新型瓦斯抽采钻孔注浆封孔方法及封堵机理

Novel gas extraction borehole grouting sealing method and sealing mechanism

为研究封孔支护力对钻孔漏气量的影响,提出主动支护式注浆封孔原理并进行理论分析,得出了漏气圈截面积与漏气量的求解方程,并对影响漏气量的因素进行了分析。结果表明,漏气量随着封孔支护力和封孔段长度的增加而减小。提高钻孔的主动支护力并选择合适的封孔段长度可以减少钻孔漏气,提高抽采钻孔瓦斯体积分数和抽采纯量。据此设计了新型的注浆封孔装置,封孔初期,利用复合囊袋和注浆压力给钻孔壁施加1 MPa左右的支护力,水泥浆液可以充分填充钻孔周围的裂隙,有效阻止裂隙漏气。后期注浆材料凝固膨胀,再次对钻孔壁形成较大的支护力,又可有效预防封孔段收缩变形形成新的漏气通道,起到减小钻孔漏气量的作用。工程实践表明,与聚氨酯封孔方法相比,同等条件下,新型注浆封孔方法钻孔瓦斯体积分数提高162.2%,钻孔的瓦斯抽采纯量提高33.83%。

In order to study the impact of sealing support force on air leakage,an active support grouting sealing theoretical principle was proposed and analyzed,then a circle cross-sectional area and the leakage amount solving equations was obtained,and the impact factors on leakage amount were also analyzed.Research results show that the leakage amount decreases with the increase of supporting force and the sealing length.To improve the initial supporting power,select the appropriate sealing length can reduce leakage amount,and improve gas extraction concentration and scalar.A novel grouting sealing device was designed in this study.During the first period,the composite pouch and grouting pressure were applied to the borehole wall with a supporting force of about 1 MPa,the cement slurry can fully fill the cracks around the sealing section of the borehole,and effectively prevent cracks leakage.Later,the grouting material becomes hard and expanded to form a large supporting force on the borehole wall,prevents the contraction of the sealing section deform to form a new leak channel,and reduces the borehole leakage amount.The site experiment results shows that under the same conditions,compared with polyurethane sealing method,the novel grouting sealing method can increase the borehole gas concentration of 162.2% and increase the borehole gas extraction pure quantity of 33.83%.