Rigid-flexible combined support method for high and steep slope of open-pit mine
Patent Information
- Application Number
- CN202611111773.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-24
- Publication Date
- 2026-10-16
AI Technical Summary
[0014] The technical solution of this embodiment adopts a graded step-like arrangement on steep fractured rock slopes, and sets up a semi-rigid first protective structure, a flexible second protective structure and a rigid third protective structure in sequence from top to bottom, forming a rigid-flexible combined synergistic support system with progressively transitioning stiffness, thereby reducing project costs and construction period while ensuring slope stability.
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Abstract
Description
Technical Field
[0001] This application belongs to the field of mining engineering technology, and in particular relates to a rigid-flexible combined support method for steep slopes in open-pit mines. Background Technology
[0002] During deep mining operations, open-pit metal mines (such as copper and iron mines) often develop steep final slopes. Due to the influence of regional geological structures, fracture zones with a width of tens to hundreds of meters often develop within the mine slopes. The rock mass within the fracture zone is mainly composed of weathered layers and fractured rock masses, which are in a loose or fragmented state, soften when exposed to water, and have poor self-stability.
[0003] Therefore, there is a need to provide a cost-effective slope protection method. Summary of the Invention
[0004] In view of the technical problems existing in the background art, this application provides a rigid-flexible combined support method for steep slopes in open-pit mines, including: The slope was surveyed to determine the distribution boundaries of the completely weathered layer, the strongly weathered layer, and the moderately weathered layer; Multiple steps are excavated along the slope; wherein, each step includes an interconnected platform, a slope surface, and a slope toe, and each step includes at least a first step and a second step, wherein the elevation of the first step is higher than that of the second step; A first protective structure is installed on the slope of the first step; A second protective structure is installed on the slope of the second step; A third protective structure is installed at the toe of the slope of the second step; The first protective structure includes an anchoring part and a surface part connected to each other, the anchoring part being disposed inside the slope surface and the surface part being disposed on the slope surface; the second protective structure includes a fixing part and a flexible part connected to each other, the flexible part being deformable; the third protective structure at least partially abuts against the flexible part.
[0005] Furthermore, the provision of a first protective structure on the slope of the first step includes: Set a control value, measure the vertical distance between the platform and the slope foot as the height value. When the height value is less than the control value, set an anchor extension connected to it at the anchoring part. The length extension direction of the anchor extension is the same as the length extension direction of the anchoring part.
[0006] Furthermore, the first step includes an upper step and a lower step, the lower step is adjacent to the second step, and the anchoring part of the upper step is disposed in the strongly weathered layer, while the anchoring part of the second step is disposed in the fully weathered layer.
[0007] Furthermore, the first protective structure installed on the slope of the first step includes: Construct the first anchor hole on the slope of the first step; The anchoring part is inserted into the first anchor hole into the strongly weathered layer; Grouting is injected into the first anchor hole; A steel mesh is provided on the slope of the first step, and the steel mesh is connected to the anchoring part; Concrete is sprayed onto the slope of the first step, so that the concrete and the steel mesh form the surface portion.
[0008] Furthermore, an intermediate platform and a foot retaining wall are provided between the first step and the second step; the anchoring end of the first protective structure is anchored into the foot retaining wall, and the top of the second protective structure abuts against the bottom of the intermediate platform.
[0009] Furthermore, the second protective structure installed on the slope of the second step includes: Flexible geogrids are laid in layers as fixing parts, with each layer of geogrid extending outward along the slope and wrapping back to be fixed inside the fill material; Layer-by-layer backfilling and compaction of filler material serves as a flexible component to form a second protective structure.
[0010] Furthermore, the backfill material is made of crushed stone stripped from the mining area, which is spread in layers and compacted layer by layer.
[0011] Furthermore, early-strength cement mortar is used for grouting into the first anchor hole.
[0012] Furthermore, the third protective structure is a rubble concrete gravity retaining wall, which is only set at the toe of the lowest step, and the back of the retaining wall abuts against the bottom of the slope of the second protective structure.
[0013] Furthermore, the slope displacement is monitored throughout the entire support construction process. When the displacement rate exceeds the preset warning value, construction is suspended and the support parameters are adjusted.
[0014] The technical solution of this embodiment adopts a graded step-like arrangement on steep fractured rock slopes, and sets up a semi-rigid first protective structure, a flexible second protective structure and a rigid third protective structure in sequence from top to bottom, forming a rigid-flexible combined synergistic support system with progressively transitioning stiffness, thereby reducing project costs and construction period while ensuring slope stability. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the rigid-flexible combined support method for steep slopes in open-pit mines provided in an embodiment of this application; Figure 2This is a structural schematic diagram of a rigid-flexible combined support method for steep slopes in open-pit mines provided in another embodiment of this application; Figure 3 This is a structural schematic diagram of a rigid-flexible combined support method for a semi-rigid soil nailing wall support layer provided in another embodiment of this application; Figure 4 This is a structural schematic diagram of the steel mesh in the semi-rigid soil nailing wall support layer provided in another embodiment of this application; Figure 5 This is a structural schematic diagram of the retaining wall in the rigid concrete retaining wall support layer provided in another embodiment of this application; Figure 6 This is a structural schematic diagram of a flexible geogrid reinforced retaining wall support layer provided in another embodiment of this application.
[0016] Explanation of reference numerals in the attached drawings: 1. Semi-rigid soil nailing wall support layer; 2. Soil nail; 3. Reinforced connecting beam; 101. Reinforcing mesh; 102. Anchorage part; 103. Surface part; 4. Flexible geogrid reinforced retaining wall support layer; 5. Geogrid; 41. Crushed stone layer; 6. Rigid concrete retaining wall support layer; 7. Intermediate platform; 8. Foot retaining wall; 81. Drainage hole; 9. Fully weathered layer; 10. Strongly weathered layer; 11. Moderately weathered layer. Detailed Implementation
[0017] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.
[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.
[0019] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.
[0020] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0021] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.
[0022] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).
[0023] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.
[0024] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.
[0025] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0026] This application provides a rigid-flexible combined support method for steep slopes in open-pit mines, including: S101. Conduct slope surveys to determine the distribution boundaries of the fully weathered layer, strongly weathered layer, and moderately weathered layer; S102. Multiple steps are excavated along the slope; wherein, each step includes an interconnected platform, slope surface and slope foot, and each step includes at least a first step and a second step, with the first step being at a higher elevation than the second step; S103. A first protective structure is installed on the slope of the first step; S104. A second protective structure is installed on the slope of the second step; S105. A third protective structure shall be installed at the foot of the slope of the second step; The first protective structure includes an anchoring part and a surface part that are connected to each other. The anchoring part is located inside the slope and the surface part is located on the slope. The second protective structure includes a fixed part and a flexible part that are connected to each other. The flexible part is deformable. The third protective structure at least partially abuts against the flexible part.
[0027] This embodiment employs a tiered, stepped arrangement on steep, fractured rock slopes, sequentially installing a semi-rigid first protective structure, a flexible second protective structure, and a rigid third protective structure from top to bottom. This forms a rigid-flexible combined support system with progressively varying stiffness, replacing traditional strong support schemes such as anti-slide piles and prestressed anchor cables. This reduces project costs and construction time while ensuring slope stability. The first protective structure, through its internal anchoring section combined with the slope surface, reinforces the weathered rock mass at the slope's midsection, constraining slope deformation, increasing the overall shear strength of the rock mass, and undertaking the main deformation control function. The second protective structure, relying on its deformable flexible structure, absorbs dynamic load energy such as blasting vibrations, reducing stress peaks and adapting to the stress concentration and deformation coordination requirements of the slope toe area. The third protective structure, as a rigid support at the lowest slope toe, provides final anti-slide resistance and constrains the overall displacement of the slope toe. The three layers form a stiffness gradient from top to bottom: semi-rigid, flexible, and rigid. Under normal working conditions, the upper semi-rigid layer dominates deformation control, while under dynamic loads, the middle flexible layer buffers and absorbs energy. Under extreme conditions, the bottom rigid layer provides restraint, achieving coordinated force distribution under multiple working conditions. There is no need to install large anti-slide piles and prestressed anchor cables, nor is there a need for specialized large-scale construction equipment. It can be carried out simultaneously with mining and stripping operations to shorten the construction window and reduce treatment costs.
[0028] It can be explained that slope detection can employ methods such as geological drilling and geophysical exploration to delineate the interfaces between soil and rock layers with different degrees of weathering, providing a geological basis for subsequent step division and support structure layout. Steps are excavated vertically along the slope in stages, with each step corresponding to a support unit. The platform serves as a construction and transportation work platform, the slope surface is the construction interface for the support structure, and the toe of the slope is the bottom turning point of the step. The first step corresponds to the upper waist area of the slope, and the second step corresponds to the lower toe area, with their elevations decreasing sequentially, forming a top-down graded support structure.
[0029] For example, the first protective structure can adopt an anchor-grid support form, wherein the anchoring part is a full-length bonded anchor that is obliquely implanted into the slope rock mass, and the surface part is a reinforced concrete grid beam arranged in a crisscross pattern. The node positions of the grid beam are rigidly connected to the exposed ends of the anchor rods. The grid beam disperses the slope load and transfers it to the deep anchored rock mass, forming a semi-rigid overall constraint on the weathered rock layer. The second protective structure can adopt a geocell plus loose filler support form, wherein the fixed part is a layered stacked geocell unit, and the flexible part is a crushed stone and soil mixture filled in the cell cavity. The cell sidewall can constrain the lateral extrusion of the filler, and the filler itself can generate a certain amount of compression deformation to buffer the blasting vibration load. The third protective structure can adopt a mortar-grouted rubble gravity retaining wall, which is built on the slope toe foundation of the lowest step. The back of the retaining wall is integrally abutted against the bottom of the slope of the second protective structure, and the final anti-sliding limit effect at the slope toe is provided by the self-weight of the masonry.
[0030] In some embodiments, the provision of a first protective structure on the slope of the first step includes: setting a control value, measuring the vertical distance between the platform and the foot of the slope as a height value, and when the height value is less than the control value, providing an anchoring extension connected to the anchoring part, wherein the length extension direction of the anchoring extension is the same as the length extension direction of the anchoring part.
[0031] The technical solution of this embodiment establishes a matching relationship between the step height and the anchorage length, and adjusts the anchorage length differently for steps of different heights to optimize anchorage efficiency while ensuring anchorage effect. When the step height is less than the control value, the relative length of the anchorage is appropriately extended, allowing the anchorage end to penetrate deeper into more stable rock strata, thus improving the anchorage reliability of shallow steps. For high steps with a height greater than the control value, the anchorage length is matched proportionally to avoid material waste caused by over-anchoring. This quantitative matching relationship ensures that the anchorage depth of each step is adapted to the step height, guaranteeing balanced support strength at each step level and avoiding the risk of instability caused by insufficient local anchorage.
[0032] It can be explained that the control value is a preset threshold for the step height. The anchorage extension and the anchorage part are continuous rods of the same material, extending coaxially to form a complete soil nailing anchorage structure. The total length of the anchorage part maintains a proportional relationship with the step height; a larger length ratio is used when the height is smaller, and a slightly smaller length ratio is used when the height is larger, balancing support effectiveness and economy.
[0033] For example, the control value is set to 15m; when the step height is less than or equal to 15m, the total length of the anchoring part is 1.2 times the step height, that is, an additional anchoring extension is added to extend the anchoring length; when the step height is greater than 15m, the ratio of the total length of the anchoring part to the step height is 1.0, and no additional extension is required.
[0034] In some embodiments, the first step includes an upper step and a lower step, the lower step being adjacent to the second step, and the anchoring part of the upper step is disposed in the strongly weathered layer, while the anchoring part of the lower step is disposed in the completely weathered layer.
[0035] This implementation scheme takes into account the differences in the burial depth of weathered rock layers at different elevations, and adopts a differentiated design for the anchorage of the upper and lower steps. This ensures that the anchorage depth matches the geological conditions and support function, controlling project costs while guaranteeing support effectiveness. The degree of weathering on the slope gradually decreases from the surface downwards, with completely weathered layers and strongly weathered layers distributed sequentially. At the elevation of the upper step, the strongly weathered layer is shallower, allowing the anchorage to penetrate the thin layer of completely weathered rock and anchor into the strongly weathered layer. The more intact strongly weathered rock mass provides stable anchoring force, forming deep constraints on the slope waist and undertaking the main deformation control function. At the lower step, the elevation is lower, the thickness of the completely weathered layer increases significantly, and the burial depth of the strongly weathered layer increases substantially. If the anchorage is still required to penetrate the thick layer of completely weathered rock and anchor into the strongly weathered layer, the length of the rod needs to be significantly increased. This not only increases the difficulty of drilling and material input, but also makes it difficult to guarantee the grouting quality when the long rod penetrates the thick loose rock. Therefore, the anchorage of the lower step ends within the completely weathered layer, using a short, dense group of anchors to reinforce the surface fractured rock mass as a whole, improving the cohesion and shear strength of the loose rock mass and restraining surface slippage and spalling. Simultaneously, the overall anti-slip resistance of the lower slope is mainly borne by the secondary protective structure below it. The toe effect of the flexible reinforced retaining wall and the overall anti-slip capacity offset the landslide thrust and absorb the concentrated stress at the slope toe. Deep anchoring at the top controls deformation, while shallow reinforcement and flexible toe reinforcement at the bottom resist slippage, ensuring that the anchorage depth of each step matches the engineering value of the corresponding layer, avoiding waste caused by over-anchoring.
[0036] It can be explained that the anchoring section of the upper step is entirely located within the strongly weathered layer, relying on the bond force between the rod and the relatively intact rock mass to provide high anchoring force; the lower step anchoring section is entirely within the completely weathered layer, improving the mechanical parameters of the surface rock mass through the group anchoring effect. The lower step is vertically connected to the second protective structure, together forming a protective system for the slope toe area. The self-weight of the second protective structure and the interface friction can effectively balance the sliding force of the lower slope, compensating for the limited bearing capacity of the shallow anchoring.
[0037] In some embodiments, setting a second protective structure on the slope of the second step includes: laying flexible geogrid in layers as a fixing part, with each layer of geogrid extending outward along the slope and wrapping around and fixing inside the fill material; backfilling and compacting the fill material layer by layer as a flexible part, the second protective structure.
[0038] This embodiment constructs a reinforced flexible retaining wall by layering geogrids and compacting fill material. The frictional interlocking force between the geogrid and the fill material enhances the overall strength of the retaining wall while preserving its deformation capacity. The geogrid, embedded as a reinforcing fixing element within the fill material, constrains lateral deformation and improves the shear strength and overall stability of the retaining wall. The geogrid ends are back-buried along the slope, reinforcing the surface constraint and preventing fill material bulging and slippage. The layered compacted fill material, acting as a flexible core, allows for appropriate deformation to absorb blasting vibration energy and buffer dynamic load impacts, making it suitable for the frequent blasting environments in mines.
[0039] It can be explained that the geogrid is laid vertically in layers at fixed intervals. Each layer of fill material is spread and compacted before the next layer of geogrid is laid, and so on, layer by layer, upwards. The geogrid back section is folded back around the slope template and then overlapped and fixed with the upper layer of geogrid to form a continuous slope reinforcement system.
[0040] For example, the geogrid is made of high-strength polyester geogrid with an ultimate tensile strength of not less than 45kN / m; the vertical laying spacing is 1m, and the compaction thickness of each layer of fill is 30cm; the back wrapping length of the geogrid on the outside of the slope is not less than 3m, and after back wrapping, it is overlapped and tied to the geogrid body for fixation.
[0041] In some implementations, the backfill material is crushed stone stripped from the quarry, which is spread in layers and compacted layer by layer.
[0042] This embodiment of the technical solution directly uses the stripped rock from mining operations as the fill material for the reinforced retaining wall, achieving on-site material sourcing, reducing the procurement and transportation costs of the fill material, and simultaneously reducing the amount of stripped waste rock discharged for disposal, thus achieving both economic and environmental benefits. The stripped rock from the mining site has good gradation and strength, and after being compacted in layers, it can form a stable fill material body that meets the load-bearing capacity and deformation requirements of the reinforced retaining wall; layered spreading and compaction can ensure the uniformity and compaction degree of the fill material, avoiding uneven settlement caused by uneven fill material.
[0043] In some implementations, early-strength cement mortar is used to grout the first anchor hole.
[0044] The technical solution of this embodiment uses early-strength grouting material, enabling the anchoring part to quickly obtain anchoring force in a short period of time. This is suitable for the short construction window period of mining and stripping operations, ensuring that the support construction and mining progress are carried out simultaneously. Ordinary cement mortar has a slow strength increase and requires a long curing period before it can bear load, which will occupy a long working face time. Early-strength cement mortar can reach a high strength ratio in a short period of time after grouting, enabling the soil nailing wall to quickly have support capacity, shortening the support construction cycle of a single step, and reducing interference with mining and stripping operations.
[0045] It can be noted that early-strength cement mortar, prepared by adding early-strength agents or using early-strength cement, exhibits rapid early-stage strength growth and stable later-stage strength. Grouting employs pressure grouting to ensure the mortar completely fills the anchor holes and bonds tightly to the rock mass surrounding the holes.
[0046] For example, the grouting material is M35 early-strength cement mortar. After 24 hours of grouting, the compressive strength is not less than 20MPa, and it can reach 70% of the design anchoring force within 48 hours, which meets the requirements of subsequent construction and load-bearing capacity.
[0047] In some implementations, the third protective structure is a rubble concrete gravity retaining wall, which is only located at the toe of the lowest step, with the back of the retaining wall abutting against the bottom of the slope of the second protective structure.
[0048] The technical solution of this embodiment only requires a rigid concrete retaining wall at the lowest slope toe, achieving slope toe reinforcement and final restraint at the lowest cost, while avoiding the abrupt stiffness changes caused by setting a rigid structure along the entire slope height. The rubble concrete gravity retaining wall relies on its own weight to provide anti-sliding and anti-overturning forces, featuring a simple structure and convenient construction. The back of the retaining wall tightly abuts against the bottom of the flexible retaining wall, restraining the lateral displacement of the flexible retaining wall's bottom and providing rigid support for the entire support system. Setting a rigid structure only at the slope toe creates a smooth stiffness gradient with the upper semi-rigid and flexible structures, avoiding stress concentration caused by abrupt stiffness changes, while significantly reducing concrete usage and controlling project costs.
[0049] It can be noted that the lowest step corresponds to the lowest elevation of the slope and is a key control point for the overall anti-slip properties of the slope. The rubble concrete retaining wall is buried to a certain depth to ensure the stability of the foundation; the back of the wall is flat and fully fits the bottom of the flexible retaining wall slope to ensure uniform force transmission.
[0050] For example, the retaining wall is made of C20 rubble concrete, with a wall height of 2.8m, a top width of 1.5m, and a foundation depth of 1.0m. The retaining wall is arranged along the toe of the slope, and the back of the wall is in close contact with the bottom of the slope surface of the reinforced retaining wall to jointly constrain the displacement of the toe of the slope.
[0051] In some implementations, slope displacement is monitored throughout the entire support construction process. When the displacement rate exceeds a preset warning value, construction is suspended and support parameters are adjusted.
[0052] The technical solution of this embodiment uses dynamic monitoring throughout the entire process to grasp the deformation state of the slope, realize information-based construction, promptly identify instability risks and adjust the support plan, and ensure slope safety during construction and operation. The geological conditions of fractured rock slopes are uncertain, and unexpected deformation may occur during construction. Real-time monitoring of the slope's surface displacement and deformation rate allows for timely work stoppage and investigation when abnormal deformation trends appear. Support parameters can be adjusted by methods such as adding soil nails and increasing the density of geogrids to prevent further deformation from causing landslides.
[0053] It can be noted that monitoring can be carried out using equipment such as slope radar and GNSS displacement monitoring stations to continuously monitor key locations on the slope. Warning values are set according to the properties of the slope rock mass and specification requirements, and are divided into two levels: warning values and control values. When the warning value is reached, the contingency plan is activated; when the control value is reached, work is immediately suspended.
[0054] For example, multiple sets of displacement monitoring points are set up on the upper part of the slope to collect slope displacement data in real time. When the displacement rate exceeds the warning value of 8 mm / h, construction is immediately suspended, the cause of deformation is analyzed, and measures such as adding reinforcing soil nails and increasing the number of reinforcement layers are taken to adjust the support plan. Construction can only be resumed after stability is confirmed.
[0055] Please see Figures 1 to 6 As shown in the figure, this embodiment of the invention also provides a specific implementation process for a rigid-flexible combined support system for steep open-pit mine slopes, which is set on steep fractured rock slopes. The slope includes a completely weathered layer 9, a strongly weathered layer 10, and a moderately weathered layer 11 from top to bottom, wherein the completely weathered and strongly weathered layers are weak fracture zones and are the main control layers for slope instability.
[0056] The support system includes: a semi-rigid soil nailing wall support layer 1 (first protective structure), a flexible geogrid reinforced retaining wall support layer 4 (second protective structure), a rigid concrete retaining wall support layer 6 (third protective structure), an intermediate platform 7, and a foot retaining wall 8.
[0057] Semi-rigid soil nailing wall support layer 1 (strong waist): Set at the waist of the slope, corresponding to the distribution area of the strongly weathered layer 10 (e.g., Figure 1 (Range from +1260m to +1305m). The slope is excavated in a stepped manner, with each step height H=15m and soil nail 2 length L=18m (satisfying L=1.2H). Soil nail 2 is set in layers and multiple rows along the slope height (5 rows in this embodiment) to form a continuous strong waist anchoring zone.
[0058] Soil nails 2 are made of HRB400 grade steel bars, 28mm in diameter, arranged in a staggered pattern with a spacing of 2.0m × 2.0m, anchor holes with a diameter of 75mm and an inclination angle of 20°. The soil nails are installed within the strongly weathered layer 10. The grouting material is M35 early-strength cement mortar with a 24-hour strength of 21MPa. A 16cm thick layer of C20 shotcrete is applied to the slope, reinforced with Φ8@200 steel mesh.
[0059] Flexible geogrid reinforced retaining wall support layer 4 (toe protection): Set in the toe area of the slope (such as...) Figure 1 Located in the lower part of the strongly weathered layer 10 (range +1245m to +1260m). The slope angle is 45° (slope ratio 1:1), with 14 layers of reinforcement spaced 1m apart vertically. Geogrid 5 uses high-strength polyester geogrid with an ultimate tensile strength of 45kN / m and an elongation at break of 11%. The outer edge of the geogrid has a 3.0m inverted wrapping length. The fill material consists of hard crushed stone stripped from the mining area, with a particle size ≤30cm and a mud content of 3%, compacted in layers to a compaction degree of 96%. The slope panel is C20 rubble concrete, 20cm thick, poured as the fill is constructed.
[0060] Rigid concrete retaining wall support layer 6 (foot support): It is only installed at the foot of the ramp of the lowest level transport platform (e.g.) Figure 1 (Medium +1245m platform slope foot). The form is a C20 rubble concrete gravity retaining wall, with a top width of 1.5m, a height of 2.8m, a bottom width of 2.2m, a foundation depth of 1.0m, a wall surface slope of 1:0.1, and a back wall slope of 1:0.2.
[0061] Intermediate platform 7 and foot retaining wall 8 (rigid-flexible connection structure): The soil nail anchor heads of the semi-rigid layer are fixed to the toe retaining wall 8 via steel reinforcement connecting beam 3 (Φ20@1m). The geogrid 5 of the flexible layer has a 3.0m tail wrap.
[0062] Please see Figures 1 to 6 As shown in the figure, this embodiment of the invention also provides a specific implementation process for another rigid-flexible combined support system for steep slopes in open-pit mines, including the following steps: S1, Geological verification and zoning: Determine the distribution boundaries of the completely weathered layer 9, the strongly weathered layer 10, and the moderately weathered layer 11.
[0063] S2, excavation from top to bottom in stages: each step is 15m high (H), and cutting the foot of the step is strictly prohibited. After each step is excavated, a 5cm thick layer of C20 concrete is sprayed to temporarily seal the slope. Mining stripping and support construction are carried out concurrently, utilizing the mining "window period" for concentrated construction.
[0064] S3, Construction of semi-rigid soil nailing wall and intermediate platform retaining wall: After the mining stripping reached the +1260m elevation, five rows of soil nailing walls were constructed in the +1260m to +1305m section.
[0065] Drill a hole (75mm diameter, 20° inclination) and install two soil nails (HRB400Φ28, 18m long). Use M35 early-strength cement mortar for grouting, with a grouting pressure of 0.5~0.8MPa and a 24h strength of 21MPa.
[0066] Within 48 hours of the soil nailing wall construction being completed, 70% of the designed anchorage force will be achieved. The +1260m intermediate platform 7 and the toe retaining wall 8 will then be poured, and the soil nail anchor heads will be connected with reinforcing bars.
[0067] S4, Layered construction flexible reinforced retaining wall: After the mining stripping reached the +1245m elevation, the reinforced retaining wall was constructed layer by layer from bottom to top, from +1245m to +1260m.
[0068] Each layer: Lay high-strength polyester geogrid 5 (anchoring part), with the ends of the geogrid wrapped back for temporary fixation for 3.0m; backfill with quarry stripped crushed stone (particle size ≤30cm, mud content 3%) to form crushed stone layer 41 (flexible part), with a layer thickness of 30cm, and compact with a vibratory roller (compaction degree 96%); repeat the above steps, with a vertical spacing of 1m, for a total of 14 layers.
[0069] S5, Construction of rigid concrete retaining wall: Excavate a foundation trench at the toe of the slope of the +1245m platform and pour a C20 rubble concrete retaining wall to form a rigid concrete retaining wall support layer 6, with a wall height of 2.8m and a top width of 1.5m.
[0070] S6, dynamic monitoring and feedback throughout the entire process: Displacement monitoring sensors (slope radar and RTK monitoring points) are installed on the upper part of the slope to be treated.
[0071] Continuous monitoring of surface displacement and blasting vibration during and after construction.
[0072] Construction should be suspended when the displacement rate exceeds the warning value (for soil slopes > 8 mm / h), the cause should be analyzed, and the support parameters should be adjusted (such as adding reinforcing soil nails, densifying the grid, etc.).
[0073] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in this application, and within the spirit and principles of this application, should be included within the scope of protection of this application.
[0074] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.
Claims
1. A method for rigid-flexible combined support of steep slopes in open-pit mines, characterized in that, include: The slope was surveyed to determine the distribution boundaries of the completely weathered layer, the strongly weathered layer, and the moderately weathered layer; Multiple steps are excavated along the slope; wherein, each step includes an interconnected platform, a slope surface, and a slope toe, and each step includes at least a first step and a second step, wherein the elevation of the first step is higher than that of the second step; A first protective structure is installed on the slope of the first step; A second protective structure is installed on the slope of the second step; A third protective structure is installed at the toe of the slope of the second step; The first protective structure includes an anchoring part and a surface part connected to each other, the anchoring part being disposed inside the slope surface and the surface part being disposed on the slope surface; the second protective structure includes a fixing part and a flexible part connected to each other, the flexible part being deformable; the third protective structure at least partially abuts against the flexible part.
2. The rigid-flexible combined support method for steep slopes in open-pit mines according to claim 1, characterized in that, The provision of a first protective structure on the slope of the first step includes: Set a control value, measure the vertical distance between the platform and the slope foot as the height value. When the height value is less than the control value, set an anchor extension connected to it at the anchoring part. The length extension direction of the anchor extension is the same as the length extension direction of the anchoring part.
3. The rigid-flexible combined support method for steep slopes in open-pit mines according to claim 1, characterized in that, The first step includes an upper step and a lower step, the lower step is adjacent to the second step, and the anchoring part of the upper step is disposed in the strongly weathered layer, while the anchoring part of the second step is disposed in the fully weathered layer.
4. The rigid-flexible combined support method for steep slopes in open-pit mines according to claim 1, characterized in that, The first protective structure installed on the slope of the first step includes: Construct the first anchor hole on the slope of the first step; The anchoring part is inserted into the first anchor hole into the strongly weathered layer; Grouting is injected into the first anchor hole; A steel mesh is provided on the slope of the first step, and the steel mesh is connected to the anchoring part; Concrete is sprayed onto the slope of the first step, so that the concrete and the steel mesh form the surface portion.
5. The rigid-flexible combined support method for steep slopes in open-pit mines according to claim 1, characterized in that, An intermediate platform and a foot retaining wall are provided between the first step and the second step; the anchoring end of the first protective structure is anchored into the foot retaining wall, and the top of the second protective structure abuts against the bottom of the intermediate platform.
6. The rigid-flexible combined support method for steep slopes in open-pit mines according to claim 1, characterized in that, The second protective structure installed on the slope of the second step includes: Flexible geogrids are laid in layers as fixing parts, with each layer of geogrid extending outward along the slope and wrapping back to be fixed inside the fill material; Layer-by-layer backfilling and compaction of filler material serves as a flexible component to form a second protective structure.
7. The rigid-flexible combined support method for steep slopes in open-pit mines according to claim 6, characterized in that, The backfill material is crushed stone stripped from the quarry, which is spread in layers and compacted layer by layer.
8. The rigid-flexible combined support method for steep slopes in open-pit mines according to claim 4, characterized in that, Early-strength cement mortar was used to grout the first anchor hole.
9. The rigid-flexible combined support method for steep slopes in open-pit mines according to claim 1, characterized in that, The third protective structure is a rubble concrete gravity retaining wall, which is only set at the toe of the lowest step, and the back of the retaining wall abuts against the bottom of the slope of the second protective structure.
10. The rigid-flexible combined support method for steep slopes in open-pit mines according to claim 1, characterized in that, The slope displacement is monitored throughout the entire support construction process. When the displacement rate exceeds the preset warning value, construction is suspended and the support parameters are adjusted.