Pressure relief grouting and water sealing methods for poorly sealed boreholes in metal mine roadways and their applications

Abstract

This invention belongs to the field of mine water control technology, and relates to a method and application of pressure relief grouting for sealing poorly sealed boreholes in metal mine roadways. The invention includes: designing and constructing pressure relief holes: opening pressure relief holes in the mine roadway with the inclination of the poorly sealed borehole to be sealed, ensuring that the pressure relief holes and the poorly sealed borehole are located within the same ore body profile, and that the pressure relief holes are located below and intersect with the poorly sealed borehole; pressure relief grouting for sealing: with the pressure relief hole opening open, pressure relief grouting is performed from the bottom up into the poorly sealed borehole until grout returns from the pressure relief hole, at which point grouting stops; after the grout filling in the poorly sealed borehole has completely solidified, grout is then injected into the pressure relief hole through its opening. This invention improves the success rate of sealing poorly sealed boreholes and overcomes the problems of high construction costs, long construction periods, and potential waste of mineral resources associated with the retaining wall grouting method.

Description

Technical Field

[0001] This invention belongs to the field of mine water control technology, and relates to the sealing technology of poorly sealed boreholes in mine roadways, and particularly to a pressure relief grouting water-stopping method and its application for poorly sealed boreholes in metal mine roadways. Background Technology

[0002] Water inrush from poorly sealed boreholes is one of the major water hazards in metal mines. There are two main types of poorly sealed boreholes in metal mines: one is where the borehole is not completely solidified and filled with cement slurry, and the other is where there is no cement slurry or other filling material in the borehole.

[0003] Currently, the main methods for sealing poorly sealed boreholes are the surface resealing method and the roadway retaining wall grouting method. The surface resealing method involves re-drilling the poorly sealed borehole at the original location and re-grouting to seal it. The roadway retaining wall grouting method involves constructing one or more retaining walls in the roadway outside the water inrush point of the borehole, and then injecting grout into the walls through grouting pipes to block the water in the borehole, achieving the effect of water sealing through grouting. However, the two existing methods each have their own drawbacks when dealing with poorly sealed boreholes that are deep and have high water pressure: the surface unsealing method often fails halfway due to inaccurate borehole inclination or curvature information, or the presence of drill bits in the original borehole, causing the drilling to deviate from the original position. The roadway retaining wall grouting method requires sufficiently thick walls and a sufficiently large rock embedment depth. When the water pressure is very high, at least two or even three retaining walls need to be constructed to ensure the pressure-bearing strength of the walls. The construction cost is high, the construction period is long, and a sufficiently thick waterproof safety pillar is required, which wastes a lot of mineral resources to prevent water from bursting through the fissures caused by rock movement during ore mining in poorly sealed boreholes.

[0004] Therefore, how to solve the problems of low success rate of traditional ground opening method, high construction cost, long construction period and waste of resources of water retaining wall grouting water stop method is the technical problem that this invention needs to solve. Summary of the Invention

[0005] The purpose of this invention is to provide a method and application for grouting and sealing poorly sealed boreholes in metal mine roadways. This method not only has a simple construction procedure, small workload, and high construction efficiency, but also low construction cost, low construction risk, and high success rate, thereby solving the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] On one hand, the present invention provides a method for grouting and sealing poorly sealed boreholes in metal mine roadways, comprising:

[0008] Design and construct pressure relief holes: In the mine roadway, pressure relief holes are opened with the same inclination as the poorly sealed borehole to be stopped from water, and the pressure relief holes and the poorly sealed borehole to be stopped from water are located in the same ore body profile, and the pressure relief holes are located below the poorly sealed borehole to be stopped from water and intersect with the poorly sealed borehole to be stopped from water.

[0009] Pressure relief grouting for water sealing: With the pressure relief hole open, pressure relief grouting is performed from the bottom of the hole upwards into the poorly sealed borehole to be sealed until grout returns from the pressure relief hole, at which point grouting is stopped; after the grout filling in the poorly sealed borehole to be sealed has completely solidified, grouting is then performed into the pressure relief hole through the opening of the pressure relief hole.

[0010] In some embodiments, the procedure for designing and constructing the pressure relief hole includes:

[0011] Step S1: Obtain the location information of the poorly sealed borehole to be stopped in the ore body. The location information includes the borehole opening location, borehole depth, borehole dip direction, borehole inclination angle, aquifer exposed by the borehole, and the positional relationship between the borehole and the ore body.

[0012] Step S2: Measure the water volume, water pressure, and water chemical composition of the poorly sealed borehole to be stopped, and analyze the source of the water inflow;

[0013] Step S3: Calculate the required grouting depth into the poorly sealed borehole to be sealed;

[0014] Step S4: Design the location, inclination, and dip angle of the pressure relief hole to ensure that the pressure relief hole and the poorly sealed borehole to be stopped are located in the same ore body profile;

[0015] Step S5: Construct the pressure relief hole according to the designed hole position, inclination and inclination angle, and after the construction of the pressure relief hole is completed, install a grouting steel pipe with a valve at the hole opening of the pressure relief hole.

[0016] In some embodiments, the pressure relief grouting and water sealing includes:

[0017] Step S6: With the valve open, perform pressure relief grouting from the bottom of the hole to the top of the poorly sealed borehole to be stopped, until grout returns from the pressure relief hole and then stop grouting.

[0018] Step S7: After the grouting filler in the poorly sealed borehole to be sealed has completely solidified, grout is injected into the pressure relief hole through the grouting steel pipe at the opening of the pressure relief hole to seal the water. After the grouting is completed, the valve is closed.

[0019] In some embodiments, in step S1, the location information is obtained by collecting drilling results, geological profiles, and hydrogeological profiles from the mineral exploration stage, combined with the exposure location of the poorly sealed borehole to be stopped from water, and a profile diagram of the positional relationship between the poorly sealed borehole to be stopped from water and the ore body is drawn based on the obtained location information.

[0020] In some embodiments, in step S2, the source of the water inflow is determined by analyzing the water chemical composition, TDS, and pH value of the poorly sealed borehole water to be stopped.

[0021] In some embodiments, in step S3, if the surrounding rock of a metal mine is used as a water-stopping layer, grout is injected into the poorly sealed borehole to a distance of 10m from the vertical ore body from the top plate of the ore body, and the required grouting depth to a distance of 10m from the vertical ore body from the top plate of the ore body is measured or drawn in the positional relationship profile.

[0022] In step S4, firstly, the location, inclination, and dip angle of the pressure relief hole are designed within the middle section of the roadway where the poorly sealed borehole to be stopped is located, to ensure that the pressure relief hole and the poorly sealed borehole to be stopped are located within the same ore body profile; at the same time, the pressure relief hole is arranged within the ore body roof and the vertical distance from the ore body roof to the ore body is not less than 10m; then, the pressure relief hole is drawn in the positional relationship profile diagram, and the actual length of the pressure relief hole is calculated according to the drawing scale. If the actual length is not greater than 30m, the pressure relief hole is constructed in the middle section of the roadway; if the actual length is greater than 30m, the pressure relief hole is arranged in the upper middle section of the roadway.

[0023] In some implementations, step S6 includes:

[0024] Step S61: In the middle section of the roadway where the poorly sealed borehole to be stopped is located, the poorly sealed borehole to be stopped is swept from bottom to top, and another grouting steel pipe equipped with a valve is installed at the swept borehole.

[0025] Step S62: Through the other grouting steel pipe, perform pressure relief grouting from the bottom of the poorly sealed borehole to the top until grout returns from the pressure relief hole, then stop grouting and close the valve on the other grouting steel pipe.

[0026] In some embodiments, step S7, after the grouting of the pressure relief hole is completed, also includes a grouting effect check step:

[0027] After the grout in the pressure relief hole has solidified, open the valve on the grouting steel pipe at the pressure relief hole. If the pressure relief hole leaks water, repeat step S7 to grout into the pressure relief hole again until no water flows out of the pressure relief hole and then stop grouting.

[0028] In some implementations, before performing at least one of steps S5 to S7, the site is cleaned and it is ensured that there is no standing water in the work area.

[0029] On the other hand, the present invention provides an application of the above-mentioned method for depressurizing and grouting poorly sealed boreholes in metal mine roadways in mine water control technology.

[0030] The present invention achieves the following technical effects compared to the prior art:

[0031] This invention proposes a method for pressure relief grouting and water sealing of poorly sealed boreholes in metal mine roadways. This method involves grouting and sealing poorly sealed boreholes from within the roadway using pressure relief holes. It solves the problem of frequent failures during the surface reopening of poorly sealed boreholes due to inaccurate borehole information (dip, inclination, depth, etc.), bent boreholes, and residual drilling tools in the original borehole. This effectively improves the success rate of water sealing for poorly sealed boreholes. Compared to the retaining wall grouting method, which also involves water sealing of poorly sealed boreholes in roadways, this invention overcomes the disadvantages of high construction costs and long construction periods when water pressure is high, requiring the construction of multiple retaining walls. It also solves the problem of wasting a large amount of mineral resources by requiring sufficiently thick safety pillars for the poorly sealed boreholes using the retaining wall method, thus improving the utilization rate of mineral resources.

[0032] The aforementioned pressure relief grouting and water-stopping method for poorly sealed boreholes in metal mine roadways is mainly applicable to water-stopping and sealing of poorly sealed boreholes in metal mine roadways. Specific beneficial effects are as follows:

[0033] (i) Small workload and low cost.

[0034] Traditional grouting methods for sealing water-retaining walls require sufficiently thick walls and deep embedment in the rock. When water pressure is high, two or even three layers of retaining walls are needed to ensure the wall's bearing capacity, resulting in high construction costs. In contrast, the method for sealing poorly sealed boreholes described in this invention has a simpler construction procedure, requires less work, and is significantly less expensive than traditional grouting methods.

[0035] (ii) Low construction risk.

[0036] This invention avoids the problem of restart failure caused by various uncertainties in ground opening, and also reduces or even eliminates the risk of water inrush caused by the huge water pressure on the inner side of the tunnel retaining wall.

[0037] (iii) It does not occupy mineral resources.

[0038] Traditional retaining walls only block water seepage through poorly sealed boreholes, without actually sealing the boreholes. During mining, it is necessary to leave safety pillars to seal poorly sealed boreholes, which not only makes construction difficult but also occupies a large amount of mineral resources.

[0039] (iv) Fast construction speed and short construction period.

[0040] The construction procedure of this invention is simple. It only requires drilling a shallow grouting hole upwards and grouting. It can generally be completed in 2 to 3 weeks (7 days a week). There is no need to re-drill and re-grout the entire hole as with the ground, nor is it as time-consuming as a retaining wall in a tunnel. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic flowchart of a method for depressurizing and grouting to stop water in poorly sealed boreholes in metal mine roadways, as disclosed in an embodiment of the present invention.

[0043] Figure 2 This is a Durov diagram of poorly sealed boreholes and groundwater levels in each layer, as disclosed in an embodiment of the present invention.

[0044] Figure 3 This is a cross-sectional view of the grouting process for sealing poorly drilled holes using ZK2801, as disclosed in an embodiment of the present invention.

[0045] Figure 4 This is a cross-sectional view of the grouting process for sealing poorly drilled holes using ZK3203, as disclosed in an embodiment of the present invention.

[0046] Figure 5 This is a schematic diagram of the grouting steel pipe disclosed in an embodiment of the present invention.

[0047] Figure 6 This is a schematic diagram of the structure of the grouting steel pipe connected to the high-pressure valve and the blowout preventer disclosed in an embodiment of the present invention.

[0048] In the diagram, the reference numerals are: 1-grouting steel pipe; 2-fish scale buckle; 3-flange; 4-high pressure valve; 5-blowout preventer. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] The purpose of this invention is to provide a method and application for grouting and sealing poorly sealed boreholes in metal mine roadways. This method not only has a simple construction procedure, small workload, and high construction efficiency, but also low construction cost, low construction risk, and high success rate, thereby solving the problems existing in the prior art.

[0051] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] like Figure 1 As shown, this embodiment provides a method for grouting and sealing poorly sealed boreholes in metal mine roadways, including the following steps:

[0053] Step S1: Obtain the location information of the poorly sealed borehole to be sealed within the ore body. This location information includes the borehole opening location, borehole depth, borehole dip direction, borehole inclination angle, the aquifer exposed by the borehole, and the positional relationship between the borehole and the ore body. Specifically:

[0054] By collecting drilling results and geological and hydrogeological profiles from previous mineral exploration phases, and combining the exposure locations of poorly sealed boreholes, the borehole numbers of poorly sealed boreholes were analyzed. Further information was obtained on the borehole opening location, borehole depth, borehole dip, borehole inclination angle, aquifers exposed by the boreholes, and the positional relationship between poorly sealed boreholes and ore bodies. A profile diagram of the positional relationship between poorly sealed boreholes and ore bodies was then drawn.

[0055] Step S2: Measure the water volume, pressure, and chemical composition of the water inflow from the poorly sealed borehole, and analyze the water source. Specifically:

[0056] The water volume, water pressure, water chemical composition, TDS (Total Dissolved Solids, also known as total dissolved solids, refers to the total amount of various inorganic and organic substances dissolved in water, and together with total water hardness, they are important indicators for evaluating the degree of water mineralization) and pH value of the water inflow from the poorly sealed borehole to be stopped. A Durov diagram (a chart tool used for water chemical classification and analysis, mainly used to show the chemical composition and interrelationships of groundwater or natural water bodies, which will not be elaborated further here) is then drawn based on the water chemical composition, TDS, and pH value of the water inflow from the poorly sealed borehole to be stopped, and the groundwater in each layer. This analysis helps to determine the source of the water inflow from the poorly sealed borehole to be stopped.

[0057] Step S3: Calculate the required grouting depth into the poorly sealed borehole to be sealed. Specifically:

[0058] Based on the hydrogeological and engineering geological characteristics of the surrounding rock of the ore body, the required grouting depth is calculated by analyzing the positional relationship profile between the poorly sealed borehole and the ore body. The hydrogeological and engineering geological conditions of the surrounding rock in metal mines are generally good, serving as a water-stopping layer. Grouting of the poorly sealed borehole to a distance of 10m vertically from the top of the ore body is sufficient. The required grouting depth is measured on the positional relationship profile between the poorly sealed borehole and the ore body. In this technical field, the required grouting depth can also be characterized as the "length of the grouting body or grout filler".

[0059] Step S4: Determine the location, inclination, and angle of the pressure relief hole. Specifically:

[0060] The poorly sealed boreholes exposed in the roadway often exhibit high water pressure (generally greater than 3 MPa). Direct grouting from the bottom of these boreholes upwards results in slow grouting and dilution of the grout by the borehole water, leading to poor grouting effectiveness and inability to completely stop the water flow. Therefore, this application proposes combining pressure relief holes with grouting to enhance the grouting effect. First, pressure relief holes are installed within the roof of the ore body, with a vertical distance of no less than 10m (generally no more than 30m) from the roof. To reduce the construction length (depth) of the pressure relief holes, they are installed on the cross-section of the poorly sealed borehole to be stopped (i.e., directly below the poorly sealed borehole with the same inclination as the borehole). The designed pressure relief holes are drawn in the cross-sectional view, and their length is calculated. If the length of the pressure relief hole is no more than 30m, it can be constructed in the middle section of the roadway. If the calculated length of the pressure relief hole is greater than 30m, since it is not easy to control the pressure relief hole to the poorly sealed borehole, the pressure relief hole should be laid in the upper middle section of the roadway, and the laying principle is the same as above.

[0061] Step S5: Construction of the pressure relief hole. Specifically:

[0062] Depression relief holes are constructed according to the designed drainage locations and orientations. Since it's not guaranteed that the pressure relief holes will be drilled precisely into poorly sealed boreholes in one go, the second, third, and Nth pressure relief holes (N being a positive integer not less than 2) can be arranged at 300×300mm intervals until the poorly sealed borehole is reached. After successful construction of the pressure relief holes, a grouting steel pipe 1 with a fish-scale buckle 2 welded to its inner end is installed at the hole opening. A flange 3 is welded to the outer end of the grouting steel pipe 1, and a high-pressure valve 4 and a blowout preventer 5 are installed sequentially. The high-pressure valve 4 and the blowout preventer 5 are common equipment in this field; their specific structures and working principles will not be described in detail here.

[0063] Before constructing the pressure relief hole, it is preferable to first clear the site. For example, clear away the gravel and debris in the roadway at the location of poorly sealed boreholes and designed pressure relief holes, so that the roadway forms an open space with a height of not less than 3.5m and a width of not less than 4m, so as to facilitate drilling, excavation and grouting for water sealing, and ensure that there is no water accumulation in the work area.

[0064] Step S6: Perform grouting for water sealing in the poorly sealed boreholes. Specifically:

[0065] First, clean the bottom of the poorly sealed borehole and install grouting steel pipe 1 (the process for this grouting steel pipe is basically the same as that for the grouting steel pipe 1 installed at the pressure relief hole opening, but the diameter is slightly smaller than that for the grouting steel pipe 1 installed at the pressure relief hole opening; the outer end of the grouting steel pipe 1 at the bottom of the poorly sealed borehole is also equipped with a high-pressure valve 4 and a blowout preventer 5). Then, grout is injected upwards from the grouting steel pipe 1 at the bottom of the poorly sealed borehole until grout returns from the pressure relief hole, at which point grouting stops, and the high-pressure valve 4 on the grouting steel pipe 1 at the bottom of the poorly sealed borehole is closed. During this operation, the high-pressure valve 4 on the grouting steel pipe 1 connected to the pressure relief hole must remain open to achieve grouting and water stoppage of the poorly sealed borehole under pressure relief conditions.

[0066] Step S7: Grouting and water-stopping construction is carried out on the pressure relief hole. Specifically:

[0067] After the grout filling (i.e., grout body) in the poorly sealed borehole has completely solidified, grouting is then carried out on the pressure relief hole through the grouting steel pipe 1. Grouting is stopped when the grouting length (depth) of the pressure relief hole reaches 10m, and the high-pressure valve 4 on the grouting steel pipe 1 at the pressure relief hole is closed. After the grout filling (i.e., grout body) in the pressure relief hole has solidified, the high-pressure valve 4 on the grouting steel pipe 1 at the pressure relief hole is opened to check the grouting effect. If there is water leakage in the pressure relief hole, grouting is carried out again through the grouting steel pipe 1 until no water flows out, and then grouting can be stopped.

[0068] The aforementioned method for pressure relief grouting and water sealing of poorly sealed boreholes in metal mine roadways is a method of pressure relief grouting and water sealing construction from within the roadway. It solves the problems that often lead to unsealing failures during the surface reopening of poorly sealed boreholes due to inaccurate borehole information (dip, inclination, hole depth, etc.), bent boreholes, and drill bits remaining in the original hole, effectively improving the success rate of water sealing of poorly sealed boreholes. Compared with the retaining wall grouting method, which is also used for water sealing of poorly sealed boreholes in roadways, this method overcomes the disadvantages of high construction costs and long construction periods caused by the need to construct multiple retaining walls when the water pressure is high. It also solves the problem of wasting a large amount of mineral resources by requiring sufficiently thick safety pillars for the poorly sealed boreholes using the retaining wall method, thus improving the utilization rate of mineral resources.

[0069] The aforementioned pressure-relief grouting method for sealing poorly sealed boreholes in metal mine roadways is applicable to sealing and plugging poorly sealed boreholes in metal mine roadways. Huibaoling Iron Mine is a typical Anshan-type iron mine with abundant water; a highly water-rich aquifer exists in the upper part of the ore deposit. During tunnel excavation and mining, the mine encountered several poorly sealed boreholes. The following section uses poorly sealed boreholes ZK2801 and ZK3203 as examples to specifically explain the construction process and principle of the aforementioned pressure-relief grouting method for sealing poorly sealed boreholes in metal mine roadways.

[0070] Example 1: The pressure relief grouting and water-stopping method for poorly sealed ZK2801 boreholes specifically includes the following steps:

[0071] Step S1: Analyze the location of the poorly sealed borehole ZK2801 and review its drilling parameters to obtain its positional information within the ore body, such as borehole location, depth, borehole dip, borehole inclination angle, exposed aquifer, and the positional relationship between the borehole and the ore body. Then, draw a cross-sectional diagram showing the positional relationship between the borehole and the ore body. Figure 3 The diagram shown is a cross-sectional view of the positional relationship between the poorly sealed borehole ZK2801 and the ore body.

[0072] Step S2: Measure the water flow rate and pressure of the poorly sealed borehole ZK2801, and analyze the source of the water flow by analyzing the water chemical composition, TDS, and pH value to inform the next step of the grouting procedure and the selection of grouting equipment. The measured water flow rate of the poorly sealed borehole ZK2801 was 50 m³. 3 / h, water pressure 4MPa; Durov diagram analysis revealed that the poorly sealed borehole ZK2801 sourced water from the upper Liguan Formation and Erqingshan Formation fracture water, such as Figure 2 As shown.

[0073] Step S3: Calculate the required grouting depth into the poorly sealed borehole ZK2801 based on the positional relationship between the borehole and the ore body and the geological conditions shown in the cross-section diagram. The surrounding rock of the ore body (biotite plagioclase granulite) is hard and intact, serving as an aquitard. The hydrogeological and engineering geological conditions are favorable. Grouting of the poorly sealed borehole ZK2801 only needs to extend to a vertical distance of 10m from the top of the ore body. Measure the length of the grouting material inside the poorly sealed borehole ZK2801 from the drawn cross-section diagram showing the positional relationship between the borehole and the ore body. Figure 3 As shown, the length of the poorly sealed borehole requiring grouting is no less than 25m (generally 25m).

[0074] Step S4: Deploy pressure relief holes, i.e., determine the location, dip direction, and inclination angle of the pressure relief holes. Since the water pressure in the poorly sealed ZK2801 boreholes is greater than 4MPa, the pressure is relatively high, requiring pressure relief grouting in conjunction with the construction of pressure relief holes to enhance the grouting effect. Calculate the length (depth) of the pressure relief holes based on the cross-sectional diagram drawn in Step S1. If the length is no greater than 30m, the pressure relief holes can be constructed within this middle section of the roadway; if the calculated length is greater than 30m, since it is difficult to control the pressure relief holes to the poorly sealed boreholes, the pressure relief holes can be deployed in the upper middle section of the roadway. The pressure relief holes should be deployed within the ore body and at a vertical distance of no less than 10m from the ore body roof, and must be located on the cross-section corresponding to the poorly sealed borehole (i.e., the pressure relief holes and the poorly sealed boreholes are on the same plane). Based on the calculated grouting length required within the poorly sealed ZK2801 borehole, which is no less than 25m, therefore, if... Figure 3 As shown, for the poorly sealed borehole ZK2801, pressure relief holes can be installed in the middle section of the roadway for pressure relief grouting.

[0075] When the conditions for installing pressure relief holes are not met in the middle section of a roadway where a poorly sealed borehole is located, or in the upper middle section of a roadway, roadway excavation is required to advance the roadway into the surrounding rock of the ore body roof to meet the conditions for constructing pressure relief holes. For example... Figure 4 As shown, the -270m middle section roadway has not yet been constructed to the vicinity of the poorly sealed borehole ZK3203. Therefore, the -270m middle section roadway will be constructed to the top of the ore body, about 10m away from the poorly sealed borehole ZK3203, where pressure relief holes will be laid.

[0076] Step S5: According to Figure 3 The design and orientation of the pressure relief holes were determined. To better locate the poorly sealed borehole ZK2801, a φ90mm diameter pressure relief hole was used, and a ZQS-100 down-the-hole drill rig was employed. Since drilling to the poorly sealed borehole ZK2801 in one attempt is not guaranteed, second, third, and Nth pressure relief holes were laid out at 300×300mm intervals until the borehole was reached.

[0077] Before constructing the pressure relief hole, it is preferable to first clear the site. Specifically: clear away the gravel and debris in the tunnel where the poorly sealed borehole and the designed pressure relief hole are located, so that the tunnel forms an open space with a height of not less than 3.5m and a width of not less than 4m, so as to facilitate drilling, excavation and grouting for water sealing. At the same time, drainage ditches can be built in the tunnel to ensure that there is no water accumulation at the work site.

[0078] After the pressure relief hole is successfully constructed, a grouting steel pipe is installed at the hole opening. The grouting steel pipe is made of 4mm thick N65 seamless steel pipe, and its structure is as follows: Figure 5As shown, the grouting steel pipe is 2.5m long. A fish-scale knot is welded to the outer wall of the end of the grouting steel pipe located inside the pressure relief hole, and a flange is welded to the end of the grouting steel pipe located outside the pressure relief hole. During installation, hemp fiber is wrapped around the fish-scale knot to increase the frictional resistance between the grouting steel pipe and the surrounding rock. A high-pressure valve and a blowout preventer are sequentially installed at the outer end of the grouting steel pipe, with the high-pressure valve in the open position to facilitate the next step of grouting for sealing poorly sealed boreholes. Figure 6 As shown, the high-pressure valve is fixed to the outer end of the grouting steel pipe, and the high-pressure valve is fixed to the blowout preventer via flanges.

[0079] Step S6: Perform grouting for water sealing in the poorly sealed borehole ZK2801. Before grouting, the site should be cleaned, such as removing gravel and debris from the tunnel at the poorly sealed borehole. The specific grouting process for water sealing is as follows:

[0080] Step S61: In the -410m section of the roadway, the poorly sealed borehole ZK2801 is emptied from the bottom upwards using a ZQS-100 down-the-hole drill rig. The emptied borehole diameter is the same as the poorly sealed borehole diameter, φ75mm, and the emptied borehole depth is 2.5m. Then, a grouting steel pipe is installed. The grouting steel pipe is made of 4mm thick N50 seamless steel pipe. Except for its diameter, which is smaller than the grouting steel pipe installed at the pressure relief hole opening, the other parameters of this grouting steel pipe are the same as those at the pressure relief hole. During this operation, the high-pressure valve on the grouting steel pipe at the pressure relief hole must remain open to allow for the installation of the grouting steel pipe at the bottom of the poorly sealed borehole ZK2801 and to facilitate grouting and water sealing of the poorly sealed borehole ZK2801 under pressure relief conditions.

[0081] Step S62: Based on the characteristics of water inflow and pressure in the poorly sealed borehole ZK2801, a ZB-6 / 5-11 pneumatic dual-liquid grouting pump is selected to grout the poorly sealed borehole ZK2801 through the bottom grouting pipe. Figure 3 As shown, grouting should be stopped and the high-pressure valve on the grouting steel pipe at the bottom of the poorly sealed borehole (ZK2801) should be closed when grout returns from the pressure relief hole. The grouting material can be a mixture of ordinary Portland cement (425# cement) and water glass, with a water glass modulus of 2.8~3.4 and a concentration of 38Be′~40Be′. It should be noted that in practical applications, the grouting material is not limited to the above-mentioned mixture of ordinary Portland cement (425# cement) and water glass, and can be flexibly adjusted according to actual needs.

[0082] Step S7: First, wait for the bottom grout of the poorly sealed ZK2801 borehole to completely solidify before grouting the pressure relief hole. Stop grouting when the grouting length of the pressure relief hole reaches 10m, and close the high-pressure valve on the grouting steel pipe at the opening of the pressure relief hole. The grouting material for the pressure relief hole is the same as the bottom grouting material for the poorly sealed ZK2801 borehole.

[0083] To ensure safe mining, the grouting effect of the pressure relief hole can be checked after the grout filling (i.e., the grouting body) has solidified. The specific inspection method is as follows: open the high-pressure valve of the grouting steel pipe at the pressure relief hole opening to check the grouting effect. If there is water leakage in the pressure relief hole, repeated grouting should be performed, and grouting should only be stopped after no water flows out. After inspection, the pressure relief hole of the poorly sealed borehole (ZK2801) was successfully grouted on the first attempt.

[0084] Example 2: The pressure relief grouting and water-stopping method for poorly sealed boreholes (ZK3203) includes the following steps:

[0085] Step S1: Analyze the location of the poorly sealed borehole ZK3203 and review its drilling parameters to obtain its positional information within the ore body, such as borehole location, depth, borehole dip, borehole inclination angle, exposed aquifer, and the positional relationship between the borehole and the ore body. Then, draw a cross-sectional diagram showing the positional relationship between the borehole and the ore body. Figure 4 The diagram shown is a cross-sectional view of the positional relationship between the poorly sealed borehole ZK3203 and the ore body.

[0086] Step S2: Measure the water flow rate and pressure of the poorly sealed borehole ZK3203, and analyze the source of the water flow by analyzing the water chemical composition, TDS, and pH value to inform the next step of the grouting procedure and the selection of grouting equipment. The measured water flow rate of the poorly sealed borehole ZK3203 was 130 m³. 3 / h, water pressure 4.4MPa; Durov diagram analysis showed that the water inflow in the poorly sealed borehole ZK3203 originated from the fracture water in the upper Liguan Formation, such as Figure 2 As shown.

[0087] Step S3: Calculate the required grouting depth into the poorly sealed borehole ZK3203 based on the positional relationship between the borehole and the ore body and the geological conditions shown in the cross-section. The surrounding rock of the ore body (biotite plagioclase granulite) is hard and intact, serving as an impermeable layer. The hydrogeological and engineering geological conditions are favorable. Grouting of the poorly sealed borehole ZK3203 only needs to extend to a vertical distance of 10m from the top of the ore body. Measure the length of the grouting material inside the poorly sealed borehole ZK3203 from the drawn cross-section showing the positional relationship between the borehole and the ore body. Figure 4As shown, the length of grouting required to seal the poorly sealed borehole of ZK3203 is not less than 160m (generally 160m).

[0088] Step S4: Determine the location, dip direction, and inclination angle of the pressure relief holes. Since the water pressure in the poorly sealed borehole ZK3203 exceeds 4 MPa, the pressure is relatively high, requiring pressure relief grouting in conjunction with the construction of pressure relief holes to enhance the grouting effect. Calculate the length (depth) of the pressure relief holes based on the cross-sectional diagram drawn in Step S1. If the length is no more than 30m, the pressure relief holes can be constructed within this middle section of the roadway. If the calculated length is greater than 30m, since it is difficult to control the pressure relief holes to the poorly sealed borehole, they can be deployed in the upper middle section of the roadway. The pressure relief holes are located within the roof of the ore body and at a vertical distance of no less than 10m from the roof. It is also essential to ensure that the pressure relief holes are located on the cross-section corresponding to the poorly sealed borehole (i.e., the pressure relief holes are located in the same plane as the poorly sealed borehole, directly below the poorly sealed borehole, and their dip direction is consistent with the dip direction of the poorly sealed borehole). Based on the calculated length of grouting required in poorly sealed boreholes (ZK3203) that is no less than 160m, therefore, if Figure 4 As shown, the poorly sealed borehole ZK3203 requires pressure relief holes to be installed from the upper -270m middle section (a middle section of 70m in Huibaoling Iron Mine) for pressure relief grouting.

[0089] When the conditions for installing pressure relief holes are not met in the middle section of a roadway where a poorly sealed borehole is located, or in the upper middle section of a roadway, roadway excavation is required to advance the roadway into the surrounding rock of the ore body roof to meet the conditions for constructing pressure relief holes. For example... Figure 4 As shown, the -270m middle section roadway has not yet been constructed to the vicinity of the poorly sealed borehole ZK3203. Therefore, the -270m middle section roadway will be constructed to the top of the ore body, about 10m away from the poorly sealed borehole ZK3203, where pressure relief holes will be laid.

[0090] Step S5: According to Figure 4 The design and orientation of the pressure relief holes were determined. To better locate the poorly sealed borehole ZK3203, a φ90mm diameter pressure relief hole was used, and a ZQS-100 down-the-hole drill rig was employed. Since drilling to the poorly sealed borehole ZK3203 in one attempt was not guaranteed, second, third, and Nth pressure relief holes were laid out at 300×300mm intervals until the borehole was reached.

[0091] Before constructing the pressure relief hole, it is preferable to first clear the site. Specifically: clear away the gravel and debris in the tunnel where the poorly sealed borehole and the designed pressure relief hole are located, so that the tunnel forms an open space with a height of not less than 3.5m and a width of not less than 4m, so as to facilitate drilling, excavation and grouting for water sealing. At the same time, drainage ditches can be built in the tunnel to ensure that there is no water accumulation at the work site.

[0092] After the pressure relief hole is successfully constructed, a grouting steel pipe is installed at the hole opening. The grouting steel pipe is made of 4mm thick N65 seamless steel pipe, and its structure is as follows: Figure 5 As shown, the grouting steel pipe is 2.5m long. A fish-scale knot is welded to the outer wall of the end of the grouting steel pipe located inside the pressure relief hole, and a flange is welded to the end of the grouting steel pipe located outside the pressure relief hole. During installation, hemp fiber is wrapped around the fish-scale knot to increase the frictional resistance between the grouting steel pipe and the surrounding rock. A high-pressure valve and a blowout preventer are sequentially installed at the outer end of the grouting steel pipe, with the high-pressure valve in the open position to facilitate the next step of grouting for sealing poorly sealed boreholes. Figure 6 As shown, the high-pressure valve is fixed to the outer end of the grouting steel pipe, and the high-pressure valve is fixed to the blowout preventer via flanges.

[0093] Step S6: Perform grouting for water sealing in the poorly sealed borehole ZK3203. Before grouting, the site should be cleaned, such as removing gravel and debris from the tunnel around the poorly sealed borehole. The specific grouting process for water sealing is as follows:

[0094] Step S61: In the -410m section of the roadway, the poorly sealed borehole ZK3203 is emptied from the bottom upwards using a ZQS-100 down-the-hole drill. The emptied borehole diameter is the same as the poorly sealed borehole diameter, φ75mm, and the emptied borehole depth is 2.5m. Then, a grouting steel pipe is installed. The grouting steel pipe is made of 4mm thick N50 seamless steel pipe. Except for its diameter, which is smaller than the grouting steel pipe installed at the pressure relief hole opening, the other parameters of this grouting steel pipe are the same as those at the pressure relief hole. During this operation, the high-pressure valve on the grouting steel pipe at the pressure relief hole must remain open to allow for the installation of the grouting steel pipe at the bottom of the poorly sealed borehole ZK3203 and to facilitate grouting and water sealing of the poorly sealed borehole ZK3203 under pressure relief conditions.

[0095] Step S62: Based on the characteristics of water inflow and pressure in the poorly sealed borehole ZK3203, a ZB-6 / 5-11 pneumatic double-liquid grouting pump is selected to grout the poorly sealed borehole ZK3203 through the bottom grouting pipe. Figure 4 As shown, grouting should be stopped and the high-pressure valve on the grouting steel pipe at the bottom of the poorly sealed borehole (ZK3203) should be closed when grout returns from the pressure relief hole. The grouting material can be a mixture of ordinary Portland cement (425# cement) and water glass, with a water glass modulus of 2.8~3.4 and a concentration of 38Be′~40Be′. It should be noted that in practical applications, the grouting material is not limited to the above-mentioned mixture of ordinary Portland cement (425# cement) and water glass, and can be flexibly adjusted according to actual needs.

[0096] Step S7: First, wait for the bottom grout of the poorly sealed ZK3203 borehole to completely solidify before grouting the pressure relief hole. Stop grouting when the grouting length of the pressure relief hole reaches 10m, and close the valve on the grouting steel pipe at the opening of the pressure relief hole. The grouting material for the pressure relief hole is the same as the bottom grouting material for the poorly sealed ZK3203 borehole.

[0097] To ensure safe mining, the grouting effect of the pressure relief hole can be checked after the grout filling (i.e., the grouting body) has solidified. The specific inspection method is as follows: open the high-pressure valve of the grouting steel pipe at the pressure relief hole opening to check the grouting effect. If there is water leakage in the pressure relief hole, repeated grouting should be performed, and grouting should only be stopped after no water flows out. After inspection, the pressure relief hole of the poorly sealed borehole (ZK3203) was successfully grouted on the first attempt.

[0098] According to the formula for grouting pressure at the bottom of a poorly sealed borehole, p=ρ 水 gh+ρ 浆液 If grouting is performed directly on poorly sealed boreholes ZK2801 and ZK3203 without using pressure relief holes, the calculated grouting pressures are 5.42 MPa and 4.19 MPa, respectively. If pressure relief is performed on poorly sealed boreholes ZK2801 and ZK3203 with pressure relief holes, the calculated grouting pressures are 2.52 MPa and 0.43 MPa, respectively. The grouting pressure is effectively reduced, and a good grouting effect is achieved.

[0099] Metal mines typically consist of inclined or steeply inclined ore bodies, with tunnel systems generally designed at the bottom of the ore body. Poorly sealed boreholes often expose water inflows within these tunnel systems at the ore body bottom. Therefore, these poorly sealed boreholes not only flood the tunnels but also pose a safety threat to nearby ore mining, especially under high water pressure, making the construction conditions more complex. This invention proposes a pressure relief grouting method for sealing poorly sealed boreholes in metal mine tunnels. By constructing pressure relief holes to assist in pressure relief, grouting can be used to seal the poorly sealed boreholes, achieving water control without affecting nearby ore mining. This invention is particularly suitable for exposing poorly sealed boreholes in metal mines with deep penetrations and high water pressure. It solves problems such as low success rates, large workloads, high construction costs, and waste of mineral resources associated with existing methods for opening poorly sealed boreholes or using grouting to seal them under high water pressure. Specific beneficial effects are as follows:

[0100] The project involves a small amount of work and has low costs.

[0101] Traditional grouting methods for sealing water-retaining walls require sufficiently thick walls and deep embedment in the rock. When water pressure is high, two or even three layers of retaining walls are needed to ensure the wall's bearing capacity, resulting in high construction costs. In contrast, the method for sealing poorly sealed boreholes described in this invention has a simpler construction procedure, requires less work, and is significantly less expensive than traditional grouting methods.

[0102] Construction risk is low.

[0103] This invention avoids the problem of restart failure caused by various uncertainties in ground opening, and also reduces or even eliminates the risk of water inrush caused by the huge water pressure on the inner side of the tunnel retaining wall.

[0104] It does not consume mineral resources.

[0105] Traditional retaining walls only block water seepage through poorly sealed boreholes, without actually sealing the boreholes. During mining, it is necessary to leave safety pillars to seal poorly sealed boreholes, which not only makes construction difficult but also occupies a large amount of mineral resources.

[0106] Construction is fast and the construction period is short.

[0107] The construction procedure of this invention is simple. It only requires drilling a shallow grouting hole upwards and grouting. It can generally be completed in 2 to 3 weeks (7 days a week). There is no need to re-drill and re-grout the entire hole as with the ground, nor is it as time-consuming as a retaining wall in a tunnel.

[0108] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and objectives of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0109] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for grouting and sealing poorly sealed boreholes in metal mine roadways, characterized in that, include: Step S1: By collecting drilling results, geological profiles, and hydrogeological profiles from the mineral exploration phase, and combining the exposure location of the poorly sealed boreholes to be sealed, obtain the location information of the poorly sealed boreholes to be sealed within the ore body, and draw a profile diagram of the positional relationship between the poorly sealed boreholes to be sealed and the ore body based on the obtained location information; the location information includes the borehole opening location, borehole depth, borehole dip, borehole inclination angle, the aquifer exposed by the borehole, and the positional relationship between the borehole and the ore body; Step S2: Measure the water volume, water pressure and water chemical composition of the poorly sealed borehole to be stopped, and analyze the source of the water inflow by the water chemical composition, TDS and pH value of the poorly sealed borehole to be stopped. Step S3: Calculate the required grouting depth into the poorly sealed borehole to be sealed; using the surrounding rock of the metal mine as a water-stopping layer, grout into the poorly sealed borehole to be sealed to a distance of 10m from the vertical ore body from the top plate of the ore body, and measure or draw the required grouting depth when grouting to a distance of 10m from the vertical ore body from the top plate of the ore body in the positional relationship profile diagram. Step S4: Design the location, dip direction, and inclination angle of the pressure relief hole to ensure that the pressure relief hole and the poorly sealed borehole to be stopped are located within the same ore body profile. First, design the location, dip direction, and inclination angle of the pressure relief hole within the same section of the roadway where the poorly sealed borehole to be stopped is located, to ensure that the pressure relief hole and the poorly sealed borehole to be stopped are located within the same ore body profile. At the same time, ensure that the pressure relief hole is installed within the ore body roof and that the vertical distance from the ore body roof is not less than 10m. Then, draw the pressure relief hole in the positional relationship profile and calculate the actual length of the pressure relief hole according to the drawing scale. If the actual length is not greater than 30m, construct the pressure relief hole within the same section of the roadway. If the actual length is greater than 30m, install the pressure relief hole within the upper middle section of the roadway. Step S5: Construct the pressure relief hole according to the designed hole position, inclination and inclination angle, and after the construction of the pressure relief hole is completed, install a grouting steel pipe with a valve at the hole opening of the pressure relief hole; Step S6: With the valve open, perform pressure relief grouting from the bottom of the hole to the top of the poorly sealed borehole to be stopped, until grout returns from the pressure relief hole and then stop grouting. Step S7: After the grouting filler in the poorly sealed borehole to be sealed has completely solidified, grout is injected into the pressure relief hole through the grouting steel pipe at the opening of the pressure relief hole to seal the water. After the grouting is completed, the valve is closed.

2. The method for grouting and sealing poorly sealed boreholes in metal mine roadways according to claim 1, characterized in that, Step S6 includes: Step S61: In the middle section of the roadway where the poorly sealed borehole to be stopped is located, the poorly sealed borehole to be stopped is swept from bottom to top, and another grouting steel pipe equipped with a valve is installed at the swept borehole. Step S62: Through the other grouting steel pipe, perform pressure relief grouting from the bottom of the poorly sealed borehole to the top until grout returns from the pressure relief hole, then stop grouting and close the valve on the other grouting steel pipe.

3. The method for grouting and sealing poorly sealed boreholes in metal mine roadways according to claim 1, characterized in that, Step S7, after the grouting of the pressure relief hole is completed, also includes a grouting effect inspection step: After the grout in the pressure relief hole has solidified, open the valve on the grouting steel pipe at the pressure relief hole. If the pressure relief hole leaks water, repeat step S7 to grout into the pressure relief hole again until no water flows out of the pressure relief hole and then stop grouting.

4. The method for grouting and sealing poorly sealed boreholes in metal mine roadways according to claim 1, characterized in that, Before performing at least one of steps S5 to S7, the site must be cleaned and the work area must be free of standing water.

5. The application of the pressure relief grouting and water-stopping method for sealing poorly sealed boreholes in metal mine roadways as described in any one of claims 1 to 4 in the field of water control technology in metal mines.

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