新集二矿地应力实测分析及其对瓦斯抽采的影响研究

In-situ Stress Measurement Analysis and Its Influence on Gas Drainage in Xinji No.2 Coal Mine

地应力是控制煤体瓦斯流动的主要因素之一。为了掌握测试地点的地应力特征及其对瓦斯抽采的影响,首先采用套孔应力解除法进行了井下地应力实测,得到在新集二矿实测深度范围内,应力解除测点的最大主应力范围18.92~19.80 MPa,最小主应力的量值11.75 MPa,最大水平主应力与自重应力比的范围1.38~1.41,测点处的应力以构造应力为主。在此基础上,根据现场参数建立数值模型,利用Comsol Multiphysics多场耦合数值模拟软件,模拟解算不同地应力条件下和不同抽采时间段,抽采钻孔周围瓦斯压力变化规律。结果表明,地应力11.75 MPa和19.80 MPa时钻孔的抽采达标时间分别在20 d和105 d左右,而地应力为30 MPa时的时间更长,即地应力越大对应的煤层瓦斯抽采达标时间越长。因此,需要采取保护层开采、水力割缝、松动爆破等增透措施,以提高瓦斯抽采效率。

In-situ stress is one of the main factors controlling the gas flow in coal seam. In order to master the in-situ stress characteristics of the test site and its influence on gas drainage, the in-situ stress measurement is carried out by the method of relieving the casing stress. The maximum main stress range of the stress relief measurement point is 18.92 to 19.80 MPa, and the minimum principal stress is 11.75 MPa within the measured depth of Xinji No.2 coal mine. The ratio of maximum horizontal principal stress to weight stress is 1.38 to 1.41, and the stress at the measuring point is mainly structural stress. On this basis, the numerical model is established according to the field parameters, and the gas pressure variation law around the borehole is simulated and calculated by Comsol Multiphysics multi-field coupling numerical simulation software. The results show that when the in-situ stress is 11.75 MPa and 19.80 MPa, the time of gas drainage reaching the standard is about 20 days and 105 days respectively, and the time is longer when the in-situ stress is 30 MPa, that is, the larger the in-situ stress, the longer the time of gas drainage reaching the standard. Therefore, it is necessary to take measures to increase the permeability of the protective layer, hydraulic cutting and loose blasting to improve the efficiency of gas extraction.