茅田界隧道变质砂岩动力响应特性研究

发布时间：2018-01-04 20:31

本文关键词：茅田界隧道变质砂岩动力响应特性研究　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：深埋长大的山岭隧道,在爆破荷载作用下,掌子面附近围岩会产生剧烈的振动,易诱发工程事故,影响工程的安全性。研究岩体的动力响应特征可以在一定程度上预测工程灾害,避免不必要的经济损失。本文以二广高速公路茅田界隧道为工程依托,开展变质砂岩峰前卸围压及声发射试验,并采用ANSYS/LS-DYNA软件进行爆破荷载作用下的数值模拟工作,对茅田界隧道变质砂岩的动力响应特性进行分析研究。首先,本文简单阐述了岩石的爆破机理、岩体动力扰动特性及等效数值模拟的方法等基本内容。结合峰前卸围压试验,研究了茅田界隧道变质砂岩破坏特征。试验结果表明:围压可以有效抑制岩样的破坏,提高岩样的承载力;高卸荷速率下岩样的破坏存在突然性,岩样表现出更强的脆性破坏特征,同时岩样的极限储能降低。其次,开展掏槽孔塑性区扩展的研究,确定掏槽孔合理的装药集度为0.54 kg/m,进而确定茅田界隧道III级围岩光面爆破的设计参数。通过定义不同初始时刻的荷载子步实现微差起爆的效果,验证了光面爆破参数的合理性。最后,采用ANSYS/LS-DYNA软件,分析了茅田界隧道变质砂岩动力响应的基本规律。数值模拟结果表明:质点振动方向与应力波传播方向一致时,主频要高于其他方向的振动主频,且主频随位移变化的灵敏度较低;质点的峰值振速、质点的峰值位移和拱顶第一主应力峰值均表现出随着爆源距的增大而减小的特征;拱顶至边墙底部的第一主应力由主拉应力向主压应力转化;茅田界隧道III级围岩的合理爆破进尺为3~4 m;隧道掌子面1 m范围内的岩体动力响应最为敏感。
[Abstract]:Deep buried mountain tunnel, under blasting load, surrounding rock near the face of the palm will produce violent vibration, easy to cause engineering accidents. Study on dynamic response characteristics of rock mass can predict engineering disasters to a certain extent and avoid unnecessary economic losses. This paper relies on Maotian Tunnel of Er-Guangzhou Expressway. The tests of unloading confining pressure and acoustic emission in front of metamorphic sandstone are carried out, and the numerical simulation work under blasting load is carried out by using ANSYS/LS-DYNA software. The dynamic response characteristics of metamorphic sandstone in Maotian Tunnel are analyzed and studied. Firstly, the blasting mechanism of rock is briefly described in this paper. Dynamic disturbance characteristics of rock mass and equivalent numerical simulation method. Combined with pre-peak unloading confining pressure test. The failure characteristics of metamorphic sandstone in Maotian Tunnel are studied. The experimental results show that confining pressure can effectively restrain the damage of rock samples and improve the bearing capacity of rock samples. At high unloading rate, the failure of rock samples is sudden, the rock samples show a stronger brittle failure characteristics, and the limit energy storage of rock samples is reduced. Secondly, the study on the expansion of cut plastic zone is carried out. The reasonable charge set of cut hole is determined to be 0. 54 kg/m. Then determine the design parameters of III class wall rock smooth blasting in Maotian boundary tunnel. By defining the load sub-step at different initial time to achieve millisecond blasting effect, verify the rationality of smooth blasting parameters. Finally. The basic law of dynamic response of metamorphic sandstone in Maotian boundary tunnel is analyzed by using ANSYS/LS-DYNA software. The numerical simulation results show that the direction of particle vibration is consistent with the direction of stress wave propagation. The main frequency is higher than the vibration frequency in other directions, and the sensitivity of the main frequency varies with the displacement is low. The peak vibration velocity of the particle, the peak displacement of the particle and the peak value of the first principal stress of the arch all show the characteristics of decreasing with the increase of the distance between the detonation sources. The first principal stress from the arch top to the bottom of the side wall is transformed from the main tensile stress to the main compressive stress; The reasonable blasting scale of III grade surrounding rock of Maotian boundary tunnel is 3 ~ 4 m; The dynamic response of rock mass within 1 m of tunnel face is the most sensitive.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U451.2

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