综放开采坚硬顶板弱化物理模拟研究

Physical Simulation Study on Hard Roof Weakening in Fully Mechanized Caving Mining

针对坚硬顶板爆破弱化后对上覆岩层运移破断规律的影响,本文以典型坚硬顶板综放工作面地质和开采技术条件为背景,通过在物理相似模拟试验中进行坚硬顶板弱化管理,对比分析综放开采顶板弱化和常规条件下覆岩运移破断规律。试验结果表明,坚硬顶板弱化管理对工作面覆岩运移形态和特征有明显改善效果;常规条件下,采场覆岩随工作面推进其运移特征呈现出"大小周期"复合破断现象,小周期破断步距约为25m,大周期步距约为50m,冒落带高度约52m,垮落岩块整体性较大,且有明显二次破断特征;坚硬顶板超前弱化工作面,其初次来压步距由75m明显缩小为35m,冒落带高度约为25m,各岩层整体协调性下沉,垮落岩块碎胀程度较高,对采空区及时充填。综上,采取坚硬顶板超前弱化管理能够有效改善采场覆岩冒落特点,可以有效降低工作面来压显现强度,试验结果为坚硬顶板有效管理提供了参考依据。

In view of the influence of hard roof blasting weakening on the breaking law of overlying strata movement,this paper,taking the geological and mining technical conditions of typical hard roof in fully mechanized caving face as the background and carrying out hard roof weakening management in physical similar simulation test,compares and analyzes the laws of overlying rock migration and breaking under roof plate weakening and conventional conditions in fully mechanized caving mining.The experimental results show that the weakening management of hard roof has a significant improvement effect on the macroscopic migration form and characteristics of the overburden in the working face.Under normal conditions,the migration characteristics of the overburden in the stope show a"large and small period"composite fracture phenomenon,with the small period fracture step distance of about 25m,the large period step distance of about 50m,the height of the caving zone of about 52m,and the integrity of the caving block is large and clear.With the working face weakened by the hard roof in advance,the first pressure step distance is obviously reduced from 75m to 35m,and the height of the caving zone is about 25m.All strata sink coordinately,the caving block has a high degree of expansion,and the mined out area is filled in time.To sum up,adopting the management of weakening hard roof in advance will effectively improve the characteristics of overburden caving in the stope and reduce the strength of pressure appearance in the working face.The test results provide the test basis for the effective management of hard roof.