Stress transfer control technology for fracturing weak structural bodies in subgrade dynamic pressure roadways
陈绍杰刘江伟李亚康吕华
CHEN Shaojie;LIU Jiangwei;LI Yakang;LYU Hua
山东科技大学 能源与矿业工程学院淮北矿业(集团)有限责任公司 袁店一矿
为了满足煤矿安全生产的需要,许多巷道都会布置在煤层底板中,如部分运输大巷、排水巷道、瓦斯抽采巷道等。采动应力容易造成底板巷道围岩应力升高,加剧底板巷道围岩变形,造成支护永久失效、顶板下沉、巷道底鼓、两帮收敛等破坏。针对此,提出了在应力传递路径上实施水力压裂,在指定的区域制造出一定空间形态的水压裂缝网,形成压裂弱结构体,实现区域范围内的应力转移,从而降低巷道区域范围内的应力,控制巷道的围岩稳定性的控制技术,并通过理论分析及现场工程验证等方式,揭示了底板动压巷道压裂弱结构体应力转移的力学机制,建立了相应的力学模型,对压裂弱结构体的合理位置、范围等影响因素进行了求解。得出:①压裂弱结构体使局部应力场发生明显变化,出现应力升高区和应力降低区,应力降低区主要分布在弱结构体与采动应力连线的方向上,主要集中在一个拱形的范围内;由于膨胀效应,在与应力来源垂直的方向上产生应力集中,出现应力升高区。②最大主应力变化幅度与压裂弱结构体的长轴长
In order to meet the needs of safe production in coal mines, many roadways are arranged in the bottom plate of coal seams, such as part of transportation alleys, drainage roadways, and gas extraction roadways. The mining stress generated by the working face causes the stress increase of the surrounding rock of the floor roadway through the transmission of the floor rock strata. It exacerbates the deformation of the surrounding rock of the floor roadway, which is easy to cause permanent support failure, roof sinking, dropsy at the bottom of the roadway, convergence of the two gangs, and other damages. In response to this, a control technology is proposed to implement hydraulic fracturing in the stress transfer path, creating a network of hydraulic fractures with a certain spatial pattern in the designated area, forming a fractured weak structural body, realizing stress transfer within the area, thus reducing the stress within the area of the roadway, and controlling the stability of the perimeter rock of the roadway, and through theoretical analysis and field engineering verification, the mechanical mechanism of stress transfer of weak structures in floor dynamic pressure roadway fracturing is revealed, the corresponding mechanical model is established, and the influence factors such as reasonable location and range of weak structures are solved. The results show that: ① Fracturing weak structure causes obvious changes in local stress field, and there are stress increasing zone and stress decreasing zone, and the stress decreasing zone is mainly distributed in the direction of the connection between weak structure and mining stress, mainly concentrated in an arch range; Due to the expansion effect, the stress concentration occurs in the vertical direction of the stress source, and the stress rise area appears. ② The magnitude of maximum principal stress change is related to the long axis L, short axis H, distance P to the roadway, horizontal angle β to the roadway line, strength C and internal friction angle α of the fractured layer, and damage variable D of the fracture in the weak structural body of the fracture. ③ The proposed method is used to design the pressure relief scheme of 103 belt concentrated roadway in Yuandian No. 1 Mine of Huaibei Mining Group. The engineering application results show that the deformation rate of roadway under dynamic pressure of floor is significantly reduced, and the rationality of the stress transfer model of fractured weak structure in roadway under strong dynamic pressure of floor is verified.
采动应力弱结构体水力压裂卸压切顶围岩控制
mining stress;weak structural bodies;hydraulic fracturing;pressure relief;roof cutting;surrounding rock control
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会