三软厚煤层综放开采大断面开切眼围岩控制技术研究

Active-passive combined support technique for large span open-off cut in thick coal seam

三软开采条件下大跨距开切眼围岩破坏程度高、支护难度大,为实现该类全煤巷道围岩稳定性控制,采用现场实测和理论分析相结合的方法,研究了大跨距切眼巷道围岩破坏特征并提出了相应的控制方法。对三软厚煤层全煤巷道围岩破坏特征进行了钻孔探测,由于顶板含有较多软弱夹层,大大降低了顶板岩层强度,造成运输巷顶板岩层破碎程度高、破坏范围大,同时顶煤较厚,极容易垮落,给锚索施工造成较大困难;针对三软大跨距切眼巷支护难题,提出了联合支护方式,并将其支护原理进行了阐述,在采用主被动联合支护方式同时利用了支护体和围岩自身的承载能力,可有效提高围岩控制效率;提出了高强稳定性锚网联合支护技术,设计了大跨距切眼巷道一排和二排巷的支护参数,进行了现场工业性试验,实测结果表明,采用主被动联合支护的条件下,切眼顶板离层量接近等于0,锚索安装后迅速提供支护力,保证了大跨距切眼巷道围岩稳定性。

In soft thick coal seams with soft roof and floor strata,rock masses surrounding the large span open-off cut experiences drastic failure degree. Supporting difficulties in such roadways is greatly improved. In order to realize surrounding rock control with such bad conditions,failure characteristics and corresponding supporting method have been researched in this study by using theoretical analysis and field measurements. Due to soft layers inserted in the roof strata, rock strength is seriously deteriorated and thus,failure degree and region of the roof strata is enlarged. At the same time, top coal is thick and soft,leading to frequent roof fall in the open-cut. Based on the failure characteristics,a combined supporting technique is proposed. Active and passive strengthening mechanisms involved in the technique are explained. With the proposed method,load-bearing capacity of both support structure and surrounding rock are efficiently utilized. After that,supporting parameters for the large span open cut are further put forward. Then,the supporting effectiveness is in situ investigated. The results show that roof subsidence is controlled and supporting load provided by cables increases to a large value quickly. The surrounding rock stability of large span open-cut is promised.