近距离爆破开挖对已建拱桥受力行为的影响研究

发布时间：2018-05-02 18:11

本文选题：爆破 + 拱桥结构　；参考：《重庆交通大学》2014年硕士论文

【摘要】：近年来，随着爆破技术的应用越来越多的深入到工程建设领域，对于采用爆破开挖方式所引起的地面震动对周围结构的影响和危害引起了广泛的关注。而桥梁结构作为主要的基础交通设施之一，无论在平时使用、抗震救灾还是灾后重建中都发挥了极其重要的作用。因此采用爆破技术所引起的震动荷载对桥梁结构受力影响的研究也愈加迫切。本文研究近距离爆破开挖对周围已建拱桥结构受力行为的影响，首先对爆破地震波的产生机理和传播、衰减规律进行理论分析，并运用ANSYS/LS-DYNA软件对不同起爆药量和起爆方式条件下的岩石爆破进行数值模拟，得到爆区内已建拱桥拱脚中心位置处的加速度时程曲线；然后通过桥梁抗震动力分析方法并运用MIDAS/Civil软件建立已有拱桥的有限元模型，分析其受力特性，分别输入霍永基爆破地震反应谱和爆破模拟得到的加速度时程曲线，进而对结构进行反应谱和时程动力分析，对比拱桥结构在不同震动荷载作用下的响应情况，得到了以下结论： ①不同起爆药量所引起的爆破震动对拱桥结构的动力影响不同。对比起爆药量分别为40.0kg、102.4kg和160.0kg时拱桥的动力响应得到：随着起爆药量的增加，结构的内力响应显著增加，但两者并不成线性关系。药量较小时，，可忽略爆破震动对结构的影响，但当爆破药量达到一定量值，其影响不容忽视，而且还可能对结构的安全性产生严重的危害，因此在实际爆破开挖时应合理选择起爆药量。 ②当起爆药量相同时，不同的起爆方式也会对结构产生不同的影响。相对于单点起爆，多点起爆会使结构产生了更大的位移、弯矩以及等效应力，但是药量较小时，其影响程度小，增加起爆药量会使其影响增大，但增长幅度不明显。 ③其他条件相同时，爆心距的增加使得爆破地震效应对结构的影响逐渐减小，在起爆药量为102.4kg的情况下，通过分析不同爆心距条件下拱桥结构的内力响应得到在100m范围内进行爆破开挖，结构均处于不安全状态，因此在爆破工程中应根据工程实际情况寻求合理的安全距离，为爆破设计提供参考依据。
[Abstract]:In recent years, with the application of blasting technology more and more deep into the field of engineering construction, the impact and harm of ground vibration caused by blasting excavation on the surrounding structure has attracted extensive attention. As one of the main basic transportation facilities, bridge structure plays an extremely important role in earthquake relief and reconstruction. Therefore, it is more and more urgent to study the effect of vibration load on bridge structure caused by blasting technology. In this paper, the influence of blasting excavation on the mechanical behavior of the surrounding arch bridge is studied. Firstly, the mechanism, propagation and attenuation of blasting seismic waves are analyzed theoretically. The numerical simulation of rock blasting under different detonation charge and mode is carried out by using ANSYS/LS-DYNA software, and the acceleration time history curve at the center of arch foot of built arch bridge in blasting zone is obtained. Then the finite element model of the existing arch bridge is established by using the seismic dynamic analysis method of the bridge and the MIDAS/Civil software. The stress characteristics of the arch bridge are analyzed, and the seismic response spectrum of blasting and the acceleration time history curve obtained by blasting simulation are inputted into the seismic response spectrum of Huo Yongji blasting respectively. Then, the response spectrum and time-history dynamic analysis of the structure are carried out, and the response of arch bridge structure under different vibration loads is compared, and the following conclusions are obtained: 1 the dynamic effect of blasting vibration caused by different initial charge on the structure of arch bridge is different. Compared with the dynamic response of the arch bridge with the initial charge of 40.0kg / 102.4kg and 160.0kg, the internal force response of the structure increases significantly with the increase of the explosive content, but there is no linear relationship between the two. The influence of blasting vibration on the structure can be neglected when the charge is small, but when the explosive quantity reaches a certain value, the influence can not be ignored, and it may also cause serious harm to the safety of the structure. Therefore, the quantity of priming charge should be reasonably selected in actual blasting excavation. When the amount of detonation charge is the same, different initiation modes will have different effects on the structure. Compared with single point detonation, multi-point initiation will make the structure produce greater displacement, bending moment and equivalent stress, but the influence degree is small when the amount of charge is small, and the increase of detonating charge quantity will increase its influence, but the increase range is not obvious. (3) when other conditions are the same, the effect of blasting seismic effect on the structure decreases gradually with the increase of blasting center distance, and when the amount of detonation charge is 102.4kg, By analyzing the internal force response of arch bridge structure under different blasting center distance, it is obtained that blasting excavation is carried out within 100 m range, and the structure is in an unsafe state. Therefore, reasonable safe distance should be found in blasting engineering according to the actual situation of the project. It provides reference for blasting design.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.22

【参考文献】