软弱围岩高速公路桥隧搭接段地震动力响应研究

发布时间：2018-12-29 11:44

【摘要】：隧道作为一种重要的交通建筑物形式,广泛用于山区公路工程,因地形、地质和环境等因素限制,公路隧道与桥梁相互连接的工程也日益增多。在遭遇较强的地震作用下,软弱围岩高速公路桥隧搭接段是较易出现较严重震害的地段。桥隧搭接段的隧道常为浅埋段,若所处地质条件较差或受围岩风化破碎等的影响,则在地震作用下极易导致隧道洞口处各关键部位的损伤或破坏。因此,为了研究软弱围岩条件下高速公路桥隧搭接段的震害特点及抗震设防措施,对桥隧搭接段地震动力响应规律开展系统而深入的研究就成为了一个重要的研究内容和前提条件。为此,本论文依托国家自然科学基金项目“基于损伤累积效应的桥隧搭接结构地震动力响应研究”(编号:51408617),开展了桥隧搭接段大型振动台模型试验测试工作,研究了软弱围岩条件下高速公路桥隧搭接段在地震作用下的动力响应特点及其变化规律,开展了相应的数值模拟分析工作并将结果与振动台试验结果进行了对比分析。本文的研究内容与结论主要包括:(1)基于相似理论和试验要求确定了主要物理量的相似常数、模型相似材料,制定了试验加载及测试方案,将汶川波和EI-Centrol波两种地震波作为输入波,开展了相似比为1:50的软弱围岩桥隧搭接段的振动台试验研究。(2)根据振动台模型试验数据,对软弱围岩条件下高速公路桥隧搭接段地震动力响应结果进行了初步分析,揭示了不同激振强度和加载方式下桥隧搭接段的加速度、动位移和围岩压力的响应特点及变化规律。通过定义加速度放大系数和差值,分析了衬砌X、Y和Z三个方向的加速度放大系数变化规律,同时探讨了不同地震波入射方向对桥隧搭接段的影响,结果表明横向入射地震波作用对结构影响相对较大。(3)基于三维桥隧搭接模型,以输入不同方向的汶川波(X方向、Y方向)为例,采用ANSYS有限元软件进行了软弱围岩高速公路桥隧搭接段地震响应的数值模拟,将数值模拟结果与模型试验结果进行了比较分析。结果表明,两者的数值接近且主要变化规律趋于一致,也从另一方面验证了试验结果的合理性。此外,还基于数值模型分析了地震力作用下隧道离洞口不同距离的测点在地震作用下的位移和应力响应特征,计算结果表明,在地震作用下衬砌水平动位移响应与距离洞口的远近有关。
[Abstract]:As an important form of traffic building, tunnel is widely used in mountain highway engineering. Due to the constraints of terrain, geology and environment, the road tunnel and bridge are connected with each other increasingly. Under the strong earthquake action, the bridge and tunnel overlap section of soft surrounding rock highway is prone to more serious earthquake damage. The tunnel of bridge and tunnel overlap section is usually shallow buried section. If the geological condition is poor or affected by the weathering of surrounding rock, it is easy to cause damage or damage to every key part of tunnel entrance under earthquake action. Therefore, in order to study the earthquake damage characteristics and seismic fortification measures of bridge and tunnel overlap section of expressway under soft surrounding rock condition, The systematic and in-depth study on seismic dynamic response of bridge and tunnel overlap section has become an important research content and prerequisite. Therefore, based on the project of National Natural Science Foundation of China, "study on Seismic dynamic response of Bridge and Tunnel overlapped structures based on damage accumulation effect" (No. 51408617), the test work of large-scale shaking table model test of bridge and tunnel overlap section is carried out in this paper. In this paper, the dynamic response of bridge and tunnel overlap section of expressway under the condition of soft surrounding rock is studied. The corresponding numerical simulation and analysis work are carried out, and the results are compared with the results of shaking table test. The main contents and conclusions of this paper are as follows: (1) based on the similarity theory and test requirements, the similarity constants of the main physical quantities are determined, the model is similar to the material, and the test loading and testing scheme is established. Two kinds of seismic waves, Wenchuan wave and EI-Centrol wave, are taken as input waves. The shaking table test of the bridge and tunnel overlap section of soft surrounding rock with the similar ratio of 1:50 is carried out. (2) according to the shaking table model test data, The seismic dynamic response results of bridge and tunnel overlap section of expressway under soft surrounding rock condition are analyzed preliminarily, and the response characteristics and variation law of acceleration, dynamic displacement and surrounding rock pressure of bridge and tunnel overlap section under different excitation intensity and loading mode are revealed. By defining acceleration magnification factor and difference, the variation law of acceleration magnification factor in three directions of lining XY and Z is analyzed, and the influence of different incident direction of seismic wave on bridge and tunnel lap section is discussed. The results show that the transverse incident seismic wave has relatively great influence on the structure. (3) based on the three-dimensional bridge and tunnel overlap model, the Wenchuan wave (X direction, Y direction) in different directions is taken as an example. The seismic response of bridge and tunnel overlap section of soft surrounding rock highway is simulated by using ANSYS finite element software. The results of numerical simulation and model test are compared and analyzed. The results show that the values of the two are close and the main variation laws tend to be the same. On the other hand, the rationality of the experimental results is verified. In addition, based on the numerical model, the displacement and stress response characteristics of different distance from the tunnel to the hole under earthquake action are analyzed. The horizontal dynamic displacement response of the lining under earthquake action is related to the distance from the hole.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U411;U442.55;U452.28

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