Earth and rockfill dam burst danger emergency rescue construction method and construction device

Abstract

The invention relates to the technical field of river embankment emergency rescue, in particular to an earth and rockfill dam burst danger emergency rescue construction method and a construction device.The earth and rockfill dam burst danger emergency rescue construction method comprises the steps that dam burst site parameters are obtained and comprise the dam water storage height, the dam burst notch width and the dam burst notch height; the breach gap width is compared with a preset critical width threshold value, if the breach gap width is smaller than the critical width threshold value, it is judged that a small breach danger exists, and then the piling depth is directly determined to achieve rapid blocking; otherwise, judging the dangerous case of large-scale dike burst, and carrying out the next step; according to the dam water storage height and the dam burst gap width, the water flow speed at the dam burst position is calculated, and the area of a water passing section defined by the piling route is calculated based on the water flow speed at the dam burst position so as to determine the piling route; and the piling position is set according to the piling route, emergency construction piling is implemented, a cofferdam structure is formed, and the dam burst position is reinforced and repaired. The piling line can be adjusted according to the actual flood scale and the size of the breakthrough notch, and the seepage-proofing and flood-preventing efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of riverbank rescue, and in particular to a construction method and a construction device for emergency rescue of earth-rock dam breach. Background Art

[0002] In recent years, with global warming, rainfall has increased year by year compared to the previous year, resulting in frequent floods in some areas, especially in some lake areas that were formed earlier. Most of these areas still use earth-rock dams with lower strength for flood control and water storage. Moreover, with years of biological action and water erosion, the flood control capacity of local areas of the dam body has declined. When faced with the challenge of heavy rainfall, seepage, piping, and even dam failure will occur, posing a huge threat to the lives and property of downstream residents. However, most of the existing plastic-steel sheet pile rescue devices for earth-rock dam breach emergency construction methods can only play a role in the early stages of the emergency. They have a certain effect on seepage and piping before the dam breach, but when the dam body breaches, these devices are difficult to withstand the surging flood. In addition, since it is difficult to drive the existing plastic-steel sheet piles into the underground bearing layer, they are easily washed away under the greater water pressure. The sheet pile integrated structure is also difficult to install in larger water flow. If the sheet piles are directly washed away by the flood, it will not only cause a waste of resources, but also cause the flood to spread further at the critical moment of rescue, posing a huge threat to people's lives and property.

[0003] Existing patent CN201710328410.2 proposes an interception net for dam breaches and its construction method. This technical solution uses steel piles and steel cables to bear the load, reducing the flow rate of the water at the breach. However, this technical solution ignores the difficulty of piling under large water flows and lacks a detailed explanation of the stability of the pile body in the water flow. Existing patent CN03100067.3 proposes an anchor box for flood control and river diversion and its use method. By transporting anchor iron plates using a high-powered air cushion vessel, before or at the same time as the anchor box arrives, the air cushion vessel's own lightweight mechanical device throws the iron plates into the water downstream of the breach, protecting the embankment foundation and the embankment roots on both sides from being collapsed by the flood, and preventing the breach from tearing and expanding. Although this technical solution has designed a large-scale anchoring box that can cope with large drops, it does not take into account the difficulty of lowering the anchoring box under conditions of excessive water flow. In addition, the case of the Dongting Lake dike burst in 2024 has shown that when the water flow speed is too high, heavy trucks will be washed away. This anchoring box does not have a specific and reasonable casting route designed for the water flow speed to avoid water flow resistance, and the anchoring box may be directly washed away. Summary of the Invention

[0004] In view of this, the present invention proposes a construction method and a construction device for emergency rescue of earth-rock dam breach, so as to solve the technical problems that the existing emergency rescue construction method for earth-rock dam breach is difficult to achieve rapid sealing of large-scale breach hazards, and the existing construction device has poor anchoring effect.

[0005] The technical solution of the present invention is achieved as follows: The present invention provides a construction method for emergency rescue of earth-rock dam breach, comprising the following steps:

[0006] S1. Obtain the parameters of the dam breach site, including the dam water storage height, breach gap width, and breach gap height;

[0007] S2. Compare the width of the breach with a preset critical width threshold. If the breach width is less than the critical width threshold, it is determined to be a small breach, and the piling depth is directly determined to achieve rapid plugging. Otherwise, it is determined to be a large breach, and the next step is performed.

[0008] S3. Calculate the water velocity at the breach according to the dam water storage height and the breach gap width. Calculate the cross-sectional area of the piling route based on the water velocity at the breach to determine the piling route.

[0009] S4. Setting the piling position according to the piling route;

[0010] S5. Carry out emergency construction and pile driving according to the pile driving location to form an anti-seepage and anti-scouring cofferdam structure;

[0011] S6. Strengthen the cofferdam structure, address leakage points, and repair breaches after the cofferdam stabilizes.

[0012] On the basis of the above technical solution, preferably, in step S2, the types of small dam breach hazards are divided into initial piping hazards and small dam breach breaches according to whether a dam breach breach occurs. The initial piping hazard is that the dam breach breach has not yet occurred, and the small dam breach breach is that the dam breach breach occurs but the gap width is less than the critical width threshold. The piling depth is determined according to the type of small dam breach hazard.

[0013] On the basis of the above technical solution, preferably, when the dangerous situation is an initial piping dangerous situation, the piping channel parameters and the soil permeability coefficient are obtained, the theoretical minimum piling depth is obtained according to the piping channel parameters, the seepage path depth is calculated according to the soil permeability coefficient, and the theoretical maximum piling depth value is calculated. 130% of the theoretical maximum piling depth value is taken as the actual piling depth;

[0014] When the dangerous situation is a small breach, the empirical piling depth is calculated according to the height of the breach, and the anti-overturning safety factor is verified according to the theoretical formula method to obtain the theoretical minimum piling depth. The theoretical maximum piling depth is calculated based on the theoretical minimum piling depth and the empirical piling depth, and 130% of the theoretical maximum piling depth is taken as the actual piling depth.

[0015] Based on the above technical solution, preferably, step S3 of calculating the water flow velocity at the dam breach specifically includes: calculating the hydraulic radius of the water flow section at the dam breach gap according to the dam water storage height and the width of the dam breach gap, calculating the channel bottom slope according to the height difference between the two ends of the water flow channel at the dam breach and the bottom width of the dam body, substituting the hydraulic radius and the channel bottom slope into the Manning formula to calculate the water flow velocity at the dam breach. The expression of the water flow velocity at the dam breach is as follows:

[0016]

[0017] Where V1 is the water velocity at the breach, in m / s; ψ is the correction coefficient, which is 1.05-1.1; n is the Manning roughness coefficient, which is 0.02-0.04; b is the width of the breach gap; h is the water storage height of the dam. represents the hydraulic radius; ΔL represents the height difference between the two ends of the water channel at the breach; L represents the bottom width of the dam body. Indicates the channel bottom slope.

[0018] Based on the above technical solution, preferably, in step S3, the cross-sectional area of the water flow formed by the piling route is calculated based on the water flow velocity at the breach site to determine the piling route, which specifically includes:

[0019] S31, assuming that the pile body only relies on the pile side soil resistance to resist the horizontal force of water flow in the horizontal direction, based on the elastic foundation reaction method, calculate the total lateral soil resistance of the pile body at depth z according to the pile burial depth and pile diameter;

[0020] S32, assuming that the horizontal force on the pile body in flowing water mainly comes from the drag force of the water, and based on the fact that the drag force on the pile body in flowing water is less than the total lateral soil resistance on the pile body, obtain the water flow velocity at the piling location;

[0021] S33, based on the flow rate remaining unchanged, calculating the cross-sectional area of water flow enclosed by the piling route according to the water flow velocity at the piling location;

[0022] S34, setting the piling route to an arched route with a central angle of 120° and a length of l, wherein the value of l is calculated based on the water-passing cross-sectional area, and determining the piling route based on the arched route.

[0023] On the basis of the above technical solution, preferably, in step S32, according to It is deduced that:

[0024]

[0025] Where F represents the drag force, C dis the drag coefficient, ρ is the density of water, A is the projected area of the pile perpendicular to the direction of water flow, V2 is the water velocity at the pile driving point, P is the total lateral soil resistance, k s is the horizontal resistance coefficient of foundation soil, D is the pile diameter, z is the depth, y is the lateral displacement of the pile, and L is the pile burial depth;

[0026] In step S33, according to Q=A1V1=A2V2, we get but:

[0027]

[0028] Where Q represents the flow rate, A2 represents the cross-sectional area of the water flow enclosed by the piling route, A1 represents the cross-sectional area of the water flow at the breach, and V1 represents the water flow velocity at the breach.

[0029] Based on the above technical solution, preferably, in step S34, the distance between the farthest piling position and the dam body is set to d1, and the straight-line distance between the piling points at both ends is d2, then the following relationship exists between l, d1, and d2:

[0030]

[0031] Where, A2 represents the cross-sectional area of water flow enclosed by the piling route, and h represents the water storage height of the dam.

[0032] On the basis of the above technical solution, preferably, step S5 includes: according to the determined piling route, supporting piles are driven from both ends of the route to the middle, and the supporting piles are driven into the underwater soil bearing layer; the plastic steel sheet piles are driven into the underwater soil layer with the support piles, and are fixed with the help of anchor rods and support piles, and a seepage-proof and scour-resistant cofferdam structure is constructed by the support piles and the plastic steel sheet piles; the displacement of the pile top is monitored in real time, and supporting piles are added behind the pile body that exceeds the limit displacement.

[0033] The present invention also provides a construction device for emergency rescue of earth-rock dam breach, the construction device is used to implement the construction method as described above, the construction device includes supporting piles and plastic steel sheet piles, the supporting piles include guard plates and H-shaped steels, the plastic steel sheet piles are provided with limiting grooves and limiting block structures for connection, a plurality of plastic steel sheet piles are connected and fixed by limiting grooves and limiting blocks, the supporting piles are arranged at intervals on the piling route and driven into the underwater soil bearing layer, the plastic steel sheet piles are arranged relying on the supporting piles and are connected and fixed to the supporting piles by anchor rods, and the supporting piles and the plastic steel sheet piles are used in combination to form a cofferdam structure with anti-scouring and anti-seepage functions.

[0034] On the basis of the above technical solution, preferably, a plurality of limit grooves are provided inside the plastic-steel sheet pile, and the plurality of limit grooves are separated by ribs. The limit block extends along one end away from the limit groove and is used to connect with the corresponding limit groove of the next plastic-steel sheet pile.

[0035] The earth-rock dam breach emergency rescue construction method and construction device of the present invention have the following beneficial effects compared with the prior art:

[0036] (1) The designed piling route not only meets the feasibility, but also takes into account the economic issues. When the flood season comes, many traditional methods such as the riprap method and the caisson method become ineffective in the face of a major flood. In addition, the case of the Dongting Lake dam breach in 2024 has shown that heavy trucks will be washed away in the face of a large water flow. It is obviously not feasible to block the gap by hard resistance. However, the present invention has achieved a scientific treatment of the entire process from risk assessment, scheme design to construction implementation by establishing a systematic earth-rock dam breach emergency construction method. It can adjust the piling route according to the actual flood scale and the size of the breach gap. On the one hand, by extending the distance from the piling point to the breach mouth, it ensures that the water flow velocity at the piling point is reduced to meet the piling requirements, solving the problem that the existing device is difficult to pile at the breach due to excessive water flow, avoiding the device being washed away by the water flow, and ensuring the stability of the pile body under the water pressure. On the other hand, the algorithm route of the present invention also takes into account the problem that the piling route that is too far away from the breach mouth meets the construction requirements of piling but the construction cost will be too high. The proposed route is both effective and saves construction costs to the greatest extent.

[0037] (2) Classify and handle dangerous situations. By subdividing small embankment breach hazards into initial piping hazards and small embankment breach gaps, and using pile depth calculation methods based on piping channel parameters and anti-overturning safety factors, accurate handling of different types of dangerous situations is achieved.

[0038] (3) Convenient construction. For small-scale dam breaches, pile driving operations can be carried out directly on the original dam body by using automobile transport equipment, thereby improving rescue efficiency. For large-scale dam breaches, pile driving operations can be carried out directly on the distant water surface by using transport ships, thereby improving rescue efficiency.

[0039] (4) Computational science: The Manning formula is used to calculate the water flow velocity at the breach point, taking into account key parameters such as the hydraulic radius and the channel bottom slope, so that the hydraulic calculation is more in line with the actual working conditions, providing reliable data support for the subsequent construction plan design; the arch pile driving route is designed based on the elastic foundation reaction method and the flow conservation principle. By optimizing the pile driving position and spacing, the overall stability of the cofferdam structure is guaranteed, and the water flow is effectively guided, reducing the impact of the water flow on the cofferdam structure.

[0040] (5) The piling route adopts an arch route with a central angle of 120° and a length of l. When the central angle is in the range of 90°-150°, the mechanical properties of the arch are relatively balanced. When selecting the central angle, the arch design with a central angle of 120° is determined by considering the comprehensive factors of force and construction. The horizontal thrust generated by the arch design with a central angle of 120° when bearing vertical load is relatively moderate. The axial pressure can be effectively transmitted to the arch foot along the axis of the arch, reducing the water pressure on the pile body. Compared with the arch design with other angles, the 120° angle design is relatively simpler in engineering implementation. It is easy to control the construction accuracy during the actual construction process. At the same time, it can maintain a reasonable spacing in the pile foundation layout, reducing construction risks.

[0041] (6) The present invention also provides a construction device consisting of sheet piles and support piles. The sheet piles and the support piles, as well as the sheet piles themselves, are tightly connected and have good water-stopping properties. They can further block floods on the basis of slowing down the water flow at the dam break. At the same time, the design of the separate support piles and plastic-steel sheet piles allows them to be installed smoothly even in the case of turbulent water flow and broken dams. They have strong flood resistance and bearing capacity. Through material innovation and structural optimization, the stability and durability of the plastic-steel sheet piles are improved, and they can effectively resist flood erosion. Fluid mechanics principles and mechanical optimization algorithms are used to optimize the cross-sectional shape and wall thickness distribution of the sheet piles, thereby enhancing the stability of the structure. When a dam break occurs, a flood defense line can be quickly formed, effectively preventing the further spread of floods. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 This is a flow chart of the emergency rescue construction method for earth-rock dam breach crisis of the present invention;

[0044] Figure 2 This is a simulation rendering of the piling route for a large embankment breach according to the present invention;

[0045] Figure 3 A schematic diagram of a small-sized dam breach plugging method according to the present invention;

[0046] Figure 4 A schematic diagram of the lengthened support pile of the present invention;

[0047] Figure 5 This is a schematic diagram of the plastic-steel sheet pile structure of the present invention;

[0048] Figure 6 This is a schematic diagram of the splicing of plastic-steel sheet piles of the present invention;

[0049] Figure 7 is a schematic diagram of a combined sheet pile of the present invention;

[0050] Figure 8 is a schematic diagram of a reinforced sheet pile according to the present invention;

[0051] Figure 9 This is a top view of the reinforcement sheet pile of the present invention.

[0052] The reference numerals are as follows:

[0053] 1. Support pile; 11. H-shaped steel; 12. Guard plate; 2. Plastic steel sheet pile; 21. Limit groove; 22. Limit block; 221. Inner extension block; 222. Outer extension block; 23. Rib; 24. Screw hole; 25. Bolt; 26. Nut. DETAILED DESCRIPTION

[0054] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] like Figure 1-2 As shown, the present invention proposes a construction method for emergency rescue of earth-rock dam breach, comprising the following steps:

[0056] S1. Rapidly obtain on-site parameters of the dam breach, including dam water storage height, breach gap width, and breach gap height;

[0057] S2. Compare the width of the breach with a preset critical width threshold. If the breach width is less than the critical width threshold, it is determined to be a small breach, and the piling depth is directly determined to achieve rapid plugging. Otherwise, it is determined to be a large breach, and the next step is performed.

[0058] S3. Calculate the water velocity at the breach according to the dam water storage height and the breach gap width. Calculate the cross-sectional area of the piling route based on the water velocity at the breach to determine the piling route.

[0059] S4. Setting the piling position according to the piling route;

[0060] S5. Carry out emergency construction and pile driving according to the pile driving location to form an anti-seepage and anti-scouring cofferdam structure;

[0061] S6. Strengthen the cofferdam structure, address leakage points, and repair breaches after the cofferdam stabilizes.

[0062] Figure 2The simulation effect diagram of the piling route of a large embankment breach is shown. Figure 2 (a) is the effect diagram of the piling process. Figure 2 (b) is the effect diagram after the piling is completed. The earth-rock dam breach emergency rescue construction method of the present invention realizes the hierarchical treatment of the emergency and the optimal allocation of resources by scientifically distinguishing between small and large dam breach hazards and adopting differentiated response strategies; for large dam breach hazards, the water flow velocity and piling parameters are accurately calculated based on the hydraulic principles to ensure the scientific nature and stability of the cofferdam structure; by extending the distance from the piling point to the breach mouth, the water flow velocity at the piling point is ensured to meet the piling requirements, which solves the problem that the existing device is difficult to pile at the breach due to excessive water flow; during the construction process, an anti-seepage and anti-scouring cofferdam structure is formed, which effectively blocks the leakage channel and can withstand the impact of water flow; at the same time, the method includes a full-process solution from emergency treatment to permanent repair, which can not only quickly control the expansion of the emergency, but also provide a safety barrier for subsequent thorough repair, thereby improving the scientific nature, efficiency and reliability of the earth-rock dam breach rescue as a whole.

[0063] Specifically, in step S2, a critical width threshold for the breach is preset based on actual conditions. The acquired breach width is compared with the critical width threshold to determine the type of breach. If the breach width is less than the critical width threshold, it is determined to be a small breach, and the piling depth is directly determined to achieve rapid sealing. Otherwise, it is determined to be a large breach, and the next step is performed. The critical width threshold is set based on actual conditions.

[0064] Among them, the types of small embankment breach hazards can be further divided into initial piping hazards and small embankment breach breaches according to whether a embankment breach breach has occurred. Initial piping hazards are when a embankment breach breach has not yet occurred, and small embankment breach breaches are when a embankment breach breach has occurred but the breach width is less than the critical width threshold. The piling depth is determined according to the type of small embankment breach hazard. For piping hazards, considering that the breach has not yet occurred, plastic-steel sheet piles 2 can be directly driven in to cut off the piping channel. For small embankment breach breaches, considering that the embankment breach breach is small, although the local water flow is large, the breach can be quickly sealed by driving the entire pile body through the dam body on both sides that has not yet been damaged and expanded, as well as the underwater soil support. Specifically, Figure 3 As shown, Figure 3 (a) shows the side view of the effect of plugging a small breach. Figure 3 (b) shows the main visual effect of plugging a small breach in the dam.

[0065] If the breach has not yet occurred and only piping occurs, that is, the danger is in the initial stage of piping, the piping channel parameters are obtained by ground penetrating radar, including the piping channel diameter D1 and the buried depth H of the bottom of the piping channel. p , the soil permeability coefficient k is determined through on-site pumping tests.

[0066] The theoretical minimum piling depth is obtained based on the piping channel parameters:

[0067] D min =H p +nD1(n=2~3)

[0068] Considering that piping should not only block existing piping channels but also prevent new piping from occurring in the surrounding soil, the minimum depth of sheet piles (i.e., theoretical piling depth) is determined in conjunction with seepage network analysis to ensure that all possible seepage paths are cut off. The seepage path extension effect is then calculated to obtain the seepage path depth:

[0069]

[0070] Where L1 represents the depth of the seepage path, ΔH represents the water head difference, d represents the depth of the sheet pile embedded in the impermeable layer, and i c represents the critical hydraulic gradient, L0 represents the natural seepage path length when no piles are driven,

[0071] According to the theoretical minimum pile driving depth (D min ) and the seepage path depth to calculate the theoretical maximum piling depth. The final actual piling depth is the theoretical maximum piling depth with a 30% safety margin added. The final actual piling depth is calculated as follows:

[0072] D 总 =max(D min ,H p +d)×1.3

[0073] If the breach is small, that is, if the danger is a small breach, first use the empirical formula method to quickly estimate the empirical piling depth based on the breach height:

[0074] D 经验min =1.5H

[0075] Where H is the notch height.

[0076] Then, the anti-overturning safety factor is calculated according to the theoretical formula method to obtain the theoretical minimum piling depth:

[0077]

[0078] Where, γ ω is the bulk density of water, K p is the passive earth pressure coefficient, K a is the active earth pressure coefficient, γ soil Indicates the bulk density of soil.

[0079] The theoretical maximum piling depth is calculated based on the theoretical minimum piling depth and the empirical piling depth. The final actual piling depth is the theoretical maximum piling depth with a 30% safety margin added. The final actual piling depth is calculated as follows:

[0080] D 总 =max(D 经验min ,D 理论min )×1.3

[0081] This invention further categorizes small dam breaches into two types: incipient piping and small breach breaches, and accurately calculates piling depths based on these different types. For incipient piping, the actual piling depth is calculated by considering piping channel parameters and soil permeability. For small breach breaches, the actual piling depth is determined by combining breach breach height and the anti-overturning safety factor. This precise classification and calculation method significantly reduces reliance on experience during rescue operations and improves the reliability of the sealing effect.

[0082] If the hazard is a large-scale dam breach, the water flow velocity at the breach is calculated based on the dam water storage height and the width of the breach gap. The distance from the piling point to the breach mouth is extended to ensure that the water flow velocity at the piling point is reduced to meet the piling requirements. The water-passing cross-sectional area enclosed by the piling route is calculated based on the water flow velocity at the breach to determine the piling route.

[0083] First, calculate the water flow velocity at the breach:

[0084] Calculate the water flow rate V1 based on the theoretical formula method (Manning formula):

[0085]

[0086] Where V1 represents the water velocity in m / s; n is the Manning roughness coefficient, which is determined based on the soil type and surface conditions. Preferably, n is between 0.02 and 0.04. For soils containing debris such as stones, the n value will be higher. For example, for a relatively smooth clay breach, n is 0.025; for a breach with a large amount of gravel and weeds, n is 0.04. R is the hydraulic radius in meters, and S is the channel bottom slope (dimensionless).

[0087] For the cross-sectional area of the breach, A1 = b × h, and the wetted perimeter P = b + 2h, the hydraulic radius is Where ΔL is the height difference between the two ends of the water channel at the breach, and L is the bottom width of the dam body.

[0088] Furthermore, considering that the breach at the breach site will gradually enlarge under the scouring of flowing water, which is different from the actual theoretical situation, a correction coefficient ψ is added to the original theoretical formula. ψ is related to the time t. However, considering that the breach rescue was completed in a short time and corresponding measures were taken to prevent the breach from further expanding, ψ was set between 1.05 and 1.1. Substituting R, S and ψ into the Manning formula, the calculation expression of the water flow velocity at the breach site is obtained as follows:

[0089]

[0090] Where V1 represents the water velocity at the breach, in m / s; ψ represents the correction coefficient; b represents the width of the breach gap; and h represents the water storage height of the dam.

[0091] This method uses the Manning formula to calculate the flow velocity at the breach site, comprehensively considering multiple parameters such as the dam's water storage height, breach breach width, hydraulic radius, and channel bottom slope. This results in more accurate flow velocity calculations. This provides a reliable hydraulic parameter foundation for the subsequent piling route design, ensuring the cofferdam structure has sufficient hydraulic resistance.

[0092] Furthermore, the cross-sectional area of the water flow formed by the piling route is calculated based on the water velocity at the breach site to determine the piling route, specifically including:

[0093] S31. Assume that the pile body only relies on the pile side soil resistance to resist the horizontal force of water flow in the horizontal direction. Based on the elastic foundation reaction method, calculate the total lateral soil resistance of the pile body at depth z according to the pile burial depth and pile diameter.

[0094] The horizontal force on the pile in flowing water mainly comes from the drag force of water. According to the drag force formula:

[0095]

[0096] Where C d is the drag coefficient (related to the shape and roughness of the pile), ρ is the density of water, A is the projected area of the pile perpendicular to the direction of water flow, and V is the water flow velocity.

[0097] Assuming that the pile body only relies on the soil resistance on the pile side to resist the horizontal force of water flow in the horizontal direction, the soil resistance on the pile side adopts the elastic foundation reaction method. The relationship between the soil resistance p per unit area on the pile side and the lateral displacement y of the pile is p = k s y(k s is the horizontal resistance coefficient of foundation soil). The total lateral soil resistance P on the pile body is obtained by integrating the lateral soil resistance along the pile body.

[0098] Assuming the pile depth is T and the pile diameter is D, the lateral soil resistance on the pile element at depth z is dP = p·dA = k sy·D·dz, then the calculation expression of the total lateral soil resistance of the pile at depth z is:

[0099]

[0100] S32. Assuming that the horizontal force on the pile body in flowing water mainly comes from the drag force of water, and based on the fact that the drag force on the pile body in flowing water is less than the total lateral soil resistance on the pile body, the water flow velocity at the piling location is obtained.

[0101] That is, the water flow velocity V2 at the piling location should satisfy It is deduced that:

[0102]

[0103] S33. Based on the flow rate remaining unchanged, the cross-sectional area of the water flow formed by the piling route is calculated according to the water flow velocity at the piling location.

[0104] Based on the continuity equation Q=A1V1=A2V2, when there is no other water source flowing in or out (ie, the flow rate Q remains unchanged), when the water flow cross-sectional area A2 increases, the flow velocity V2 will decrease.

[0105] Therefore, the cross-sectional area of the water flow enclosed by the piling route is A2 should meet the following requirements:

[0106]

[0107] S34, setting the piling route to an arched route with a central angle of 90°-150° and a length of l, wherein the value of l is calculated based on the water-passing cross-sectional area, and determining the piling route based on the arched route.

[0108] The piling route adopts an arch route with a central angle of 120° and a length of l. When the central angle is in the range of 90°-150°, the mechanical properties of the arch are relatively balanced. When selecting the central angle, the comprehensive factors of force and construction are taken into consideration to determine the arch design with a central angle of 120°. The arch design with a central angle of 120° generates relatively moderate horizontal thrust when bearing vertical loads, and the axial pressure can be effectively transmitted to the arch foot along the axis of the arch, reducing the water pressure on the pile body. Compared with arch designs with other angles, the 120° angle design is relatively simpler in engineering implementation, and it is easy to control the construction accuracy during the actual construction process. At the same time, it can maintain a reasonable spacing in the pile foundation layout to reduce construction risks. Assuming that the distance between the farthest piling position and the dam body is d1, and the straight-line distance between the piling points at both ends is d2, there is the following relationship between l, d1, and d2:

[0109]

[0110] Where l is obtained based on the cross-sectional area of the water flow, and the change in water depth Δh can be ignored.

[0111] According to the actual dangerous situation of the dam body, the parameters are determined and input into the line algorithm set by the computer to determine the line of piling. The piling route is an arch with a central angle of 120°.

[0112] Based on the elastic foundation reaction method and the principle of flow conservation, this invention scientifically calculates the water velocity and cross-sectional area at the piling point. By extending the distance between the piling point and the breach, the water velocity at the piling point is reduced, avoiding the difficulty of piling in existing devices due to excessive water velocity at the breach. The invention also designs an arched piling route with a central angle of 120°. This arched structure not only effectively disperses the impact force of the water flow, but also maximizes the arch effect to enhance the overall stability of the cofferdam. Furthermore, by determining the arch dimensional parameters through clear mathematical relationships, the piling route design is reproducible and operational.

[0113] Furthermore, step S5 includes: according to the determined piling route, driving support piles 1 from the middle of the route to both sides, and driving the support piles 1 into the underwater soil bearing layer; driving the plastic steel sheet piles 2 into the underwater soil layer with the support piles 1, and fixing them with the anchor rods and support piles 1; monitoring the displacement of the pile top in real time, and adding support piles 1 behind the pile body that exceeds the limit displacement.

[0114] Specifically, the piling equipment is moved to the designated point: according to the determined piling route, the piling equipment is first arranged at the top of the arch, and the piles are gradually driven from the middle to the two sides, so that the water flow can first bypass the sheet piles to the breach. In this way, the water flow at the piling point is at a greater distance from the breach during the piling process, and the flow rate is smaller, making it easier to drive the piles. When piling, the support piles 1 are first driven into the bearing layer of the underwater soil to provide support for the plastic-steel sheet piles 2 to prevent the plastic-steel sheet piles 2 from being washed away by the water; then the plastic-steel sheet piles 2 are driven into the underwater soil layer with the support piles 1, and fixed with anchor rods and support piles 1, wherein the support piles 1 and the plastic-steel sheet piles 2 can be spliced and lengthened according to actual needs. After the support piles 1 and the plastic-steel sheet piles 2 are driven into the soil, the displacement of the pile tops is monitored in real time, and support piles 1 are added to the pile bodies that have exceeded the limit displacement in a timely manner.

[0115] Preferably, the support pile 1 is formed by connecting a guard plate 12 and an H-shaped steel 11, and the spacing between the webs of the two H-shaped steels 11 is 2.6m, ensuring that the plastic steel sheet pile 2 is 50mm away from the webs of the H-shaped steels 11 on both sides, so as to ensure that there is appropriate space for the soil to be squeezed in when driving into the soil, to avoid the underwater soil being too dense due to squeezing, and to reduce the difficulty of pile driving. The support pile 1 is driven into the underwater soil bearing layer. The length of the support pile 1 can be lengthened according to the depth of the water. The lengthening method is to select an integrated welding and straightening machine for gas shielded welding, which has a fast welding speed and high weld quality. The cross-section between the two H-shaped steels 11 is butt-welded to the cross-section joints, and a guard plate 12 is added to the outside of the flange plate and lap joints are welded around the guard plate 12 to provide support for the plastic steel sheet pile 2 and prevent the plastic steel sheet pile 2 from being washed away by running water.

[0116] Furthermore, to address the initial piping hazard, during the installation of plastic-steel sheet piles (2) in step S5, after the piles are driven to the calculated actual driving depth, tracer monitoring is used to prevent bypassing. If bypassing occurs, plastic-steel sheet piles (2) are added adjacent to the driven piles. For small breaches, real-time monitoring of pile top displacement is performed after reaching the driving depth. If displacement exceeds 2 cm / h, the pile depth is increased and additional support piles (1) can be added. If the breach widens after driving, sandbags can be deployed for temporary slope stabilization.

[0117] like Figure 4-9 As shown, the present invention also provides a construction device for emergency rescue of earth-rock dam breach, which is used for the construction method as described above. The construction device includes support piles 1 and plastic steel sheet piles 2. The support piles 1 are formed by connecting a guard plate 12 and an H-shaped steel 11. The plastic steel sheet piles 2 are provided with a limit groove 21 and a limit block 22 structure for connection. The plurality of plastic steel sheet piles 2 are connected and fixed by the limit groove 21 and the limit block 22. The support piles 1 and the plastic steel sheet piles 2 are used in conjunction to form a cofferdam structure with anti-scour and anti-seepage functions.

[0118] Specifically, if Figure 4 As shown, the support pile 1 is lengthened by welding a plurality of H-beams 11. H-beams 112 and 113 are butt-welded, and guard plates 121 are overlap-welded to the outer flanges of H-beams 112 and 113 to form a single unit. In one embodiment, the H-beams 11 have dimensions of HW200×400×13×21.

[0119] like Figure 5-9As shown, the interior of the plastic-steel sheet pile 2 is hollow in design, wherein the cavity passes through the upper and lower ends of the plastic-steel sheet pile 2, and the interior of the cavity is separated by ribs 23 along the width direction of the plastic-steel sheet pile 2 to form a number of limit grooves 21, and a limit block 22 is provided at one end of the limit groove 21. The number of the limit blocks 22 and the limit groove 21 corresponds, and the limit block 22 includes an inner extension block 221 and an outer extension block 222, wherein the inner extension block 221 is located in the limit groove 21, and the outer extension block 222 extends along the end away from the limit groove 21, and a screw hole 24 is provided on the outer extension block 222. The plastic-steel sheet pile 2 is initially fixed by plugging the outer extension block 222 into the limit groove 21 of the next plastic-steel sheet pile 2, and is further fixed by the screw hole 24.

[0120] The plastic-steel sheet pile 2 of the present invention uses a new plastic-steel material and a hollow section rib 23 design, which enhances the stability and load-bearing capacity of the structure. The template design can reduce costs, standardize the production of components, and reduce manufacturing costs and storage and transportation costs. In addition, the components can be flexibly disassembled and combined, optimizing the loading plan and reducing the risk of transportation damage.

[0121] In one embodiment, the length of the plastic steel sheet pile 2 is 2.5m, the height is 3m, and the thickness is close to the distance between the two flanges of the H-shaped steel 11 (about 179mm). The thickness of the upper and lower edges of the plastic steel sheet pile 2 is 20mm, and the thickness of the left and right edges of the plate is 40mm. The internal cavity of the plastic steel sheet pile 2 is provided with three 100mm thick ribs 23, and the internal cavity of the plastic steel sheet pile 2 is divided into four limit grooves 21 by the ribs 23. Two limit blocks 22 are provided at the upper and lower ends of the plastic steel sheet pile 2. The upper limit block 22 is located on both sides, and the lower limit block 22 is located in the middle. The limit blocks 22 include a 400mm long extension block 222 and a 400mm long inner extension block 221. The extension block 222 is provided with a screw hole 24. At the same time, a corresponding screw hole 24 is provided on the far side of each extension block 222 of the sheet pile. The plastic steel sheet pile 2 can be lengthened by splicing, such as Figure 6 As shown, Figure 6 a is a schematic diagram of the corresponding relationship between two plastic-steel sheet piles 2 before splicing; Figure 6 b is a schematic diagram of the process of splicing two plastic-steel sheet piles 2; Figure 6 Figure c is a schematic diagram of two plastic-steel sheet piles 2 after being assembled. The limiting grooves 21 and limiting blocks 22 of the two sheet piles are aligned, and the screw holes 24 of the two sheet piles are aligned. Bolts 25 are inserted into the four screw holes 24, and nuts 26 are tightened at the back to stabilize the sheet piles into a single unit.

[0122] like Figure 7-9 As shown, Figure 7 a is a schematic diagram of the supporting pile 1 and the plastic-steel sheet pile 2 before they are used together; Figure 7Figure b is a schematic diagram of the plastic-steel sheet pile 2 being driven and secured against the support pile 1. During piling, two H-shaped steel beams 11 are first driven into the underwater soil bearing layer. The distance between the two H-shaped steel beams 11 corresponds to the width of the plastic-steel sheet pile 2, providing support for the plastic-steel sheet pile 2 and preventing it from being washed away by the flowing water. The plastic-steel sheet pile 2 is then driven into the underwater soil layer against the H-shaped steel beams 11 and secured against the anchor rods and support pile 1. The support pile 1 and plastic-steel sheet pile 2 can be spliced and lengthened as needed.

[0123] This invention is easy to operate and highly efficient. Its optimized design simplifies the construction process, reducing the complexity and time costs of manual operations. Its modular design and standardized component production improve assembly efficiency and reduce construction difficulty. It is highly adaptable and flexible to installation, and can be designed with flexible installation methods to accommodate complex water conditions and specific dam hazards, enabling rapid installation and securement in the event of a dam breach.

[0124] The design of separate support piles 1 and plastic-steel sheet piles 2 allows for smooth installation even in turbulent water and dam collapse. The plastic-steel sheet piles 2 offer strong flood resistance. Through innovative materials and structural optimization, their stability and durability have been enhanced, effectively protecting them from flooding.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A construction method for emergency rescue of earth-rock dam breach, characterized in that: The following steps are involved: S1. Rapidly obtain on-site parameters of the dam breach, including dam water storage height, breach gap width, and breach gap height; S2. Compare the width of the breach with a preset critical width threshold. If the breach width is less than the critical width threshold, it is determined to be a small breach, and the piling depth is directly determined to achieve rapid plugging. Otherwise, it is determined to be a large breach, and the next step is performed. S3. Calculate the cross-sectional area of the piling route based on the on-site parameters and the water velocity at the breach site to determine the piling route; S4. Setting the piling position according to the piling route; S5. Carry out emergency construction and pile driving according to the pile driving location to form an anti-seepage and anti-scouring cofferdam structure; S6. Strengthen the cofferdam structure, address leakage points, and repair breaches after the cofferdam stabilizes.

2. The method for emergency rescue of earth-rock dam breach according to claim 1, characterized in that: In step S2, the types of small dam breach hazards are divided into initial piping hazards and small dam breach breaches according to whether a dam breach breach has occurred. Initial piping hazards refer to dam breach breaches that have not yet occurred, while small dam breach breaches refer to dam breach breaches that have occurred but the gap width is less than the critical width threshold. The piling depth is determined according to the type of small dam breach hazard.

3. The method for emergency rescue of earth-rock dam breach according to claim 2, characterized in that: When the hazard is an initial piping hazard, obtain the piping channel parameters and soil permeability coefficient, calculate the theoretical minimum piling depth based on the piping channel parameters, calculate the seepage path depth based on the soil permeability coefficient, and calculate the theoretical maximum piling depth based on the theoretical minimum piling depth and the seepage path depth. Take 130% of the theoretical maximum piling depth as the actual piling depth; When the dangerous situation is a small breach, the empirical piling depth is calculated according to the height of the breach, and the anti-overturning safety factor is verified according to the theoretical formula method to obtain the theoretical minimum piling depth. The theoretical maximum piling depth is calculated based on the theoretical minimum piling depth and the empirical piling depth, and 130% of the theoretical maximum piling depth is taken as the actual piling depth.

4. The method for emergency rescue of earth-rock dam breach according to claim 1, characterized in that: Step S3 of calculating the water flow velocity at the breach includes: calculating the hydraulic radius of the water flow section at the breach gap based on the dam water storage height and the breach gap width; calculating the channel bottom slope based on the height difference between the two ends of the water flow channel at the breach and the bottom width of the dam body; substituting the hydraulic radius and channel bottom slope into the Manning formula to calculate the water flow velocity at the breach. The expression for the water flow velocity at the breach is as follows: Where V1 is the water velocity at the breach, in m / s; ψ is the correction coefficient, which is 1.05-1.1; n is the Manning roughness coefficient, which is 0.02-0.04; b is the width of the breach gap; h is the water storage height of the dam. represents the hydraulic radius; ΔL represents the height difference between the two ends of the water channel at the breach; L represents the bottom width of the dam body. Indicates the channel bottom slope.

5. The method for emergency rescue of earth-rock dam breach according to claim 1, characterized in that: In step S3, the cross-sectional area of the water flow formed by the piling route is calculated based on the water flow velocity at the breach site to determine the piling route, which specifically includes: S31, assuming that the pile body only relies on the pile side soil resistance to resist the horizontal force of water flow in the horizontal direction, based on the elastic foundation reaction method, calculate the lateral soil resistance at the depth z of the pile body buried in the soil according to the pile diameter and the lateral displacement of the pile, and calculate the total lateral soil resistance based on the integration of the burial depth; S32, assuming that the horizontal force on the pile body in flowing water mainly comes from the drag force of the water, and based on the fact that the drag force on the pile body in flowing water is less than the total lateral soil resistance on the pile body, obtain the water flow velocity at the piling location; S33, based on the flow rate remaining unchanged, calculating the cross-sectional area of water flow enclosed by the piling route according to the water flow velocity at the piling location; S34, setting the piling route to an arched route with a central angle of 120° and a length of l, wherein the value of l is calculated based on the water-passing cross-sectional area, and determining the piling route based on the arched route.

6. The method for emergency rescue of earth-rock dam breach according to claim 5, characterized in that: In step S32, according to It is deduced that: Where F represents the drag force, C d is the drag coefficient, ρ is the density of water, A is the projected area of the pile perpendicular to the direction of water flow, V2 is the water velocity at the pile driving point, P is the total lateral soil resistance, k s is the horizontal resistance coefficient of foundation soil, D is the pile diameter, z is the depth, y is the lateral displacement of the pile, and T is the pile burial depth; In step S33, according to Q=A1V1=A2V2, we get but: Where Q represents the flow rate, A2 represents the cross-sectional area of the water flow enclosed by the piling route, A1 represents the cross-sectional area of the water flow at the breach, and V1 represents the water flow velocity at the breach.

7. The method for emergency rescue of earth-rock dam breach according to claim 5, characterized in that: In step S34, the distance between the farthest piling position and the dam body is set to d1, and the straight-line distance between the piling points at both ends is d2. Then, the following relationship exists between l, d1, and d2: Where, A2 represents the cross-sectional area of water flow enclosed by the piling route, and h represents the water storage height of the dam.

8. The method for emergency rescue of earth-rock dam breach according to claim 1, characterized in that: Step S5 includes: according to the determined piling route, driving support piles from both ends of the route to the middle, and driving the support piles into the underwater soil bearing layer; driving the plastic steel sheet piles into the underwater soil layer with the support piles, and fixing them with anchor rods and support piles, and constructing an anti-seepage and anti-scour cofferdam structure through the support piles and plastic steel sheet piles; real-time monitoring of pile top displacement, and adding support piles behind the pile body that exceeds the limit displacement.

9. A construction device for emergency rescue of earth-rock dam breach, characterized in that: The construction device is used to implement the construction method described in any one of claims 1 to 8. The construction device includes supporting piles and plastic-steel sheet piles. The supporting piles are formed by connecting guard plates and H-shaped steels. The plastic-steel sheet piles are provided with limiting grooves and limiting block structures for connection. A plurality of plastic-steel sheet piles are connected and fixed by limiting grooves and limiting blocks. The supporting piles are arranged at intervals on the piling route and driven into the bearing layer of the underwater soil. The plastic-steel sheet piles are arranged on the supporting piles and are connected and fixed to the supporting piles by anchor rods. The supporting piles and the plastic-steel sheet piles are used in combination to form a cofferdam structure with anti-scouring and anti-seepage functions.

10. The earth-rock dam breach emergency rescue construction device according to claim 9, characterized in that: A plurality of limiting grooves are provided inside the plastic-steel sheet pile, and the limiting grooves are separated by ribs. The limiting block extends along one end away from the limiting groove and is used for corresponding connection with the limiting groove of the next plastic-steel sheet pile.

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