Method for reinforcing and treating road slope of open-pit mine with double structural plane combination failure

Abstract

The application discloses a method for reinforcing and treating a road side slope with double structural surface combination damage in an open-pit mine, and the method comprises the following steps: arranging a concrete retaining wall (3) at a shear outlet of a gently-inclined structural surface of the side slope; vertically arranging a row of drill holes in the middle of the upper surface of the concrete retaining wall (3) and inserting a lower rail pile (1.1) into the drill holes; vertically arranging a row of drill holes on a step platform and inserting an upper rail pile (1.2) into the drill holes; welding the exposed section of the upper rail pile (1.2) outside the drill holes to a steel bar in a connecting beam (4); and passing a prestressed anchor cable (2) through the connecting beam (4) on the top of the upper rail pile (1.2) and pouring a concrete anchor pier on the outer surface of the connecting beam (4). After the reinforcement and treatment by the method, the anti-sliding capacity of the lower gently-inclined structural surface can be enhanced, the upper steeply-inclined structural surface is prevented from being excessively reinforced, the stability of the road side slope with double structural surface combination damage in the open-pit mine is ensured, and the method has the characteristics of simple structure, low construction cost and fast reinforcement construction speed.

Description

Technical Field

[0001] This invention belongs to the field of open-pit mine road slope treatment technology, specifically relating to a method for reinforcing and treating road slopes damaged by a combination of two structural surfaces in non-coal open-pit mines. It is particularly suitable for reinforcing and treating road slopes damaged by a combination of two sets of bedding structural surfaces with a lower gently sloping structural surface inclination angle ≤30° and an upper steeply sloping structural surface inclination angle in the range of 50° to 75°. Background Technology

[0002] Under the influence of its own weight and other external forces, open-pit mine slopes tend to slide from higher to lower elevations. When structural planes exist within the slope, their strength is typically much lower than that of the rock and soil mass. Therefore, slope instability often occurs along these structural planes or combinations thereof. This is especially true when steeply dipping structural planes exist at the top of the slope. Under the weight of the upper steeply dipping rock mass, the lower slope mass adheres to the gently dipping structural plane, resulting in layered failure and creating a double-structural-plane combined failure type of slope damage.

[0003] Common measures for slope protection in mines include slope reduction and load mitigation, anchor bolt and cable reinforcement, shotcrete and mesh slope protection, and frame beam reinforcement. Single reinforcement methods often fail under complex loads and stresses. Therefore, multiple reinforcement methods are frequently used in combination for support. For example, the combined slope support structure in patent number CN202021774972.3 uses anchor bolts and retaining walls to form a combined support structure, which can improve the structural strength of the slope. However, this results in the mine road becoming unusable after slope reinforcement. Therefore, to ensure safe mine production, there is an urgent need for a reinforcement method that can both improve the stability of mine slopes and ensure the continued accessibility of mine roads.

[0004] "Dual-surface combined failure type" is a special slope structural surface failure mode that differs from other typical single-surface slope failure modes. Although the upper part of the slope rock mass has a steeply dipping structural surface, the sliding force along the steeply dipping structural surface is small, and the slope rock mass will not undergo shear failure. The focus of slope reinforcement for this type of slope is to strengthen the gently dipping structural surface at the bottom of the slope, ensuring that the shear strength of the lower rock mass is greater than the sliding force formed by the gravity of the rock mass attached to the upper steeply dipping structural surface, rather than excessively reinforcing the upper steeply dipping structural surface. Mature and reliable reinforcement methods have been developed for typical single-surface slope failure modes, such as the pile-anchor-beam combined structure proposed in patent number CN106049511B for single-surface sliding failure. However, there are currently no targeted reinforcement measures for dual-surface combined failure modes. Therefore, a reinforcement and treatment method suitable for road slopes with dual-surface combined failure in open-pit mines is needed. Summary of the Invention

[0005] The purpose of this invention is to address the lack of reinforcement measures for road slopes damaged by a combination of two structural surfaces in open-pit mines, and the difficulty of adapting existing mine road slope reinforcement measures to the situation of road slopes damaged by a combination of two structural surfaces in open-pit mines. This invention provides a simple, low-cost, and fast reinforcement construction method that can enhance the anti-sliding capacity of the lower gently sloping structural surface, avoid over-reinforcing the upper steeply sloping structural surface, and ensure the stability of road slopes damaged by a combination of two structural surfaces in open-pit mines.

[0006] To achieve the above-mentioned objectives of this invention, the following technical solution is adopted for the reinforcement and treatment of road slopes damaged by a combination of dual structural surfaces in open-pit mines:

[0007] This invention is suitable for the reinforcement and treatment of road slopes damaged by a combination of two structural surfaces in open-pit mines. The road slopes in open-pit mines have two sets of bedding structural surfaces: a gently sloping lower surface and a steeply sloping upper surface. The gently sloping surface has an inclination angle ≤30°, and the steeply sloping surface has an inclination angle in the range of 50° to 75°. The invention is characterized by a reinforcement and treatment structure divided into two parts: the lower reinforcement and treatment structure is located at the bottom of the open-pit mine road slope and is composed of lower steel rail piles and concrete retaining walls connected together; the upper reinforcement and treatment structure is located on a stepped platform above the gently sloping surface and consists of upper steel rail piles and prestressed anchor cables.

[0008] 1) The lower reinforcement and treatment structure shall be implemented according to the following technical solution:

[0009] ① First, clear the gravel at the bottom of the road slope in the open-pit mine. Then, install a concrete retaining wall at the shear outlet of the gently sloping structural surface of the slope. The slope of the outer surface of the concrete retaining wall should not exceed the slope of the lower step slope, so as to provide construction conditions for the subsequent installation of the lower rail piles on the upper surface of the concrete retaining wall.

[0010] ② According to the designed hole depth and a spacing of 2.5 to 5m, a row of holes is arranged vertically downward in the middle of the upper surface of the concrete retaining wall. The lower rail piles are inserted into the holes. The lower rail piles should penetrate into the stable bedrock inside the bedding plane. After the lower rail piles are inserted, fine stone concrete is poured in.

[0011] 2) The superstructure reinforcement and treatment shall be implemented according to the following technical solution:

[0012] ① Arrange a row of boreholes vertically downward on the stepped platform according to the designed hole depth and a spacing of 2.5 to 5m. Insert the upper rail piles into the boreholes. The upper rail piles should penetrate into the stable bedrock inside the bedding plane. The exposed section of the upper rail pile outside the borehole should be ≥30cm in length. After inserting the upper rail piles, pour fine stone concrete.

[0013] ② The exposed section of the upper rail pile outside the borehole is welded to the reinforcing bars in the connecting beam, thereby connecting the exposed section of the upper rail pile into a whole; the connecting beam is long and narrow and is made of concrete.

[0014] ③ Pass the prestressed anchor cable through the top connecting beam of the upper rail pile and pour concrete anchor piers on the outer surface of the connecting beam. The prestressed anchor cable extends into the stable bedrock below the gently dipping structural surface and is cast with cement mortar to form the anchor body.

[0015] The stability of the roadside slope damaged by the double-structure combination of the open-pit mine after the above-mentioned reinforcement process has been significantly improved, and the mine road can continue to be used.

[0016] Typically, the prestressed anchor cable consists of a row of prestressed steel strands that pass through the connecting beam, the gently dipping structural surface, and extend into the stable bedrock beneath the gently dipping structural surface.

[0017] To promptly drain water from the mine slope steps and improve the stability of the mine slope, a drainage system is installed on the mine slope steps. The drainage system consists of drainage holes arranged above the gently sloping structural surface of the mine slope and drainage ditches arranged around the steeply sloping structural surface. Before the concrete pouring construction, PVC pipes are pre-embedded in the drainage holes, passing through the concrete retaining wall to the outer surface.

[0018] Based on experimental research and economic analysis, it is advisable to place the drainage holes 0.5 to 2m above the gently sloping structural surface, with a diameter of 100 to 120mm being preferred, and the slope of the drainage hole parallel to the gently sloping structural surface. The drainage ditch is a masonry drainage ditch with a mortar finish on the bottom, and its dimensions are (0.5 to 1.2m) × (0.5 to 1.2m).

[0019] As a preferred embodiment of the present invention, the width of the upper surface of the concrete retaining wall is ≥2m, the depth of the lower surface extends into the road platform by 0.9 to 1.2m, and the slope of the outer surface is less than the slope of the lower step.

[0020] Furthermore, the concrete retaining wall is constructed using C30 concrete, and the width of the upper surface of the concrete retaining wall should be greater than 2m.

[0021] Furthermore, after inserting the upper rail piles, C20 fine aggregate concrete is used for grouting; after inserting the lower rail piles, C20 fine aggregate concrete is used for grouting; it is preferable to use C30 concrete for the connecting beam.

[0022] Furthermore, the prestressed anchor cable extends into the stable bedrock below the gently dipping structural surface and is cast into an anchor body using M30 cement mortar.

[0023] Generally, the spacing between the lower rail piles is 3 to 4 meters, and the spacing between the upper rail piles is also 3 to 4 meters. The horizontal spacing between adjacent prestressed anchor cables is 3 to 4 meters.

[0024] The present invention is suitable for the reinforcement and treatment of road slopes damaged by a combination of dual structural surfaces in open-pit mines. After adopting the above technical solution, it has the following positive effects:

[0025] (1) The key to reinforcing the slope damaged by the combination of dual structural surfaces is to strengthen the gently dipping structural surface at the bottom of the slope. The reinforcement structure of the present invention can greatly improve the shear resistance of the gently dipping structural surface and greatly enhance the anti-sliding ability of the lower gently dipping structural surface, avoid excessive reinforcement of the upper steeply dipping structural surface, effectively limit the bedding sliding of the landslide body, and ensure the safe production of the mine.

[0026] (2) The lower rail piles of the lower reinforcement treatment structure of the present invention vertically penetrate the concrete retaining wall and penetrate into the gently inclined structural surface, connecting the lower rail piles, concrete retaining wall, landslide body and deep bedrock into a whole, which can greatly improve the overall stability of the reinforcement structure.

[0027] (3) The upper reinforcement structure of the present invention effectively improves the shear strength of the reinforcement structure by combining the upper rail piles, connecting beams and prestressed anchor cables, and ensures that the reinforcement structure will not slide along the gently inclined structural surface.

[0028] (4) By using prestressed anchor cables and rail piles that penetrate deep into the bedrock of the slope, the stress state at the gently sloping structural surface of the slope can be effectively improved. At the same time, the slope and the concrete retaining wall can be integrated into a whole area, which can improve the stability of the road slope of the open-pit mine double structural surface combination damage. Attached Figure Description

[0029] Figure 1 This is a schematic cross-sectional view of the combined reinforcement structure of the present invention, which is suitable for the reinforcement and treatment of road slopes damaged by a combination of dual structural surfaces in open-pit mines.

[0030] Reference numerals in the attached drawings: 1.1-Lower rail pile; 1.2-Upper rail pile; 2-Prestressed anchor cable; 3-Concrete retaining wall; 4-Connecting beam; 5-Gently inclined structural surface; 6-Steeply inclined structural surface; 7-Drainage hole; 8-Drainage ditch. Detailed Implementation

[0031] To further describe the present invention, the following detailed description, in conjunction with the accompanying drawings, describes the method for reinforcing and treating roadside slopes damaged by a combination of dual structural surfaces in open-pit mines.

[0032] Depend on Figure 1The schematic cross-sectional view of the combined reinforcement structure shown in the present invention, applicable to the reinforcement and treatment method of road slopes damaged by a combination of two structural surfaces in open-pit mines, indicates that in this embodiment, the road slope in the open-pit mine has two sets of bedding structural surfaces: a gently dipping structural surface 5 at the bottom and a steeply dipping structural surface 6 at the top; the gently dipping structural surface 5 has an inclination angle ≤30°, and the steeply dipping structural surface 6 has an inclination angle greater than 50°. Specifically, the reinforcement and treatment structure is divided into two parts: the lower reinforcement and treatment structure is located at the bottom of the road slope in the open-pit mine and is composed of lower steel rail piles 1.1 and concrete retaining walls 3 connected together; the upper reinforcement and treatment structure is located on a stepped platform above the gently dipping structural surface 5 and is composed of upper steel rail piles 1.2 and prestressed anchor cables 2.

[0033] 1) The lower reinforcement and treatment structure shall be implemented according to the following technical solution:

[0034] ① First, clear the gravel at the bottom of the road slope in the open-pit mine. Then, install a concrete retaining wall 3 at the shear outlet of the gently sloping structural surface 5. The concrete retaining wall 3 is made of C30 concrete. The slope of the outer surface of the concrete retaining wall 3 should not exceed the slope of the lower step slope. The width of the upper surface of the concrete retaining wall 3 is ≥2m, and the depth of the lower surface extends 1m below the road platform.

[0035] ② According to the designed hole depth and a spacing of 3-4m, a row of holes is arranged vertically downward in the middle of the upper surface of the concrete retaining wall 3. The lower rail pile 1.1 is inserted into the hole. The lower rail pile 1.1 should penetrate into the stable bedrock inside the bedding plane. After the lower rail pile 1.1 is inserted, C20 fine stone concrete is poured in.

[0036] 2) The superstructure reinforcement and treatment shall be implemented according to the following technical solution:

[0037] ① Arrange a row of boreholes vertically downwards on the stepped platform according to the designed hole depth and a spacing of 3-4m. Insert the upper rail pile 1.2 into the borehole. The upper rail pile 1.2 should penetrate into the stable bedrock inside the bedding plane. The exposed section of the upper rail pile 1.2 outside the borehole should be ≥30cm in length. After inserting the upper rail pile 1.2, pour C20 fine stone concrete.

[0038] ② Weld the exposed section of the upper rail pile 1.2 outside the borehole to the reinforcing bars in the connecting beam 4. The connecting beam 4 is long and narrow and is cast with C30 concrete.

[0039] ③ Pass the prestressed anchor cable 2 through the top connecting beam 4 of the upper rail pile 1.2 and pour concrete anchor blocks on the outer surface of the connecting beam 4. The prestressed anchor cable 2 extends into the stable bedrock below the gently inclined structural surface 5, with an anchoring length of 8m. The anchor body is formed by casting M30 cement mortar. The prestressed anchor cable 2 is composed of a row of prestressed steel strands that pass through the connecting beam 4 and the gently inclined structural surface 5 and extend into the stable bedrock below the gently inclined structural surface 5. The horizontal spacing between adjacent prestressed anchor cables 2 is 3-4m.

[0040] In this embodiment, a drainage system is also provided on the mine slope steps. The drainage system consists of drainage holes 7 arranged above the gently sloping structural surface 5 of the mine slope and drainage ditches 8 arranged around the steeply sloping structural surface 7. Before the concrete pouring construction, PVC pipes are pre-embedded through the concrete retaining wall 3 to the outer surface of the drainage holes 7. The drainage holes 7 are arranged 0.5 to 2m above the gently sloping structural surface 5, with a diameter of 100 to 120mm and an upward slope parallel to the gently sloping structural surface 5. The drainage ditches 8 are masonry drainage ditches with mortar plastering at the bottom and a size of (0.5 to 1.2m) × (0.5 to 1.2m).

[0041] This invention, a method for reinforcing and treating road slopes with combined structural surfaces in open-pit mines, has been experimentally applied in a large open-pit iron mine in China. The lower gently sloping structural surface has an inclination angle of 25°, while the upper steeply sloping structural surface has an inclination angle of 62°. Multiple landslides occurred along the road slope, severely impacting mine safety and even leading to temporary shutdowns. After reinforcement using this invention, the stability of the road slope with combined structural surfaces in the open-pit mine was improved, withstanding a once-in-a-century heavy rainfall event. This ensured the stability of the road slope, allowing for sustainable road access and guaranteeing the orderly operation of mine production. The method has received high praise from the user.

[0042] Industrial application verification shows that the method of the present invention has the characteristics of simple structure, low construction cost and fast reinforcement construction speed. The construction cost is more than 30% lower than that of the pile-anchor-beam combination reinforcement structure, and the construction speed is more than 40% higher, achieving unexpected technical effects.

Claims

1. A method for reinforcing and treating road slopes damaged by a combination of two structural surfaces in open-pit mines, wherein the road slope in an open-pit mine has two sets of bedding structural surfaces, the lower part being a gently dipping structural surface (5) and the upper part being a steeply dipping structural surface (6); the dip angle of the gently dipping structural surface (5) is ≤30°, and the dip angle of the steeply dipping structural surface (6) is in the range of 50° to 75°; characterized in that The reinforcement and treatment structure adopted is divided into two parts: the lower reinforcement and treatment structure is located at the bottom of the road slope of the open mine, and is composed of lower steel rail piles (1.1) and concrete retaining walls (3) connected together; the upper reinforcement and treatment structure is located on the step platform above the gently inclined structural surface (5), and is composed of upper steel rail piles (1.2) and prestressed anchor cables (2). 1) The lower reinforcement and treatment structure shall be implemented according to the following technical solution: ① First, clear the gravel at the bottom of the road slope of the open-pit mine, and set up a concrete retaining wall (3) at the shear outlet of the gently sloping structural surface (5) of the slope. The slope of the outer surface of the concrete retaining wall (3) should not exceed the slope of the lower step slope. ② According to the designed hole depth and a spacing of 2.5 to 5m, a row of holes is vertically arranged downward in the middle of the upper surface of the concrete retaining wall (3). The lower rail piles (1.1) are inserted into the holes. The lower rail piles (1.1) should penetrate into the stable bedrock inside the bedding plane. After the lower rail piles (1.1) are inserted, they are filled with fine stone concrete. 2) The superstructure reinforcement and treatment shall be implemented according to the following technical solution: ① Arrange a row of boreholes vertically downward on the stepped platform according to the designed hole depth and a spacing of 2.5 to 5m. Insert the upper rail piles (1.2) into the boreholes. The upper rail piles (1.2) should penetrate into the stable bedrock inside the bedding plane. The exposed section of the upper rail piles (1.2) outside the borehole should be ≥30cm in length. After inserting the upper rail piles (1.2), pour fine stone concrete. ② The exposed section of the upper rail pile (1.2) outside the borehole is welded to the reinforcing bars in the connecting beam (4). The connecting beam (4) is long and narrow and is made of concrete. ③ Pass the prestressed anchor cable (2) through the top connecting beam (4) of the upper rail pile (1.2) and pour concrete anchor piers on the outer surface of the connecting beam (4). The prestressed anchor cable (2) extends into the stable bedrock below the gently inclined structural surface (5) and is cast with cement mortar to form an anchor body.

2. The method for reinforcing and treating road slopes damaged by a combination of dual structural surfaces in open-pit mines as described in claim 1, characterized in that: The prestressed anchor cable (2) consists of a row of prestressed steel strands that pass through the connecting beam (4), the gently inclined structural surface (5) and extend into the stable bedrock below the gently inclined structural surface (5).

3. The method for reinforcing and treating road slopes damaged by a combination of dual structural surfaces in open-pit mines as described in claim 1, characterized in that: A drainage system is also provided on the slope steps of the mine. The drainage system consists of drainage holes (7) arranged above the gently sloping structural surface (5) of the mine slope and drainage ditches (8) arranged around the steeply sloping structural surface (6). Before the concrete pouring construction, PVC pipes are pre-embedded in the drainage holes (7) and pass through the concrete retaining wall (3) to the outer surface.

4. The method for reinforcing and treating road slopes damaged by a combination of dual structural surfaces in open-pit mines as described in claim 3, characterized in that: The drainage holes (7) are located 0.5 to 2m above the gently sloping structural surface (5), with a diameter of 100 to 120 mm and an upward slope parallel to the gently sloping structural surface (5); the drainage ditch (8) is a masonry drainage ditch with mortar plastering at the bottom and a size of (0.5 to 1.2m) × (0.5 to 1.2m).

5. The method for reinforcing and treating road slopes damaged by a combination of dual structural surfaces in open-pit mines, as described in claims 1, 2, 3, or 4, is characterized in that: The width of the upper surface of the concrete retaining wall (3) is ≥2m, the depth of the lower surface extends into the road platform by 0.9 to 1.2m, and the slope of the outer surface is < the slope of the lower step.

6. The method for reinforcing and treating road slopes damaged by a combination of dual structural surfaces in open-pit mines as described in claim 5, characterized in that: The concrete retaining wall (3) is made of C30 concrete and the width of the upper surface of the concrete retaining wall (3) should be greater than 2m.

7. The method for reinforcing and treating road slopes damaged by a combination of dual structural surfaces in open-pit mines as described in claim 5, characterized in that: After inserting the upper rail pile (1.2), C20 fine stone concrete is poured; after inserting the lower rail pile (1.1), C20 fine stone concrete is poured; the connecting beam (4) is cast with C30 concrete.

8. The method for reinforcing and treating road slopes damaged by a combination of dual structural surfaces in open-pit mines as described in claim 5, characterized in that: The prestressed anchor cable (2) is inserted into the stable bedrock below the gently dipping structural surface (5) and cast into an anchor body using M30 cement mortar.

9. The method for reinforcing and treating road slopes damaged by a combination of dual structural surfaces in open-pit mines as described in claim 5, characterized in that: The spacing between the lower rail piles (1.1) is 3-4m, the spacing between the upper rail piles (1.2) is 3-4m, and the horizontal spacing between adjacent prestressed anchor cables (2) is 3-4m.

10. The method for reinforcing and treating road slopes damaged by a combination of dual structural surfaces in open-pit mines as described in claim 6, characterized in that: After inserting the upper rail pile (1.2), C20 fine stone concrete is poured; after inserting the lower rail pile (1.1), C20 fine stone concrete is poured; the prestressed anchor cable (2) is inserted into the stable bedrock below the gently dipping structural surface (5) and cast with M30 cement mortar to form the anchor body; the spacing of the lower rail pile (1.1) is 3-4m, the spacing of the upper rail pile (1.2) is 3-4m, and the horizontal spacing between adjacent prestressed anchor cables (2) is 3-4m.

Images