基于围岩破坏特征的穿层钻孔“三堵两注”封孔效果研究

Study on Sealing Effect of"Three Plugging and Two Injection"about Pre-pumping Borehole through Layer Based on Failure Characteristics of Surrounding Rock

针对单一低透气性煤层底抽巷穿层预抽钻孔存在抽采浓度衰减快、有效抽采时间短的问题,采用理论分析及数理统计相结合的手段,考察了底抽巷围岩变形特征与穿层钻孔抽采衰减规律并分析了其相关性,认为巷道成型、钻孔施工等一系列过程中存在后期发育的围岩裂隙,提出了基于巷道围岩变形的“三堵两注”封孔工艺,探讨合理的二次注浆时机。结果表明:首次注浆后抽采浓度随围岩变形逐渐衰减,与常规“两堵一注”封孔工艺抽采效果类似;二次注浆进一步封堵钻孔围岩后期发育的裂隙,抽采浓度较注浆前显著提高。以中马村矿3901地区为例,确定穿层钻孔合理二次注浆封孔时机应为巷道围岩变形稳定,即钻孔施工后约2个月,为类似矿井安全高效开采提供借鉴。

In view of the problems of pre-pumping borehole through layer at single and low permeability coal seam,which attenuation of extraction concentration were fastly and time of effective extraction were shortly,theoretical analysis and mathematical statistics were used,the deformation characteristics of surrounding rock and attenuation law of extraction concentration were investigated the correlation were analyzed,there were the problem of deformation and failure of surrounding rock in a series of processes such as roadway forming,drilling construction,pumping and mining management,etc,which the later developed fissure.It was proposed which"three plugging and two injection"based on the failure characteristics of surrounding rock about pre-pumping borehole through layer,the reasonable opportunity of secondary grouting was discussed and verified.The results show that after the first grouting,the extraction concentration decreased gradually with the failure of surrounding rock,which was similar to the conventional"two plugging and one injection"borehole sealing process;because of the later developed fissure was blocked further by the secondary grouting,the extraction concentration was significantly higher than that before grouting.Taking 3901 area of Zhongmacun mine as the research object,it was determined that the reasonable opportune for secondary grouting of pre-pumping bore through layer,which time was the deformation and stability of roadway surrounding rock,that is to say,about two month after drilling construction,it was provided that reference of safe and efficient mining of similar mines(areas).