浅部煤矿井下地应力分布特征研究及应用

采用煤矿井下小孔径水压致裂地应力测量装置，在山西、陕西、内蒙古、宁夏、新疆等5省（自治区）的10余个浅部煤矿区，进行了88个测点的地应力测量，最浅测点的埋深仅为38 m。根据地应力测量数据，分析了浅部煤矿井下地应力分布特征与变化趋势，并与深部煤矿进行了比较。通过实例分析，介绍了地应力测量结果在浅部煤矿井下工程中的应用情况。浅部煤矿井下地应力受多种因素影响，测量数据离散性很大，随测点埋深的变化规律不明显；地应力场以σH>σh>σV型为主，水平应力占绝对优势。最大水平主应力与垂直主应力的比值主要集中在1~3之间；最小水平主应力与垂直主应力的比值大部分在0.5~2.0；平均水平主应力与垂直主应力的比值大多处于1.0~2.5；最大主应力与最小主应力之差同垂直主应力的比值离散性较大，最大值超过2。将地应力测量数据应用于浅部煤矿煤柱尺寸优化、锚杆支护参数设计，在保证巷道安全与支护效果的前提下，提高了煤炭资源采出率，降低了巷道支护成本。

Characteristics of underground in-situ stress distribution in shallow coal mines and its applications

By means of the small borehole hydraulic fracturing measurement unit designed for underground coal mines，the 88 in-situ stress measurement sites were conducted in more than 10 coal mining fields located in the Shanxi，Shaanxi，Inner Mongolia，Ningxia and Xinjiang province or autonomous region.The shallowest site was only 38 m below the surface.The distribution features and variation trend of the in-situ stresses in shallow underground coal mines were analyzed based on the measurement data，and the comparison with those obtained in deep underground coal mines was made.The applications of the in-situ stress measurement results in a shallow coal mine were introduced through a case study.It is shown that the in-situ stress measurement results present large discreteness，and there is no obvious variation discipline with buried depth，as the in-situ stresses in shallow coal mines are affected by a lot of factors.The in-situ stress pattern is mainly the type of σH>σh>σV with the dominant horizontal stresses.The ratio between the maximum horizontal principal stresses and vertical principal stresses mostly focuses on the interval of 1 to 3；The ratio between the minimum horizontal principal stresses and vertical principal stresses is mainly on the interval of 0.5 to 2.0；The ratio between the mean horizontal principal stresses and vertical principal stresses mainly locates on the interval of 1.0 to 2.5.The ratio between the difference of the maximum and minimum principal stresses and vertical principal stresses presents large discreteness with the maximum value more than 2.The in-situ stress measurement results were applied to optimize coal pillar sizes and rock bolting design，the coal recovery rate was enhanced，and the rock bolting costs were decreased in the premise of entry safety and reinforcement effectiveness.