隧洞开挖爆破诱发的围岩振动特性研究

发布时间：2019-05-18 10:34

【摘要】：水电能源作为绿色无污染能源之一,得到了高度重视与大规模开发。水电工程建设中涉及大量的隧洞开挖爆破,爆破开挖诱发的围岩振动及其影响一直是岩土工程界重点关注的问题之一,全面分析隧洞开挖爆破诱发的围岩振动特性对于优化隧洞开挖爆破设计、改进爆破施工工艺以及控制工程灾害等方面都有重要理论意义和工程应用价值。论文针对隧洞开挖爆破中地应力卸载诱发振动、爆炸荷载与地应力瞬态卸载耦合作用诱发振动和爆破空气冲击波诱发振动的机理及振动特性等问题,采用理论分析与数值模拟相结合的方法研究了隧洞开挖爆破诱发的围岩振动特性。论文的主要工作和研究成果如下:(1)结合瞬态卸荷理论和瀑布沟水电站1#尾水洞实测爆破振动数据,讨论了地应力卸载诱发围岩振动的产生机理及特性。得到开挖面地应力在爆破过程中瞬态卸载产生较大附加动应力,诱发地震波在围岩中传播时产生振动。地应力卸载诱发的振动频率低,与爆炸荷载诱发振动分布在高低差别明显的两个频率带,振动峰值在开挖面近区小于爆炸荷载诱发振动的峰值,在远区大小相当,并随着地应力值和开挖面面积的增大而增大;(2)基于拉格朗日侵蚀算法,数值模拟了不同地应力条件下岩体爆破裂纹的扩展过程,研究了爆炸荷载和地应力卸载耦合作用诱发的围岩振动特性。结果表明,较低地应力条件下,爆破振动主要由爆炸荷载诱发,振动持续时间较短,峰值较小;中高地应力条件下,振动持续时间较长,振动信号突变较为频繁,峰值随地应力水平的提高而增大,振动能量随频率分布在高低差别明显的两个频带,较低频带的能量比例随地应力增大而增加;不同侧压力系数条件下,随着侧压力系数增大,振动峰值在地应力增大的方向上明显增大;比较高低地应力条件下的振动特性,地应力卸载的耦合作用增加了振动的持续时间,增大了峰值,使振动低频部分增多;(3)基于河北丰宁抽水蓄能电站地质探洞中的爆破试验数据,理论分析和数值模拟研究了隧洞开挖爆破空气冲击波超压诱发围岩振动的机理及特性。得到小断面隧洞爆破空气冲击波超压较大并将诱发围岩振动,该振动具有振速高、持续时间长和衰减慢等特征。空气冲击波超压诱发的围岩受迫振动发生时间受空气冲击波传播速度控制。诱发振动可分为空气冲击波超压作用于前部围岩产生并经围岩传播过来的振动,和空气冲击波超压传播到围岩壁面直接引起的振动,实测空气冲击波诱发的振动主要是由于空气冲击波超压直接作用于洞壁围岩造成的振动。
[Abstract]:As one of the green and pollution-free energy sources, hydropower energy has been highly valued and developed on a large scale. In the construction of hydropower engineering, a large number of tunnel excavation blasting is involved. The vibration of surrounding rock induced by blasting excavation and its influence have always been one of the key problems in geotechnical engineering. The comprehensive analysis of the vibration characteristics of surrounding rock induced by tunnel excavation blasting is of great theoretical significance and engineering application value for optimizing the blasting design of tunnel excavation, improving blasting construction technology and controlling engineering disasters. In this paper, the mechanism and vibration characteristics of ground stress unloading induced vibration, coupling of explosion load and ground stress transient unloading and blasting air shock wave induced vibration in tunnel excavation blasting are discussed. The vibration characteristics of surrounding rock induced by blasting in tunnel excavation are studied by means of theoretical analysis and numerical simulation. The main work and research results of this paper are as follows: (1) based on the transient unloading theory and the measured blasting vibration data of No. 1 tailing tunnel of Pubugou Hydropower Station, the mechanism and characteristics of surrounding rock vibration induced by ground stress unloading are discussed. It is found that the transient unloading of the ground stress of the excavated surface produces a large additional dynamic stress and causes vibration when the seismic wave propagates in the surrounding rock. The vibration frequency induced by ground stress unloading is low, which is obviously different from that induced by explosion load in two frequency bands. The peak value of vibration is smaller than the peak value of explosion load induced vibration in the near area of excavation surface, and the size of vibration induced by explosion load is the same in the far area. It increases with the increase of ground stress value and excavation surface area. (2) based on Lagrangian erosion algorithm, the propagation process of blasting cracks in rock mass under different ground stresses is simulated, and the vibration characteristics of surrounding rock induced by the coupling of explosion load and ground stress unloading are studied. The results show that under the condition of low ground stress, the blasting vibration is mainly induced by explosion load, the vibration duration is short and the peak value is small. Under the condition of medium and high ground stress, the vibration duration is long, the vibration signal mutation is more frequent, and the peak and anywhere stress level increases. The vibration energy is distributed in two frequency bands with obvious difference in frequency. The energy ratio of the lower frequency band increases with the increase of ground stress. Under the condition of different lateral pressure coefficients, with the increase of lateral pressure coefficient, the peak value of vibration increases obviously in the direction of the increase of ground stress. Compared with the vibration characteristics under the condition of high and low ground stress, the coupling effect of ground stress unloading increases the duration of vibration, increases the peak value, and increases the low frequency part of vibration. (3) based on the blasting test data in the geological exploration tunnel of Fengning pumped Storage Power Station in Hebei Province, the mechanism and characteristics of surrounding rock vibration induced by overpressure of blasting air shock wave in tunnel excavation are studied by theoretical analysis and numerical simulation. It is obtained that the overpressure of air shock wave in small section tunnel blasting is large and will induce the vibration of surrounding rock. The vibration has the characteristics of high vibration speed, long duration and slow attenuation. The occurrence time of forced vibration of surrounding rock induced by air shock wave overpressure is controlled by the propagation velocity of air shock wave. The induced vibration can be divided into the vibration caused by the overpressure of the air shock wave acting on the front surrounding rock and propagating through the surrounding rock, and the vibration caused directly by the overpressure of the air shock wave to the wall of the surrounding rock. The vibration induced by the measured air shock wave is mainly caused by the overpressure of the air shock wave directly acting on the surrounding rock of the tunnel wall.
【学位授予单位】：武汉大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV554

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