Method for constructing inner dump type strip mine pit bottom reservoirs section by section

A method for constructing inner dump type strip mine pit bottom reservoirs section by section, comprising the procedures of single reservoir construction, multi-reservoir section-by-section construction and water resource storage, and specifically comprising the following steps:

• S1:
• processing side slopes:
• discarding 5-10-meter-thick clay at a lowest step of an inner waste dump (1) of a strip mine when the width of a constructed pit bottom (4) of the strip mine reaches about 150-300 m, so as to form an inner waste dump isolation layer (2), and stopping advancing of the inner waste dump (1) of the strip mine after the inner waste dump isolation layer (2) is formed;
• S2:
• after processing the side slopes, discharging concrete to slope faces of lowest steps (3) of the end slopes on two sides of the pit bottom (4) of the strip mine by adopting a guniting mode, so as to form an end slope isolation layer (6), thus completing end slope processing;
• S3:
• carrying out concrete guniting on the pit bottom (4) of the strip mine, and filling the pit bottom with the concrete and performing compaction to seal the bottom, so as to form a pit bottom isolation layer (7), wherein the laying thickness is 2-5 m, a slope is formed from the surface of the pit bottom isolation layer (7) to the end slopes on the two sides, and the pit bottom (4) is relatively high in the middle, and relatively low near the end slopes on the two sides;
• S4:
• after sealing the bottom, starting discarding gravel (8) into a pit of the strip mine, wherein the discarded gravel is massive gravel having larger pores that is stripped from the strip mine and does not disintegrate while touching water, and the height of the discarded gravel (8) is the height of the lowest steps (3) of the end slopes of the strip mine;
• S5:
• during gravel (8) discarding, laying geotextile when the gravel reaches the height of the lowest steps (3) of the end slopes, so as to form a roof isolation layer (9), and completing capping work after the roof isolation layer (9) is formed, wherein waste is normally dumped in the upper inner waste dump (1) at the same time;
• S6:
• with gradual forward advancement of the pit of the strip mine, re-adopting clay on the lowest steps (3) of the end slopes of the inner waste dump (1) while it reaches 150-300 m, so as to form a reservoir sealing isolation layer (10), wherein the construction of a single pit bottom (4) reservoir is completed, namely, reservoir sealing is realized, and a plurality of sets of moisture sensors are arranged symmetrically on two sides of each isolation layer to monitor soil moisture in the location in real time;
• S7:
• after the completion of construction of the single reservoir, repeating the above steps:
• constructing a plurality of reservoirs step by step along with advancement of the strip mine in an advancing direction of the strip mine, so as to form section-by-section reservoirs;
• S8:
• then storing water resources:
• firstly completing installation of water storage wells (11):
• during the construction of the single reservoir, directionally drilling holes in the end slopes on the two sides of the strip mine obliquely downward from the surface, and burying water pipes, wherein one end of each of the drill holes is located on the surface, and the other end of the drill hole is located in the lower part of the roof isolation layer (9) of the reservoir;
• S9:
• then continuing to complete installation of water fetching wells (12):
• during the construction of the single reservoir, directionally drilling holes in the end slopes on the two sides of the strip mine obliquely downward from the surface to form the water fetching wells (12), and installing pumping units, wherein one end of each of the water fetching wells (12) is located on the surface of the strip mine, and the other end of the water fetching well is located in the upper part of the pit bottom isolation layer (7) of the pit bottom (4) reservoir and near the end slopes;
• and
• S10:
• finally storing the water resources:
• after the completion of construction of the single reservoir, injecting the water resources into the pit bottom (4) reservoir via the water storage wells (11), wherein the water resources are stored in the pores of the gravel, and when water is needed, the water resources are pumped to the surface via the water fetching wells (12).