考虑土-结构相互作用的弹簧-地下结构体系静力推覆试验技术及其试验研究

Static pushover test technology and experimental study of spring-underground structure system considering soil-structure interaction

地下结构静力推覆试验由于具有模型结构尺寸较大、应力水平可控等优点,适用于研究抗震性能问题。为了解决考虑土-结构相互作用的土-地下结构体系静力推覆试验过程复杂、费用昂贵的问题,研究了试验过程相对简单、可近似考虑土-结构相互作用的弹簧-地下结构体系静力推覆试验技术,通过引入弹簧单元模拟结构所受初始土压力及推覆过程中的土-结构相互作用,通过压缩模型两侧弹簧及施加竖向均布荷载以模拟结构所受初始土压力,通过限制模型底部水平位移,并在模型侧顶部作用水平推力将模型自初始状态推至破坏以模拟结构所受水平地震作用。以1995年日本阪神地震中破坏的Daikai车站为原型,制作几何缩尺比为1/5的模型,基于上述试验装置设计了详细的试验方案,开展弹簧-地下结构体系静力推覆试验以验证该试验方法的可行性。通过试验得到模型受力全过程剪力-层间位移能力曲线、模型结构裂缝发展部位及结构破坏形态,分析试验结果可知,在地震作用过程中,周围土体对地下结构的约束作用明显,周围土体的存在提高了地下结构的抗侧向倒塌能力,中柱是模型结构的薄弱构件。

Static pushover test of underground structures is an ideal method in seismic research due to its large model structure size and controllable stress level. In order to solve the problem of complex and expensive static pushover test process for soil-underground structure system considering soil-structure interaction, a simple static pushover test technology considering spring-underground structure system was proposed which can approximately consider the soil-structure interaction. Steel springs were set to simulate the initial earth pressure and soil-structure interaction during the pushover process. In the test, the springs on both sides of the structure were compressed and vertical uniformly distributed load was applied to simulate the initial earth pressure on the structure. The springs also limited the horizontal displacement of the bottom of the structure, and a horizontal thrust was applied on the top of one side of the structure to push the structure from the initial state to failure to simulate the horizontal seismic action on the structure. The test object was a scaled model of the Daikai station damaged in the 1995 Hanshin earthquake in Japan, and the geometric scale ratio of the model structure was 1/5. Based on the test device, a detailed test scheme was designed, and the feasibility of this test assumption was verified by carrying out the test. The relationship between the shear capacity of the test object and structural inner-story drift could be obtained by analyzing the test results. The weak components and the failure mode of the structure were studied. It can be seen that the surrounding soil had an obvious restraint effect on the underground structures during the earthquake process, and the surrounding soil improved the lateral collapse resistance of the underground structures, the middle column was the weak member of the model structure.