软弱围岩隧道初期支护参数优化研究

发布时间：2018-07-05 20:24

本文选题：隧道 + 锚杆长度　；参考：《重庆交通大学》2015年硕士论文

【摘要】：随着我国经济的迅速发展,隧道工程的发展已经取得了突破性进展,然而我国还不是全面掌握隧道先进技术的科技强国,针对不同环境下的隧道工程,我们仍需依靠所积累的实践经验。新掘进的隧道一般采用初期支护来保护新开挖的临空面,防止围岩变形和破坏的持续发展。初期支护能够限制围岩的变形,提高围岩的稳定性和承载力,但针对软弱围岩下的对隧道支护形式和支护参数的研究仍然跟不上工程实际需求的步伐,对软弱围岩下初期支护的参数优化仍需不断探讨。本文依托工程为贵州毕威高速中某隧道,该隧道围岩属软弱围岩,地下水不发育。本文根据依托工程的相关工程资料和参数研究了软弱围岩下初期支护的参数,并根据计算结果来选择支护参数。具体成果如下:(1)岩性、岩体结构和裂隙、地应力、工程因素等都是影响软弱围岩下隧道结构稳定性的因素。而软弱围岩下隧道结构的破坏特征包括破坏方式多、变形量大、变形速度高、持续时间长、破坏范围大和位置不一等。破坏的模式包括掉块、膨胀破坏、挤压破坏、滑动破坏等。(2)利用有限元软件MIDAS/GTS对锚杆长度取2.5m、3.0m、3.5m、4.0m、4.5m五种工况进行计算。通过对比,3m~4.5m时所对比的各个值变化量很小,对锚杆的长度影响很小,因此取3m作为本工程锚杆长度的最佳值。(3)利用有限元软件MIDAS/GTS对锚杆间距取0.8m、1.0m、1.2m、1.5m四种工况进行建模计算。结果表明,1m后的锚杆布置间距对侧墙位移和仰拱上鼓影响较为明显,而1m间距布置则最优。(4)利用有限元软件MIDAS/GTS对钢拱架型号取工14、工18、工22b三种工况进行计算,对比分析围岩应力场、围岩位移场、锚杆轴力、喷射混凝土轴力和弯矩。通过计算,工22型号下围岩位移、锚杆轴力、喷射混凝土弯矩轴力各值最小。但从经济性考虑,选取工18号钢拱架作为本工程的优选拱架型号。(5)对该隧道施工进行监控量测,量测结果和优先于计算结果进行对比发现,有限元计算的结果相对于监控量测来说是偏于安全的,即有限元计算的结果较监控量测的实测数据偏小。有限元模拟结果与实测数据发展趋势相同,验证了两者趋势的一致性,同时也验证了有限元数值模拟的可行性。
[Abstract]:With the rapid development of our country's economy, the development of tunnel engineering has made a breakthrough progress. However, China is not a scientific and technological power that can master advanced tunnel technology in an all-round way, aiming at tunnel engineering in different environments. We still have to rely on our accumulated practical experience. The newly excavated tunnel usually uses the initial support to protect the newly excavated face and to prevent the continuous development of the surrounding rock deformation and destruction. The initial support can limit the deformation of surrounding rock, improve the stability and bearing capacity of surrounding rock, but the research of tunnel support form and supporting parameters under weak surrounding rock still can not keep up with the actual demand of engineering. The parameter optimization of initial support under soft surrounding rock still needs to be discussed. Based on the project of Guizhou Biwei High Speed Middle Tunnel, the surrounding rock of this tunnel belongs to weak surrounding rock and groundwater is not developed. Based on the relevant engineering data and parameters of the supporting engineering, this paper studies the parameters of the initial support under the soft surrounding rock, and selects the supporting parameters according to the calculation results. The concrete results are as follows: (1) lithology, rock mass structure and fracture, ground stress and engineering factors are the factors that affect the stability of tunnel structure under weak surrounding rock. The failure characteristics of tunnel structure under soft surrounding rock include many failure modes, large amount of deformation, high deformation speed, long duration, large range of failure and different location, etc. The failure modes include block drop, expansion failure, extrusion failure, sliding failure and so on. (2) the length of anchor rod is calculated by using midas / GTS software 2.5 mN3.0mP3.5mN4.0mg / 4.5m, etc. (2) the finite element software Midas / GTS is used to calculate the length of anchor rod. The variation of each value is very small and has little effect on the length of anchor rod. Therefore, 3m is taken as the best value of anchor rod length. (3) the finite element software Midas / GTS is used to model and calculate the distance between anchors under four working conditions: 0.8 m ~ (-1) ~ (2) m ~ (1.2) m ~ (1.5) m ~ (-1) ~ (-1) m ~ (-1)? The results show that the spacing of anchors after 1 m has a significant effect on the displacement of side wall and the upward drum of inverted arch, while the spacing of 1m is the best. (4) the steel arch type is calculated under the three working conditions of 14, 18 and 22b by using the finite element software Midas / GTS. The stress field of surrounding rock, displacement field of surrounding rock, axial force of anchor rod, axial force of shotcrete and bending moment are compared and analyzed. By calculation, the displacement of surrounding rock, the axial force of anchor rod and the axial force of bending moment of shotcrete are minimum. However, considering the economy, Gong18 steel arch frame is selected as the optimal arch type of the project. (5) the tunnel construction is monitored and measured, and the measured results are compared with the calculation results. The result of finite element calculation is more safe than that of monitoring measure, that is to say, the result of finite element calculation is smaller than the measured data of monitoring measurement. The result of finite element simulation is the same as that of measured data, which verifies the consistency of the two trends and the feasibility of finite element numerical simulation.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U455.7

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