深埋厚顶板工作面采场应力演化规律及区域水力压裂卸压技术研究

Stope stress evolution law of deep and thick roof working face and the regional hydraulic fracturing and pressure relief technology

针对深埋厚砂岩顶板赋存条件下工作面回采过程中采场应力高、两巷变形量大、顶板断裂能量大等强矿压显现问题,采用FLAC数值模拟了130207深埋高应力采场应力演化规律和采场位移演化规律,结果表明,工作面推进至一次见方和二次见方时,会出现高应力集中,集中系数最高可达2.5~4.0;二次见方期间回风巷帮部水平位移可达390 mm,底鼓量可达413 mm。为确保工作面安全回采,制定了区域水力压裂卸压方案,依据关键层理论和组合梁理论计算得出130207工作面关键致灾层位为22.83 m厚粗粒砂岩层和40.23 m厚粗粒砂岩层,依据Hubbert-Willsi非渗透性地层破裂压力计算公式得出起裂压力为13.06 MPa。区域水力压裂后,工作面周期来压步距、来压持续距离明显减小,超前支承压力影响范围及应力集中系数明显降低,工作面日最大能量和日平均能量明显减小,这说明定向区域水力压裂技术效果良好。

Aiming at solving the problems of high stope stress,large deformation amount and large roof fracture energy of the working face under the condition of recovery under deep and thick sandstone roof,the stress evolution law and stope displacement evolution law of No.130207 deep buried high-stress stope was simulated using the FLAC numerical simulation,and the results indicate that when the working face is advanced to the primary square and the second square,there will be high stress concentration with the concentration coefficient up to 2.5~4.0.The horizontal displacement of the air return roadway during the second square period can reach 390 mm.The floor heave volume can reach 413 mm.In order to ensure safe recovery of working face,a regional hydraulic fracturing and pressure relief scheme was formulated.Based on key stratum theory and composite beam theory,the key disaster-causing layer of No.130207 is at 22.83 m thick coarse-grained sandstone layer and 40.23 m thick coarse-grained sandstone layer.The crack initiation pressure is 13.06 MPa according to the calculation formula of Hubbert-Willsi non-permeable formation rupture pressure.After regional hydraulic fracturing,face periodical weighting interval and the continuous weighting distance are significantly reduced,the influence range and stress concentration coefficient of the advance abutment pressure are significantly reduced,and the daily maximum energy and daily average energy of the working face are significantly reduced,which indicates that the hydraulic fracturing technology in the directional area has a favorable effect.