Study On The Stability Of The Bottom Structure Of The Natural Caving Method Of The Pulang Copper Mine

China is a country rich in mineral resources,but the per capita consumption is low.The most of mineral resources are low-grade poor ore.The level of comprehensive utilization of resources in china is lower than the developed countries.For many years,the underground mining in china keep back only low quality mineral.So low quality mineral proportion in unexplored deposits are increasing.In recent years,mineral resources have become one of the important factor restricting china's economic development.In china want to increasing demand for mineral resources.So the development of low-grade resources in china have become the future development trend.The block caving method is the only method that can be comparable in cost to open cut method.The block caving has a low cost,large capacity,easy organization and management and many other advantages.The block caving method was used in the most of countries in the world.The stability of base structure of the block caving method is more complex than other method.Undercutting,Ore breaking and drawing of the block caving will have effect to base structure,So this factors are cause to do not want to use block caving method.This paper is based on the engineering geology of the first panel of Pulang Copper Mine.Combined with "Pulang copper mine block caving method of base structure of the destruction mechanism and stability research project".Study on the theory and application of the stability of the base structure of the block caving.The main research contents and conclusions are as follows:1.The engineering geology survey of the first panel of Pulang Copper Mine was carried out to analyze the geomechanics parameters.Study the impact of the block caving method on the base structure.According to the results of rock mass classification and the development of joints and fissures in the first panel,the regional division of the first panel is carried out.2.The influence of the bottom cutting on the base structure was analyzed.Draw advancing cutting and retreating cutting the maximum principal stress is less than retreating cutting.The tensile stress value and the tensile stress area of advancing cutting in bearer are obviously lower than those of the retreating cutting.Tensile stress of cutting values differ by about 1 times.That the use of advancing cutting manner more conducive to a stable base structure.3.Study tunnel through fault base on the different angle,thickness of the fault.When tunnel excavation found that the stress relief area occurs especially in the fault,angle is larger,maximum principle stress is reduced,thickness is larger,the deformation of surrounding rock and plastic zone are larger.4.The tunnel nearby bottom cutting has high stress situation.The tunnel end of bottom cutting should be made to strengthen the support.Supporting measure was used in different area and different rock mass.The drawhole is easy to damage,the beam support can replace to the steel arch supporting.5.According to the measured drawing modeling of Punlang copper mine found that the tunnel intersection has stress concentration phenomenon.When the area of the tip of the bearer smaller found that stress concentration is more obviously.