A dynamic compaction device and system for reducing the height of a tailings dam heap

Abstract

The utility model provides a kind of for reducing the elevation of tailing pond heap surface of dynamic compaction device and system, and dynamic compaction device includes shock-absorbing rammer, and the shock-absorbing rammer includes parent hammer, and the hammering end of parent hammer is provided repeated stack shock-absorbing pad and rigid pad, and the rigid pad includes multiple spacer and a bottom pad, and the spacer is arranged between two shock-absorbing pads, and the bottom pad is arranged the outermost farthest from the hammering end, and the shock-absorbing pad and rigid pad are fixedly connected with parent hammer by connecting piece.The utility model realizes the elevation of tailing pond heap surface by using dynamic compaction method to reduce by shock-absorbing and vibration isolation two kinds of measures.

Description

Technical Field

[0001] This utility model relates to the field of geotechnical engineering technology, specifically to a dynamic compaction device and system for reducing the elevation of tailings dam surface. Background Technology

[0002] Tailings soil is mostly composed of tailings silt, fine sand, silty clay, and silty soil, generally in a loose to slightly dense state. For tailings ponds where the tailings pile is close to its final elevation, the tailings soil is already quite thick, and the groundwater level is relatively low. These geological conditions are very suitable for using dynamic compaction to compact the tailings soil, thereby lowering the elevation of the tailings pond surface.

[0003] However, dynamic compaction has a significant drawback: the intense vibrations generated can severely impact the stability and safety of tailings dams. Tailings dams are often very high, reaching tens or even hundreds of meters; a dam failure would cause substantial casualties and property damage, significantly impacting the socio-economic situation and people's livelihoods. This is the main reason why there are currently no engineering examples of using dynamic compaction to lower the elevation of tailings dam surfaces. Therefore, to utilize dynamic compaction to lower the elevation of tailings dam surfaces, it is essential to minimize the impact of dynamic compaction on the tailings dam. Utility Model Content

[0004] The purpose of this utility model is to address the shortcomings of existing technologies by providing a dynamic compaction device and system for reducing the elevation of tailings dam surface. It achieves the reduction of tailings dam surface elevation through dynamic compaction by means of vibration reduction and vibration isolation.

[0005] To solve the above-mentioned technical problems, on the one hand, this utility model provides a dynamic compaction device for reducing the elevation of tailings dam surface, including a vibration-damping hammer. The vibration-damping hammer includes a mother hammer. The hammering end of the mother hammer is provided with repeatedly stacked vibration-damping pads and rigid pads. The rigid pad includes multiple spacers and a bottom pad. The spacers are arranged between two vibration-damping pads. The bottom pad is arranged on the outermost side furthest from the hammering end. The vibration-damping pads and rigid pads are fixedly connected to the mother hammer through connectors.

[0006] In some embodiments, the hammer end of the female hammer has a threaded hole, the connector is a long bolt, the long bolt is threaded only at the bottom, and the portion of the long bolt that passes through the damping pad and the rigid pad is a smooth circular surface.

[0007] In some embodiments, the thickness of the bottom pad is greater than that of the spacer pad.

[0008] In some embodiments, the vibration damping pad is made of high-damping rubber, neoprene rubber, or natural rubber.

[0009] In some embodiments, the rigid pad is made of Q355B structural steel.

[0010] On the other hand, this utility model provides a system for reducing the elevation of the tailings dam surface, including the dynamic compaction device for reducing the elevation of the tailings dam surface, and also includes a vibration isolation wall, which is arranged between the dynamic compaction area and the tailings dam.

[0011] In some embodiments, the vibration isolation wall includes a deep mud mixing pile vibration isolation wall, or a mud vibration isolation wall, or a mud-straw vibration isolation wall, or a water-air bag vibration isolation wall.

[0012] In some embodiments, the water-air bag vibration isolation wall includes multiple composite bags, each composite bag has a valve at its top for controlling the connection between the composite bag and the outside world, the composite bag contains water and gas, the water level is not less than the groundwater level, the gas is located above the water, and the gas pressure is between 20 and 30 kPa.

[0013] In some embodiments, the mud-straw vibration isolation wall includes a straw wall and an earthen wall, with the straw wall located below the earthen wall.

[0014] In some embodiments, a monitoring system is included, which includes a surface displacement monitoring device, a deep displacement monitoring device, a vibration parameter monitoring device, a pore water pressure monitoring device, and a permeability pressure monitoring device. The monitoring points of the surface displacement monitoring device are arranged on the top of the soil between the vibration isolation wall and the tailings dam, as well as on the top of the tailings dam, to monitor horizontal and vertical displacement. The deep displacement monitoring device is arranged between the vibration isolation wall and the tailings dam, near the tailings dam, and is used to monitor the deep horizontal displacement. The vibration parameter monitoring device is arranged on the top of the soil near both sides of the vibration isolation wall, the top of the tailings dam, and the top of the soil near the tailings dam between the vibration isolation wall and the tailings dam, for monitoring vibration parameters. The pore water pressure monitoring device is arranged in the soil near both sides of the vibration isolation wall and in the soil near the tailings dam between the vibration isolation wall and the tailings dam, and is used to monitor the pore water pressure. The seepage pressure monitoring device is located inside the tailings dam and is used to monitor seepage pressure.

[0015] The beneficial effects of this utility model are as follows: 1. This utility model employs two measures, vibration reduction and vibration isolation, to reduce the elevation of the tailings dam surface using dynamic compaction. The vibration-reducing hammer significantly reduces the impact of dynamic compaction vibration by eliminating the peak impact force, while maintaining high compaction energy and achieving good compaction effect. By adjusting the number of rubber pads, different levels of dynamic compaction vibration reduction requirements can be met using only the same hammer. The vibration isolation wall provides good vibration isolation protection for buildings and structures near the dynamic compaction site.

[0016] 2. This utility model provides four types of vibration isolation walls (deep mud mixing pile vibration isolation wall, mud vibration isolation wall, mud-straw vibration isolation wall, and water-air bag vibration isolation wall), which can be flexibly selected according to project requirements, geological conditions, material availability, and cost. Deep mud mixing pile vibration isolation walls are a relatively ideal vibration isolation structure with good vibration isolation effect; by adjusting their depth and width, they can meet the vibration isolation requirements under different working conditions. Mud vibration isolation walls, mud-straw vibration isolation walls, and water-air bag vibration isolation walls have the advantages of simple construction, good vibration reduction effect, and low cost. 3. The real-time monitoring and management mechanism for tailings dam safety established by this utility model, through the system integration monitoring system (including real-time monitoring of multiple parameters such as vibration, displacement, pore water pressure, and seepage pressure), combined with the early warning mechanism and construction feedback control, can dynamically monitor the stability of the tailings dam during the dynamic compaction process. Once an abnormality is detected, the construction parameters can be adjusted or the operation can be suspended immediately, which greatly reduces the risk of dynamic compaction construction to the safety of the tailings dam. Combined with the vibration reduction and isolation technology of this utility model, it provides a safe, simple, fast, economical and effective method for reducing the elevation of the tailings dam surface. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the vibration-damping ramming hammer of this utility model; Figure 2 This is a top view of the vibration-damping ramming hammer of this utility model; Figure 3 This is a plan view of the dynamic compaction treatment according to this utility model; Figure 4 This is a cross-sectional view of the dynamic compaction treatment and monitoring of this utility model; Figure 5 This is a detailed plan view of the mud mixing pile of this utility model; Figure 6 This is a detailed plan view of the water-air bag vibration isolation wall of this utility model; Figure 7 This is a detailed cross-sectional view of the water-air bag vibration isolation wall of this utility model; Figure 8 This is a schematic diagram of the layout of the dynamic compaction points according to this utility model. Figure 9 This is a schematic diagram of the layout of the dynamic compaction and full compaction method of this utility model.

[0018] Figure 10 The construction procedures of this utility model are as follows; Figure 11 This is a schematic plan of a tailings dam.

[0019] Figure reference numerals: 1. Handle; 2. Hammer; 3. Connector; 4. Shim; 5. Vibration damping pad; 6. Rigid pad; 7. Tailings dam; 8. Vibration isolation wall; 9. Test area; 10-1. First surface displacement monitoring point; 10-2. Second surface displacement monitoring point; 10-3. Third surface displacement monitoring point; 11-1. First vibration parameter monitoring device; 11-2. Second vibration parameter monitoring device; 11-3. Third vibration parameter monitoring device; 11-4. Fourth vibration parameter monitoring device; 12. Deep displacement monitoring device; 13-1. First pore water pressure monitoring device; 13-2. Second pore water pressure monitoring device; 13-3. Third pore water pressure monitoring device; 14. Permeability pressure monitoring device; 15. Slurry mixing pile; 16. Composite bag; 17. Valve; 18. Geotextile; 19. First pass of dynamic compaction point; 20. Second pass of dynamic compaction point; 21. Full compaction point. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0021] In order to reduce the elevation of the tailings dam surface using dynamic compaction, this utility model makes improvements in terms of vibration reduction and vibration isolation.

[0022] Vibration reduction refers to improving the tamping hammer to reduce the vibration generated when it strikes the ground. This utility model targets the strong compaction of large areas and deep tailings soil. The requirements for the vibration-reducing tamping hammer are: to maintain good compaction effect while effectively controlling the impact of vibration. Existing tamping hammers or vibration reduction measures cannot meet these requirements.

[0023] Vibration isolation involves setting up vibration isolation barriers to reduce the outward propagation of vibration waves generated by dynamic compaction. Existing vibration isolation barriers mainly include vibration isolation trenches and stress relief holes. However, these barriers are either not deep enough to meet the vibration isolation requirements of the project for which this utility model is proposed, or the tailings soil is mostly fine sand or silty fine sand, making the boreholes prone to collapse and thus failing to provide vibration isolation.

[0024] This utility model provides a system for reducing the elevation of tailings dam surface, including a dynamic compaction device, a vibration isolation wall 8, and a monitoring system.

[0025] like Figure 1 , 2As shown, the dynamic compaction device includes a vibration-damping hammer, which includes a mother hammer 2. A handle 1 is fixedly installed at the upper end of the mother hammer 2. The hammering end (i.e., the lower end) of the mother hammer 2 is provided with repeatedly stacked vibration-damping pads 5 and rigid pads 6. The rigid pad 6 includes multiple spacers and a bottom pad. The spacers are arranged between two vibration-damping pads 5, and the bottom pad is arranged on the outermost side furthest from the hammering end. The vibration-damping pads 5 and the rigid pads 6 are fixedly connected to the mother hammer 2 through connectors 3.

[0026] In other words, multiple vibration damping pads 5 are fixedly installed at the lower end of the mother hammer 2, and a rigid pad 6 is installed between two adjacent vibration damping pads 5. A rigid pad 6 is also installed at the bottom of the lowest vibration damping pad 5. The rigid pad 6 between two adjacent vibration damping pads 5 is a spacer, and the lowest rigid pad 6 is a bottom pad. The thickness of the bottom pad is greater than that of the spacer. For example, the thickness of the spacer is 3~6mm, and the thickness of the bottom pad is 10~15mm.

[0027] Among them, the vibration damping pad 5 can be made of high-damping rubber, neoprene rubber, or natural rubber. The number of vibration damping pads 5 used in a specific project needs to be determined based on the test compaction, so as to ensure that the vibration index in the area where vibration needs to be controlled meets the proposed requirements. The rigid pad 6 needs to have high strength, high impact toughness, fatigue resistance, and other properties, and can be made of low-alloy high-strength Q355B structural steel.

[0028] In addition, the connector 3 can be a long bolt, the hammer end of the female hammer 2 has a threaded hole, the long bolt is only threaded at the bottom to fit with the threaded hole of the female hammer 2, the part of the long bolt that passes through the vibration damping pad 5 and the rigid pad 6 is a smooth round surface, and a washer 4 is provided at the nut of the long bolt.

[0029] This invention utilizes the elastic deformation characteristics of rubber by placing a rubber pad at the bottom of the main hammer 2. This effectively reduces the peak impact force of dynamic compaction, thereby reducing the vibration caused by dynamic compaction to the surrounding site while maintaining high compaction energy and effect. The main principle of the vibration-damping hammer is as follows: The root cause of dynamic compaction vibration is the large instantaneous impact load (F) generated when the hammer (mass M) impacts the foundation at a certain velocity (v), producing strong vibration waves that propagate outwards. If a rubber pad is placed at the bottom of the main hammer 2, the rubber pad will undergo elastic deformation upon impact, transforming the instantaneous impact into a "buffering" effect, significantly extending the impact time Δt, reducing the peak impact load, and thus achieving a significant vibration reduction effect. Furthermore, the rubber pad also absorbs the impact energy of the main hammer 2 and regulates the vibration wave frequency, contributing to vibration reduction.

[0030] Selection of the weight and type of the main hammer 2: The tailings soil in the tailings dam is very thick, requiring a maximum effective reinforcement depth for dynamic compaction; considering the safety of the tailings dam 7, the vibration impact on the surrounding area should be minimized. Since existing vibration reduction and isolation measures can control the impact of dynamic compaction vibration on the surrounding area, the focus here is on the effective reinforcement depth. The heavier the main hammer 2, the deeper the reinforcement; therefore, a larger main hammer 2, such as 20~60t, is preferable. With the same weight, the smaller the bottom area of ​​the main hammer 2, the deeper the effective reinforcement depth for dynamic compaction. Therefore, the hammer bottom diameter can be 1.2~2.5m; a smaller diameter is used when the main hammer 2 is lighter, and a larger diameter is used when the main hammer 2 is heavier.

[0031] First, it needs to be explained that the vibration isolation principle of the vibration isolation wall 8 is based on the abrupt change in wave impedance between the filling material and the in-situ tailings soil. The wave impedance Z of the soil is equal to the product of its density ρ and wave velocity V: Z = ρV. If the density of the filling material in the selected vibration isolation wall 8 is lower than that of the tailings soil, and its shear wave velocity is much lower than that of the tailings soil, then the wave impedance of the vibration isolation wall 8 will be much smaller than that of the tailings soil. When the vibration wave propagates from the relatively dense tailings soil layer to the vibration isolation wall 8, due to the abrupt change in wave impedance, a considerable portion of the vibration wave energy will be reflected at the interface of the vibration isolation wall 8 and "bounced back" to the side of the dynamic compaction construction area. Only a small portion of the energy can pass through the vibration isolation wall 8 and continue to propagate to the protected area.

[0032] Based on the above vibration isolation principle, as long as the wave impedance of the filling material in the vibration isolation wall 8 is much smaller than the wave impedance of the tailings soil, the vibration isolation wall 8 can play a good vibration isolation role. Therefore, the filling material in the vibration isolation wall 8 can be air, water, mud, or other substances with a wave impedance smaller than that of the tailings soil. Using these materials as filling materials for the vibration isolation wall 8 can achieve a good vibration isolation effect.

[0033] The vibration isolation wall 8 of this utility model includes a deep mud mixing pile 15 vibration isolation wall, or a mud vibration isolation wall, or a mud-grass vibration isolation wall, or a water-air bag vibration isolation wall, and the vibration isolation wall 8 is set at the boundary of the dynamic compaction treatment area.

[0034] Among them, the vibration isolation wall of the deep mud mixing pile 15 is a vibration isolation wall 8 composed of multiple rows of deep mud mixing piles 15. The construction process of the vibration isolation wall of the deep mud mixing pile 15 is as follows: 1) Lay out the location of the mixing piles for the deep mud mixing pile 15 vibration isolation wall.

[0035] 2) The deep mud mixing pile 15 adopts a four-spray, four-mix process, the flow of which is as follows: The mixing pile machine is positioned → the high-pressure grouting pump is turned on → drilling and spraying grout to the intended depth → lifting the drill and spraying grout to the design surface of the mixing pile → repeated mixing, drilling down and spraying grout to the intended depth → mixing the drill rod and spraying grout, lifting the drill to the design surface of the mixing pile → pile completion → construction of the next pile. By constructing two or more rows of mud mixing piles 15 in overlapping or tangential arrangements, a deep mud mixing pile 15 vibration isolation wall that can play a vibration isolation role is formed, such as... Figure 5 As shown, the left diagram illustrates the overlapping situation of the mud mixing pile 15, and the right diagram illustrates the tangent situation of the mud mixing pile 15. F represents the diameter of the mud mixing pile 15, G represents the overlapping width of the mud mixing pile 15, and H represents the width of the vibration isolation wall of the deep mud mixing pile 15.

[0036] The width of the deep mud mixing pile 15 vibration isolation wall is 1.2m~2.5m, the depth is 5m~25m, and the diameter of the mixing pile is 0.6~0.8m. Bentonite is used as the mud material, with a bentonite content of 8%~15% of the tailings soil mass and a water-cement ratio of 0.5~0.7. The prepared slurry should not be left to stand for too long and should be used immediately after mixing. Sufficient slurry should be prepared at one time to ensure uninterrupted slurry supply to the grouting system, meeting the requirements for uniform and continuous grouting. The concentration and specific gravity of each bucket of slurry must be measured. Only after reaching the values ​​determined by construction tests and meeting the requirements can it be injected into the storage tank and continuously pumped by the grouting pump during mixing and grouting. The centering error between the mixer drill bit and the center point of the pile position shall not exceed 5cm, the horizontal error of the mixing pile machine shall not exceed 2cm, and the verticality shall not be less than 0.8%. A four-spray, four-mix process shall be adopted for pile formation. The mixing head shall descend at a uniform speed of no more than 0.8m / minute for drilling, mixing, and grouting, and rise at a speed of no more than 0.6m / minute for raising the mixing and grouting. Grouting elevation requirements: The top elevation of the grouting shall start from the bottom of the foundation trench, and the final grouting bottom shall be the predetermined elevation of the deep mud wall bottom.

[0037] Mud slurry vibration isolation wall is a vibration isolation wall made by filling the trench with mud slurry.

[0038] Construction process of mud vibration isolation wall: 1) Laying out the location of the mud slurry vibration isolation wall.

[0039] 2) Mud preparation. Bentonite is used as the mud material, and pure mud is prepared with a water-cement ratio of 0.5-0.7. This pure mud is then mixed with locally sourced soil. The amount of bentonite added is 8%-15% of the mass of the locally sourced soil; the clay content in the prepared mud is 8%-15%, and the density is 1.2-1.5 g / cm³. 3 .

[0040] 3) Use mechanical equipment to excavate trenches according to the planned vibration isolation trench dimensions, and backfill the trenches with pre-prepared mud slurry to form mud slurry vibration isolation walls.

[0041] The width of the mud vibration isolation wall is 1.2m~2.0m, and the depth is 4m~6m. The mud can be prepared by mixing bentonite as raw material with an appropriate amount of water and tailings soil; or it can be prepared by taking clay from the local area.

[0042] Mud-straw vibration isolation walls are vibration isolation walls made by filling trenches with easy and soft materials such as straw.

[0043] Construction process of mud-straw vibration isolation wall: 1) Lay out the location of the mud and straw vibration isolation wall.

[0044] 2) Use mechanical equipment to excavate the trench according to the planned vibration isolation trench size.

[0045] 3) Lay soft materials such as straw and stalks into the trench to form a grass wall. The height of the grass wall should not be less than 60% of the depth of the vibration isolation trench.

[0046] 4) Take soil from the local area, loosen and fill it back into the trench to the ground level to form an earthen wall, thus forming a mud and straw vibration isolation wall that can play a vibration isolation role.

[0047] The width of the mud-straw vibration isolation wall is 1.2m to 2.0m, and the depth is 4m to 6m. The backfill soil can be taken from the local area and bulldozed. It does not need to be layered or compacted. Machinery and equipment are not allowed to move on the mud-straw vibration isolation wall.

[0048] Water-air bag vibration isolation walls are vibration isolation walls 8 formed by filling trenches with composite bags 16 filled with water and air, such as... Figure 6 , 7 As shown, the water-air bag vibration isolation wall comprises multiple composite bags 16, each containing water and gas. The water level is not less than the groundwater level, and the gas is positioned above the water. The gas pressure is between 20 and 30 kPa. The width of each composite bag 16 is equal to the width of the trench, and the depth (or height) of each composite bag 16 is slightly less than the depth of the trench. Multiple composite bags 16 are arranged along the direction of the trench to form the water-air bag vibration isolation wall. A valve 17 is installed at the top of each composite bag 16. The valve 17 controls the connection between the composite bag 16 and the outside environment; that is, air and water can be injected into the composite bag 16 through the valve 17.

[0049] Construction process of water-air bag vibration isolation wall: 1) Material preparation: Purchase composite bags 16 according to the proposed dimensions and relevant requirements of the vibration isolation wall 8. The width of the composite bag 16 is the same as the width of the vibration isolation wall 8, and the height should be 200~300mm smaller than the proposed height of the vibration isolation wall 8. The length of a single composite bag 16 is 5~10m.

[0050] 2) Before burying and installing the composite bags 16, all composite bags 16 must undergo a 24-hour air pressure sealing test. Only when the corresponding requirements are met can they be installed and used.

[0051] 3) Installation process of water-air bag vibration isolation wall: excavate trench → inflate composite bag 16 → sink composite bag 16 → fill composite bag 16 with water and inflate.

[0052] 4) Use an excavator to excavate the trench according to the planned dimensions of the vibration isolation trench. When the trench is excavated to the point where a single composite bag 16 can be installed, the geotextile 18 and the composite bag 16 should be laid in a timely manner to prevent the trench from collapsing after a long excavation period.

[0053] 5) Before installing geotextile 18 and composite bag 16, sharp objects such as branches and wires should be removed from the bottom and sidewalls of the trench.

[0054] 6) Use a high-pressure blower to inflate the composite bag 16 to a pressure of 5~10 kPa, wrap the composite bag 16 with geotextile 18, and use double-sided tape to stick and fix the two together, and then sink them into the trench.

[0055] 7) Open valve 17 of composite bag 16, fill composite bag 16 with water to above the groundwater level, and then pressurize with air to 20~30kPa.

[0056] Minimum water level: The water level must be above the groundwater level to ensure that the composite bag 16 will not float due to buoyancy. High water level: The composite bag 16 should not be completely filled, especially in low temperatures, to avoid water freezing and expanding, which could cause the composite bag 16 to rupture. The water level can be increased to 50-80% of the height of the composite bag 16.

[0057] 8) If the trench is too wide, gaps will appear between the composite bag 16 and the trench wall after water filling. Sandy soil should be backfilled between the geotextile 18 and the trench wall to fill the gaps.

[0058] The width of the water-air bag vibration isolation wall is 1.0m~2.0m, and the depth is 4m~6m. The depth of the trench depends on the physical and mechanical properties of the soil and the excavation depth of the excavating machinery, and can be determined by trial excavation.

[0059] The composite bag material (Type 16) must be a composite material with a tensile strength ≥15MPa, such as HDPE (high-density polyethylene) or PVC mesh fabric. The material must be resistant to ultraviolet radiation, acid and alkali corrosion, and temperature changes (-20℃ to 80℃), and its puncture strength must be ≥80N. The tensile strength of the composite bag material and its seams should meet the following requirements: In the formula, T h γ is the tensile strength (kN / m) of the composite bag 16 material and its seams; K is the safety factor, taken as 2.0~3.0; h is the height of the composite bag 16 (m); γ w The specific weight of water (kN / m³) 3 ).

[0060] Geotextile 18 refers to woven geotextile 18 with a unit mass of not less than 200g / m.2 Tensile strength ≥10kN / m (longitudinal and transverse), elongation at break (longitudinal / transverse) 10%~30%, CBR bursting strength ≥1.8kN, tearing strength (longitudinal / transverse) ≥0.8kN.

[0061] Technical requirements for valve 17 of composite bag 16: The body of valve 17 must be made of stainless steel, with a design pressure ≥ 0.6 MPa and a corrosion allowance ≥ 2 mm. Valve 17 must have a fully open / fully closed function. The flow rate at a dynamic pressure of 0.05 MPa must be ≥ 0.05 L / s, and the flow rate at 0.5 MPa must be ≤ 0.33 L / s.

[0062] Regarding the selection of vibration isolation wall 8: The selection of vibration isolation wall 8 should follow these principles: ① Reliable, able to meet the vibration isolation requirements of the protected building; ② Relatively simple and easy to implement; ③ Adaptable to local conditions, using local materials; ④ Relatively economical cost. The characteristics of the above four types of vibration isolation walls 8 are as follows: 1. Deep mud mixing pile 15 vibration isolation wall is a reliable, feasible and mature vibration isolation wall 8. For various vibration isolation requirements, the required vibration isolation effect can be achieved by adjusting its depth and width; however, its cost is relatively high.

[0063] 2. The three vibration isolation measures—mud slurry vibration isolation walls, mud-straw vibration isolation walls, and water-air bag vibration isolation walls—share a common feature: they all require trenching followed by backfilling. Their vibration isolation effectiveness depends on the depth to which the trench can be excavated. These three types of vibration isolation walls have varying vibration isolation effects, with water-air bag vibration isolation walls offering slightly better results, but the differences are not significant. The choice of which vibration isolation wall to use mainly depends on material resources. If mud slurry resources are readily available and there is no need to purchase clay materials externally, mud slurry vibration isolation walls can be prioritized. If it is harvest season and materials such as straw can be purchased cheaply, mud-straw vibration isolation walls can be prioritized.

[0064] Therefore, for a specific project, the type of vibration isolation wall 8 can be determined through testing. This involves excavating a vibration isolation wall 8 (such as a water-air bag vibration isolation wall) and verifying its ability to meet vibration isolation requirements. If it meets the required vibration isolation requirements, then, based on the aforementioned comparison principles, one type of vibration isolation wall 8 can be selected for implementation from water-air bag vibration isolation walls, mud-straw vibration isolation walls, and mud slurry vibration isolation walls. If it fails to meet the relevant vibration isolation requirements, then a deep mud-mixing pile 15 vibration isolation wall is selected as the implemented vibration isolation structure.

[0065] The monitoring system is used to monitor the impact of dynamic compaction on different locations and to understand the safety status of tailings dam 7 during the construction process. This monitoring information is used to guide the dynamic compaction construction, and if necessary, construction can be stopped immediately, the compaction parameters adjusted, and then construction can resume to fully ensure the safety of tailings dam 7.

[0066] The monitoring system includes a surface displacement monitoring device, a deep displacement monitoring device 12, a vibration parameter monitoring device, a pore water pressure monitoring device, and a permeability pressure monitoring device 14. The vibration parameter monitoring device uses a vibration pickup meter, the deep displacement monitoring device 12 uses an inclinometer, the pore water pressure monitoring device uses a pore water pressure gauge, the permeability pressure monitoring device 14 uses a piezometer, and the surface displacement monitoring device uses a total station.

[0067] The layout, installation, data collection and processing of monitoring points, as well as the early warning values ​​of monitoring indicators such as the leaching line, shall be carried out in accordance with the relevant provisions of the following specifications: "Safety Regulations for Tailings Dams (GB 39496-2020)", "Technical Specifications for Safety Monitoring of Tailings Dams (AQ2030-2010)", and "Technical Specifications for Online Safety Monitoring Systems of Tailings Dams (GB51108 2015)".

[0068] like Figure 4 As shown, the approximate locations of each monitoring point are indicated: The surface displacement monitoring device includes a first surface displacement monitoring point 10-1, a second surface displacement monitoring point 10-2, and a third surface displacement monitoring point 10-3, which are respectively arranged on the top of the tailings dam 7 and the top of the soil between the vibration isolation wall 8 and the tailings dam 7. The deep displacement monitoring device 12 is arranged between the vibration isolation wall 8 and the tailings dam 7, close to the tailings dam 7; The vibration parameter monitoring device includes a first vibration parameter monitoring device 11-1, a second vibration parameter monitoring device 11-2, a third vibration parameter monitoring device 11-3, and a fourth vibration parameter monitoring device 11-4, which are respectively arranged on the top of the tailings dam 7, the top of the soil between the vibration isolation wall 8 and the tailings dam 7 near the tailings dam 7, and the top of the soil near both sides of the vibration isolation wall 8. The pore water pressure monitoring device includes a first pore water pressure monitoring device 13-1, a second pore water pressure monitoring device 13-2, and a third pore water pressure monitoring device 13-3, which are respectively arranged in the soil between the vibration isolation wall 8 and the tailings dam 7 near the tailings dam 7, and in the soil near both sides of the vibration isolation wall 8. The seepage pressure monitoring device 14 is installed inside the tailings dam 7 to monitor the seepage pressure.

[0069] like Figure 10 As shown, the methods for treating tailings ponds using this system include: (1) Collect data; like Figure 11 As shown, taking a tailings dam as an example, relevant information about the tailings dam and tailings dam 7 is collected, with a focus on understanding the structure and safety status of tailings dam 7, the distribution and physical and mechanical properties of tailings soil, the groundwater level of the tailings dam, and the drainage system of the tailings dam.

[0070] (2) Design of preliminary dynamic compaction construction scheme 1) The vibration isolation wall 8 is set parallel to the tailings dam 7, with a distance of 10~20m between them. For the proposed location of the vibration isolation wall 8, the safety factor of the tailings dam 7 after setting a certain vibration isolation wall 8 should be calculated according to the relevant specifications, and the calculation results must meet the specifications.

[0071] 2) The type of vibration isolation wall 8 to be used should be determined after comprehensive consideration of factors such as vibration isolation requirements, site soil conditions, trench excavation depth, weather conditions, and cost of vibration isolation wall 8; if necessary, the type of vibration isolation wall 8 can be determined through on-site testing.

[0072] 3) Monitoring Design: Vibration pickup meters are used to monitor the impact range of dynamic compaction vibration; pore water pressure gauges and piezometers are mainly used to monitor changes in the phreatic line of tailings dam 7 and potential signs of sand liquefaction; surface displacement monitoring devices and deep displacement monitoring devices 12 are mainly used to monitor the deformation and stability of the dam. Instrument parameter requirements, installation requirements, monitoring frequency, and monitoring methods (manual and automatic monitoring) must all comply with relevant specifications.

[0073] 4) Key points of dynamic compaction design: a) The main purpose of dynamic compaction is to reduce the elevation of the tailings dam surface; no requirements are placed on the bearing capacity of the site or the uniformity of the tailings soil; b) Use a multi-layer rubber pad vibration damping hammer, with a hammer weight of 20-60t, a cylindrical hammer, and a hammer base diameter of 1.2-2.5m; c) The single-point impact energy should be 1000-11000kN·m, determined through trial compaction. A higher impact energy should be used provided that the dynamic compaction vibration does not cause the tailings dam to exceed the specifications; d) The spacing between compaction points should be 2.0-3.0 times the hammer diameter; e) Hammer termination criteria: The average settlement of the last two blows should not exceed 100mm, the ground around the compaction pit should not experience excessive bulging, and there should be no difficulty in lifting the hammer due to excessive pit depth; f) After completing the point compaction, level the site with a bulldozer; g) Perform a full compaction within the dynamic compaction area, with a 1 / 4 overlap between compaction points. The impact energy is 1000~1500 kN·m.

[0074] (3) Construction of vibration isolation wall 8 Based on the aforementioned method of selecting the vibration isolation wall 8, a vibration isolation wall 8 is selected for implementation.

[0075] The tailings dam uses water-air bag vibration isolation walls. The specific construction steps include: 1) Vibration isolation wall 8, 320m long.

[0076] 2) Main parameters of the water-air bag vibration isolation wall: width 1.5m, depth 6m. Dimensions of a single composite bag: width 1.5m, height 5.8m, length 5~6m. A total of 164 5m long composite bags and 1650 6m long composite bags are required.

[0077] 3) Perform a 24-hour air pressure seal check on all composite bags 16. Pressurize the composite bag 16 with 60 kPa and close the valve. Within 24 hours, the pressure inside the composite bag 16 must not be less than 59 kPa.

[0078] 4) Main work process for installing water-air bag vibration isolation wall: Inflate composite bag 16 → Excavate trench → Sink composite bag 16 → De-inflate composite bag 16 and fill with water.

[0079] 5) Inflate the composite bag 16 with low-pressure air, with a pressure value not exceeding 10 kPa; use geotextile 1818 as follows: Figure 7 Wrap the composite bag 1616 from bottom to top, and then use double-sided tape to attach the geotextile 1818 to the composite bag 1616.

[0080] 6) Use an excavator to dig trenches according to the planned dimensions of the vibration isolation trench, and remove sharp objects such as branches and wires from the bottom and sidewalls of the trenches.

[0081] 7) When the trench excavation length is approximately the length of two composite bags 16, the geotextile 1818 and composite bags 1616 can be promptly lowered to the bottom of the trench.

[0082] 8) Open valve 17 of composite bag 16 and fill composite bag 16 with water using a water pump. The water filling level should not be lower than the groundwater level. In low-temperature seasons (temperatures below -5°C), the water filling level should not be higher than 85% of the height of composite bag 16.

[0083] 9) If the trench is too wide, gaps will appear between the composite bag 16 and the trench wall after water filling. Sandy soil should be backfilled between the geotextile 18 and the trench wall to fill the gaps.

[0084] 10) Repeat steps 5) to 9) to install the remaining composite bags 16.

[0085] (4) Install and debug monitoring equipment 1) such as Figure 4 As shown, vibration sensors, pore water pressure gauges, osmotic pressure gauges, and ground displacement measuring points are installed according to design requirements and relevant specifications.

[0086] Installation of the vibration sensor: Select the installation location according to the design requirements. Dig a pit with a diameter of approximately 20-30cm and a depth of 50-100cm in the ground, ensuring the bottom of the pit is flat and compacted. Place the vibration sensor vertically into the bottom of the pit, and backfill the surrounding area with fine soil or gravel, compacting it in layers to ensure close contact between the vibration sensor and the soil. The installation direction of the vibration sensor must be consistent with the direction of the monitored vibration to avoid signal distortion caused by angular deviation. The vibration sensor cable should be led out from the pit wall, pass through a PVC flexible conduit to the ground surface, and prevent it from being damaged by soil compression. Seal the ground outlet with sealant to prevent rainwater from seeping in.

[0087] Installation of pore water pressure gauges: Select the installation location according to design requirements. Each group of pore water pressure gauges consists of 3-5 probes, installed at different depths, with one probe installed every 3-5 meters. Each probe is installed individually per borehole; probes in the same group must be drilled and installed separately, and cannot be installed in the same borehole. During installation, the probes must be kept fully saturated, and no air should be present inside the probe cavity or within the permeable aggregate. After the probes are in place, seal the borehole with a dry bentonite ball.

[0088] 2) Debug all monitoring sensors, record the initial readings, and connect them to the online monitoring platform.

[0089] 3) During the dynamic compaction construction process, the entire process is monitored and the monitoring data is transmitted online in real time.

[0090] Throughout the entire process of dynamic compaction construction, the safety monitoring and early warning handling of tailings dam 77 shall be carried out according to the following procedures: ①The main control parameters for the safety of tailings dam 7 are: the burial depth of the wetting line, the peak vibration velocity of tailings dam 7, and the change in pore water pressure, etc. ② Establish a monitoring data sharing platform, and upload all monitoring data to the platform in real time; ③ A safety monitoring team was established to monitor and assess the safety of tailings dam 7; ④ If a warning situation occurs, immediately activate the early warning response: immediately stop the dynamic compaction construction. Relevant technical personnel should immediately retrieve data through the data sharing platform to analyze the cause of the warning; ⑤ Technical personnel went to the site to further understand the situation, confirm the cause of the warning, and discuss adjustments to the construction plan; ⑥ Conduct trial compaction according to the revised construction plan. If the trial compaction results confirm that the new construction plan is safe, continue the dynamic compaction construction according to the new plan.

[0091] (5) Perform zoned test compaction to determine the number of vibration damping pads and compaction parameters to be used in each zone.

[0092] 1) Divide the construction area into zones. For example... Figure 3 As shown, A represents the range of the dynamic compaction treatment area, and D represents the distance between the tailings dam 7 and the vibration isolation wall 8. Each zone is set at a distance K (K=30~50m) from the mud vibration isolation ditch, and is divided into zones A1, A2, A3, A4, etc. In each zone, a 20*20m area is selected on the side closest to the tailings dam 7 for test compaction, i.e., test zone 9, to determine the dynamic compaction parameters of the zone.

[0093] 2) Vibration control index for test compaction: During dynamic compaction, the peak vibration velocity measured by the vibration pickups (9-1 and 9-2) near the tailings dam 7 shall not exceed the control value in Table 7.4.6 of the "Standard for Allowable Vibration of Building Engineering" (GB50868-2013).

[0094] 3) Test compaction method: ① Select a vibration-damping tamper with n layers of rubber pads, and perform test compaction with single-click impact energy of k×500kN・m (k=1,2,3,…,p), where p is determined according to the maximum lifting height of the vibration-damping tamper. If when k=j (j≤p), the vibration index (such as acceleration) is close to or just exceeds the allowable control value (e.g., vibration index ∈ [0.98×allowable control value, 1.02×allowable control value]), then the dynamic compaction parameters for this zone are: the vibration-damping tamper has n layers of rubber pads, and the single-click impact energy is (j-1)×500 kN・m. ② If the vibration-damping tamper has n layers of rubber pads, and the vibration index still does not exceed 0.98 × allowable control value when the single-shot impact energy reaches the planned maximum impact energy p × 500 kN·m, then reduce the number of rubber pad layers by one and test tamping again until the number of rubber pad layers is f. When the vibration index is close to or just exceeds the allowable control value, the dynamic compaction parameters for the zone are: the number of rubber pad layers of the vibration-damping tamper is (f+1) layers, and the single-shot impact energy is the planned maximum impact energy. ③ If the number of rubber pad layers is 0, and the vibration index still does not exceed 0.98 × allowable control value when tamped with the maximum impact energy, then the impact energy for this zone is the planned maximum impact energy, and rubber pad vibration damping is not required. ④ Based on the number of vibration-damping rubber pad layers and single-point impact energy determined by the above test compaction, further test compaction should be carried out in accordance with the relevant provisions of the "Technical Specification for Dynamic Compaction Foundation Treatment (CECS+279-2010)" to determine more reasonable parameters such as compaction point spacing, number of single-point impacts, number of compaction passes, and cessation of compaction.

[0095] (6) Zonal dynamic compaction. Based on the number of rubber pad layers and dynamic compaction parameters determined by the trial compaction, dynamic compaction is carried out on each zone according to the following procedure: 1) Clear and level the construction site, and measure the site elevation; 2) Lay out the position of point 19 for the first round of dynamic compaction; 3) Position the crane, place the tamping hammer at the first strong compaction point 19, and measure the hammer top elevation before compaction; 4) Lift the rammer to the predetermined height, activate the release device, and allow the rammer to fall freely. After the rammer lands, lower the hook and measure the elevation of the top of the rammer. If the rammer is found to be tilted due to the inclination of the pit bottom, the pit bottom should be leveled in time. 5) Repeat step 4) to complete the compaction of a single compaction point according to the planned number of compaction blows and the principle of stopping compaction; 6) Change the tamping point and repeat steps 3) to 5) to complete the first round of tamping at point 19. Figure 8 As shown; 7) After the specified time interval (7 to 10 days, depending on the dissipation of pore water pressure after the first round of dynamic compaction), complete the second round of dynamic compaction at point 20 according to steps 2) to 6) above. 8) Level the site with a bulldozer; 9) Use low compaction energy (1000~1500 kN·m) to compact this zone according to the full compaction point 21, such as... Figure 9 As shown; 10) Use a bulldozer to level the compacted ground. 11) Measure the elevation of the ground after dynamic compaction and calculate the total compaction settlement volume; 12) Drain the water from composite bag 16; 13) Recycle composite bags 16 and geotextiles 18.

[0096] 14) Use a bulldozer to backfill the vibration isolation wall with soil on site.

[0097] If the vibration isolation wall 8 is a mud vibration isolation wall, then the mud slurry 1-2m thick on the surface of the mud vibration isolation wall is dug out and spread on the ground, and then the trench is backfilled with tailings soil and compacted.

[0098] Throughout the entire process of dynamic compaction, the stability and safety status of tailings dam 7 is monitored in real time, and the dynamic compaction construction is monitored and guided throughout the entire process. If the vibration index of tailings dam 7 exceeds the allowable control value due to dynamic compaction, or if there is an abnormality in the seepage line of tailings dam 7, the dynamic compaction construction must be stopped immediately; the relevant causes must be analyzed and the compaction parameters modified before the dynamic compaction construction can continue.

[0099] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A dynamic compaction device for reducing the elevation of tailings dam surface, characterized in that: The device includes a vibration-damping ram, which includes a mother hammer (2). The hammering end of the mother hammer (2) is provided with repeatedly stacked vibration-damping pads (5) and rigid pads (6). The rigid pads (6) include multiple spacers and a bottom pad. The spacers are arranged between two vibration-damping pads (5). The bottom pad is arranged on the outermost side furthest from the hammering end. The vibration-damping pads (5) and the rigid pads (6) are fixedly connected to the mother hammer (2) by a connector (3).

2. The dynamic compaction device for reducing the elevation of tailings dam surface according to claim 1, characterized in that: The hammer (2) has a threaded hole at the hammering end. The connector (3) is a long bolt with a thread only at the bottom. The part of the long bolt that passes through the damping pad (5) and the rigid pad (6) is a smooth circular surface.

3. The dynamic compaction device for reducing the elevation of tailings dam surface according to claim 1, characterized in that: The thickness of the bottom gasket is greater than that of the spacer.

4. The dynamic compaction device for reducing the elevation of tailings dam surface according to any one of claims 1 to 3, characterized in that: The vibration damping pad (5) is made of high-damping rubber, neoprene rubber, or natural rubber.

5. The dynamic compaction device for reducing the elevation of tailings dam surface according to any one of claims 1 to 3, characterized in that: The rigid pad (6) is made of Q355B structural steel.

6. A system for reducing the elevation of a tailings dam surface, characterized in that: The device for reducing the elevation of the tailings dam surface, as described in any one of claims 1 to 5, further includes a vibration isolation wall (8) arranged between the dynamic compaction area and the tailings dam (7).

7. The system for reducing the elevation of tailings dam surface according to claim 6, characterized in that: The vibration isolation wall (8) includes a deep mud mixing pile (15) vibration isolation wall, or a mud vibration isolation wall, or a mud-grass vibration isolation wall, or a water-air bag vibration isolation wall.

8. The system for reducing the elevation of tailings dam surface according to claim 7, characterized in that: The water-air bag vibration isolation wall includes multiple composite bags (16), and a valve (17) is provided on the top of the composite bag (16). The valve (17) is used to control the connection between the composite bag (16) and the outside world. The composite bag (16) contains water and gas. The height of the water is not less than the groundwater level. The gas is located above the water and the pressure of the gas is between 20 and 30 kPa.

9. The system for reducing the elevation of tailings dam surface according to claim 7, characterized in that: The mud-straw vibration isolation wall includes a straw wall and an earthen wall, with the straw wall located below the earthen wall.

10. The system for reducing the elevation of a tailings dam surface according to any one of claims 6 to 9, characterized in that: The system includes a monitoring system, which includes a surface displacement monitoring device, a deep displacement monitoring device (12), a vibration parameter monitoring device, a pore water pressure monitoring device, and a permeability pressure monitoring device (14). The monitoring points of the surface displacement monitoring device are arranged on the top of the soil between the vibration isolation wall (8) and the tailings dam (7) and on the top of the tailings dam (7) to monitor horizontal and vertical displacement. The deep displacement monitoring device (12) is arranged between the vibration isolation wall (8) and the tailings dam (7) near the tailings dam (7) to monitor the deep horizontal displacement; The vibration parameter monitoring device is arranged on the top of the soil near both sides of the vibration isolation wall (8), the top of the tailings dam (7), and the top of the soil near the tailings dam (7) between the vibration isolation wall (8) and the tailings dam (7) to monitor vibration parameters. The pore water pressure monitoring device is arranged in the soil near both sides of the vibration isolation wall (8) and in the soil near the tailings dam (7) between the vibration isolation wall (8) and the tailings dam (7) to monitor the pore water pressure. The permeation pressure monitoring device (14) is arranged inside the tailings dam (7) to monitor permeation pressure.

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