Study On In-situ Stress Distribution Law And Its Application In Pingdingshan Mining Area

Most of roadways in Pingdingshan mining area have entered deep and some ofthem have already reached1100m deep, which is far more than the critical deepmining depth. With the increase of mining depth, more and more engineering disastersand accidents come up caused by high ground stress, high temperature, high gas andhigh hydraulic pressure. Thus severe challenges are put forward on the safe andhigh-efficient exploitation in deep coal resources. In order to judge the stability ofroadway surrounding rock after excavation and long-time security of support design,it is necessary to study in-situ stress, which is the fundamental forces inducing theseunderground engineering disasters. In this article in-situ stress distribution and itsapplication were studied by in-situ measurements and inverse analysis based onterrain and geological data in Pingdingshan mining area. The main conclusions wereas follows:(1) pingdingshan mining area was distributed into three partitions according tothe comprehensive analysis of measured in-situ stress data and regional geology andtectonic evolution and the3partitions are: western zoneⅠ (including No.5mine,No.7mine, No.9mine, No.11mine), central zone Ⅱ (including No.1mine, No.2mine, No.3mine, No.4mine, No.6mine) and eastern zone Ⅲ (No.8mine, No.10mine, No.12mine).(2) In-situ stresses were measured in nine holes using the hollow inclusion stressrelease method on four typical mine of Pingdingshan mining area. The measuredresults show that the in-situ stress characteristics match their partitions’characteristics.That is: the western zoneⅠ is mainly controlled by gravity stress (the side pressurecoefficients are0.60~0.92), the central zone Ⅱ shows a weak tectonic stressfield(the side pressure coefficients are1.02~1.90), and the eastern zone Ⅲ has astrong tectonic stress field with side pressure coefficients1.37~2.69.(3) in-situ stress field inversion analysis was conducted on the three partitionsusing multiple regression analysis method. Firstly, partition scopes were selectedcombining with geological terrain factors of Pingdingshan mining area. Then3Dgeological models of the three partitions were built by use of Surfer and ANSYS. Atlast, the in-situ stress field distribution regularities of each partition were gained basedon the in-situ measured data by inversion analysis.(4) Numerical simulations were carried out to study the deep roadway failure mode at different stress levels, side pressure coefficients and angles betweenmaximum horizontal principal stress and roadway axial direction based on groundstress field distribution achieved above. Deep mine roadway stability controlcountermeasures were put forward according to the failure mode.