| Mineral resources development in the qinghai-tibet plateau regions has important strategic significance for alleviating the national part of energy and resources supply crisis.The regional tectonic and high altitude characteristics determine the mining of mineral resources is facing high tectonic stress disturbance and fragile ecological protection.Backfilling mining can reduce surface subsidence,protect the surface ecological,is the first selection of underground mining method in high altitude mining area.Strata exist in the form of complete bending band structure after backfilling mining,which make the effect of horizontal tectonic stress for strata movement cannot be ignored.Around strata movement problems of backfilling mining for slowly inclined large and thick ore body in tectonic stress environment,using the combining methods of artificial intelligence,field test,theoretical analysis,laboratory test and numerical simulation,this paper studyed on strata movement mechanism,deformation law and surface subsidence control countermeasures of backfilling mining under the action of tectonic stress.The main research results were as follows:(1)Three-dimensional geostress field intelligent inversion method was proposed based on PSO-ERF algorithm.Combination of machine learning of random forests(RF)algorithm and efficient optimization of particle swarm(PSO)algorithm,the in-situ stress measured-geostress field model boundary parameter inversion algorithm(PSO-ERF)is proposed based on particle swarm optimization to improve the random forest model(ERF).Based on this algorithm,mining area three-dimensional geostress field intelligent inversion method was proposed.Using which the three-dimensional geostress field of Jia Ma mine was back analysed.It has a good consistency between geostress inversion results and the measured values.(2)Mechanics model of roof subsidence for backfilling mining under the action of tectonic stress was established.The influence mechanism of horizontal compressive tectonic stress on overburden rock deformation was analyzed,it was concluded that horizontal compressive tectonic stress was beneficial to reduce strata subsidence.The backfilling body was regarded as elastic foundation,overburden as deep beam,the simply supported deep beams on elastic foundation model was formulated for strata movement problems of slowly inclined large and thick(horizontal)orebodies under hard strata using backfilling mining,using the theory of beam on elastic foundation and elastic mechanics analysis method,the analytical solution of stress and strain of roof for backfilling mining was deduced.Through theoretical calculation,the influence on the roof subsidence was analyzed of backfilling body foundation coefficient,horizontal stress lateral pressure coefficient,mining depth,mining filling length,,the interaction relationship between backfilling body and roof was determined,and the mutual influence mechanism of backfilling body strength and roof subsidence control for the large area mining was revealed.(3)Strata movement regularity of backfilling mining under the action of tectonic stress was revealed.The strata movement and pillar abutment pressure change rule under different lateral pressure coefficients and strength of backfilling body was analyzed using numerical simulation methods,the arch effect that horizontal tectonic stress is beneficial to reduce the stress of roof subsidence was analyzed,which confirmed the conclusion that horizontal compressive tectonic stress play a role of removing part of roof pressure to both sides of the surrounding rock,and the greater the lateral pressure coefficient,the more the stress transfer effect was significant.(4)Backilling body strength design method for slowly inclined large and thick ore body backfilling mining under tectonic stress environment was proposed,which considered the surface subsidence control.The relationship between backfilling body foundation coefficient and modulus elasticity was build,according to the relationship between the surface subsidence and backfilling body foundation coefficient,the comprehensive strength design method for backfilling body was proposed based on surface subsidence control.The paper research results has important guiding significance for strata movement and surface subsidence control of high tectonic stress field slowly inclined large-thick ore body backfilling mining,relevant results can also be applied in similar ore body conditions of backfilling mining in gravity stress type mine.This paper has 87 figures,18 tables and 180 references. |
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