Method for supporting thick-layer soft rock slope of strip mine

Abstract

The invention discloses a strip mine thick-layer soft rock slope supporting method, and relates to the technical field of slope supporting. Comprising the following steps that according to strip mine thick-layer soft rock slope data, supporting structure size parameters are designed, surface sealing is conducted on a thick-layer soft rock slope, anchor rod arrangement holes are drilled, pre-stressed anchor rods are installed in the anchor rod arrangement holes and fixed through grouting, lattice beams are installed, and concrete is poured to form a thick-layer soft rock slope support; before supporting construction, the concrete is sprayed on the surface of the thick-layer soft rock slope to be supported to seal the surface of the broken rock stratum, the integrity of the broken rock stratum can be guaranteed, the drilling hole forming rate is increased, and therefore follow-up anchor rod installation is facilitated, and the supporting construction efficiency and quality are improved to a certain degree; and the anchor rods and the lattice beams are fixedly combined, and concrete is poured to form a reinforced concrete support, so that the contact between the formed support structure and the side slope is stable enough, the overall stability of the side slope can be further improved, and the support is not prone to being damaged due to side slope settlement.

Description

Technical Field

[0001] The invention relates to the technical field of slope support, and in particular to a method for supporting thick soft rock slopes in open-pit mines. Background Art

[0002] Thick soft rock in open-pit mines refers to thick and soft rock layers encountered in the process of open-pit mining. These soft rock layers usually have low compressive strength, high porosity and permeability, and poor cementation. In the process of open-pit mining, the presence of thick soft rock will affect the stability of the slope and mine safety. The soft rock slope along the bedding of open-pit mines is one of the common slope types in open-pit mining. It refers to the slope formed during the open-pit mining process due to the excavation of thick soft rock layers. These soft rock layers usually have low strength and high deformation capacity in their natural state, so the soft rock slope along the bedding of open-pit mines needs to be supported.

[0003] Traditional anchor-type support cannot meet the support requirements for thick soft rock slopes. Due to the particularity of thick soft rock, the integrity of the broken rock layer cannot be guaranteed when drilling holes in the slope, resulting in a low drilling rate. Moreover, relying on traditional support methods, the contact between the formed support structure and the slope is not stable enough, making the slope support easily damaged due to slope settlement, and the protective effect is poor. Therefore, the present invention proposes a thick soft rock slope support method for open-pit mines to solve the problems existing in the prior art. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to propose a method for supporting thick soft rock slopes in open-pit mines, so as to solve the problem that the existing conventional slope support methods cannot meet the support requirements for thick soft rock slopes and cannot ensure the integrity of the broken rock strata, resulting in a low drilling rate, and the contact between the formed support structure and the slope is not stable enough, making the slope support easily damaged due to slope settlement.

[0005] In order to achieve the purpose of the present invention, the present invention is implemented by the following technical scheme: a method for supporting thick soft rock slope in an open-pit mine, comprising the following steps:

[0006] Step 1: Collect geological and hydrogeological data of the thick soft rock slope to be supported, and then record the topographic and geomorphic characteristics of the thick soft rock slope. According to the collected data and the recorded topographic and geomorphic characteristics, conduct stability analysis on the slope and design the size parameters of the support structure;

[0007] Step 2: Use sprayed concrete to seal the surface of the broken rock layer of the thick soft rock slope, then mark the anchor arrangement position according to the support structure designed in step 1, and drill anchor arrangement holes at the anchor pre-arrangement position after the concrete is cured;

[0008] Step 3: Clean the anchor hole, insert the pre-prepared prestressed anchor into the anchor hole, and then inject grout into the anchor hole to tightly combine the prestressed anchor with the rock mass in the anchor hole;

[0009] Step 4: According to the support structure designed in step 1, a reinforced structural frame is made as a lattice beam. Then the lattice beam is installed on the surface of the thick soft rock slope and fixed to the exposed ends of the lattice beam and prestressed anchor rods by wire bolts. Then concrete is poured on the basis of the lattice beam and anchor rods, and drainage ditches and blind ditches are reserved on the concrete pouring layer. After the concrete is solidified, a reinforced concrete support is formed.

[0010] A further improvement is that in step one, the geological data includes rock and soil type, distribution and physical and mechanical property data, the hydrogeological data includes groundwater level and permeability coefficient data, and the topographic features include slope, height and aspect parameters.

[0011] A further improvement is that in step 1, when performing stability analysis, the limit equilibrium theory is used to perform slope stability analysis, the slope safety factor is calculated, and the finite element analysis method is used to evaluate the stress and deformation of the slope under different working conditions.

[0012] A further improvement is that in step 2, the specific steps of spraying concrete are: first clean the slope surface, remove loose rocks and debris, then lay a metal mesh on the slope surface, then load the concrete into the sprayer, and use high-pressure air to spray the concrete onto the slope surface from bottom to top, combining with the metal mesh to form a protective layer.

[0013] A further improvement is that when spraying concrete, the concrete sprayed on the slope surface is cured by spraying 2 hours after final setting, and the curing time is greater than 14 days.

[0014] A further improvement is that in step three, the specific steps for cleaning the anchor arrangement holes are: first install an air blow pipe at the air outlet at the output end of the compressed air machine, adjust the air pressure to 10 Bar, then aim the air blow pipe at the anchor arrangement hole, start from the hole mouth, and gradually blow air to the bottom of the hole to remove rock powder and debris in the hole.

[0015] A further improvement is that in step three, after the grouting material in the anchor rod arrangement hole is solidified, the prestressed anchor rod is tensioned using tensioning equipment according to a preset prestress value, and after the tensioning is completed, the prestressed anchor rod is locked using a locking device.

[0016] A further improvement is that in step 4, the concrete casting layer is sprayed and cured 3 hours after the final setting of the concrete casting layer, and the curing time is greater than 15 days. After the curing is completed, a slope monitoring instrument is installed to monitor the slope status in real time.

[0017] The beneficial effects of the present invention are as follows: before the support construction, the present invention sprays concrete on the surface of the thick soft rock slope to be supported to seal the surface of the broken rock layer, thereby ensuring the integrity of the broken rock layer and increasing the drilling hole rate, thereby facilitating the subsequent anchor installation and improving the support construction efficiency and quality to a certain extent; and by fixing the anchor and the lattice beam and pouring concrete to form a reinforced concrete support, the load can be effectively dispersed, so that the formed support structure is sufficiently stable in contact with the slope. Compared with the traditional single anchor support structure, the overall stability of the slope can be further improved, and the support is not easily damaged due to slope settlement. The protective effect on the slope is better, and the stability and safety of the thick soft rock slope in the open-pit mine are effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic flow chart of the open-pit mine thick soft rock slope support method of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Open-pit mining, also known as open-pit mining or open-pit mining, refers to a mining method that digs a mining area on the surface and directly digs the ore body from the surface to obtain mineral resources. Compared with underground mining, open-pit mining has the advantages of low mining cost, high production efficiency, and high resource recovery rate, but it may also bring greater environmental impact. Thick soft rock in open-pit mines refers to thick and soft rock layers encountered in the process of open-pit mining. These soft rock layers usually have low compressive strength, high porosity and permeability, and poor cementation. In the process of open-pit mining, the presence of thick soft rock will affect the stability of the slope and mine safety;

[0022] The soft rock slope along the bedding layer of an open-pit mine is one of the common slope types in open-pit mining. It refers to the slope formed during the open-pit mining process due to the excavation of a thick soft rock layer. These soft rock layers usually have low strength and high deformation capacity in their natural state. Due to the particular physical and mechanical properties and structural properties of soft rock, it is easily affected by external forces during mining, resulting in deformation and damage of the slope. Therefore, slope stability and long-term excavation safety are one of the main links in mining soft rock mining areas. In the actual mining construction process, it is necessary to support the soft rock slope along the bedding layer of the open-pit mine;

[0023] Based on the findings in the prior art, the existing conventional slope support methods have many deficiencies in the actual construction process. For example, the traditional anchor support cannot meet the support requirements for thick soft rock slopes. Due to the particularity of thick soft rock, the integrity of the broken rock layer cannot be guaranteed when drilling holes in the slope, resulting in a low drilling rate. In addition, the support structure formed by the traditional support method is not stable enough in contact with the slope, which makes the slope support easily damaged due to slope settlement, and the protection effect is poor, which in turn affects the slope stability and mine safety.

[0024] The concrete used in this embodiment is prepared by mixing cement, river sand, crushed stone, water, water reducing agent, early strength agent and fly ash in a mass ratio of 200:100:100:150:1:1:30;

[0025] The grouting material used in this embodiment is prepared by mixing cement, water, river sand and air entraining agent in a mass ratio of 200:100:100:1;

[0026] The prestressed anchor rods and metal mesh used in this embodiment are both made of stainless steel.

[0027] For the problems existing in the above-mentioned prior art, see Figure 1 This embodiment provides a method for supporting thick soft rock slopes in an open-pit mine, comprising the following steps:

[0028] Step 1: Design the dimension parameters of the support structure based on the data of the thick soft rock slope of the open-pit mine. First, collect the geological data and hydrogeological data of the thick soft rock slope to be supported, and then record the topographic and geomorphic characteristics of the thick soft rock slope. According to the collected data and the recorded topographic and geomorphic characteristics, the stability analysis of the thick soft rock slope of the open-pit mine is carried out. When conducting the stability analysis, the limit equilibrium theory is used to analyze the slope stability and calculate the slope safety factor. At the same time, the finite element analysis method is used to evaluate the stress and deformation of the slope under different working conditions. Then, according to the stability analysis results, the dimension parameters of the support structure are designed, including the type of anchor to be used, the length of the anchor, the diameter of the anchor and the spacing between adjacent anchors, as well as the specifications of the lattice beam, the thickness of the concrete pouring, and the size of the drainage ditch. By comprehensively considering the geological parameters of the thick soft rock slope of the open-pit mine, the best slope support structure can be determined;

[0029] The geological data collected in this embodiment include rock and soil type, distribution and physical and mechanical property data, hydrogeological data include groundwater level and permeability coefficient data, and topographic features include slope, height and aspect parameters;

[0030] Step 2: Surface seal the thick soft rock slope and drill anchor holes

[0031] First, clean the surface of the thick soft rock slope to be supported, remove loose rocks and debris, ensure that the spraying surface is flat, and then lay a metal mesh on the slope surface to enhance the integrity and crack resistance of the shotcrete, and ensure that there is enough gap between the metal mesh and the rock surface so that the shotcrete can be fully filled. Then, load the concrete into the sprayer, and spray the concrete onto the slope surface from bottom to top using high-pressure air to form a tight protective layer with a thickness of 10 cm, which increases the anti-slip ability of the slope. At the same time, it can also seal cracks, prevent water intrusion, reduce weathering and erosion of the rock mass, and prevent further damage and slippage of the rock mass. After the concrete sprayed on the slope surface is finally set for 2 hours, it is cured by spraying, and the curing time is greater than 14 days. Then, mark the anchor arrangement position according to the support structure designed in step 1, and drill anchor holes at the anchor pre-arrangement position after the concrete is cured. In this embodiment, the broken rock layer is surface-sealed by spraying concrete on the surface of the thick soft rock slope to be supported, thereby ensuring the integrity of the broken rock layer and increasing the drilling porosity.

[0032] Step 3: Install the prestressed anchor in the anchor hole and fix it by grouting

[0033] Since unclean anchor holes will lead to insufficient bonding between the anchor and the rock mass, affecting the support effect of the anchor, the present embodiment first installs an air blow pipe at the air outlet at the output end of the compressed air machine, adjusts the air pressure to 10 Bar, and then aims the air blow pipe at the anchor hole to ensure that the airflow can reach the bottom of the hole directly. Starting from the hole mouth, gradually blow air to the bottom of the hole to remove rock powder and debris in the hole. Repeat the blowing several times to ensure that there is no residue in the hole, so as to achieve the cleaning of the anchor hole. After cleaning, ensure that the hole wall is clean without loose rocks and impurities, and then slowly insert the prestressed anchor prepared in advance into the anchor hole. The prestressed anchor rod is then grouted to avoid damaging the inner wall of the anchor rod arrangement hole. Then, the pre-prepared grouting material is injected into the anchor rod arrangement hole to ensure that the grouting is full and dense, and the prestressed anchor rod is tightly combined with the rock mass in the anchor rod arrangement hole. After the grouting material in the anchor rod arrangement hole is solidified, the anchor rod is tensioned according to the preset prestress value to avoid over-tension or under-tension. After the tensioning is completed, the prestressed anchor rod is locked with a locking device to maintain the prestress. The prestressed anchor rod is fixed by grouting, which can provide sufficient support force before the slope is significantly deformed, thereby more effectively controlling the deformation of the slope and improving the overall stability and safety of the slope.

[0034] Step 4: Install lattice beams and pour concrete to form thick soft rock slope support

[0035] According to the support structure designed in step one, a steel structure frame is made as a lattice beam, and then the lattice beam is installed on the surface of the thick soft rock slope and the exposed end of the lattice beam and the prestressed anchor are bolted and fixed by wire, and then concrete is poured on the basis of the lattice beam and the anchor, and drainage ditches and blind ditches are reserved on the concrete pouring layer to ensure smooth drainage, which can effectively reduce the water pressure inside the slope and reduce the deformation of the rock mass. After the concrete is solidified, a reinforced concrete support is formed. After the concrete is poured, the concrete pouring layer is sprayed and cured 3 hours after the final setting of the concrete pouring layer. The curing time is greater than 15 days. After the curing is completed, slope monitoring instruments are installed, including inclinometers, settlement meters, crack meters, and stress meters, to monitor the slope status in real time, so as to help construction personnel promptly discover potential problems with the support and take corresponding measures to prevent accidents. In this embodiment, the anchor and the lattice beam are fixedly combined and concrete is poured to form a reinforced concrete support, which can effectively disperse the load. Compared with the traditional single anchor support structure, the combined support structure can further improve the overall stability of the slope.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for supporting thick soft rock slopes in an open-pit mine, characterized in that: The following steps are involved: Step 1: Collect geological and hydrogeological data of the thick soft rock slope to be supported, and then record the topographic and geomorphic characteristics of the thick soft rock slope. According to the collected data and the recorded topographic and geomorphic characteristics, conduct stability analysis on the slope and design the size parameters of the support structure; Step 2: Use sprayed concrete to seal the surface of the broken rock layer of the thick soft rock slope, then mark the anchor arrangement position according to the support structure designed in step 1, and drill anchor arrangement holes at the anchor pre-arrangement position after the concrete is cured; Step 3: Clean the anchor hole, insert the pre-prepared prestressed anchor into the anchor hole, and then inject grout into the anchor hole to tightly combine the prestressed anchor with the rock mass in the anchor hole; Step 4: According to the support structure designed in step 1, a reinforced structural frame is made as a lattice beam. Then the lattice beam is installed on the surface of the thick soft rock slope and fixed to the exposed ends of the lattice beam and prestressed anchor rods by wire bolts. Then concrete is poured on the basis of the lattice beam and anchor rods, and drainage ditches and blind ditches are reserved on the concrete pouring layer. After the concrete is solidified, a reinforced concrete support is formed.

2. The method for supporting thick soft rock slope in an open-pit mine according to claim 1, characterized in that: In step 1, the geological data include rock and soil type, distribution and physical and mechanical property data, the hydrogeological data include groundwater level and permeability coefficient data, and the topographic features include slope, height and aspect parameters.

3. The method for supporting thick soft rock slope in an open-pit mine according to claim 1, characterized in that: In the step 1, when performing stability analysis, the limit equilibrium theory is used to perform slope stability analysis, the slope safety factor is calculated, and the finite element analysis method is used to evaluate the stress and deformation of the slope under different working conditions.

4. The method for supporting thick soft rock slope in an open-pit mine according to claim 1, characterized in that: In step 2, the specific steps of spraying concrete are: first clean the slope surface, remove loose rocks and debris, then lay a metal mesh on the slope surface, then load the concrete into the sprayer, and use high-pressure air to spray the concrete onto the slope surface from bottom to top, combining with the metal mesh to form a protective layer.

5. The method for supporting thick soft rock slope in an open-pit mine according to claim 4, characterized in that: When spraying concrete, the concrete sprayed on the slope surface is cured by spraying 2 hours after final setting, and the curing time is more than 14 days.

6. The method for supporting thick soft rock slope in an open-pit mine according to claim 1, characterized in that: In step three, the specific steps for cleaning the anchor arrangement hole are: first install an air blow pipe at the air outlet at the output end of the compressed air machine, adjust the air pressure to 10 Bar, then aim the air blow pipe at the anchor arrangement hole, start from the hole mouth, and gradually blow air to the bottom of the hole to remove rock powder and debris in the hole.

7. The method for supporting thick soft rock slope in an open-pit mine according to claim 1, characterized in that: In the step three, after the grouting material in the anchor rod arrangement hole is solidified, the prestressed anchor rod is tensioned using tensioning equipment according to a preset prestress value, and after the tensioning is completed, the prestressed anchor rod is locked using a locking device.

8. The method for supporting thick soft rock slope in an open-pit mine according to claim 1, characterized in that: In the step 4, the concrete casting layer is sprayed and cured 3 hours after the final setting of the concrete casting layer, and the curing time is greater than 15 days. After the curing is completed, a slope monitoring instrument is installed to monitor the slope status in real time.

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