水作用下软岩隧道锚承载力试验研究

发布时间：2018-03-09 06:30

本文选题：隧道式锚碇　切入点：缩尺模型试验　出处：《重庆大学》2016年硕士论文　论文类型：学位论文

【摘要】：隧道式锚碇作为目前跨江悬索大桥的重要锚碇结构之一,其作用是将主缆锚碇于桥头岸边的岩石或土层中,其稳定性直接影响着悬索桥后期运营和安全使用。桥岸库水位上升,不仅影响库岸边坡的稳定性,也对边坡中隧道式锚碇承载力及变形产生影响。评估桥岸库水位上升对隧道式锚碇安全性影响,确保其正常运营,具有重要的社会和经济意义。本课题依托几江长江大桥隧道式锚碇工程,隧道式锚碇构建于软岩岩体之中。水对软岩具有显著软化作用,为了合理评价隧道式锚碇在正常使用和长期运营过程中的安全性和稳定性,本文以几江长江大桥隧道式锚碇为研究对象,采用模型试验、理论计算和数值模拟相结合的方法,研究水对隧道锚抗拔承载力及稳定性的影响。主要研究内容如下:1采用极限平衡理论分别推导了两类典型隧道式锚碇破坏模式(模式一为锚碇沿着锚碇体表面拔出破坏和模式二为锚碇带动周围一定范围岩体破坏)对应的承载力理论计算公式。模式一,计算几江长江大桥隧道锚锚碇体理论极限承载力为7.58×105kN,抗滑稳定安全系数7.01;模式二,计算天然状态模型锚理论极限拉拔承载力为2333kN与试验最大承载力2400kN相近。2开展两组1:30隧道锚模型试验(泡水状态和天然状态),研究模型锚泡水前、后锚碇及围岩体在拉拔荷载下的变形状态、极限承载能力及破坏模式,研究结果表明:泡水状态模型锚地表测点位移和钻孔中的测点位移总体大于天然状态模型锚,水对模型锚变形软化效应明显。天然状态模型锚极限拉拔承载力2400kN,泡水状态极限拉拔承载力1872kN,模型锚被水浸泡后,拉拔承载能力下降幅度为22%。两组模型锚破坏模式相似,均为倒楔形破坏。3在两组1:30模型试验锚成果基础上,采用ABAQUS模拟两组模型锚加载受力全过程,并结合均匀设计方法对模型锚锚区围岩基本力学参数进行反演,获得接近现场两组模型锚试验的围岩力学参数。根据反演的参数,利用ABAQUS对天然状态和泡水状态模型锚进行正向数值计算,并将两组模型锚数值计算结果与现场试验锚结果进行对比,数值计算和试验结果比较接近,说明此种数值分析方法是可行的。4利用ABAQUS软件研究锚区边坡水位变化对隧道锚承载力影响,研究结果表明:从正常水位到最高洪水水位,由于水对锚碇区岩体的软化作用,隧道锚承载力逐渐降低。在正常水位、小南海成库后水位和最高洪水水位三种工况下,隧道锚承载力别为10P(P为单锚碇设计荷载,P=108MN)、9.24P和8.17P。在1P作用下,从正常水位到最高洪水位,隧道锚锚碇后端围岩、锚碇拱顶上部等部位出现小范围塑性区,但没有形成塑性区贯通,说明隧道锚围岩整体处于弹性工作状态。水位上升增大隧道锚位移和应力,但不影响隧道锚整体稳定性。
[Abstract]:Tunnel Anchorage is one of the important Anchorage structures of suspension bridge across the river at present. Its function is to anchor the main cable in the rock or soil layer at the head of the bridge. Its stability directly affects the late operation and safe use of the suspension bridge, and the water level of the bridge bank rises. It not only affects the stability of bank slope, but also affects the bearing capacity and deformation of tunnel Anchorage in slope. It is of great social and economic significance. This subject relies on the tunnel Anchorage project of Jijiang and Yangtze River Bridge, which is constructed in soft rock mass. Water plays a significant role in softening soft rock. In order to evaluate reasonably the safety and stability of tunnel Anchorage in normal use and long-term operation, this paper takes the tunnel Anchorage of Jijiang and Yangtze River Bridge as the research object, and adopts the method of model test, theoretical calculation and numerical simulation. The main contents of this study are as follows: 1. By using the limit equilibrium theory, two typical failure modes of tunnel anchorages are derived (mode one is the anchor drawing along the surface of the anchorages), and the main contents are as follows: (1) the ultimate equilibrium theory is used to deduce two typical failure modes of tunnel anchorages. The theoretical formula for calculating the bearing capacity corresponding to the failure and mode two is the Anchorage driving a certain range of rock mass failure around the Anchorage. The theoretical ultimate bearing capacity of the tunnel Anchorage body of Jijiang and Yangtze River Bridge is calculated to be 7.58 脳 10 ~ 5kN, and the safety factor of anti-slide stability is 7.01. The theoretical ultimate drawing capacity of natural state model anchor is 2333kN, which is close to the maximum test capacity of 2400kN. 2 groups of 1:30 tunnel anchor model tests (bubble state and natural state) are carried out. The deformation state, ultimate load-carrying capacity and failure mode of the rear Anchorage and surrounding rock under pull-out load are studied. The results show that the displacement of the measured points in the Anchorage and the borehole is larger than that in the natural state model. The effect of water on deformation softening of model anchor is obvious. The ultimate drawing capacity of natural state model anchor is 2400kN, and the ultimate drawing capacity of model anchor is 1872 KN in bubble state. After the model anchor is soaked in water, the drawing-bearing capacity of model anchor decreases by 22. The failure modes of the two groups of model anchors are similar. Based on the results of two groups of 1:30 model test anchors, the whole loading process of two groups of model anchors is simulated by ABAQUS, and the basic mechanical parameters of surrounding rock in the anchor zone of the model are inversed with uniform design method. The mechanical parameters of surrounding rock near two groups of model anchors are obtained. According to the inversion parameters, the model anchors in natural state and bubble state are calculated by ABAQUS. The numerical results of the two groups of model anchors are compared with those of the field test anchors. The numerical results and the experimental results are close to each other. It is feasible to use ABAQUS software to study the influence of slope water level change on tunnel anchor bearing capacity. The results show that from normal water level to maximum flood water level, water softens the rock mass in Anchorage area. The anchoring capacity of the tunnel decreases gradually. Under the three working conditions of normal water level, post-reservoir water level and maximum flood water level in the small South China Sea, the anchoring capacity of the tunnel is different from 10 Pu P to 9. 24 P and 8. 17 P. Under the action of 1 P, the anchoring capacity of the tunnel is from normal water level to the highest flood level. The surrounding rock at the back end of the tunnel Anchorage has a small plastic zone in the upper part of the arch roof of the Anchorage, but no plastic zone is formed, which indicates that the surrounding rock of the tunnel anchor is in an elastic working state, and the rise of water level increases the displacement and stress of the anchor in the tunnel. But it does not affect the overall stability of tunnel anchor.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U448.25

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