(1) Surface drainage. Generally, drainage ditches are built outside the slope rock mass to prevent surface water from flowing into the surface cracks of the slope rock mass. The drainage ditch is required to have a certain gradient, generally 5 ‰; The section size shall meet the drainage needs when the maximum rainfall occurs; The trench bottom shall not leak; The ditch shall be maintained regularly to prevent blockage.
Mine surface drainage The top surface of the slope shall also have a certain gradient to prevent ponding on the top of the slope. If there is much rainfall in the slope with large open fissures, in this case, in addition to channeling for water diversion, the fissures must also be blocked. Gravel or gravel should be used to fill the deep part, and clay should be used to seal the fissure mouth.
Mine surface drainage (2) Groundwater drainage. Groundwater refers to the water below the water table, i.e. in the saturated zone. The groundwater can be drained or the water level can be lowered to reduce the harm of groundwater, which can not only improve the stability of the existing slope, but also increase the slope angle while maintaining the same stability. The drainage of groundwater shall be carried out before the unstable change of slope. It is necessary to collect detailed data on the characteristics and distribution of groundwater in slope rock mass.
Mine groundwater drainage Groundwater drainage includes natural drainage and manual drainage. When open-pit mining cuts through the natural groundwater surface, groundwater will flow into the stope. In this way, the stope will be drained, and the water level in the slope will be lowered to cause natural drainage. Because the cracks in the rock mass do not reach the slope surface, it is not enough to rely only on natural drainage, but also must cooperate with manual drainage to achieve the desired purpose. The scale of the drainage system is related to the scale of the slope to be drained, and its efficiency is related to the number of rock discontinuities it passes through. The specific drainage method shall be determined according to the overall slope height, permeability of slope rock mass, economic conditions, operation conditions and other factors.
Mine groundwater drainage ① Horizontal drain holes. Driving horizontal or nearly horizontal drainage holes from the slope is effective for reducing the water pressure at the bottom of the crack or near the potential failure surface. The location and spacing of horizontal drainage holes depend on the geometric shape of the slope and the distribution of structural planes in the rock mass. In hard rock slopes, water generally flows along joints. If horizontal holes can pass through these joints, the drainage effect will be good.
The main advantages of the horizontal drainage hole are: the construction is relatively fast and the installation is simple; Draining by gravity, almost no maintenance; The layout is flexible and can adapt to the change of geological conditions. Disadvantages are that the drainage has limited influence and can only be installed after the slope is formed.
Mine groundwater drainage ② Vertical drainage holes. Drilling a vertical shaft at the top of the slope, equipped with a deep well pump or submersible pump, is one of the effective methods for slope drainage. In hard rock mass, most of the water flows through structural fractures. In rock slope, the drainage well must be perpendicular to the structural plane with water to improve the drainage effect.
Compared with horizontal drainage holes, the main advantage of vertical drainage wells is that they can be installed and drained before slope excavation, and no matter when they are installed, such devices will not interfere with mining operations. Draining before mining has great benefits, because in some cases, the cost of pumping water from drainage wells may be compensated by the reduction of blasting and transportation costs. The extracted water is often clean and can be used in the concentrator or other aspects.
③ Underground drainage roadway. It is often economically reasonable to excavate drainage water tunnel in the rock behind the slope as a drainage measure for large slopes. For large slopes, due to the limited drainage capacity of boreholes, it is likely that a large number of holes need to be drilled. For a given slope, only one or two water sources are usually needed to drain the roadway.
Underground drainage roadway of mine
