过4.5m后,水平位移减小幅度趋于平缓。锁脚锚杆长度宜取4.5m-6m。
[Abstract]:The rock heaps are widely distributed in the mountainous areas of Yunnan Province. The bad geology of rock heaps is often encountered in the tunnel construction, which brings many difficulties to the tunnel construction, such as causing tunnel collapse, lining cracking, surface deformation and landslide, which affect the construction progress and safety.With the rapid development of highway construction in the western mountainous area, there are more and more tunnels passing through the rock pile. The engineering geological problems related to the rock pile are urgently needed to be solved in order to realize the rapid and safe construction of the tunnel.On the basis of summing up the characteristics of rockfill tunnel along Ma-Zhao Expressway, this paper adopts the method of combining theoretical analysis, numerical calculation and field measurement to excavate the tunnel entrance of rockpile tunnel.The construction parameters, such as the length of step, the length of anchor bolt and the angle of inclined insertion, in the three-step and seven-step construction method are studied and analyzed, and the optimum construction parameters of shallow burying section at the entrance of rock pile tunnel are given.The main research contents and results are as follows: (1) combined with the rock mass along the Maaliu-Zhaotong Expressway, the characteristics, forming conditions and engineering characteristics of the rock pile are analyzed.Based on the theory of elastic foundation beam, Taishaji theory and silo theory, the calculation model of optimum excavation advance of shallow buried section of rock pile tunnel is put forward, which is based on the theory of elastic foundation beam, the theory of Taishaji and the theory of silo.The optimum analysis of the construction advance of the tunnel entrance section under different conditions is carried out.The results show that under the support of pipe-shed, the reasonable excavation scale is about 1.0 m. The Midas-NX finite element software is used to establish the multi-condition three-dimensional numerical model of shallow buried section of the tunnel entrance of the rockpile tunnel.The three-dimensional simulation calculation of the construction process of the three-step and seven-step method for shallow burying section of rock pile tunnel is completed. The law of stress and deformation of surrounding rock and supporting structure of tunnel under different construction parameters are analyzed systematically, and the results are compared with the field test results.The results show that with the increase of step length, the vertical displacement and horizontal convergence of surrounding rock become larger, while the axial force and bending moment of steel arch gradually decrease, and the tensile stress of shotcrete layer decreases.Considering the deformation of surrounding rock and the stress of supporting structure, the length of step in shallow buried section of rock pile tunnel should be about 4m. 2) with the increase of the angle of bolt insertion, the horizontal displacement of different parts is the same.The horizontal displacement of the upper step decreases gradually, and the horizontal displacement of the lower step decreases first and then increases.With the increase of the length of locking bolt, the horizontal displacement of arch foot, side wall and the foot of wall decreases. When the length of anchor rod exceeds 4.5 m, the horizontal displacement decreases slightly.The length of locking bolt should be 4.5m-6m.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U455.4

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