A method for anchoring and treating the slope of a waste acid mine waste rock pile

Abstract

The present application belongs to the technical field of slope anchoring and treatment, and relates to a method for anchoring and treating a slope of an abandoned acid mine waste rock pile, wherein anchor pipe rods are installed in the slope region of the abandoned acid mine waste rock pile, a repair reagent is first injected into the waste rock pile through the anchor pipe rods, cement mortar is then injected, and curing is performed until the design strength is reached; anchor pipe rods are installed in the deep region of the abandoned acid mine waste rock pile containing stored acid wastewater, and a repair reagent is injected into the waste rock pile through the anchor pipe rods. The present application injects a repair reagent and cement mortar into the abandoned acid mine waste rock pile through anchor pipe rods, reduces disturbance to the waste rock pile, the repair reagent can passivate the acid waste rock layer around the anchor pipe rods, reduces corrosion to the anchor pipe rods, ensures long-term anchoring, the anchor pipe rods in the slope region can be more closely combined with loose rock-soil bodies, the anchoring effect is better, and the repair reagent injection combined with the anchor pipe rods in the deep region can strengthen treatment of the region containing stored acid wastewater.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of slope anchoring and treatment, and particularly relates to a method for anchoring and treating a waste acid mine waste rock pile slope. BACKGROUND

[0002] After the closure of a mine, due to the previous extensive mining mode, the slag, waste rock and waste residue left by mining and smelting are stacked in disorder and exposed in the mining area, which greatly affects and damages the geological environment. The cumulative amount of tailings and waste rock in China has exceeded 60 billion tons, of which about 83% of the tailings accumulation is formed by iron, copper and gold mining, and about 75% of the waste rock accumulation is formed by coal gangue, precious metal or sulfur mining.

[0003] Due to the heavy metals and sulfur elements in the waste rock and tailings generated by most metal mines and coal mines, a large amount of acidic substances is generated under the combined action of air, water and bacteria. After leaching by rainfall, surface water and groundwater, acid mine wastewater pollutes the surrounding soil and groundwater. Many necessary treatment measures are taken for the source waste rock pile of acid mine wastewater, but there are still related treatment difficulties to be solved.

[0004] Firstly, during the ecological restoration and treatment of the mining area, the stability of the waste rock pile slope is closely related to the engineering safety. The tailings and waste rock that have been naturally accumulated for a long time have the characteristics of looseness and strong water permeability. When supporting and reinforcing the slope, whether traditional anchor rods or anchor cable technology is used to reinforce the waste rock pile slope, the phenomenon of difficult hole forming or hole collapse occurs, causing difficulty in construction. Secondly, the composition of traditional anchoring and grouting is cement, sand, additive, and water mixed in a certain proportion. The composition ratio is adjusted according to the design requirements of the mortar strength, but for the acid mine waste rock pile, the acid waste rock pile and its leaching water have corrosiveness to the steel structure of the anchor rod or anchor cable, which affects the functionality and integrity of the anchoring structure day by day, and is a serious hidden danger to the safety of the slope structure. Thirdly, the treatment of the waste rock pile usually involves the addition of related repair agents. If excavation and stirring are used, it will cause great disturbance to the original slope and is difficult to backfill and compact. If in-situ spraying is used, the repair effect cannot be guaranteed, and the depth of agent immersion is insufficient or unevenly distributed. SUMMARY

[0005] The purpose of the present application is to provide a method for anchoring and treating a waste acid mine waste rock pile slope, which can reduce the disturbance to the waste rock pile, overcome the problem of loose and easy hole collapse of the acid mine waste rock pile, quickly and effectively complete the treatment of the acid waste residue of the slope and the anchoring of the slope, and ensure the long-term effectiveness and safety of the repair and treatment of the waste acid mine.

[0006] To achieve the above object, the technical scheme of the present application is a kind of anchoring and treatment method of waste acid mine waste rock pile slope, anchor pipe rod is installed in the slope area of waste acid mine waste rock pile, first inject repair reagent into waste rock pile through anchor pipe rod, then inject cement mortar, and then maintain to reach design strength;Anchor pipe rod is installed in deep area containing stock acid wastewater in waste acid mine waste rock pile, and repair reagent is injected into waste rock pile through anchor pipe rod.

[0007] Further, the installation method of anchor pipe rod is as follows: first drill a hole, then place the anchor pipe into the hole, fix it, then use a pump to deliver a small amount of clean water to carry out the residue at the bottom of the hole, then extend the anchor rod into the anchor pipe until the head of the anchor rod is fixed with the tip of the anchor pipe.

[0008] Further, after grouting in the slope area and the deep area is completed, the tail of the anchor pipe is fixed with the tail of the anchor rod.

[0009] Further, the anchor pipe is assembled by welding in order of tail non-hole section, encryption hole section, normal hole section and head non-hole closed section.

[0010] Further, the angle between the anchor pipe rod in the slope area and the horizontal plane is 30°, and the anchor pipe rod in the deep area is perpendicular to the horizontal plane.

[0011] Further, the repair reagent includes neutralizing and passivating agent, biological passivating agent and long-acting neutralizing agent, and the method for injecting repair reagent is as follows: sequentially inject neutralizing and passivating agent, biological passivating agent and long-acting neutralizing agent.

[0012] Further, each kind of passivating agent is injected twice with an interval of 20-40 min, and the interval between two kinds of passivating agents is 1-2 h.

[0013] Further, the cement mortar in the slope area is grouted twice, the first grouting is performed 1-2 h after the injection of repair reagent is completed, and the second grouting is performed 11-13 h after the first grouting.

[0014] Further, the first grouting is normal pressure grouting, the prepared cement mortar is injected from the bottom of the anchor pipe upward, so that the cement mortar flows back from the bottom of the anchor pipe, and the grouting is stopped when the outflowing slurry is similar to pure cement mortar, if there is hole shrinkage, the grouting needs to be supplemented, and then the hole is sealed with cotton yarn and mortar.

[0015] Further, the second grouting is pressurized splitting grouting, which is performed upward from the bottom of the hole, the grouting steel pipe is first extended to the vicinity of the bottom end of the anchor pipe, the sealing cover is installed, the high-pressure grouting pipe is connected, the exhaust valve is opened, the pressure is gradually increased, the gas or residual water in the pipe is discharged, when the exhaust valve flows out of pure slurry, the exhaust valve is blocked, the pressure is continuously increased, and the changes of grouting amount and hole pressure gauge pressure are observed and recorded during the operation.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] (1) The anchoring and treatment method of the present application has wide application range, strong practicability, engineering scalability, and convenient construction, and can be widely used for treatment of acid mine waste rock loose slope, and is applicable to acid solid waste scenes such as waste rock yard, tailings pond, and dump;

[0018] (2) The anchoring and treatment method of the present application can avoid or reduce excavation disturbance to the waste rock slope, is beneficial to the overall stability of the slope, reduces the excavation and backfill engineering quantity of the project, and can effectively reduce dust pollution of the project;

[0019] (3) The anchoring and treatment method of the present application can effectively control and block the corrosion of acid wastewater generated by acid waste rock leaching to the steel structure of the anchor pipe, and ensure the long-term stability of the structure;

[0020] (4) The anchoring and treatment method of the present application can conveniently and flexibly add various repair reagents by using the structural characteristics of the anchor pipe, realize neutralization, passivation, reduction and other functions, and the concentration, amount, spacing and frequency of the injection of the reagents can be flexibly adjusted, thereby improving the mobility and accuracy of the reagent injection;

[0021] (5) The anchoring and treatment method of the present application can solve the construction problems of loose waste rock after weathering, such as difficulty in forming a hole, easy collapse of the hole and shrinkage of the hole, by injecting cement mortar after the completion of the repair reagent injection by using the structural characteristics of the anchor pipe;

[0022] (6) The injection process of the present application can passivate the acid waste rock layer around the anchoring structure, form a good corrosion-resistant passivation layer around the anchoring structure, and protect the anchoring structure body;

[0023] (7) The injection process of the present application is convenient to construct, and the repair reagent and the cement mortar for anchoring are completed by the same set of adding device, and the adding device itself also serves as part of the anchoring structure, thereby simplifying the adding, replacing and removing procedures. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0025] Figure 1 The structural schematic diagram of the anchor pipe rod provided for the embodiments of the present application;

[0026] Figure 2 is Figure 1 the enlarged schematic diagram of E in the middle

[0027] Figure 3 for Figure 1 FF sectional view;

[0028] Figure 4 A flowchart illustrating the anchoring and treatment method for waste rock pile slopes in abandoned acid mines, as provided in an embodiment of the present invention.

[0029] In the diagram: 1. Anchor pipe; 2. Anchor rod; 3. Grouting hole; 4. Steel pressure plate; 5. Slope line; 6. Reinforcing bar; 7. First reinforcing pipe reinforcement; 8. Second reinforcing pipe reinforcement; 9. Grout; A. Tail section without opening; B. Dense opening section; C. Normal opening section; D. Head section without opening. Detailed Implementation

[0030] 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.

[0031] like Figures 1-4 As shown in the figure, this embodiment provides a method for anchoring and treating the slope of a waste rock pile in an abandoned acidic mine, including the following steps:

[0032] 1) Determine the injection points and anchor bolt parameters in the slope area based on the actual conditions of the abandoned acid mine waste rock pile;

[0033] Based on the extent of the deep zone containing existing acidic wastewater in the abandoned acidic mine waste rock pile and the thickness of the acidic wastewater saturated zone, the injection points and anchor pipe parameters in the deep zone are determined.

[0034] 2) Assemble the anchor pipe 1 and anchor rod 2 for the injection points in the slope area and deep area respectively. Weld the tail section A without holes, the densely drilled section B, the normal drilled section C and the head section D without holes in sequence to form the anchor pipe 1. Weld the bracket at the designed position of the anchor head end of the anchor rod 2.

[0035] 3) Sequentially perform the following steps: injection point positioning, drilling angle positioning, drilling rig positioning, drilling, hole cleaning, and hole position inspection. During construction, the boreholes in the slope area should maintain an angle of 30° with the horizontal plane, and the boreholes in the deep area should maintain a perpendicular angle with the horizontal plane to facilitate the injection of the agent. The borehole diameter in the slope area should meet the design requirements for cement mortar filling, and the borehole diameter in the deep area should meet the installation requirements for the anchor rod. The hole position inspection should verify the actual distribution of the air-sealed zone and the water-saturated zone to improve the accuracy of the injection.

[0036] 4) After the drilling is completed, the anchor pipe rod is installed in the hole formed in the edge area and deep area of the abandoned acid mine waste rock pile. The specific method is: the assembled anchor pipe 1 is directly sent into the corresponding hole by an air drill, after the anchor pipe 1 is fixed, a small amount of clean water is first pumped to carry out the residue at the bottom of the hole, then the assembled anchor rod 2 is inserted into the anchor pipe 1 until the support at the head of the anchor rod 2 contacts the inner wall of the anchor pipe 1, at this time the head of the anchor rod 2 is inserted into the head of the anchor pipe 1 to form a fixed structure;

[0037] 5) In the edge area, the repair agent is first injected into the waste rock pile through the anchor pipe rod, then the cement mortar is injected, and then the maintenance is performed until the design strength is reached;

[0038] In the deep area, the repair agent is injected into the waste rock pile through the anchor pipe rod, and generally no cement mortar needs to be injected.

[0039] The anchor pipe rod in the embodiment adopts the form of anchor pipe 1 + anchor rod 2, which takes the advantages of the two anchor structures of the anchor pipe 1 and the anchor rod 2. The pipe wall structure of the anchor pipe 1 can be used for adding the repair agent and injecting the cement mortar for slope fixing, Figure 1 The middle slurry 9 is cement mortar or a repair agent, and the anchor rod 2 is sleeved into the anchor pipe 1. After the injection and maintenance of the repair agent and the curing cement mortar are completed, the anchor pipe 1 and the anchor rod 2 together form a complete anchor structure and connect the anti-seepage and ecological structure layer of the surface layer of the waste rock pile. When repairing and reinforcing the edge of the acid mine waste rock pile, for the loose and strong water-permeable waste rock pile edge type, the anchor pipe rod of the embodiment solves the problems of hole collapse and hole shrinkage in the construction process due to the looseness of the waste rock pile, on the other hand, by taking advantage of the looseness and strong water permeability, various agents can be conveniently and accurately injected for waste rock pile repair and management, and finally the cement mortar is injected to form a firm and corrosion-resistant composite anchor structure with the surrounding waste rock and soil, and the repair agent combined with the dense opening section at the end of the anchor pipe 1 can form a local passivation layer on the surface layer of the waste rock pile, which can reduce the generation of acid wastewater to a certain extent.

[0040] The effective radius of the injection point is arranged according to the repair process, and the local heavy pollution area can be encrypted; the anchor pipe rod parameters include the length, size, strength, wall thickness, opening and other parameters of the anchor rod 2 and the anchor pipe 1, and the length of each section of the tail non-opening section A, the encryption opening section B, the normal opening section C and the head non-opening closed section D, which need to be calculated and designed in combination with specific slope engineering and repair engineering, and adjusted as needed. The encryption opening section B and the normal opening section C of the anchor pipe 1 are provided with grouting holes 33, and the tail non-opening section A and the head non-opening closed section D are not provided with grouting holes 3, and the tip of the head non-opening closed section D can fix the head of the anchor rod 2. The bracket at the anchor head end of the anchor rod 2 is used to position the installation position of the anchor rod 2 in the anchor pipe 1, control the anchor rod 2 to be in the central axis position of the anchor pipe 1, and the anchor head end of the anchor rod 2 abuts against the tip of the anchor pipe 1. As an embodiment, the bracket includes an inner ring, an outer ring and a steel bar for connecting the inner ring and the outer ring, the inner ring is sleeved on the anchor head end of the anchor rod 2 and is welded and fixed, and since the inner ring, the outer ring and the anchor rod 2 are concentrically arranged, the anchor rod 2 can be guaranteed to be in the central axis position of the anchor pipe 1, and when the outer ring contacts the inner wall of the anchor pipe 1, the anchor rod 2 reaches the specified position in the anchor pipe 1, at which time the end of the anchor rod 2 is fixed with the tip of the anchor pipe 1.

[0041] For the slope area, the tail non-opening section A has a fixed length and is processed according to the design; the length of the encryption opening section B is 1-1.2m, the axial opening interval is 45-55mm, preferably 50mm, and the circumferential opening interval angle and the opening size of the pipe wall can be adjusted according to the diameter of the anchor pipe 11, but the circumferential opening interval angle is less than or equal to 90°, that is, there are at least 4 openings in the circumferential direction of the pipe wall, which not only has the function of normal grouting and waste rock pile combination, but also is located near the surface of the slope and has an encryption opening, which can form a locally reinforced passivation layer in the surface layer of the waste rock pile, and can reduce the acidic waste water generated by the acidic waste rock pile to a certain extent; the length of the normal opening section C can be adjusted according to the need of slope anchoring design, the axial opening interval is 90-110mm, preferably 100mm, and the circumferential opening interval angle is 120°, that is, there are 3 openings in the circumferential direction of the pipe wall.

[0042] For the deep area, the tail non-opening section A is processed according to the different injection depths of the repair agent, and the encryption opening section B, the normal opening section C and the head non-opening closed section D are adjusted according to the thickness of the acid waste water saturated zone, so that the opening section is located in the saturated zone.

[0043] Further, the tail end of the anchor rod 2 is welded with a rod fixing steel bar 6, the middle of the rod fixing steel bar 6 is spot welded with the tail of the anchor rod 2, and the two ends of the rod fixing steel bar 6 are welded with the pipe wall of the anchor pipe 1, and the rod fixing steel bar 6 can be arranged in multiple and cross arrangement to improve the integrity of the anchor rod 2 and the anchor pipe 1.

[0044] Further, the tail of the anchor pipe 1 is fixed with a steel pressing plate 4 on the non-hole section A, and the steel pressing plate 4 is pressed on the slope and welded and fixed with the anchor pipe 1 through the steel bar after the anchor pipe 1 and the anchor rod 2 are installed. The first pipe fixing steel bar 7 and the second pipe fixing steel bar 8 are welded on the tail non-hole section A, and the first pipe fixing steel bar 7 and the second pipe fixing steel bar 8 are located on the side of the steel pressing plate 4 close to the anchor head. Optimally, the first pipe fixing steel bar 7 is arranged in the transverse direction and spot-welded with the anchor pipe 1, used for connecting all the anchor pipes 1 in this direction, and the second pipe fixing steel bar 8 is arranged in the length direction of the anchor pipe 1 and welded with the anchor pipe 1.

[0045] In the embodiment, the repair agent includes neutralizing and passivating agent, biological passivating agent and long-acting neutralizing agent, and the configuration ratio of each component is adjusted according to the slope repair requirements. Specifically,

[0046] The neutralizing and passivating agent can be sodium hydroxide, calcium hydroxide, etc., which can be used for impact addition in the deep local acidic wastewater area to treat the stock of acidic wastewater in the saturated water zone of the waste rock pile, and can also be used for surface layer acid rock passivation to treat the acid wastewater in the aeration zone; the neutralizing and passivating agent can promote the formation of hydroxide precipitate of trivalent iron and the co-precipitation of various heavy metals, the generated Fe precipitate has a coating effect, and the alkaline environment caused by the neutralizing and passivating agent can inhibit the growth of Thiobacillus ferroxidans and the catalysis of microorganisms, forming a passivation layer around the anchor pipe rod to protect the integrity of the anchoring structure and function, having multiple effects of passivation and protection;

[0047] The biological passivating agent can be potassium salt, sodium salt, etc., which is used to increase the alkali content of the waste rock pile, promote the conversion of dissolved iron and sulfate ions in the acid mine wastewater into biological minerals under the action of Thiobacillus on the waste rock pile, and further strengthen the passivation effect of the surface of the waste rock;

[0048] The long-acting neutralizing agent can be calcium carbonate, etc., which is used as a long-acting buffer and wrapped in the effective radius area around the anchor pipe 1, and long-term maintains the neutralizing effect with the acid waste rock and acid wastewater.

[0049] Optimally, attention should be paid to the sequence when the repair agent is injected, the amount of the repair agent is used according to the repair design, the repair agent should be used as soon as it is mixed, and the injection should be slow and uniform. The specific injection method is as follows:

[0050] Firstly, the neutralizing and passivating agent is injected into the acid waste rock layer of the slope, and the injection speed should be slow and uniform, the flow rate is determined according to the water injection test, and the total amount is determined according to the design, and the metering pump is used to control the injection flow rate and pressure;

[0051] Then, after the injection of the neutralizing and passivating agent is completed, the biological passivating agent is injected into the acid waste rock layer of the slope after 2h, and the injection speed should be slow and uniform, the flow rate is determined according to the water injection test, and the total amount is determined according to the design, and the metering pump is used to control the injection flow rate and pressure.

[0052] Then, after the completion of the biological passivation agent injection, the long-acting neutralizing agent is injected into the acid wastewater zone of the slope acid waste rock layer, the injection speed should be kept slow and uniform, the flow rate is determined according to the water injection test, and the total injection amount is determined according to the design, and a metering pump is used to control the injection flow rate and pressure;

[0053] The dosage of each passivation agent is used according to the repair design, and each passivation agent is injected twice with an interval of 30 minutes.

[0054] In this embodiment, after the long-acting passivation agent injection in the slope area is completed, cement mortar is finally injected after an interval of 2 hours. The cement mortar is used as the final filling gel material of the anchor pipe 1, and is proportioned according to the design strength. The cement mortar is diffused to the outside of the anchor pipe 1 through the opening on the anchor pipe 1, and after the final setting, forms a final composite anchoring body with the corresponding anchoring effective area of the anchor pipe 1, provides anchoring force, and maintains the slope stability of the area. Optimally, the cement mortar is grouted twice:

[0055] The first grouting is normal pressure grouting. The prepared cement mortar is injected from the bottom of the anchor pipe 1 upwards, so that the cement mortar flows back from the bottom of the anchor pipe 1 outward. When the outflowing slurry is similar to pure cement mortar, the grouting is stopped. If there is hole shrinkage, grouting needs to be supplemented, and then the hole is sealed with cotton yarn and mortar;

[0056] The second grouting is pressurized splitting grouting, which is upward from the hole bottom. The grouting steel pipe is first inserted into the vicinity of the bottom end of the anchor pipe 1, a sealing cover is installed, a high-pressure grouting pipe is connected, an exhaust valve is opened, and the pressure is gradually increased for grouting. The gas or residual water in the pipe is discharged. When the exhaust valve flows out of the pure slurry, the exhaust valve is blocked, and the pressurized grouting is continued. During the operation, the grouting amount and the change of the hole pressure gauge pressure are observed and recorded;

[0057] The cement mortar injection in the slope area should be grouted in groups. After the grouting is completed, the anchor pipe 1 is fixed with the tail of the anchor rod 2 through the solid rod reinforcement 6, and cured for 28 days to reach the design strength requirement and perform the tensile test.

[0058] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for anchoring and treating slopes of abandoned acidic mine waste rock piles, characterized in that: Anchor pipes are installed on the slope of the waste rock pile in the abandoned acid mine. A repair agent is first injected into the waste rock pile through the anchor pipes, followed by cement mortar, and then it is cured until the design strength is reached. Anchor pipes are installed in the deep areas of abandoned acidic mine waste rock piles containing existing acidic wastewater, and remediation agents are injected into the waste rock piles through the anchor pipes; The anchor pipe rod includes an anchor pipe and an anchor rod, and the anchor rod is disposed in the anchor pipe; the anchor pipe is assembled by welding a tail section without holes, a densely holed section, a normally holed section, and a head section without holes in sequence; the repair agent includes a neutralizing passivating agent, a biological passivating agent, and a long-acting neutralizing agent, and the method of injecting the repair agent is as follows: inject the neutralizing passivating agent, the biological passivating agent, and the long-acting neutralizing agent in sequence; A remediation agent is injected into the waste rock pile through an anchor pipe to form a passivation layer on the surface of the waste rock pile; the two passivation agents are separated by an interval of 1-2 hours.

2. The anchoring and treatment method for the slope of abandoned acidic mine waste rock piles as described in claim 1, characterized in that: The installation method of the anchor pipe rod is as follows: first, drill a hole, then place the anchor pipe into the hole and fix it. After fixing, first use a pump to deliver a small amount of clean water to remove the residue at the bottom of the hole, and then extend the anchor rod into the anchor pipe until the head of the anchor rod is fixed to the tip of the anchor pipe.

3. The anchoring and treatment method for the slope of abandoned acidic mine waste rock piles as described in claim 2, characterized in that: After grouting is completed in the slope area, the tail of the anchor pipe is fixed to the tail of the anchor rod.

4. The anchoring and treatment method for the slope of abandoned acidic mine waste rock piles as described in claim 1, characterized in that: The anchor pipe rods in the slope area form a 30° angle with the horizontal plane, while the anchor pipe rods in the deep area are perpendicular to the horizontal plane.

5. The anchoring and treatment method for the slope of abandoned acidic mine waste rock piles as described in claim 1, characterized in that: Each passivating agent was injected twice, with an interval of 20-40 minutes.

6. The anchoring and treatment method for the slope of abandoned acidic mine waste rock piles as described in claim 1, characterized in that: The cement mortar in the slope area is injected in two stages. The first grouting is carried out 1-2 hours after the repair agent is injected, and the second grouting is carried out 11-13 hours after the first grouting.

7. The anchoring and treatment method for the slope of abandoned acidic mine waste rock piles as described in claim 6, characterized in that: The first grouting is atmospheric pressure grouting. The prepared cement mortar is injected from the bottom of the anchor pipe from bottom to top, so that the cement mortar flows back from the bottom of the anchor pipe. When the grout flowing out is similar to pure cement mortar, the grouting is stopped. If there is grout shrinkage at the hole opening, grouting needs to be added, and then the hole is sealed with cotton yarn and mortar.

8. The anchoring and treatment method for the slope of abandoned acidic mine waste rock piles as described in claim 6, characterized in that: The second grouting is pressurized fracturing grouting, which is carried out from the bottom of the hole upwards. First, the grouting steel pipe is inserted into the vicinity of the bottom end of the anchor pipe, the sealing cap is installed, the high-pressure grouting pipe is connected, the exhaust valve is opened, and the grouting is gradually pressurized to expel the gas or residual water in the pipe. When pure grout flows out of the exhaust valve, the exhaust valve is sealed and the pressurized grouting continues. During the operation, pay attention to observing and recording the changes in the grouting volume and the pressure of the pressure gauge at the borehole.

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