活动断层错动下跨断层隧道动力响应及破坏机理研究

发布时间：2018-03-31 14:08

本文选题：隧道工程　切入点：动力响应　出处：《西南交通大学》2017年硕士论文

【摘要】：穿越活动断层的隧道结构在强震作用下受力变形情况极为复杂,活动断层一旦发生错动,将会对隧道结构的安全产生显著影响。本文首先基于位移表示定理研究断层错动引起的理论位移场,引入断层错动速度函数表征断层错动速率。建立大型三维隧道动力响应模型,分析断层错动形式、错动速率等问题。采用断层错动、地震动综合加载并考虑断层错动速度函数的方式模拟强震作用下穿越活动断层隧道实际工程情况,分析研究隧道结构受力变形机理,结合实际工程震害对比分析。最后针对跨断层隧道工程问题,进行隧道减震措施研究。本文的主要成果如下:(1)研究了均匀弹性全空间内断层错动引起的理论位移场,基于位移表示定理,得到目前断层模拟中常用的矩形有限断层引起的位移公式,理论公式表明断层错动速率对错动引起的位移场影响不可忽视。(2)开展跨断层隧道三维动力数值模拟,对比了三种断层错动形式对隧址区围岩和隧道结构的影响,得出正断层错动形式对隧道结构安全最为不利。同时进行了断层错动速率研究,研究表明:断层错动速率越大,引起的隧道衬砌主应力越大,结构安全系数较低,在断层及附近应力集中位置表现明显。对比采用不同错动速度函数的断层错动工况可以得出,断层错动速度变化的平滑性对结构主应力及安全也有一定影响。(3)分析强震作用下穿越活动断层隧道结构受力和变形特征,发现在断层或附近位置隧道结构变形主要由断层错动位移控制,距离断层较远位置处的隧道结构变形主要由水平地震动引起,结构内力基本与变形情况相符,断层错动速率对隧道结构受力有一定影响,地震动引起结构的变形及内力波动幅值在断层附近位置放大。(4)对比汶川地震中龙溪隧道实际震害,可以发现:在断裂带两侧一定范围内,震害特别严重,在拱顶、拱肩处出现局部坍塌,仰拱处出现隆起、开裂等严重震害,斜向破裂主要发育在拱脚及附近位置的钢筋混凝土中,以剪切和剪张裂缝为主,震害现象与本文结构变形内力分析结果相符,说明本文研究可以一定程度上反映穿越活动断层隧道震害机理。(5)本文开展了柔性接头、减震层以及二级减震措施减震效果的数值模拟研究,计算结果中减震层、柔性接头、二级减震措施对结构主应力最大降低比例分别约为30%、50%、55%,二级减震措施减震效果最好。柔性接头措施能有效控制断层错动影响范围,建议在跨活动断层的隧道工程中采用,并配合其他减震措施确保隧道安全。
[Abstract]:The stress and deformation of tunnel structure through active fault is very complicated under strong earthquake, once the active fault is staggered, First of all, based on the displacement representation theorem, the theoretical displacement field caused by fault dislocation is studied. The fault dislocation velocity function is introduced to characterize the fault dislocation velocity. A large 3D tunnel dynamic response model is established to analyze the fault dislocation form, fault velocity and so on. The method of synthetically loading ground motion and considering the fault staggered velocity function is used to simulate the actual engineering situation of the tunnel crossing the active fault under strong earthquake, and to analyze and study the mechanism of stress and deformation of the tunnel structure. Combined with the comparative analysis of earthquake damage in practical engineering, finally, aiming at the problem of cross-fault tunnel engineering, the seismic absorption measures of tunnel are studied. The main results of this paper are as follows: 1) the theoretical displacement field caused by fault dislocation in uniform elastic space is studied. Based on the displacement representation theorem, the displacement formulas caused by rectangular finite faults are obtained, which are commonly used in fault simulation at present. The theoretical formula shows that the effect of fault dislocation rate on displacement field caused by fault dislocation can not be ignored. (2) Three-dimensional dynamic numerical simulation of cross-fault tunnel is carried out, and the effects of three types of fault dislocation on surrounding rock and tunnel structure in tunnel area are compared. At the same time, the fault dislocation rate is studied. The study shows that the greater the fault dislocation rate, the greater the main stress of tunnel lining and the lower the safety factor of the tunnel lining. The stress concentration in and around the fault is obvious. The smoothness of the velocity variation of fault dislocation has a certain influence on the principal stress and safety of the structure. (3) the stress and deformation characteristics of the tunnel structure through the active fault under strong earthquake are analyzed. It is found that the deformation of tunnel structure in or near the fault is mainly controlled by the dislocation displacement of the fault, and that the deformation of the tunnel structure at a distance from the fault is mainly caused by horizontal ground motion, and the internal force of the structure is basically consistent with the deformation. The deformation of the structure caused by ground motion and the amplitude of the fluctuation of internal force in the vicinity of the fault are magnified in the position near the fault, and the actual earthquake damage of Longxi tunnel in Wenchuan earthquake is compared. It can be found that the earthquake damage is especially serious in a certain range on both sides of the fault zone. There are local collapses at the arch top, arch shoulder, uplift at the inverted arch, cracking and so on. The diagonal fracture mainly occurs in the reinforced concrete of the arch foot and its vicinity, and the shear and shear-tension cracks are the main ones. The seismic damage phenomenon is consistent with the results of the internal force analysis of the deformation of the structure in this paper. It shows that the research in this paper can reflect to some extent the earthquake damage mechanism of the tunnel through active fault.) in this paper, the numerical simulation study of flexible joints, shock absorption layers and secondary damping measures is carried out. The results show that the damping layers and flexible joints are in the calculation results. The maximum reduction ratio of the secondary damping measures to the principal stress of the structure is about 30% and 55% respectively, and the second stage measures are the best. The flexible joint measures can effectively control the influence of fault dislocation, and it is suggested that the measures should be used in the tunnel projects that span active faults. And cooperate with other shock absorption measures to ensure tunnel safety.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U451

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