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    Rock mass instability and movement mainly depend on rock properties, rock stratum structure, geological structure, mining depth, ore body dip angle, mining method, pillar and its recovery status, empty area shape, scale, empty area existence time and treatment method, Hydrogeological conditions, surface topography and other factors. Under the influence of different factors, the rock mass movement shows different characteristics, and the degree of influence is also different.
    Rock properties, especially physical and mechanical properties, are one of the main factors affecting the stability of the empty zone and the process of rock movement. The particularity and complexity of rock properties are the main reason for the complexity of rock mass movement problems.
    The weak formation of various structures (faults, joints, fissures, layers, fracture zones, etc.) in the rock mass reduces the strength of the rock mass. The majority of our metal and nonmetal mines large-scale rock movement examples show: rock often start moving along the large surface structure is weak, mostly cracks when moving the development and expansion of the existing weak side. It can be said that the weak surface of the geological structure affects the development of rock mass movement caused by mining to a considerable extent, and controls its expansion range.
    Rock visions inclination determined in the feature space region, thus affecting the stress state and the failure process of top and bottom slate stone. The roof rock stratum in the central part of the gently inclined ore body is generally subjected to compression and sinking. Then the crack is broken; the ore or surrounding rock adjacent to the unextracted section is mostly damaged by shearing. In the steeply inclined ore body, the ups and downs of the upper part of the ore body are mostly shearing.
    As the dip angle of the ore body increases, the horizontal movement of the ore body increases horizontally, and the range of movement of the rock mass increases; while the normal component of the gravity of the cover rock subjected to the upper plate decreases. Therefore, the empty zone formed by the steeply inclined ore body mining has better stability at a certain depth, but the mining depth is increased and a large-scale empty zone is formed, and there is a possibility of sudden large-scale collapse.
    The empty areas of different dip angle ore bodies have different effects on the ground. Under the same conditions of the goaf area, in the unit area, the steeply inclined empty area has a more concentrated damage effect on the surface affected area than the slow inclined empty area, and it is easy to become a column-type vertical shearing damage. In the treatment of the empty area effect, there is also a difference between the two. Regardless of whether the empty area is treated by the filling method or the caving method, when the compression ratio of the loose body is the same, the larger steep inclined ore body is not easy to maintain the empty area, and the loose body is easy to follow the mining. Falling and moving down or falling down is one of the reasons for the constant settlement of the earth's surface.
    Mining depth. The size and duration of the empty area have a great impact on the movement of the rock mass.
    Most of the steeply inclined thin veins are in mountainous terrain and exposed to the surface. The mining area has different characteristics due to the depth of exploitation of the surface rock and the intensity of the vein group. When the pulse group is sparse and the pulse distance is greater than 20~30m . When the depth of mining is shallow and there is a certain number of ore-supporting empty areas, the rock mass movement and surface subsidence caused by the opening are less; the vein group is dense and the mining depth is increased. Can cause large-scale rock mass movement and damage the surface. The rock mass movement in the goaf of the steeply inclined tungsten vein group in the central and southern regions is mostly in the above-mentioned law.
In a case of catastrophic, the empty area of ​​the shallow thick ore body is easy to develop to the surface, causing surface subsidence and damage; deepening, the time required for the movement of the two gangs of the empty area to the surface is increasing, and the area affected by the surface It also increases; if the depth exceeds a certain value, the rock movement may not affect the surface or influence.
    When the goaf is not filled, the thickness of the ore body is an important factor in determining the height of the caving. The thickness is higher. The rock movement process is severe, and the subsidence and other deformations of the rock layer also increase, especially when the ore body is flat.
    When the rock mass moves to the surface, the depth and thickness of the mining affect the size of the moving angle. The maximum sinking value of the surface is related to the degree of mining. When fully plucked, the surface sinks to a maximum and no longer increases with the increase of the empty area. In metal mines, due to large changes in ore body shape, some connected empty areas are small in scale, and most of them are not fully exploited, and the maximum sinking value of the surface increases with the increase of goaf.
    The size of the empty area directly affects its stability and the range of rock movement activities. Large-area continuous empty areas are more likely to fall, and the range of rock movement is large. When adjacent airspaces are close together, their effects can contribute to each other and the damage is exacerbated. When the main station of the underground space is divided and isolated by the pillar or the non-mineral belt with sufficient strength, the stability is improved and the rock movement amplitude is reduced. Under the same water area, the length and width are close. A large span has a large difference between the length and width values, and a smaller span is more likely to collapse.
    Different mining methods and empty area treatment methods have different rock mass movement characteristics. The empty area is treated by the caving method or the post-harvest method of caving surrounding rock. The movement of the rock mass can be fully developed and it is easy to develop to the surface. When the overburden is stable, its caving may lag behind the recovery and form an empty area. To ensure the safety of the recovery, a rock cavern of sufficient thickness should be maintained under it. The use of filling method or post-harvest filling treatment of empty areas can better control or reduce the amplitude and severity of rock movement, and its movement process has a slow feature, even if the rock movement develops to the surface. The extent of its impact and the extent of damage to the surface are also small. When the empty section is supported by the permanent pillar, as long as the stability of the surrounding rock and the strength of the pillar are sufficient, the empty zone can be stabilized for a long time. However, when the area of ​​the empty area is enlarged and the time is too long, the pillars will be overloaded and destroyed, which will cause the rock to collapse in a large area and may spread to the surface. The impact and vibration of large blasting affect the stability of the empty area; the practice of some mines proves that the destruction of the pillar and the collapse of the empty area are often related to the large-scale blasting of adjacent sections.
    When the terrain is gentle, the movement of the surface rock mass generally takes the form of a submerged basin or a collapse funnel, and the range of influence is limited to the moving belt formed by the empty area. When the terrain is steep, the development of the rock in the empty area to the surface may cause landslides, landslides, rolling stones and mudslides. Its intensity and reach are often beyond the range of the entire rock movement.
    The formation of goafs redistributes the stresses of a certain range of rock masses around them, resulting in rock deformation, damage and movement. If the amount of fallen rock does not eliminate the empty zone, another cycle of deformation, displacement and damage will occur at the new empty zone boundary. The form, extent and time of rock mass movement and damage caused by empty areas are restricted by a series of factors, some affecting only the production under the joint, and some affect the surface, surface cracking, subsidence and collapse. Under terrain conditions, landslides, landslides, rolling stones, mudslides, etc. may occur.