蒙陕深埋矿区工作面涌水量全生命周期演化规律

Evolution law of water inflow in full life cycle of working face in deep buried Inner Mongolia-Shaanxi mining area

  • 摘要: 蒙陕深埋矿区属于新开发矿区,煤炭开采扰动下水文地质特征仍不清楚,基建和生产过程中发生了多种类型的水害问题,其中工作面回采过程中和回采结束后的涌水变化特征研究处于空白,给井下排水系统设置和防治水工作开展增加了难度。为查清工作面回采前后的全生命周期涌水量演化规律,开展顶板含水层分布、导水裂隙带发育、涌水量变化等方面的实测研究。结果表明:煤层顶板地层均属于河流/河湖相沉积,空间上呈含隔水层互层状展布,隔水层的主要岩性为泥岩、砂质泥岩;受控于鄂尔多斯盆地伊陕斜坡的单斜构造,含煤地层高程在蒙陕接壤区最低,其顶板侏罗纪煤系含水层属于区域性地下水滞流区。煤层顶板地层在中生代沉积旋回作用下,发育了3层直接充水含水层,其中直罗组七里镇砂岩(Ⅰ号含水层)距离3-1煤层顶板77.4~109.4 m,呈富水强、水压高的特点;导水裂隙带实测高度为103.4 m,裂采比18.8,工作面回采过程中导水裂隙带将发育至Ⅰ号含水层。工作面回采前期,随着导水裂隙带向上发育沟通不同含水层,采空区涌水量呈阶段性增加,工作面回采至300 m左右,采空区涌水出现第一个峰值;工作面回采中后期,导水裂隙带持续周期性发育,导致顶板含水层破坏范围不断扩大,采空区涌水量仍呈台阶式增加;工作面回采结束前后,采空区范围内顶板导水裂隙带发育最强烈、范围最大,出现采空区涌水量最高值;工作面回采结束后,在其顶板隔水层中泥质组分的自弥合作用下,隔水层逐渐再造,导水裂隙宽度变窄、数量变少,采空区涌水量“缓坡式”衰减(每小时几十立方米以内)。对工作面涌水量实现全生命周期演化规律掌握,可以为蒙陕深埋矿区井下工作面防治水工作提供科学依据。

     

    Abstract: The deep buried Inner Mongolia-Shaanxi mining area was newly developed, where the hydrogeological characteristics under the disturbance of coal mining were still unclear. Various types of water damage problems had occurred in the process of infrastructure construction and production. Among them, no research was conducted for the variation characteristics of water inflow during and after mining in working face, which increased the difficulty in the arrangement of underground water drainage system and the work of water prevention and control. In order to find out the evolution law of water inflow in the full life cycle of working face before and after mining, the field research was conducted in terms of the distribution of roof aquifer, the development of water diversion fracture zone and the change of water inflow. The results show that the roof strata of coal seam belongs to fluvial/lacustrine sediments, which are spatially distributed in interbed of aquifer and aquiclude, and the main lithology of aquiclude is mudstone and sandy mudstone. Controlled by the monoclinal structure of Yishan slope in Ordos Basin, the coal-bearing stratum has the lowest elevation in the contiguous area of Inner Mongolia and Shaanxi, and the Jurassic coal measure aquifer in its roof belongs to the regional groundwater stagnation area. Besides, three direct water filled aquifers are developed in the roof strata of coal seam under the action of Mesozoic sedimentary cycle. Among them, Qilizhen sandstone (No. I aquifer) in Zhiluo Formation is 77.4-109.4 m away from the 3-1 coal seam roof, which is characterized by strong water abundance and high water pressure. The water conducting fracture zone has the measured height of 103.4 m at the fracture mining ratio of 18.8, and it is developed to No. I aquifer during the process of working face mining. In the early stage of working face mining, different aquifers are connected with the upward development of water conducting fracture zone, so that the water inflow in mined-out area increases periodically. When the working face is mined to about 300 m, the first peak is presented for the water inflow in the mined-out area. In the middle and late stage of mining, the water conducting fracture zone is developed periodically, resulting in the continuous expansion of damage to the roof aquifer, and the water inflow in the mined-out area still increases by step. Before and after the completion of mining in the working face, the roof water conducting fracture zone in the mined-out area is developed in greatest intensity and range, with the highest water inflow occurring in the mined-out area. After the mining of the working face is completed, the aquiclude is gradually reconstructed under the self-healing cooperation of the argillaceous components in the roof aquiclude, with the width and quantity of water conducting fissures narrowed in width and reduced in number, and thus the water inflow in the mined-out area is attenuated gently (within tens of cubic meters per hour). Mastering the evolution law of water inflow in full life cycle of working face could provide a scientific basis for water prevention and control of underground working face in the deep buried Inner Mongolia-Shaanxi mining area.

     

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