摘要
针对晋煤集团寺河煤矿东五盘区东翼集中巷受多次强烈采动影响、巷间煤柱尺寸小、服务周期长、向斜轴部应力集中程度高等特点,应用水力压裂切顶卸压技术,改善围岩应力状态,为大采高留巷围岩变形控制提供了一个新途径。研究了水力压裂切顶卸压技术在大采高留巷中的作用本质,工作面回采前利用高压水在护巷煤柱上覆岩层中形成一个“准破裂面”,工作面回采时,在采场周期来压的作用下,采空区顶板沿“准破裂面”断裂,减少悬臂梁的跨距,卸载或转移工作面侧向悬臂梁传递到护巷煤柱的高应力。综合考虑井下现场作业空间狭小、工作面高位钻孔、地面L型抽放井等多个影响因素,设计水力压裂切顶卸压方案,压裂钻孔双侧布置,深孔长度40 m,浅孔长度32 m。为保证压裂效果,超前工作面50~100 m进行压裂施工,倒退式压裂,间隔为2~3 m。通过监测与分析水力压裂切顶卸压效果得出,顶板岩层裂缝起裂压力约24 MPa,扩展压力在21~23 MPa。切顶卸压后两帮移近量降低53%,顶板下沉量降低33%,底鼓量降低18%,同时显著减小帮锚索受力变化幅度。压裂后煤柱垂直应力在超前工作面50 m至滞后工作面50 m范围内出现峰值点,未压裂的煤柱垂直应力的峰值点出现在滞后工作面150 m至350 m范围。
In view of the characteristics of the fifth panel of Sihe coal mine,such as the repeatedly strong mining effects,small size of coal pillars,long service period and high degree of stress concentration in the axis of the syncline,the stress state of surrounding rock was improved by hydraulic fracturing cutting and unloading technology.It improves the stress state of the surrounding rock and provides a new way for the surrounding rock deformation control of the large mining height roadway.The nature of hydraulic fracturing cutting and unloading technology in large mining height retaining roadway was studied.A“quasi-fracture surface”was formed in the overburden of the coal pillar using the high pressure water before the working face is recovered.While the working face is mined,the gob roof broke along"the quasi fracture surface"under the influence of periodic weighting,which reduces the span of the cantilever beam and transferred the high stress of the lateral cantilever beam to the retaining coal pillar.Considering a number of influencing factors such as narrow underground working space,high working face drilling,and ground L-type drainage wells,the hydraulic fracturing topping pressure relief scheme was proposed.The fractured borehole is arranged on both sides,and the deep hole length is 40 m.The shallow hole length is 32 m.In order to ensure the fracturing effect,the fracturing construction is carried out on the front working face 50~100 m,and the reverse fracturing is separated by 2~3 m.Through monitoring and analyzing the pressure relief effect of hydraulic fracturing and cutting,it is concluded that the crack initiation pressure of the roof rock layer is about 24 MPa and the expansion pressure is 21~23 MPa.After the topping is relieved,the amount of movement of the two ribs is reduced by 53%,the amount of roof sag is reduced by 33%,and the amount of bottom drum is reduced by 18%.At the same time,the magnitude of the force change of the anchor cable is significantly reduced.After the fracturing,the vertical stress of the coal pillars peaks from 50 m in the leading working face to 50 m in the lagging working face.The peak point of the vertical stress of the unfractured coal column appears in the range of 150 m to 350 m on the lagging working face.
作者
孙志勇
张镇
王子越
王涛
付玉凯
SUN Zhiyong;ZHANG Zhen;WANG Ziyue;WANG Tao;FU Yukai(Coal Mining and Design Department,Tiandi Science and Technology Co.,Ltd.,China Coal Technology Engineering Group,Beijing 100013,China)
出处
《煤炭科学技术》
CAS
CSCD
北大核心
2019年第10期190-197,共8页
Coal Science and Technology
基金
中国煤炭科工集团有限公司创新创业资金专项资助项目(2018MS021)
国家自然科学基金青年基金资助项目(51304119)
国家自然科学基金煤炭联合基金资助项目(U1261211)
关键词
大采高留巷
多巷布置
水力压裂
卸压机理
retaining roadway with large mining height
multi entry layout
hydraulic fracturing
pressure relief mechanism
作者简介
孙志勇(1985—),男,山东诸城人,助理研究员,硕士。E-mail:jaycke_520@163.com。
