开挖爆破作用下锚碇隧道围岩稳定性的应用研究

发布时间：2018-02-21 06:50

本文关键词： 锚碇隧道围岩稳定振动速度围岩损伤掌子面纵向间距　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：隧道式锚碇在公路悬索桥建设中得到越来越多的重视,其施工质量要求也越来越严格。锚碇隧道是利用隧道围岩体对锚塞体的作用平衡拉力,因其具有变截面、小净距等工程特点,因此,对锚碇隧道围岩的完整性和稳定性要求更高。钻爆法是隧道开挖的主要手段,所以研究开挖爆破作用下锚碇隧道围岩稳定性具有重要意义。本文结合雅康高速大渡河特大悬索桥雅安岸锚碇隧道爆破施工项目,分别利用现场监测和数值计算方法分析隧道围岩稳定性,归纳出具有实践意义的结论,以指导类似隧道工程的施工建设。本文研究内容和取得成果具体如下:根据锚碇隧道的工程特点,基于上台阶掘进爆破施工现场监测数据,研究分析先行洞迎爆侧的振速峰值、振动频率、振动衰减规律,并用围岩变形数据验证隧道围岩稳定性。由分析结果可知,后行洞爆破施工时,先行洞迎爆侧最大振动速度由掏槽孔爆破引起;为保证各微差爆破段相互独立,各段延迟时间应大于最大振速的振动持续时间;振动速度峰值以后行洞掌子面平行断面处为中心向前后方随距离的增大表现为衰减趋势,且掌子面后方振速峰值衰减速度大于掌子面前方;振动衰减规律不满足萨道夫斯基公式;先行洞拱顶沉降为11.5mm,沉降速率最大值为1.5mm/d,后行洞拱顶沉降为8mm,沉降速率最大值为2mm/d,均满足安全要求,围岩稳定性较好。本文利用ANSYS/LS-DYNA软件建立与工程实际相符的数值模型,岩石损伤的质点峰值振速临界值选取30cm/s,计算周边孔爆破时围岩的损伤范围。由计算结果可知,随质点与炮孔壁的距离增大,质点振速峰值迅速衰减,距离超过20cm之后,衰减幅度明显减小。30cm处的质点振速峰值为33cm/s,35cm处的质点振速峰值为28cm/s,则可以推测周边孔爆破产生的围岩损伤范围在33cm左右。为分析各因素对隧道围岩稳定性的影响,本文利用有限元软件以控制变量法模拟讨论了埋深、净距、隧道断面尺寸、先后洞掌子面纵向间距等工况。分别得到以下结论:隧道处于浅埋状态时,随埋深增大,则先行洞迎爆侧拱腰位置的振速会随之减小,当埋深增加到20m后,振动速度基本不再变化;净距越大,振动速度越小;断面尺寸对先行洞迎爆侧拱腰处的振动速度基本没有影响;先后洞掌子面间距变化对先行洞迎爆侧振速峰值的影响不明显,掌子面前方围岩受影响范围在15m以内,掌子面后方围岩受影响范围在7m以内。同时,还分析了掌子面纵向间距对先行洞拱顶沉降的影响,得出结论:前三施工步对先行洞拱顶沉降影响最大,且间距越小,前期沉降量越大,占总沉降量的比例也越大;隧道施工对围岩拱顶沉降影响范围在12m左右,为保证工程安全,本工程先后洞掌子面纵向间距取15m。
[Abstract]:Tunnel Anchorage is paid more and more attention to in the construction of highway suspension bridge, and its construction quality requirement is more and more strict. Because of the characteristics of engineering such as small clear distance, the integrality and stability of surrounding rock of Anchorage tunnel are required higher. The drilling and blasting method is the main method of tunnel excavation. Therefore, it is of great significance to study the stability of surrounding rock of Anchorage tunnel under the action of excavation blasting. This paper combines with the blasting construction project of Ya-an Anchorage Tunnel of Yakang Expressway Dadu River suspension Bridge. The stability of surrounding rock of tunnel is analyzed by field monitoring and numerical calculation, and the conclusions of practical significance are concluded. In order to guide the construction of similar tunnel projects, the research contents and achievements are as follows: according to the engineering characteristics of Anchorage tunnel, based on the monitoring data of blasting construction, the peak value of vibration velocity on the blasting side of the first tunnel is studied and analyzed. Vibration frequency, vibration attenuation law, and surrounding rock deformation data are used to verify the stability of tunnel surrounding rock. In order to ensure that each millisecond blasting section is independent of each other, the delay time of each segment should be greater than the vibration duration of the maximum vibration velocity, and after the peak value of vibration velocity, the center of the parallel section of the palm face of the tunnel will show a attenuation trend with the increase of the distance. The peak attenuation velocity of the square vibration velocity behind the palm is larger than that of the front of the palm, and the law of vibration attenuation is not satisfied with the Sadolski formula. The settlement of the arch roof of the first hole is 11.5mm, the maximum settlement rate is 1.5mm / d, the settlement of the dome is 8mm and the maximum rate of settlement is 2mm / d. all of them meet the safety requirements and the stability of surrounding rock is good. In this paper, the numerical model, which is in accordance with the engineering practice, is established by using ANSYS/LS-DYNA software. The critical value of peak particle velocity of rock damage is 30 cm / s to calculate the damage range of surrounding rock during blasting. The results show that with the increase of the distance between particle and hole wall, the peak value of particle vibration velocity rapidly attenuates, and when the distance exceeds 20cm, the damage range of surrounding rock is calculated. The attenuation amplitude is obviously reduced. The peak value of particle vibration velocity at 33cm / s-1 35cm is 28 cm / s, and the damage range of surrounding rock caused by peripheral hole blasting is about 33cm. In order to analyze the influence of various factors on the stability of tunnel surrounding rock, the attenuation amplitude is obviously reduced. In this paper, the finite element software is used to simulate and discuss the conditions of buried depth, net distance, tunnel section size and vertical spacing of tunnel face by using the control variable method. The conclusions are as follows: when the tunnel is in shallow burying state, the buried depth increases with the tunnel depth. Then the vibration velocity of the arch at the side of the first hole will decrease, when the buried depth increases to 20 m, the vibration velocity will not change basically, the larger the net distance, the smaller the vibration velocity. The cross section size has no effect on the vibration velocity of the arch waist of the blasting side of the antecedent tunnel, and the change of the space between the face surfaces of the successive holes has no obvious effect on the peak value of the vibration velocity of the front side of the tunnel, and the influence range of surrounding rock in front of the front face of the tunnel is less than 15m. At the same time, the influence of the longitudinal distance of the face on the settlement of the arch roof of the antecedent tunnel is analyzed. It is concluded that the first three steps of construction have the greatest influence on the settlement of the arch roof of the leading cave, and the smaller the distance, the smaller the distance between the first three construction steps. The larger the pre-settlement, the greater the proportion of the total settlement, the influence range of tunnel construction on the settlement of surrounding rock arch is about 12m, in order to ensure the safety of the project, the longitudinal distance between the face of the tunnel and the face of the tunnel is 15m.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U455.6;U451.2

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