Reconstruction efficient ditching method for new horizontal development water pressure environment of deep open-pit mine

Abstract

The invention relates to a reconstructed efficient trenching method for a new horizontal development water pressure environment of a deep open pit mine, which is characterized in that lithology and fracture distribution characteristics of rock mass in an access trenching area are ascertained, and each construction section of an access trench channel is subdivided into a water burst area, a conventional area and a first explosion area according to the lithology and the fracture distribution characteristics. And dewatering wells are uniformly arranged in and outside the primary explosion area and the water gushing area, drainage wells are arranged outside the primary explosion area and the water gushing area, and after surface fissure water is drained in advance, rapid penetration explosion is carried out from the primary explosion section to the two sides to form a catchment loose muck pile. And presplitting blast holes are drilled between the drainage well and the channel first blasting area and between the drainage well and the channel first blasting area, explosive loading is enhanced at the bottom, detonation is conducted with the adjacent channel construction sections at the same time, and a through drainage channel is formed between the drainage well and the bottom of the in-out channel muck pile. After penetration and blasting are completed, a water pump in the drainage well continuously pumps water at full load, so that the muck pile water level is lower than an electric shovel working face, and the electric shovel is matched with an automobile flat loading vehicle to continuously dig ditches to a new horizontal working face at full-section height. The method has the advantages of improving the penetrating and blasting effect, improving the ditching efficiency, flexibly selecting the development opportunity and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of open-pit mining, and in particular relates to an efficient trenching method for recreating a new horizontal water pressure environment for deep open-pit mines in rainy areas. Background Art

[0002] Trenching operation is a new level of development preparation work that must be carried out for the deepening and continuous production of open-pit mines. Compared with normal mining and stripping operations, it is located at the lowest point of the mining area and is greatly affected by water gushing. The working surface is narrow and there are few free surfaces for blasting. It is one of the weakest links in open-pit production, which seriously restricts the production capacity of open-pit mines and has a significant impact on the planning and mining layout of open-pit mines, the reserve of prepared ore, and the balance of stripping ratio.

[0003] As the mining depth continues to increase, surface runoff and underground water flow gather in large quantities to the shallow groundwater layer at the bottom of the pit. During the roller drilling process, the crushed powder and slag are difficult to discharge and the hole wall is constantly eroded, which makes the previous horizontal blasting too deep and the broken rock blocks in the affected area loose and collapse, which is easy to cause the bottom of the hole to be filled with broken blocks or the hole to be blocked by large blocks, causing perforation problems such as large-scale hole loss, repeated drilling or increased secondary holes, and blasting problems such as punching, root base, and high large block rate, which seriously affect the quality and progress of the project and greatly increase the processing cost of subsequent processes. After the blasting of the trench area begins, the hydraulic balance of the internal rock mass is destroyed, resulting in a large amount of water flowing into the loose blast pile. On the one hand, the blast pile quickly collects water to form a high-pressure water environment, which is easy to penetrate to the surrounding area along the blast cracks, causing the perforation effect to deteriorate. On the other hand, the blast pile in the trench continuously collects water and trenching cannot be carried out continuously. It is necessary to suspend the excavation many times to arrange temporary drainage pits and plant pumps to pump water, which seriously restricts trenching efficiency and affects production safety. In addition, in the rainy areas in the south, the rainy season is long and the cycle for new level development is limited. Problems such as blasting and drainage are frequently exposed during trench digging, which can easily cause delays in mining progress and lead to production accidents such as insufficient ore recovery and difficulty in ore allocation.

[0004] Therefore, it is particularly urgent to develop an efficient trenching method that can adapt to the water pressure environment reconstruction of new horizontal development of deep open-pit mines in rainy areas in order to achieve continuous, stable and efficient production. Summary of the invention

[0005] The invention discloses a high-efficiency trenching method for recreating a water pressure environment in a new horizontal development of a deep open-pit mine, so as to solve any of the above and other potential problems in the prior art.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: a high-efficiency trenching method for recreating the water pressure environment for new level development in deep open pit mines, the method comprising the following steps:

[0007] S1) Explore the lithology and fracture distribution characteristics of the rock mass in the access trench excavation area, optimize the layout of the access trench according to the hardness of the lithology and the development of fractures, and divide the access trench into a water inrush area, a conventional area, and a first blast area;

[0008] S2) Uniformly arrange precipitation wells inside and outside the first blast area and the water inrush area in the access trench, arrange drainage wells outside the first blast area and the water inrush area of the trench, and conduct advance drainage. After drainage, start from the first blast section and quickly penetrate and blast towards both sides to form a water-collecting loose blast heap;

[0009] S3) Drill pre-splitting blast holes between the drainage wells and the first blast area and the water inrush area of the trench, strengthen the charge at the bottom and detonate simultaneously with the adjacent trench construction segments, and form a through hydrophobic channel at the bottom of the drainage well and the access trench blast heap;

[0010] S4) After the penetration and blasting are completed, the water pumps in the drainage wells continuously pump water at full load, so that the water level of the blast heap is lower than the electric shovel working surface, and the electric shovel cooperates with the truck to load the whole section height continuously to excavate the trench to the new horizontal working surface.

[0011] Furthermore, the specific steps of the S1) are as follows:

[0012] S1.1) Initially select the access trench excavation area according to the optimal mine transportation system. By arranging a dense network of physical exploration lines similar to the blasting hole pattern and drilling water exploration holes at key nodes, detailedly investigate the lithology, water inrush volume, and fracture zone development characteristics in the area, and adjust the access trench excavation direction and starting position to determine the final plan;

[0013] S1.2) Determine the number of construction segments according to the blasting hole pattern layout and the number of drill holes that can be drilled by a rotary drill in one shift for the new horizontal development, and divide each section of the access trench into three categories: a water inrush area, a conventional area, and a first blast section. Among them, the interval of the physical exploration line network is 5 - 10 m, the number of segmented construction is 5 - 8 sections, and the number of water exploration holes ensures that there is no less than 1 for each construction segment.

[0014] Furthermore, the water inrush area, the conventional area, and the first blast section in the S1.2) are divided according to the detailed exploration results of the lithology and fracture distribution in the access trench. Among them, the water inrush area is the area in the access trench where the lithology is poor or the fractures are more developed according to the exploration geophysical prospecting and water exploration drill hole data;

[0015] The conventional area is the area in the access trench where the lithology is harder and the fractures are not developed according to the exploration geophysical prospecting and water exploration drill hole data;

[0016] The first blast section is a certain construction segment in the access trench where the lithology is harder and the fractures in the middle and upper parts are more developed.

[0017] Furthermore, the specific steps of the S2) are as follows:

[0018] S2.1) Arrange several precipitation wells within the water gushing area of the ditch or on the side of the main water gushing source outside the ditch, and then arrange several drainage wells at a distance of 1.5 - 2.0 times the minimum resistance line outside the first blasting section and the water gushing area for advanced drainage respectively;

[0019] S2.2) After the surface fissure water in the area to be dug is drained dry, start perforation blasting with the first blasting area as the starting section, strengthen the charge during the first blast, and then rapidly advance in segments along the front and back of the ditch for construction, forming a water - collecting loose blasting heap for all the ditches in and out of the access ditch;

[0020] Furthermore, the number of the precipitation wells in S2.1) is 4 - 8, the diameter is 0.5 - 1.5 m, the depth is 0.4 - 0.5 times the open - pit bench height, and is 6 - 7.5 m when the bench height is 15 m. The precipitation wells are damaged together with the ditch - digging blasting after the perforation of the corresponding construction segment is completed.

[0021] Furthermore, the number of the drainage wells in S2.1) is 2 - 3, the depth is 1.2 - 1.5 times the open - pit bench height, and is 18 - 24 m when the bench height is 15 m. The drainage wells can be abandoned and damaged together with the bench - expanding project after the ditch - digging is completed and the new - level drainage system is established.

[0022] Furthermore, the specific steps of S3) are as follows:

[0023] S3.1) Arrange 1 - 2 straight - line through - drainage channels between the drainage wells, the first blasting area of the ditch and the water gushing area, and drill a row of dense pre - split blast holes along the designed through - drainage channels;

[0024] S3.2) Strengthen the charge amount at the bottom of the pre - split blast holes and increase the stemming length at the upper part, and detonate simultaneously with the adjacent ditch - construction segments. Based on the original micro - fissures or closed fissures in the rock mass between the bottom of the drainage well and the bottom of the access - ditch blasting heap, a large number of blast - generated fissures are generated to form a directional open through - fissure zone drainage channel

[0025] Furthermore, for the pre - split blast holes in S3.1): the depth is greater than the open - pit bench height by 2 - 3 m, and the hole depth is 17 - 18 m when the bench height is 15 m; the interval is taken as 10 - 12 times the diameter of the blast - hole drilling rig, and the hole interval is 2.5 - 3.0 m when using a 250 - mm cone bit for drilling;

[0026] For the pre - split blast holes in S3.2), the charge - loading length at the bottom of the pre - split blast holes is not less than the pre - split blast - hole interval, and the stemming length at the upper part of the pre - split blast holes is not less than the minimum resistance line of the mine.

[0027] Furthermore, the total power of the water pumps in S4) needs to be greater than 2 - 3 times the maximum annual water gushing volume during ditch - digging.

[0028] The beneficial effects of the present invention are as follows: The above technical solutions have the following characteristics:

[0029] (1) Good blasting and drilling effect. Dewatering wells are arranged in the water-rich sections inside and outside the access ramps to effectively drain the fissure water in the rock mass, especially the water in the upper fracture zone caused by the overdrilling of the previous bench blasting. This improves the drilling effect of blast holes, enhances the efficiency of the drill rig, avoids a large number of waste holes caused by blast hole collapse, ensures the effective depth of blast holes, reduces the occurrence frequency of re-drilling and lost holes, and effectively improves the blasting quality (bench bottom and large blocks);

[0030] (2) High ditch excavation efficiency. Dewatering wells are arranged outside the access ramps and continuous pumping is carried out after the muck pile is formed, which can effectively drain the accumulated water inside the muck pile and control the water level inside the muck pile. During the ditch excavation process, it is reduced or even unnecessary to arrange mobile drainage pits inside the muck pile, thus shortening the time for excavating drainage pits and installing pump pipelines, and greatly improving the ditch excavation efficiency;

[0031] (3) More flexible selection of development time. Affected by rainfall and underground water inflow, the new bench development time of open-pit mines in southern regions generally needs to select dry seasons lasting more than one month. At the same time, it is greatly affected by climate such as typhoons, and the development time is not fixed every year, which has a great impact on the production plan. The method of the present invention can actively discharge shallow fissure water and drain the accumulated water inside the muck pile by using dewatering wells and drainage wells, creating good conditions for ditch excavation and blasting operations, effectively shortening the total ditch excavation period, and making the selection of development time more extensive and flexible;

[0032] At the same time, this method can not only actively reduce the water pressure in the ditch area, greatly improve the hole-forming rate of perforation, improve the blasting effect, but also complete the advanced drainage inside the muck pile, avoid frequent excavation of temporary drainage pits and pumping drainage with pumps, realize efficient and continuous ditch excavation operations, solve the adverse impact of water inflow on new bench development from the source, quickly complete the new bench ditch excavation project, and ensure the continuous, stable and efficient production of open-pit mines. Brief Description of the Drawings

[0033] Figure 1 is a three-dimensional schematic diagram of a high-efficiency ditch excavation method for reconstructing the water pressure environment of a new bench in a deep open-pit mine according to the present invention.

[0034] Figure 2 is a schematic diagram of the survey line, borehole layout and water inflow characteristic zoning of the ditch and its periphery in the method of the present invention;

[0035] Figure 3 is a schematic diagram of the layout design of the combined scheme of dewatering wells and drainage wells in the access ramps in the method of the present invention;

[0036] Figure 4 is a schematic diagram of the functions of drainage and dewatering wells during the perforation and blasting operations in the access ramps in the method of the present invention;

[0037] Figure 5 It is a schematic diagram of trenching and blasting operations in the method of the present invention;

[0038] Figure 6 It is a schematic diagram of the expansion operation in the method of the present invention;

[0039] Figure 7 It is a schematic diagram of forming a new water tank in the method of the present invention;

[0040] Figure 8 for Figure 4 Schematic diagram of the blast drainage in the middle AA section;

[0041] Attached photos:

[0042] Ⅰ channel, Ⅰ-1 inlet and outlet ditch, Ⅰ-2 opening ditch, Ⅰ-1a water gushing area, Ⅰ-1b conventional area, Ⅰ-1c first blasting section, Ⅱ working gang, 1 water exploration borehole, 2 exploration detection line, 3a dewatering well, 3b drainage well, 4a temporary water tank, 4b new horizontal temporary water tank, 5a blasting hole, 5b pre-splitting blasting surface, 6 blasting pile, 7 road, 8 ditch slope, 9 shovel-shaped working surface, 10 new horizontal working surface, 11a original fissure, 11b blasting fissure, 12 well-type submersible pump, 13 water level monitor, 14 flow monitor, 15 drainage pipeline, 16a perforation control water level line, 16b trenching control water level line. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions of various embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making innovative work are within the scope of protection of the present invention.

[0044] A high-efficiency trenching method for recreating a water pressure environment for a new level of development in a deep open-pit mine, the method comprising the following steps:

[0045] S1) Explore the lithology and fracture distribution characteristics of the rock mass in the trenching area, optimize the layout of the trenches according to the hardness of the rock and the development of fractures, and subdivide the trenches into water gushing areas, conventional areas and first blasting areas;

[0046] S2) Drainage wells are evenly arranged inside and outside the first blasting area and water gushing area in the inlet and outlet ditch, and drainage wells are arranged outside the first blasting area and water gushing area in the ditch, and advance drainage is carried out. After drainage, blasting is carried out quickly from the first blasting section to both sides to form a loose blasting pile with water collection;

[0047] S3) Drill pre-splitting blastholes between the drainage well and the first blasting area and the water gushing area of ​​the trench, reinforce the charge at the bottom and detonate simultaneously with the adjacent trench construction sections, and form a through drainage channel at the bottom of the drainage well and the inlet and outlet trench blast pile;

[0048] S4) After the perforation and blasting are completed, the water pump in the drainage well pumps water continuously at full load, making the water level of the blasted heap lower than the working surface of the electric shovel. The electric shovel cooperates with the truck to carry out full-section high continuous trenching to the new horizontal working surface in a flat loading manner.

[0049] Furthermore, the specific steps of the S1) are as follows:

[0050] S1.1) Initially select the access trench excavation area according to the optimal mine transportation system. By arranging a dense mesh physical exploration line similar to the blasting hole pattern and drilling water exploration holes at key nodes, investigate in detail the lithology, water inflow, and fracture zone development characteristics in the area, and adjust the access trench excavation direction and starting position to determine the final plan;

[0051] S1.2) Determine the number of construction segments according to the blasting hole pattern layout and the number of drill holes per shift of the rotary drill available for the new horizontal development. Divide each section of the access trench into three types: water inflow area, conventional area, and first blasting section. Among them, the interval of the physical exploration line network is 5 - 10 m, the number of segmented construction is 5 - 8 sections, and the number of water exploration holes ensures that there is no less than 1 for each construction segment.

[0052] Furthermore, the water inflow area, conventional area, and first blasting section in the S1.2) are divided according to the detailed exploration results of the lithology and fracture distribution in the access trench. Among them, the water inflow area is the area in the access trench where the lithology is relatively poor or the fractures are relatively developed based on the exploration geophysical prospecting and water exploration drill hole data;

[0053] The conventional area is the area in the access trench where the lithology is relatively hard and the fractures are not developed based on the exploration geophysical prospecting and water exploration drill hole data;

[0054] The first blasting section is a certain construction segment in the access trench where the lithology is relatively hard and the fractures in the middle and upper parts are relatively developed.

[0055] Furthermore, the specific steps of the S2) are as follows:

[0056] S2.1) Arrange several dewatering wells in the water inflow area of the trench or on the side of the main water inflow source outside the trench, and then arrange several drainage wells at a distance of 1.5 - 2.0 times the minimum resistance line outside the first blasting section and the water inflow area to carry out advanced drainage respectively;

[0057] S2.2) After the surface fissure water in the excavation area is drained dry, start perforation and blasting with the first blasting area as the starting section, and strengthen the charge during the first blast. Then quickly advance along the front and back construction segments of the trench, and form a water-collecting loose blasted heap for all the trenches in the access trench;

[0058] Furthermore, the number of the dewatering wells in S2.1) is 4 to 8, the diameter is 0.5 to 1.5 m, the depth is 0.4 to 0.5 of the open-pit mine step height, and when the step height is 15 meters, it is 6 to 7.5 m. After the perforation of the construction section is completed, the dewatering wells are destroyed together with the trenching blasting.

[0059] Furthermore, the number of the drainage wells in S2.1) is 2 to 3, and the depth is 1.2 to 1.5 times the height of the open-pit mine step, which is 18 to 24 meters when the step height is 15 meters. After the trenching is completed and the new horizontal drainage system is established, the drainage wells can be abandoned and destroyed along with the wall expansion project.

[0060] Further, the specific steps of S3) are:

[0061] S3.1) Arrange 1-2 straight sections of through-drainage channels between the drainage well and the first blasting area and the water gushing area of ​​the channel, and drill a row of dense pre-splitting blastholes along the designed through-drainage channels;

[0062] S3.2) Increase the charge at the bottom of the pre-splitting blasthole and the length of the filling at the top, and detonate simultaneously with the adjacent trench construction stages. Generate a large number of explosive cracks on the basis of the original micro-cracks or closed cracks in the rock mass between the bottom of the drainage well and the bottom of the inlet and outlet trench blast pile, forming a directional opening through the fracture zone drainage channel

[0063] Further, the pre-splitting blasthole in S3.1) has a depth greater than the step height of the open pit mine by 2 to 3 meters, and when the step height is 15 meters, the blasthole depth is 17 to 18 meters; the interval is 10 to 12 times the diameter of the blasthole drill, and when the 250mm cone drilling is used, the blasthole interval is 2.5 to 3.0 meters;

[0064] The bottom charging length of the pre-splitting blasthole in S3.2) is not less than the pre-splitting blasthole interval, and the upper filling length of the pre-splitting blasthole is not less than the minimum resistance line of the mine.

[0065] Furthermore, the total power of the water pump in S4) needs to be 2 to 3 times greater than the maximum water inflow from trenching in previous years.

[0066] Example:

[0067] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown in FIG. , an embodiment of the present invention provides a method for efficiently digging trenches for recreating a new horizontal water pressure environment in a deep open pit mine, comprising the following steps:

[0068] (1) Explore the channel [Ⅰ] and its surrounding areas, and divide the area to be dug into a water-inrush area [Ⅰ-1a] and a normal area [Ⅰ-1b] according to the water inflow and rock mass properties;

[0069] (2) Use a rotary drilling rig to drill dewatering wells [3a] in the water-inrush area [Ⅰ-1a] and install well-type submersible pumps. After the water level drops, select a section with harder lithology as the first blasting section [Ⅰ-1c], and quickly carry out blasting to form a loose muck pile [6] to collect the surrounding water inflow;

[0070] (3) Arrange dewatering wells [3b] outside the channel, connect the wells to the bottom of the muck pile by controlled blasting, and install high-power pumps

[12] to continuously pump water to ensure that the water level in the muck pile is lower than the trench excavation control water level line [16b];

[0071] (4) After the excavation blasting of the access trench is completed, use an electric shovel and trucks to perform full-section continuous trench excavation to the new horizontal working face

[10] in a flat loading manner.

[0072] To further illustrate the superiority of this trench excavation method, the trench excavation operation will be further described in combination with the new horizontal development project of an open-pit mine.

[0073] ① This new horizontal development trench excavation method combines geophysical exploration technology and drilling water exploration holes. Arrange water exploration boreholes [1] and dense hole network survey lines [2] in the channel [Ⅰ] leveled by a bulldozer to obtain the internal water content distribution and lithology characteristics in the access trench [Ⅰ-1] area. Further analyze and divide the area with larger water volume into a water-inrush area [Ⅰ-1a], the area with smaller water volume into a normal area [Ⅰ-1b], and at the same time select the section with developed fractures, harder lithology and close to the bottom of the channel in the water-inrush area as the first blasting section [Ⅰ-1c];

[0074] ② According to the single-well dewatering range and water-inrush distribution characteristics, formulate a combined layout plan for dewatering wells [3a] and dewatering wells [3b]. Use a rotary drilling rig to drill dewatering wells [3a] in the water-inrush area [Ⅰ-1a] and dewatering wells [3b] on the outside of the first blasting section [Ⅰ-1c], and quickly install well-type submersible pumps

[12] and arrange drainage pipelines

[15] for drainage. After the water level drops, complete the perforation blasting work on the first blasting section [Ⅰ-1c] to form a loose muck pile [6] to collect the surrounding water inflow. At the same time, form a pre-splitting blasting surface [5b] between the muck pile [6] and the dewatering well [3b], and further generate blasting-induced fractures [11b] on the basis of the original fractures [11a] to facilitate the rapid drainage of the water collected in the muck pile [6];

[0075] ③ Regulate the water level in the muck pile [6] to be lower than the perforation control water level line [16a], and quickly complete the full-section one-time perforation blasting operation for each section in the access trench [Ⅰ-1] area, appropriately increasing the charge amount and densifying the hole pattern parameters to enhance the blasting effect;

[0076] ④Regulate the water level in the muck pile to be lower than the trench excavation control water level line [16b], and quickly carry out continuous trench excavation operations in each section of the access trench [Ⅰ-1] area by using electric shovels in cooperation with trucks for flat loading. At the same time, perforation and blasting operations can be arranged in the area near the bottom of the starting trench [Ⅰ-2]. After the trench reaches the bottom, further carry out horizontal excavation of the starting trench muck pile to quickly form a blasting free surface;

[0077] ⑤After the excavation of the starting trench is completed, quickly expand the slope and extract ore in the area near the temporary sump [4a]. When a larger working face is formed, a new horizontal temporary sump [4b] is formed, a new horizontal drainage system is constructed, and the abandoned drainage well and the upper-level temporary sump are blasted. At this time, the new horizontal development project is completed.

[0078] The said trench [I] includes the access trench [Ⅰ-1] and the starting trench [Ⅰ-2]. Among them, the access trench [Ⅰ-1] is arranged with a gentle slope. Its length, width are related to the transport truck and the shunting method, and the slope is related to the climbing ability of the transport truck. The starting trench [Ⅰ-2] is arranged horizontally. Its length is equivalent to the length (or width) of the new level, and its width is the same as or larger than that of the access trench [Ⅰ-1];

[0079] The said water exploration borehole [1] is used to initially judge the hole-forming rate of perforation in the access trench [Ⅰ-1] area, which is convenient for formulating the blasting construction sequence plan. It is preferred to use the drilling parameters of the drill rig to reflect the lithology, and the borehole imaging photography to reflect the fracture development characteristics and water inrush situation. The number of holes ensures that there is one in each blasting section of the access trench [Ⅰ-1];

[0080] The said exploration line [2] is used to initially judge the distribution of water inrush fracture zones in the access trench [Ⅰ-1] area. It is preferred to use the dense-hole network ground penetrating radar technology for full-coverage exploration. The grid survey lines are not less than 3 along the direction of the access trench [Ⅰ-1], and there is one in the direction perpendicular to the access trench [Ⅰ-1] for each blasting section of the access trench [Ⅰ-1];

[0081] The said water inrush area [Ⅰ-1a] is the area in the access trench [Ⅰ-1] where the lithology is relatively poor or the fractures are relatively developed according to the exploration geophysical prospecting and water exploration borehole data;

[0082] The said normal area [Ⅰ-1b] is the area in the access trench [Ⅰ-1] where the lithology is relatively hard and the fractures are not developed according to the exploration geophysical prospecting and water exploration borehole data;

[0083] The said first blasting section [Ⅰ-1c] is a certain area in the normal area [Ⅰ-1b] where the lithology is relatively hard and the fractures in the middle and upper parts are relatively developed. It is preferably close to the bottom of the access trench [Ⅰ-1];

[0084] The precipitation well [3a] mainly serves to enhance the blasting effect and is generally arranged inside or outside the channel water inrush area [Ⅰ-1a]. Its diameter is determined according to the drilling equipment, water inrush volume, and pump size, preferably 0.5 - 1.5 m. The depth is 0.4 - 0.5 times the height of the open-pit bench. For example, when the bench height is 15 m, it is preferably 6 - 7.5 m. The number can be designed according to the water inrush volume and the drainage volume of a single well, preferably 4 - 8. After the perforation of the construction section where it is located is completed, the precipitation well is destroyed together with the trench blasting;

[0085] The drainage well [3b] mainly serves to drain the accumulated water in the blasted muck and is generally arranged outside the water inrush area [Ⅰ-1a]. Its diameter is the same as that of the precipitation well [3a], and it can also be appropriately widened according to the drainage requirements, preferably 1 - 2 m. The depth is 1.2 - 1.5 times the height of the open-pit bench. For example, when the bench height is 15 m, it is preferably 18 - 24 m. The number can be designed according to the water inrush volume and the drainage volume of a single well, preferably 2 - 3. After the trench excavation is completed and the new horizontal drainage system is established, the drainage well can be abandoned and destroyed together with the bench expansion project;

[0086] The pre-splitting blasting surface [5b] is to low-disturbance and directionally open the fracture channel between the channel blasted muck [6] and the drainage well [3b] by controlling blasting. Preferably, a row of dense pre-splitting blasting holes is arranged along the drainage well [3b] perpendicular to the access trench [Ⅰ-1]. Based on the non-penetrating primary microfractures or closed fractures [11a], a large number of blast-induced fractures [11b] are generated, and an open and penetrating fracture water inrush channel is formed;

[0087] The perforation control water level line [16a] and the trench excavation control water level line [16b] respectively correspond to the different requirements in different stages of the new horizontal trench excavation operation. In the early stage, the purpose is to reduce the fissure water inside the rock mass to enhance the hole-forming rate of perforation, and in the later stage, the purpose is to drain the accumulated water in the blasted muck to achieve continuous trench excavation operation.

[0088] In summary, the application of this technical method in the deep new horizontal development of a large domestic deep-dip open-pit copper mine shows that compared with the existing technology, it not only significantly improves the hole-forming rate of perforation, improves the blasting effect, and realizes continuous trench excavation, but also effectively shortens the trench excavation period and ensures the safety of construction workers and equipment.

[0089] The above has introduced in detail a high-efficiency trench excavation method for reconstructing the water pressure environment in the new horizontal development of a deep-dip open-pit mine provided by the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

[0090] As used in the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not distinguish components by the difference in names, but by the difference in functions of the components. As used throughout the specification and claims, the terms "comprising" and "including" are open-ended terms and should be interpreted as "comprising / including but not limited to". "Substantially" means within an acceptable error range. Those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The following description in the specification is the preferred embodiment for implementing the present application, but the description is for the purpose of explaining the general principles of the present application and not for limiting the scope of the present application. The protection scope of the present application shall be subject to that defined by the appended claims.

[0091] It should also be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a commodity or system including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent in such commodity or system. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the commodity or system including the said element.

[0092] It should be understood that the term "and / or" used herein is only a correlative relationship describing the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0093] The above description shows and describes several preferred embodiments of the present application. However, as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the application concept described herein through the above teachings or the technology or knowledge in the relevant field. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present application shall fall within the protection scope of the appended claims of the present application.

Claims

1. A high-efficiency trenching method for recreating the water pressure environment for new level development of deep open pit mines, characterized in that: The following steps are involved: S1) Explore the lithology and fracture distribution characteristics of the rock mass in the trenching area, optimize the layout of the trenches according to the hardness of the rock and the development of fractures, and subdivide the trenches into water gushing areas, conventional areas and first blasting areas; S2) Drainage wells are evenly arranged inside and outside the first blasting area and water gushing area in the inlet and outlet ditch, and drainage wells are arranged outside the first blasting area and water gushing area in the ditch, and advance drainage is carried out. After drainage, blasting is carried out quickly from the first blasting section to both sides to form a loose blasting pile with water collection; S3) Drill pre-splitting blastholes between the drainage well and the first blasting area and the water gushing area of ​​the trench, reinforce the charge at the bottom and detonate simultaneously with the adjacent trench construction sections, and form a through drainage channel at the bottom of the drainage well and the inlet and outlet trench blast pile; S4) After the blasting is completed, the water pump in the drainage well continues to pump water at full capacity, so that the water level of the blasting pile is lower than the electric shovel working surface. The electric shovel cooperates with the truck flat loading vehicle to continuously dig trenches to the new horizontal working surface.

2. The method according to claim 1, characterized in that: The specific steps of S1) are: S1.1) Preliminarily select the entry and exit trenching area based on the optimal mine transportation system, arrange a dense mesh physical exploration line similar to the blasting hole network and drill water exploration holes at key nodes, investigate the lithology, water inflow and fracture zone development characteristics in the area in detail, adjust the entry and exit trenching direction and starting position to determine the final plan; S1.2) The number of construction sections is determined based on the blasting hole network layout and the number of holes drilled by the rotary drill rig in one day for new horizontal development, and each section of the entrance and exit ditch is divided into three categories: water gushing area, conventional area and first blasting section. The physical exploration line network interval is 5 to 10m, the number of construction sections is 5 to 8 sections, and the number of water exploration holes is ensured to be no less than 1 in each construction section.

3. The method according to claim 2, characterized in that The water-gushing area, conventional area and first blasting section in S1.2) are divided according to the detailed exploration results of lithology and fracture distribution in the inlet and outlet trenches, among which the water-gushing area is the area with poor lithology or well-developed fractures in the inlet and outlet trenches selected according to the exploration geophysical and water exploration drilling data; The conventional area is an area in the inlet and outlet trench that is selected based on geophysical exploration and water exploration drilling data and has relatively hard lithology and undeveloped fractures; The first blasting section is a construction section in the entrance and exit trench where the rock is harder and the cracks in the middle and upper parts are more developed.

4. The method according to claim 1, characterized in that: The specific steps of S2) are: S2.1) Arrange several drainage wells in the water gushing area of ​​the channel or on the side of the main water gushing source outside the channel, and then arrange several drainage wells at the first explosion section and outside the water gushing area at a distance of 1.5 to 2.0 times the minimum resistance line, and carry out advance drainage respectively; S2.2) After the surface fissure water in the trenching area is drained, perforation blasting is started with the first blasting area as the starting section, and the charge is increased in the first shot. Then, the construction is quickly advanced in sections along the front and back of the trench, and all the trenches in and out of the trench are formed into loose blast piles for water collection.

5. The method according to claim 4, characterized in that The number of the dewatering wells in S2.1) is 4 to 8, with a diameter of 0.5 to 1.5 m and a depth of 0.4 to 0.5 of the step height of the open pit mine, and 6 to 7.5 m when the step height is 15 m. After the drilling of the construction section is completed, the dewatering wells are destroyed together with the trenching blasting.

6. The method according to claim 4, characterized in that The number of the drainage wells in S2.1) is 2 to 3, and the depth is 1.2 to 1.5 times the height of the open-pit mine step, which is 18 to 24 meters when the step height is 15 meters. After the trenching is completed and the new horizontal drainage system is established, the drainage wells can be abandoned and destroyed along with the wall expansion project.

7. The method according to claim 1, characterized in that The specific steps of S3) are: S3.1) Arrange 1-2 straight sections of through-drainage channels between the drainage well and the first blasting area and the water gushing area of ​​the channel, and drill a row of dense pre-splitting blastholes along the designed through-drainage channels; S3.2) Increase the charge at the bottom of the pre-splitting blasthole and the length of the filling at the top, and detonate simultaneously with the adjacent trench construction sections. Generate a large number of explosive cracks on the basis of the original micro-cracks or closed cracks in the rock mass between the bottom of the drainage well and the bottom of the inlet and outlet blast pile, forming a directional opening through-fracture zone drainage channel.

8. The method according to claim 7, characterized in that The pre-splitting blasthole in S3.1) has a depth greater than the step height of the open pit mine by 2 to 3 meters, and when the step height is 15 meters, the blasthole depth is 17 to 18 meters; the interval is 10 to 12 times the diameter of the blasthole drill, and when the 250mm cone drilling is used, the blasthole interval is 2.5 to 3.0 meters; The bottom charging length of the pre-splitting blasthole in S3.2) is not less than the pre-splitting blasthole interval, and the upper filling length of the pre-splitting blasthole is not less than the minimum resistance line of the mine.

9. The method according to claim 1, characterized in that: The total power of the water pump in S4) needs to be 2 to 3 times greater than the maximum water inflow from trenching in previous years.

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