松软煤层加固用泡沫水泥浆的实验研究

Experimental study of foamed cement slurry for soft coal seam reinforcement

摘要:

针对松软煤层顺层钻进长钻孔成功率低、煤层机械强度低的难题，提出将机械发泡式泡沫水泥浆通过高压旋喷的方式注入松软煤层进行随钻加固的技术思路。室内试验中，通过改变松软煤岩与泡沫水泥浆的比例，模拟注浆后形成不同固结效果的松软煤岩-泡沫水泥固结体。以抗压强度和气体渗透率作为主要评价指标，研究了松软含煤量对固结体性能的影响规律。结果表明：（1）与纯泡沫水泥浆的固结体相比，当松软煤岩含量（以下简称“含煤量”）为5%时，固结体的气体渗透率略有降低，气体渗透率随养护时间增加而降低；（2）含煤量≥10%，固结体气体渗透率随含煤量增大而升高；（3）固结体的早期抗压强度（养护1 d）随含煤量的升高先升高后降低。养护时间增加至7 d后，固结体强度随含煤量升高而降低；（4）含煤量在20%~25%之间的固结体养护7 d后，抗压强度在8.65~9.94 MPa，气体渗透率在9.08~36.52 mD之间。研究成果可以为松软煤层的随钻护壁与瓦斯抽采提供有益借鉴。

Abstract:

In view of the problems of low success rate and low mechanical strength of long drilling holes along the soft coal bedding， the technical idea of injecting mechanical foamed cement slurry into the soft coal seam by the way of high-pressure rotary spraying while drilling to inforce the fomation is proposed. In the laboratory test， the proportion of soft coal rock and foamed cement slurry was changed to simulate the soft coal rock and foamed cement consolidation body which has different consolidation effects after grouting. In addition， taking compressive strength and gas permeability as the main evaluation indicators， the influence of soft coal content on the performance of the consolidated body was studied. The results show that： （1） Compared with the consolidated body of pure foamed cement slurry， when the content of soft coal rock （hereinafter referred to as “coal content”） was 5%， the gas permeability of the consolidated body decreases slightly， and the gas permeability decreased with the increase of curing time； （2） When the coal content was greater than or equal to 10%， the gas permeability of the consolidated body increased with the increase of coal content； （3） The early compressive strength （cured for 1d） of the consolidated body increases first and then decreases with the increase of coal content. After 7 d of curing time， the strength of the consolidated body decreased with the increase of coal content； （4） After the coal content was between 20%~25% and the consolidation body was cured for 7 d， the compressive strength was 8.65~9.94 MPa， and the gas permeability was 9.08~36.52 mD. The research results can provide useful reference for the wall protection while drilling and gas extraction in soft coal seam.