A permeable homogeneous earth dam heightening structure

Abstract

This utility model relates to the field of homogeneous earth dam heightening technology, and proposes a heightening structure for a permeable homogeneous earth dam, including a heightened dam body located above the original homogeneous earth dam body, a plastic concrete anti-seepage wall that vertically penetrates the heightened dam body and the original homogeneous earth dam body, and a curtain grouting structure located below the anti-seepage wall; the heightened dam body takes the top of the original homogeneous earth dam body as the starting point of the slope, the upstream dam slope is not steeper than the original dam slope, and the downstream dam slope is slightly gentler than the original dam slope, and from upstream to downstream it is divided into a dam top soil material area, a dam shell material area, and a mattress drainage area. The mattress drainage area is connected to the original dam drainage prism, and a filter layer area is provided at the contact surface between the dam top soil material area and the dam shell material area, and at the contact surface between the dam shell material area and the original homogeneous earth dam body and the mattress drainage area; the contact area with the original homogeneous earth dam body uses soil material with similar properties, so that the new and old dam bodies can be naturally integrated without tensile stress. With its simple structure, convenient construction, minimal disturbance, no impact on reservoir operation, reduced waste disposal, and complete coupling of the old and new dam bodies under stress, it can improve safety and economy.

Description

Technical Field

[0001] This utility model relates to the field of homogeneous earth dam heightening technology, and in particular to a heightening structure for a permeable homogeneous earth dam. Background Technology

[0002] Most existing homogeneous earth dams were built in the 1950s and 60s. Homogeneous earth dams are widely used in the construction of medium and low dams due to their simple structure and low cost. In the 1950s and 60s, the surveying and design methods and construction technology had certain limitations, especially the construction equipment was not advanced. Most dams suffered from uneven compaction, uneven properties of fill soil, inadequate drainage, and no reinforcement of the contact zone between the dam body and the foundation. As the service life increased, the dam bodies all showed varying degrees of problems such as slope instability, concentrated and loose seepage, deformation and cracking.

[0003] With social development, the requirements for water resource utilization have also increased. Many reservoirs can no longer meet the requirements of current engineering tasks. Most reservoirs have been in operation for more than 50 years, and siltation has reduced their beneficial storage capacity. It is imperative to reassess the water resources of existing reservoirs and increase their capacity and height.

[0004] Many homogeneous earth dams are now consolidated and stable, but earth-rock dams are "loose" structures formed by compacting earth and rock. If the dam is heightened, the stress in the original dam body will be reactivated and redistributed. If the heightening scheme is not good, the old and new dam bodies will not be able to couple the forces, leading to the destruction of the dam structure.

[0005] Therefore, there is an urgent need for a permeable homogeneous earth dam heightening structure to solve the problems mentioned in the background technology. Utility Model Content

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a permeable homogeneous earth dam heightening structure to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A heightening structure for a permeable homogeneous earth dam includes: a heightened dam body located above the original homogeneous earth dam; a plastic concrete cutoff wall located at the axis of the heightened dam body, penetrating vertically downwards from the top of the dam body and the original homogeneous earth dam body; and a curtain grouting structure located below the plastic concrete cutoff wall. The heightened dam body uses the original homogeneous earth dam crest as the starting point of the slope. The upstream dam slope is not steeper than the original homogeneous earth dam slope, and the downstream dam slope is slightly gentler than the original homogeneous earth dam slope. The heightened dam body is divided into three sections from upstream to downstream: the dam crest soil material area, the dam shell material area, and the mattress drainage area. The dam crest soil material area is located in the top area of ​​the upstream side of the heightened dam body. The dam shell material area is located in the middle and downstream side of the heightened dam body. The mattress drainage area is located in the bottom area of ​​the downstream side of the heightened dam body and connects with the original dam drainage prism. The contact surfaces between the dam crest soil material area and the dam shell material area, as well as the contact surfaces between the dam shell material area and the original homogeneous earth dam body and the mattress drainage area, are all provided with a filter layer.

[0008] Preferably, the dam crest soil material zone comprises topsoil and a fully weathered layer, and the permeability coefficient of the dam crest soil material zone is ≤1×10⁻⁶. -4 cm / s.

[0009] Preferably, the dam shell material zone includes a first dam shell zone and a second dam shell zone located at the center of the first dam shell zone; the first dam shell zone is located between the dam crest soil zone and the mattress drainage zone; the first dam shell zone uses strongly and weakly weathered material from the quarry, with a permeability coefficient ≥1×10⁻⁶. -3 cm / s; the second dam shell area uses excavated material, and no requirements are placed on the permeability coefficient.

[0010] Preferably, the second dam shell area is provided with several equidistant crushed stone drainage layers, the crushed stone drainage layers are horizontal, the distance between adjacent crushed stone drainage layers is 5m, and the thickness of the crushed stone drainage layer is 0.5m.

[0011] Preferably, the drainage zone of the mattress is made of a slightly weathered material with a permeability coefficient of ≥1×10⁻⁶. -1 cm / s.

[0012] Preferably, the thickness of the plastic concrete cutoff wall is 0.6-0.8m, and the permeability coefficient of the plastic concrete cutoff wall is ≤1×10⁻⁶. -6 cm / s.

[0013] Preferably, the thickness of the filter layer at the contact surface between the dam crest soil area and the dam shell material area is ≥2m, and the thickness of the filter layer at the contact surface between the dam shell material area and the original homogeneous earth dam body and the mattress drainage area is ≥0.8m; the relative density of the filter layer is ≥0.70, and the permeability coefficient is 1×10⁻⁶. -3 -1×10 -2 cm / s.

[0014] This utility model discloses a heightening structure for a permeable homogeneous earth dam, which has the following beneficial effects.

[0015] This utility model is designed for expanding and raising an existing reservoir. The dam filling and raising does not affect the normal operation of the reservoir, and the disturbance to the original dam body is only surface clearing. The structure of this utility model is relatively simple, with clear zoning, and it broadens the selection of filling material sources. Except for the topsoil, tree roots, and humus, all other excavated materials are used as zoning filling materials according to their different properties. Except for the topsoil, tree roots, and humus, the material yard contains usable materials from the topsoil to the bedrock, minimizing waste, reducing the pressure on the waste yard, and mitigating soil erosion. It adopts a combination of plastic concrete cutoff wall and curtain grouting, with a single cutoff body, few weak points, and good seepage prevention effect. The plastic concrete cutoff wall is a flexible body with a large ultimate strain, which can well adapt to the deformation of the original homogeneous earth dam body and the newly filled dam body. The four zoning of the original homogeneous earth dam body and the gradual transition of material properties between the original dam body and the original dam body allow the raised dam structure to be fully coupled with the original homogeneous earth dam body to bear the force. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of the heightened permeable homogeneous earth dam structure proposed in the embodiments of this application.

[0017] Figure 2 This is a top view of the heightened permeable homogeneous earth dam structure proposed in the embodiments of this application.

[0018] In the attached diagram: 1. Soil area at the top of the dam; 2. First dam shell area; 3. Second dam shell area; 4. Mattress drainage area; 5. Filter layer area; 6. Plastic concrete anti-seepage wall; 7. Curtain grouting; 8. Original homogeneous earth dam; 9. Original dam drainage prism; 10. Crushed stone drainage layer; 11. Original drainage prism filter layer; 12. Interface between the old and new dam bodies. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0020] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0021] Example 1 Reference Figure 1 and Figure 2As shown, a permeable homogeneous earth dam heightening structure includes a heightened dam body located above the original homogeneous earth dam 8, a plastic concrete cutoff wall 6 located at the axis of the heightened dam body and extending vertically downward from the top of the dam body and the original homogeneous earth dam 8, and a curtain grouting 7 located below the plastic concrete cutoff wall 6. It should be noted that in this embodiment, the dam body is raised using a backward-tilting method, with the original homogeneous earth dam 8 as the benchmark. This method can make full use of the original homogeneous earth dam 8 structure to reduce the total amount of engineering work. Plastic concrete anti-seepage wall 6 is used as the anti-seepage body to avoid excessive excavation and disturbance to the original homogeneous earth dam 8. Using a single anti-seepage body can avoid excessive overlap of the anti-seepage body, reduce weak points caused by the anti-seepage body, and meet the requirements for normal operation of the reservoir during construction.

[0022] The method of combining plastic concrete cutoff wall 6 with curtain grouting 7 results in a single cutoff body with fewer weak points and good seepage prevention effect. Plastic concrete cutoff wall 6 is a flexible body with a large ultimate strain, which can well adapt to the deformation of the original homogeneous earth dam 8 and the newly filled dam body. For projects that have increased the height of the original homogeneous earth dam 8, most of these homogeneous earth dams that have reached the end of their service life were built in the 1960s and 1970s. Due to the limited survey, design and construction conditions at that time, these earth dams have uneven compaction, large compression coefficient and water permeability. Setting up cutoff wall can effectively cut off seepage and avoid using other seepage prevention methods such as large excavation and multiple seepage prevention combinations.

[0023] The heightened dam body uses the crest of the original homogeneous earth dam 8 as its starting point. The upstream slope is not steeper than the original homogeneous earth dam 8, while the downstream slope is slightly gentler. The heightened dam body is divided into three zones from upstream to downstream: the dam crest soil material zone 1, the dam shell material zone, and the cushion drainage zone 4. The dam crest soil material zone 1 is located at the top of the upstream side of the heightened dam body; the dam shell material zone is located on the middle and downstream side of the heightened dam body; the cushion drainage zone 4 is located at the bottom of the downstream side of the heightened dam body, connecting with the original dam drainage prism 9. A filter layer zone 5 is provided at the contact surfaces between the dam crest soil material zone 1 and the dam shell material zone, as well as at the contact surfaces between the dam shell material zone and the original homogeneous earth dam 8 and the cushion drainage zone 4. Figure 1 As shown, the filter layer 5 is connected to the original drainage prism filter layer 11.

[0024] It should be noted that in this embodiment, the heightened dam body adopts a zoned design, which can broaden the selection of material sources, make full use of excavated material, reduce waste to reduce the pressure on the waste disposal site, and reduce soil erosion. In the contact area with the original homogeneous earth dam 8, i.e., the interface 12 between the new and old dam bodies, soil with similar properties (including fully weathered material) is selected to allow the new and old dam bodies to fuse naturally, without generating tensile stress at the interface. Excavated material is given priority in the thickening and heightening of the dam shell material area, and weathered material is selected from the quarry for the remaining portion.

[0025] The original homogeneous earth dam 8 was filled in 4 zones, and the material properties between the dam body and the original dam body gradually transitioned. The heightened dam body structure can be fully coupled with the original homogeneous earth dam 8 to bear the load.

[0026] Preferably, in this embodiment, the dam crest soil zone 1 uses topsoil and fully weathered soil, and the permeability coefficient of the dam crest soil zone 1 is ≤1×10⁻⁶. -4 cm / s.

[0027] In this embodiment, the dam crest soil material zone 1 is used for trenching of the anti-seepage wall and auxiliary anti-seepage. The properties of the dam crest soil material zone 1 are required to be similar to those of the original homogeneous earth dam 8. The dam shell material zone is filled with excavated soil and rock, stone chips, and weathered material from the quarry. There is no need to pursue high-quality riprap, so as to reduce the amount of excavation of structures and waste material from the quarry. It also better meets the requirements of hydraulic gradient transition and coordinated deformation of earth-rock dam.

[0028] Preferably, in this embodiment, the dam shell material zone includes a first dam shell zone 2 and a second dam shell zone 3 located at the center of the first dam shell zone 2; the first dam shell zone 2 is located between the dam crest soil zone 1 and the mattress drainage zone 4; the first dam shell zone 2 uses strongly and weakly weathered material from the material yard, with a permeability coefficient of ≥1×10⁻⁶. -3 cm / s; The second dam shell zone 3 uses excavated material, and there are no requirements for the permeability coefficient. During the construction of the second dam shell zone 3, the deformation difference between it and the first dam shell zone 2 can be adjusted by reducing the thickness of the compacted layer and the filling rate.

[0029] It should be noted that by setting up the first dam shell zone 2 and the second dam shell zone 3, the selection of material sources can be broadened, and the excavated material can be used as dam shell material in a reasonable and scientific manner by utilizing the zoning.

[0030] In this embodiment, the filling material for the dam shell area is required to have certain strength and permeability, with a permeability coefficient ≥1×10⁻⁶. -3 If the permeability coefficient is small and there is no significant gradient between the permeability coefficient and the upstream area, a gravel drainage layer of 10 cm / s can be added to solve problems such as excess pore water pressure during construction.

[0031] Preferably, in this embodiment, the second dam shell area 3 is provided with several equidistantly arranged crushed stone drainage layers 10. The crushed stone drainage layers 10 are horizontal, the distance between adjacent crushed stone drainage layers 10 is 5m, and the thickness of the crushed stone drainage layer 10 is 0.5m, so as to accelerate the discharge of pore water inside during construction.

[0032] Preferably, in this embodiment, the drainage zone 4 of the mattress is made of a weakly weathered material with a permeability coefficient of ≥1×10⁻⁶. -1 cm / s.

[0033] The bottom padding drainage area 4 can also stabilize the old dam body during construction and fix the dam body toe after filling.

[0034] In this embodiment, the filling material is riprap, which is connected with the original dam drainage prism 9 for joint drainage.

[0035] Preferably, in this embodiment, the thickness of the plastic concrete cutoff wall 6 is 0.6-0.8m, and the permeability coefficient of the plastic concrete cutoff wall 6 is ≤1×10⁻⁶. -6 cm / s.

[0036] Preferably, in this embodiment, the filter layer 5 at the contact surface between the dam crest soil zone 1 and the dam shell material zone has a thickness of ≥2m. This protects the contact surface of the dam crest soil zone 1 from seepage damage and also coordinates deformation. The filter layer 5 at the contact surface between the dam shell material zone and the original homogeneous earth dam body 8 and the mattress drainage zone 4 has a thickness of ≥0.8m. This protects the original homogeneous dam soil from seepage damage and prevents the mattress drainage zone 4 from clogging. The filter layer 5 filler material is required to be dense, with strong water resistance and weathering resistance, continuous gradation, and meet the drainage requirements of the filter soil. After filling, the relative density is required to be ≥0.70, and the permeability coefficient is 1×10⁻⁶. -3 -1×10 -2 cm / s, in this embodiment, the filter layer 5 packing material is a mixed gravel material, mainly medium and coarse sand.

[0037] Example 2 Based on Example 1, this example provides a method for implementing a heightening structure for a permeable homogeneous earth dam, including the following steps: (1) The drainage area 4 of the mattress is filled with excavated stone chips or weakly weathered material to ensure drainage performance; The filling of the bedding drainage zone 4 begins at the bottom of the dam body, prioritizing the use of excavated gravel or weakly weathered material to ensure that the drainage performance meets design requirements. During the filling process, the layer thickness and compaction are strictly controlled, and quality testing is conducted after each layer is completed to ensure that the compaction indicators meet the specifications. The bedding drainage zone 4 is tightly connected to the original dam body's drainage prisms, forming a complete drainage system to enhance the overall stability of the dam body.

[0038] (2) The dam shell material area and the dam top soil material area 1 are filled layer by layer. The original homogeneous earth dam 8 is compacted by rolling, roughening and then laying soil and compacting. The number of rolling passes is increased to improve the modulus and bonding force of the contact zone. The filling of the dam shell material area is carried out layer by layer from bottom to top. The excavated material with poor properties is filled in the middle and upper part of the dam shell material area, and the material with good properties is filled at the bottom. A filter layer with a thickness of not less than 0.8m is set at the contact points between the dam shell material area and the original homogeneous earth dam 8, and at the contact points between the dam shell material area and the mattress drainage area 4. In this case, the thickness is 1m. When the dam shell material area is filled to the top soil area 1, it needs to be filled and raised simultaneously. A filter layer with a thickness of ≥2m is set at the contact points between the dam shell material area and the top soil area 1 to protect the soil area from seepage damage and to coordinate deformation. A certain thickness is also required to facilitate mechanical construction.

[0039] The filling of the dam crest soil zone 1 needs to be carried out synchronously with the downstream dam shell soil zone. The filling materials should make full use of the excavated soil, the surface soil of the dam shell material yard, and the completely weathered soil. The dimensions of this zone should consider not only the structural needs of the trench area but also the factors of construction convenience. At the junction of the original homogeneous earth dam 8 and the newly filled dam body, the original homogeneous earth dam 8 body should be compacted twice first. After roughening the surface, the new fill soil should be laid and compacted. Increasing the number of compaction passes by two times will improve the modulus of the contact zone. Roughening and compaction will increase the bonding force of the joint surface and improve the modulus of this part.

[0040] (3) Consolidation settlement of the dam body. The original dam body and the soil area on the top of the dam are soil areas. After the heightening and filling, a consolidation settlement time needs to be reserved. At least 5 months should be reserved. The settlement time can be adjusted according to monitoring. After the dam body filling is completed, sufficient consolidation settlement time needs to be reserved before the construction of the anti-seepage wall. The consolidation time is first reserved through calculation, and then finally adjusted according to the dam body deformation monitoring results. In this case, the original dam body height was 40.2m, and the dam body height was increased to 50.5m. The dam body reserved a consolidation settlement time of 5 months.

[0041] (4) Construction of the plastic concrete anti-seepage wall 6: continuous pouring in sections to ensure integrity and density; The construction of the plastic concrete cutoff wall 6 is a crucial step in the entire project. Before construction, the trenching area must be accurately laid out, and specialized machinery must be used for trenching operations. Most of the plastic concrete cutoff wall 6 is located within the original homogeneous earth dam 8. During trenching, the stability of the trench walls must be monitored in real time to prevent collapse. The plastic concrete cutoff wall 6 is poured using a segmented continuous construction method to ensure the integrity and density of the wall.

[0042] (5) Dam foundation curtain grouting 7, a hole-forming method for pre-embedding grouting pipes in plastic concrete anti-seepage wall 6.

[0043] (6) Initial monitoring of the dam body: The initial monitoring of the dam body mainly takes place during the consolidation and settlement stage and the initial water impoundment stage. It is necessary to closely monitor the deformation and stress changes of the dam body.

[0044] (7) After the dam body is filled and seepage prevention is completed and the dam body becomes stable, ecological slope protection is carried out on the upstream and downstream slopes, taking into account both functionality and aesthetics. The slope protection materials should be local vegetation or environmentally friendly materials to improve the overall landscape effect while protecting the ecological environment.

[0045] The above are merely preferred embodiments of this utility model, but the scope of protection of this utility model is not limited thereto. Substitutions may include replacements for some structures, devices, or method steps, or they may be complete technical solutions. Equivalent substitutions or modifications made based on the technical solution and inventive concept of this utility model should all be covered within the scope of protection of this utility model.

Claims

1. A heightening structure for a permeable homogeneous earth dam, characterized in that, include: The heightened dam body is located above the original homogeneous earth dam; the plastic concrete cutoff wall is located at the axis of the heightened dam body and runs vertically downward from the top of the dam body and the original homogeneous earth dam body; and the curtain grouting is located below the plastic concrete cutoff wall. The heightened dam body uses the original homogeneous earth dam crest as the starting point of the slope. The upstream dam slope is not steeper than the original homogeneous earth dam slope, and the downstream dam slope is slightly gentler than the original homogeneous earth dam slope. The heightened dam body is divided into three sections from upstream to downstream: the dam crest soil material area, the dam shell material area, and the mattress drainage area. The dam crest soil material area is located in the top area of ​​the upstream side of the heightened dam body. The dam shell material area is located in the middle and downstream side of the heightened dam body. The mattress drainage area is located in the bottom area of ​​the downstream side of the heightened dam body and connects with the original dam drainage prism. The contact surfaces between the dam crest soil material area and the dam shell material area, as well as the contact surfaces between the dam shell material area and the original homogeneous earth dam body and the mattress drainage area, are all provided with a filter layer.

2. The permeable homogeneous earth dam heightening structure according to claim 1, characterized in that, The dam crest soil zone comprises topsoil and a fully weathered layer, and the permeability coefficient of the dam crest soil zone is ≤1×10⁻⁶. -4 cm / s.

3. The permeable homogeneous earth dam heightening structure according to claim 1, characterized in that, The dam shell material zone includes a first dam shell zone and a second dam shell zone located at the center of the first dam shell zone; the first dam shell zone is situated between the dam crest soil zone and the bedding drainage zone; the first dam shell zone uses strongly and weakly weathered material from the quarry, with a permeability coefficient ≥1×10⁻⁶. -3 cm / s; the second dam shell area uses excavated material, and no requirements are placed on the permeability coefficient.

4. The permeable homogeneous earth dam heightening structure according to claim 3, characterized in that, The second dam shell area is provided with several equidistant crushed stone drainage layers. The crushed stone drainage layers are horizontal, the distance between adjacent crushed stone drainage layers is 5m, and the thickness of the crushed stone drainage layer is 0.5m.

5. The heightening structure for a permeable homogeneous earth dam according to claim 1, characterized in that, The drainage zone of the mattress is made of a slightly weathered material with a permeability coefficient of ≥1×10⁻⁶. -1 cm / s.

6. The heightening structure for a permeable homogeneous earth dam according to claim 1, characterized in that, The thickness of the plastic concrete cutoff wall is 0.6-0.8m, and the permeability coefficient of the plastic concrete cutoff wall is ≤1×10⁻⁶. -6 cm / s.

7. The permeable homogeneous earth dam heightening structure according to claim 1, characterized in that, The thickness of the filter layer at the interface between the dam crest soil zone and the dam shell material zone is ≥2m, and the thickness of the filter layer at the interface between the dam shell material zone and the original homogeneous earth dam body and the bedding drainage zone is ≥0.8m; the relative density of the filter layer is ≥0.70, and the permeability coefficient is 1×10⁻⁶. -3 -1×10 -2 cm / s.

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