Study On Applying Key Strata Theory To Mining Subsidence In The Loess-covered

The western region rich in coal resources and reserves, and it is important toChina’s energy strategy. In the west, thick loess layer covering the area accounted for morethan60%of the area of mining geological and mining conditions of the are complex,fragile ecological environment. In the thick loess layer mining surface subsidence andcracks caused by damage, not only damage the buildings on the ground, and resulting in alarge area of farm land damaged mountain avalanche, landslides, soil erosion, destructionof forest vegetation is serious, which resulting in further intensify desertification. Thethesis takes Baode coal mine as the engineering background, and the Loess coveringmining the main influencing factors are studied. This paper a combination of theoreticalanalysis, numerical simulation and other methods. The destruction of overlying strata andsurface subsidence in Baode coal mine werestudied.In this paper,7typical geological drilling key stratum structure of Baode coalMine are identified. The type of layer structure of Baode coal mine includes single keystratum structure and multiple key stratum structure. And the breaking of the main keystratum forms of discrimination, the three forms of mining the main key stratum:irregularly caving, the formation of stable "bond-beam beam" structure and bending. Andthe three main key stratum break form impact on surface subsidence are introduced. Themain key stratum break form and different thickness of loess lay is simulated and analyzed.The influence of surface subsidence by using3DEC numerical analysis software, to verifythe main key stratum of the surface subsidence control role, and further draws theconclusion that the main key stratum break from different impact on surface subsidence:When the main key stratum broken into irregular caving, overburden showed fullthickness cutting, surface subsidence, subsidence of a step shape.When the main key stratum to form a stable "bond-beam beam" structure, the groundsurface settlement is smaller than the former. When the main key stratum curved surface into a sink, a continuous deformation, andsubsidence is small and the main key stratum above until the surface is bending.In the surface subsidence loess layer plays a supporting role, the thickness of loesslayer and surface horizontal displacement was positively correlated.Therefore, the key strata control the movement and damage of overlying strata inBaode coal mine.After the mining overburden movement from the bottom to the top of group internalmovement, dynamic process control of strata movement on the key layer breakingmovement. When the sub key strata break, the soft rock which it controls also occurssynchronously with the break of deformation, and along with the excavation, the periodicbreaking down. When the main key stratum reaches the breaking limit, the main key layeris broken when the main key layer is broken down and the surface occurs synchronously.