崩落法回采时顶板岩层崩落过程监测与分析

Monitoring and Analysis of Collapse Process of Overlying Rock Strata in Extraction by Caving Method

用崩落法回采倾斜矿体时顶板围岩的崩落过程是目前没有很好解决的问题。通过地质钻孔,采用电路连通判断法,对程潮铁矿采场顶板的崩落过程进行了监测。监测结果表明,顶板的崩落过程是非常复杂的,受到岩体质量、岩体中的弱面、初始地应力场、空区形状及松散充填体等的影响,而且具有明显的跳跃特征。在组成矿体顶板的各种岩层中,质量高的岩层是控制崩落过程的关键层。关键层较难崩落,但在崩落时具有突发性,会产生较大厚度岩层的突然垮塌。受主关键层的影响,在地表塌陷之前,有相当长一段时间不出现崩落或者崩落速度很慢。而当主关键层崩落后,表地会在较短的时间之内突然塌陷。研究结果表明,复杂岩层顶板的崩落过程及崩落时间的预测必须考虑岩层性质及其空间分布特点,其中,关键层的识别是非常重要的。

The collapse of the overlying rock strata in the extraction of inclined orebody by caving method remains to be a problem that hasn t well solved. The roof collapse process in Chengchao Iron Mine was monitored by the judgment method based on the connection condition of cable passing through boreholes. The monitoring results show that the roof collapse process is very complex and affected by the rockmass weight, weak faces of the rockmass, initial ground stress field, mined - out area shape and loose filling body and the process is characterized by evident skipping. Of the various types of rock strata, the one of high quality is the key stratum in controlling the collapse process. The key stratum is not easy to cave, but once it is caved, there will be a sudden collapse of a rather thick stratum. Due to the effect of the main key stratum, caving will not occur or at a very slow rate for a long time before its collapse but there will be sudden ground subsidence in a short time after its collapse. The investigation results indicate that the properties of rock strata and their special distribution should be considered in the prediction of the collapse process and time of complex overlying rock strata, of which the identification of the key stratum is very important.