Research On Geo-dynamic Environment And Strata-pressure Behavior Of Tongxin Mine

The Jurassic coal seam and Permo-carboniferous coal seam are coexistent in Datong coalfield. The shallow coal resources of Jurassic system has tended to be exhausted, the recoverablereserves of deep Permo-carboniferous coal seam can come up to30-billion ton. The Tongxinmine field, which is the main mine with10M MTPA for recovering the Permo-carboniferoussystem, with the typical characteristics of mining condition “two-hard and double-system”, andcome up against varied problems of intense strata behavior, large structure vertical failure on theoverburden rock,the goaf crack zones got through between double-system coal seam, thesurrounding rock instability of gateway, etc. during the recovery process, which affect the safeand efficient production in the mines. Therefore, under the mining condition of “two-hard anddouble-system” in the Tongxin mine field, based on the geo-dynamic environment analysis, it isespecially important and urgent to research the dynamic condition, the overburden stratamovement and the failure law, the control technology of intense strata behavior, the safetymining technical scheme for the strata behaviors, which is significant for the the realization ofsustainable development in Datong Coal Mine Group and the construction of country’s largestcoal base in the north of Shanxi Province.This paper comprehensively applied the theory and method of geo-dynamic divide and themining pressure and strata control theories, based on the study of the occurrence characteristicsof “two-hard and double-system” coal seam and the formation characteristics of rock mass inTongxin mine field, analyzed and evaluated the geo-dynamic environment from the regionaltectonic movement, the tectonic stress field and the seismic activity, discussed its actionmechanism for strata behavior, overburden rock construction and motion during the recoveryprocess; researched the extrusion in horizontal direction and the lifting in vertical direction of thenew tectonic movement--Kouquan fault in Datong mining area, which has control effect on thestrata behavior. Based on the structure block division, building the geotectonic model of Tongxinmine field, combined in-situ stress measurement, and made the indepth analysis on the rock massstress state, divided the increasing zone, the decreasing zone and the gradient zone of the tectonicstress; revealed the Influence to the strata behavior intense under the effect of roof lithology,fault structure, stress and multi-factors; made region division to the strata behavior intensitybased on the identification of multi-factor pattern recognition; making use of borehole data, built the3D geological model of the overburden strata, analysed the distribution characteristics ofoverburden strata construction and the lithological association between the double-system coalseam; put forward the instability model and the instability criterion of the vertical large structureof overburden strata face-contact of the “two-hard and double-system”. Based on the similarmaterial simulation and the numerical calculation; put forward the control technology of intensestrata behavior in the mining face and gateway. On the basis of researching the overburden stratamovement and the failure, the separated strata grouting, the slice mining, the backfill mining andother safety mining schemes were come up with.This paper discussed the geo-dynamic environment in Datong mining area and its controlaction of the strata behavior during the recovery process for the first time; put forward theinstability model and the instability criterion of the vertical large structure of overburden strataface-contact of the “two-hard and double-system” under the mining condition in Tongxin minefield; formed the research ideas for strata behavior and control of “geo-dynamic environmentanalysis-overburden rock structures and its evolution-strata behavior and control-safety miningscheme optimization”. The research results above have important guiding significance formastering the law of strata behavior under the similar mining conditions, and realizing the safeand efficient production in Datong mining area.