本文選題：豎井開挖　切入點：微差爆破　出處：《長沙理工大學》2014年碩士論文　論文類型：學位論文

【摘要】：通風豎井是長大公路隧道的重要配套工程之一。豎井通過聯(lián)絡通道與主隧道連接,當開挖接近聯(lián)絡通道時,爆破震動將使聯(lián)絡通道內(nèi)質(zhì)點產(chǎn)生較大振動速度,可能導致聯(lián)絡通道開裂掉塊；在爆破開挖的影響下,應力場也將重新分布,影響聯(lián)絡通道初支及圍巖的穩(wěn)定性,因此,豎井的爆破方案在滿足開挖效果的同時,應重點研究豎井爆破開挖對聯(lián)絡通道動力響應。本文介紹了巖石爆破破壞的機理及圍巖松動圈的形成過程和厚度計算公式,分析了爆破動載作用下圍巖松動圈的擴展原理,提出了基于微差爆破機理的開挖方案設計,以降低對聯(lián)絡通道動力影響。結合福建省漳永高速龍巖段官田隧道通風豎井的工程特點,綜合比較正井法、反井法的優(yōu)劣,選擇反井法施工,利用反井導井作為爆破自由面,計算確定爆破參數(shù),設計5種不同微差時間的爆破方案。運用Midas/GTS軟件建立模型,確定爆破荷載曲線,推導峰值荷載公式,通過Matlab軟件進行疊加,得到微差爆破的荷載時程曲線,模擬爆破開挖過程。通過數(shù)值模擬計算,分析豎井爆破開挖對聯(lián)絡通道振速、應力等影響,可知：(1)豎井選用不同微差時間方案在同一施工段爆破開挖時,聯(lián)絡通道上振速、應力都隨著微差時間的減小而增大,當選用方案3微差時間為75ms時,振速、應力等對聯(lián)絡通道影響最小。(2)聯(lián)絡通道初支最大合振速在數(shù)值上與Y方向較為接近,比X、Z方向大很多,故其變化規(guī)律也與Y方向類似,當微差時間為25ms時,聯(lián)絡通道的振動合速度會超過國家爆破安全規(guī)程允許值的下限10cm/s。且從合振速云圖中也可知,合振速最大值分布于聯(lián)絡通道縱軸線拱頂上。(3)在豎井爆破開挖時,豎井與聯(lián)絡通道交叉面附近圍巖的最大及最小主應力均未超過巖體抗拉強度允許值,不會對圍巖造成破壞,當微差時間為25ms時,最小主應力最大,隨著最小主應力的減小,圍巖的松動圈逐漸縮小。
[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.
【學位授予單位】：長沙理工大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U455.8

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本文編號：1607146