竖井不同爆破开挖方式对联络通道动力响应分析

发布时间：2018-03-13 16:16

本文选题：竖井开挖　切入点：微差爆破　出处：《长沙理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：通风竖井是长大公路隧道的重要配套工程之一。竖井通过联络通道与主隧道连接,当开挖接近联络通道时,爆破震动将使联络通道内质点产生较大振动速度,可能导致联络通道开裂掉块；在爆破开挖的影响下,应力场也将重新分布,影响联络通道初支及围岩的稳定性,因此,竖井的爆破方案在满足开挖效果的同时,应重点研究竖井爆破开挖对联络通道动力响应。本文介绍了岩石爆破破坏的机理及围岩松动圈的形成过程和厚度计算公式,分析了爆破动载作用下围岩松动圈的扩展原理,提出了基于微差爆破机理的开挖方案设计,以降低对联络通道动力影响。结合福建省漳永高速龙岩段官田隧道通风竖井的工程特点,综合比较正井法、反井法的优劣,选择反井法施工,利用反井导井作为爆破自由面,计算确定爆破参数,设计5种不同微差时间的爆破方案。运用Midas/GTS软件建立模型,确定爆破荷载曲线,推导峰值荷载公式,通过Matlab软件进行叠加,得到微差爆破的荷载时程曲线,模拟爆破开挖过程。通过数值模拟计算,分析竖井爆破开挖对联络通道振速、应力等影响,可知：(1)竖井选用不同微差时间方案在同一施工段爆破开挖时,联络通道上振速、应力都随着微差时间的减小而增大,当选用方案3微差时间为75ms时,振速、应力等对联络通道影响最小。(2)联络通道初支最大合振速在数值上与Y方向较为接近,比X、Z方向大很多,故其变化规律也与Y方向类似,当微差时间为25ms时,联络通道的振动合速度会超过国家爆破安全规程允许值的下限10cm/s。且从合振速云图中也可知,合振速最大值分布于联络通道纵轴线拱顶上。(3)在竖井爆破开挖时,竖井与联络通道交叉面附近围岩的最大及最小主应力均未超过岩体抗拉强度允许值,不会对围岩造成破坏,当微差时间为25ms时,最小主应力最大,随着最小主应力的减小,围岩的松动圈逐渐缩小。
[Abstract]:Ventilation shaft is one of the important supporting projects of long and long highway tunnel. The shaft connects with the main tunnel through the connection channel. When the tunnel is excavated close to the contact tunnel, the blasting vibration will cause the larger vibration velocity of the particle in the contact tunnel. Under the influence of blasting excavation, the stress field will also be redistributed, which will affect the stability of the initial branch and surrounding rock of the connecting passage. Therefore, the blasting scheme of shaft can satisfy the excavation effect at the same time. In this paper, the mechanism of rock blasting failure, the formation process of surrounding rock loose circle and the formula of thickness calculation are introduced, and the expansion principle of surrounding rock loose circle under blasting dynamic load is analyzed. The excavation scheme design based on the mechanism of millisecond blasting is put forward to reduce the influence on the dynamic of the contact channel. Combined with the engineering characteristics of the ventilation shaft of Guantian Tunnel in Zhangyong High-speed Longyan Section in Fujian Province, the advantages and disadvantages of the positive well method and the inverse well method are compared. The inverse well method is chosen to be used as the blasting free surface, the blasting parameters are calculated and determined, and five blasting schemes with different millisecond time are designed. The model is established by Midas/GTS software, the blasting load curve is determined, and the peak load formula is derived. The loading time history curve of millisecond blasting is obtained by Matlab software, and the blasting excavation process is simulated. Through numerical simulation, the effects of shaft blasting excavation on the vibration velocity and stress of the connecting passage are analyzed. It can be seen that when the shaft is excavated with different millisecond time schemes in the same construction section, the vibration velocity and stress increase with the decrease of the millisecond time, and when the millisecond difference time of option 3 is 75 Ms, the vibration velocity increases. The maximum closing velocity of the initial branch of the contact channel is numerically close to the Y direction, which is much larger than that of the XG Z direction, so its variation law is similar to the Y direction, and when the difference time is 25 Ms, the maximum closing velocity of the initial branch is similar to that of the Y direction. The vibration velocity of the contact channel will exceed the lower limit of 10 cm / s of the allowable value of the national blasting safety code. Furthermore, it can be seen from the cloud diagram of the combined vibration velocity that the maximum value of the combined vibration velocity is distributed on the vertical axis dome of the contact channel. The maximum and minimum principal stresses of surrounding rock near the intersection plane of shaft and connection passage do not exceed the allowable value of rock mass tensile strength and will not cause damage to the surrounding rock. When the difference time is 25 Ms, the minimum principal stress is maximum, and the minimum principal stress decreases with the decrease of minimum principal stress. The loose circle of surrounding rock gradually shrinks.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455.8

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