复合构造区域煤岩体应力分布及冲击地压危险性评价

The stress distribution of coal and rock mass and the risk evaluation of rock burst in the composite structure area

  • 摘要: 工作面构造区域应力异常集中与冲击地压关系密切,而基于煤岩体波速与应力的良好相关性,地震波CT探测技术广泛用于冲击地压危险性评价与预警,但现有研究仅针对简单条件或单一构造区域,未对存在多种地质构造形成的复合构造区域进行探讨。以山东某矿2305综放工作面为例,针对其复合构造区域内微震事件集中且曾发生过冲击地压的情况,采用地震波CT探测技术获取构造区域内煤岩体应力分布情况,并引入含地震波波速和波速梯度的特征指数c分析应力分布特征及冲击地压危险性。研究结果表明:① 微震事件分布集中与邻近构造相关,可将集中区域按构造数量分为单一或复合区域,按受扰动程度分为强或弱扰动区域。② 强扰动复合构造区域静态应力集中程度最高,弱扰动单一构造区域应力集中程度最低;断层单一构造区域应力增高水平与受扰动程度呈正相关关系;低扰动复合构造区域内向斜较断层应力增高显著。③ 构造区域围岩静态应力集中是导致围岩活动剧烈的主要原因,综合考虑围岩静载荷与采动影响下动载荷增量情况,可得出不同微震事件集中区域的冲击地压危险性。

     

    Abstract: The abnormal concentration of stress in the structure area of the working face is closely related to the rock burst. Based on the good correlation between the wave velocity and stress of the coal and rock mass, the seismic wave CT detection technology is widely used in the evaluation and warning of the risk of rock burst. However, the existing researches are mainly focused on simple conditions or single structure area. The composite structure area formed by multiple geological structures has not been discussed. Taking the 2305 fully mechanized working face of a mine in Shandong as an example, in the context of the concentration of microseismic events in the composite structure area and the occurrence of rock bursts, the seismic wave CT detection technology is used to obtain the stress distribution of coal and rock mass in the structure area and the characteristic index c including speed and speed gradient of seismic wave is introduced to analyze the stress distribution characteristics and the risk of rock burst. The research results show that: ① The concentration of microseismic events is related to adjacent structures. The concentrated areas can be divided into single or composite areas according to the number of structures, and can be divided into strongly or weakly disturbed areas according to the degree of disturbance. ② The strongly disturbed area composite structure area has the highest static stress concentration, and the weakly disturbed single structure area has the lowest stress concentration. The stress increase level of the fault single structure area is positively correlated with the degree of disturbance. The syncline in the weakly disturbed composite structure area has a significantly higher stress than the fault area. ③ The static stress concentration of the surrounding rock in the structure area is the main cause of intense surrounding rock activity. Based on the static load of surrounding rock and the dynamic load increment under the influence of mining, the risk of rock burst in the concentrated area of different microseismic events can be obtained.

     

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