Core wall rockfill dam based on soft rock composite dam foundation

Abstract

The application discloses a kind of based on soft rock composite dam foundation core wall earth-rockfill dam, including composite dam foundation and filling on the upper dam body of composite dam foundation, composite dam foundation includes bedrock and filling on the lower dam body of bedrock, lower dam body has concrete cutoff wall, the lower part of concrete cutoff wall extends to bedrock, lower dam body further includes first upstream soft rock filling area, second upstream soft rock filling area filling in the upstream side of concrete cutoff wall in sequence, lower dam body further includes first downstream soft rock filling area, lower filter layer and second downstream soft rock filling area filling in the downstream side of concrete cutoff wall in sequence, second downstream soft rock filling area has drainage prism at dam foot.The lower dam body of the application is filled with soft rock as filling material, the lower dam body and bedrock form a composite dam foundation, greatly improve the utilization rate of soft rock, make the most of on-site material, reduce dam investment;The lower dam body of the application has concrete cutoff wall, which can effectively improve the impermeability of the lower dam body, the lower filter layer on the downstream side of the first downstream soft rock filling area can effectively prevent it from being carried out due to seepage force, thereby avoiding the inclination of the concrete cutoff wall, and improving the stability of the lower dam body.

Description

Technical Field

[0001] This invention relates to core wall dams, and more particularly to a core wall earth-rock dam based on a soft rock composite dam foundation. Background Technology

[0002] Earth-rock dams are widely used in important infrastructure projects such as high dams and large reservoirs due to their excellent engineering characteristics, including adaptability to complex terrain and geological conditions, economy of using locally sourced materials, and the speed and convenience of roller compaction. In actual projects, due to current material source limitations, and considering both engineering economy and environmental protection, soft rock is often used as fill material in parts of the downstream dam area. After compaction, soft rock can achieve a high density, and after meeting the requirements of deformation coordination and seepage safety and stability of the entire dam body, it can be installed on the dam.

[0003] In recent years, the increasing height of dams in many projects has led to a corresponding increase in stress on the dam body. However, soft rock's poor mechanical properties and weakened strength upon contact with water cause it to become wetted and rheological, exacerbating uncoordinated dam deformation and ultimately resulting in a series of failure modes, such as panel crushing failure, panel voids, hydraulic splitting of the core wall, and cracks in the dam crest due to uneven settlement. These problems seriously endanger the overall safety of the dam. Currently, existing earth-rock dams primarily use hard rock as the main material and soft rock as a supplementary material during construction, with the soft rock mainly used in downstream dry areas. This results in a soft rock utilization rate of less than 40%, leading to soft rock waste and preventing the complete utilization of excavated material. Furthermore, extensive excavation and blasting are required to obtain hard rock, increasing project investment to some extent. Therefore, improving the utilization rate of soft rock while avoiding uncoordinated dam deformation is crucial for dam engineering. Summary of the Invention

[0004] In view of this, the present invention proposes a core wall earth-rock dam based on soft rock composite dam foundation, which improves the utilization rate of soft rock, makes the best use of materials, reduces construction costs, and achieves coordinated deformation of the dam body with high stability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: The core-wall earth-rock dam based on a soft rock composite foundation of the present invention includes a composite foundation and an upper dam body filled on the composite foundation. The composite foundation includes bedrock and a lower dam body filled on the bedrock. The lower dam body has a concrete cutoff wall that extends downward into the bedrock. The lower dam body also includes a first upstream soft rock fill zone and a second upstream soft rock fill zone sequentially filled on the upstream side of the concrete cutoff wall. The lower dam body also includes a first downstream soft rock fill zone, a lower filter layer, and a second downstream soft rock fill zone sequentially filled on the downstream side of the concrete cutoff wall. A drainage prism is provided at the toe of the second downstream soft rock fill zone. The beneficial effects are: the lower dam body of the present invention uses soft rock as fill material, and the lower dam body and bedrock combine to form a composite foundation, which greatly improves the utilization rate of soft rock, makes full use of on-site materials, and reduces dam investment. The lower dam body of the present invention has a concrete anti-seepage wall, which can effectively improve the anti-seepage effect of the lower dam body. The lower filter layer on the downstream side of the first downstream soft rock filling area can effectively prevent it from being carried out by seepage force, thereby preventing the concrete anti-seepage wall from tilting and improving the stability of the lower dam body.

[0006] Preferably, the upper dam body includes an upper core wall, and the upstream side of the upper core wall is filled with an upstream rockfill area, an upstream drainage layer, a second upstream filter layer, and a first upstream filter layer in sequence from upstream to downstream; the downstream side of the upper core wall is filled with a first downstream filter layer, a second downstream filter layer, a first downstream drainage layer, and a downstream rockfill area in sequence from downstream to downstream, and the first downstream drainage layer has a first horizontal portion extending horizontally downstream from its bottom; the lower dam body also includes a second downstream drainage layer filled between the lower filter layer and the second downstream soft rock filling area, the second downstream drainage layer has a second horizontal portion extending horizontally downstream from its bottom to the drainage prism, and the upper part of the second downstream drainage layer is integrally filled with the first horizontal portion.

[0007] The beneficial effects are: the present invention fills both sides of the upper core wall with two kinds of filter materials, which effectively prevents the upper core wall and the first downstream soft rock filling area from being carried out by seepage force. This not only improves the seepage prevention performance of the upper core wall, but also prevents the concrete seepage prevention wall from tilting downstream.

[0008] The first downstream drainage layer of the present invention is connected to the second downstream drainage layer in the lower dam body through the first horizontal part to form an integral whole. The second horizontal part of the second downstream drainage layer extends downstream to the drainage prism, which effectively ensures the drainage performance of the upper and lower dam bodies. It can promptly discharge the water generated by the upper and lower dam bodies during water storage, rainfall and other processes, maintain the relative dryness of the upper and lower dam bodies, and avoid adverse phenomena such as wetting or mudding in the soft rock filling area as much as possible.

[0009] Preferably, the upstream rockfill area of ​​the upper dam body is filled with sandstone or limestone from the lower reservoir, and the distance between the bottom of its upstream face and the top of the upstream face of the second upstream soft rock filling area is ≥10 m; the downstream rockfill area is filled with limestone from the upper reservoir, limestone from the lower reservoir, or excavated material, and the distance between the bottom of its downstream face and the top of the downstream face of the second downstream soft rock filling area is ≥20 m, which is beneficial for proper slope and thus reduces uneven settlement.

[0010] Preferably, the slope of the upstream face of the first downstream drainage layer is 1:0.25, the slope of its downstream face is 1:0.4, and the filling height of its first horizontal section is 4 m to 8 m; the slope of the downstream face of the second downstream drainage layer is 1:0.5, and its filling thickness is 8 m to 15 m, effectively ensuring the relative dryness of the lower dam body.

[0011] Preferably, the slope of the upstream face of the upstream rockfill area of ​​the upper dam body is 1:2 to 1:3, and the slope of the downstream face of the downstream rockfill area of ​​the upper dam body is 1:1.5 to 1:2.

[0012] More preferably, the upstream face of the upstream rockfill area also has an upstream slope protection, and the downstream face of the downstream rockfill area also has a downstream slope protection, which effectively prevents the upstream and downstream dam slopes from becoming unstable.

[0013] Preferably, the upper part of the concrete cutoff wall extends into the upper core wall, effectively improving the seepage prevention performance of the dam. More preferably, the lower dam body further includes reinforcement zones filled on both sides of the concrete cutoff wall. The beneficial effect is that by filling reinforcement zones on both sides of the concrete cutoff wall, the present invention effectively improves the tensile strength and verticality of the concrete cutoff wall, thereby ensuring the seepage prevention effect.

[0014] Compared with existing technologies, the advantages of this invention are as follows: The lower dam body of this invention uses soft rock as the main filling material, and the lower dam body and bedrock combine to form a composite dam foundation, which greatly improves the utilization rate of soft rock, making full use of materials on site and avoiding the phenomenon of large amounts of soft rock waste, thereby significantly reducing the investment in the dam. In addition, the lower dam body of this invention has a concrete cutoff wall, which can effectively improve the seepage prevention effect of the lower dam body. The lower filter layer on the downstream side of the first downstream soft rock filling area can effectively prevent it from being carried out by seepage force, thereby preventing the concrete cutoff wall from tilting and improving the stability of the lower dam body. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the present invention.

[0016] Figure 2 yes Figure 1 Enlarged schematic diagram after the bedrock has been removed. Detailed Implementation

[0017] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0018] It should be noted that, in the description of this invention, relational terms such as “first” and “second” are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0019] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] like Figure 1-2 As shown, the core-wall earth-rock dam based on soft rock composite foundation of the present invention includes a composite dam foundation and an upper dam body 1 filled on the composite dam foundation. The composite dam foundation includes bedrock 2 and a lower dam body 3 filled on the bedrock 2. The lower dam body 3 is filled with soft rock and includes a concrete cutoff wall 3.1. The lower part of the concrete cutoff wall 3.1 extends downward into the bedrock 2 and is grouted with curtain grouting to form an integral whole with the bedrock 2. The upper part of the concrete cutoff wall 3.1 extends into the upper core wall 1.1 of the upper dam body 1. The thickness of the concrete cutoff wall is 1.0 m to 2.0 m, which further improves the seepage prevention performance of the dam body. The lower dam body 3 also includes a first upstream soft rock filling area 3.2 and a second upstream soft rock filling area 3.3, which are sequentially filled on the upstream side of the concrete cutoff wall 3.1 from upstream to downstream. It also includes a first downstream soft rock filling area 3.4, a lower filter layer 3.5, and a second downstream soft rock filling area 3.6 (a relatively dry area), which are sequentially filled on the downstream side of the concrete cutoff wall 3.1. The second downstream soft rock filling area 3.6 has a drainage prism 3.7 at the dam toe, which effectively reduces the seepage line of the present invention. The lower dam body 3 is mainly constructed of soft rock, which forms a composite dam foundation with the bedrock 2 below that can be coordinated with deformation. This not only improves the utilization rate of soft rock, but also reduces the damage caused by uncoordinated deformation, thereby ensuring the sustainable operation of the dam.

[0021] Combination Figure 1-2It can be seen that the upper dam body 1 includes an upper core wall 1.1 (constructed with clay) coaxial with the concrete cutoff wall 3.1. The upper dam body 1 also includes, from upstream to downstream, an upstream rockfill area 1.2 (constructed with sandstone or limestone from the lower reservoir), an upstream drainage layer 1.10, a second upstream filter layer 1.3, and a first upstream filter layer 1.4, which are constructed sequentially on the upstream side of the upper core wall 1.1. On the downstream side of the upper core wall 1.1, from downstream to downstream, there are a first downstream filter layer 1.5a, a second downstream filter layer 1.5b, a first downstream drainage layer 1.6, and a downstream rockfill area 1.7 (constructed with limestone from the upper reservoir, limestone from the lower reservoir, or...). (Constructed by excavation and filling of the tunnel), the first downstream drainage layer 1.6 has a first horizontal section 1.6b extending horizontally downstream from its bottom, combined with the upstream rockfill area 1.2 and the downstream rockfill area 1.7, which not only supports the entire upper dam body 1, but also blocks the upstream water pressure and provides support for the clay core wall; the upper core wall 1.1 has two layers of filter material on each side (i.e., two types of filter material are used for filling), which are combined with the lower filter layer 3.5, which not only prevents the upper core wall 1.1 and the first downstream soft rock filling area 3.4 from being carried out by seepage force, but also improves the seepage prevention performance of the upper core wall 1.1 and prevents the concrete seepage prevention wall 3.1 from tilting downstream; The lower dam body 3 also includes a second downstream drainage layer 3.8 filled between the lower filter layer 3.5 and the second downstream soft rock filling area 3.6. The second downstream drainage layer 3.8 has a second horizontal section 3.8b extending horizontally downstream from its bottom to the drainage prism 3.7, and its upper part is filled in integrally with the first horizontal section 1.6b. The first downstream drainage layer 1.6 is connected to the second downstream drainage layer 3.8 in the lower dam body 3 to form a whole. The second horizontal section 3.8b of the second downstream drainage layer 3.8 extends downstream to the drainage prism 3.7, which can promptly discharge the water generated by the upper dam body 1 and the lower dam body 3 during water storage, rainfall, etc., maintain the relative dryness of the dam body, and avoid adverse phenomena such as wetting or mudding in the soft rock filling area as much as possible.

[0022] During actual construction, the slope of the upstream face of the first downstream drainage layer 1.6 is 1:0.25, the slope of its downstream face is 1:0.4, and the filling height of its first horizontal part 1.6b is 4 m to 8 m; the slope of the downstream face of the second downstream drainage layer 3.8 is 1:0.5, and its filling thickness is 10 m, effectively ensuring the relative dryness of the lower dam body 3.

[0023] Combination Figure 2It is known that the concrete cutoff wall 3.1 has modulus-enhancing zones 3.9 on both sides. The modulus of the modulus-enhancing zones 3.9 is between the adjacent soft rock filling zone and the concrete cutoff wall 3.1, which effectively reduces the deformation incoordination caused by the difference in modulus between the soft rock filling zone and the concrete core wall 3.1. This improves the tensile strength and verticality of the concrete cutoff wall 3.1, avoids uneven settlement of the concrete cutoff wall 3.1 due to uneven load, wetting and rheology during the upper loading and water storage process, avoids the deformation incoordination between upstream and downstream caused by these uneven settlements, improves the tensile strength and verticality of the concrete cutoff wall 3.1, and prevents it from being damaged by large tensile stress.

[0024] During actual construction, the slope of the upstream face of the upstream rockfill area 1.2 is 1:2.25, and the distance between the bottom of the upstream face of the upstream rockfill area 1.2 and the top of the upstream face of the second upstream soft rock filling area 3.3 is... L 1 ≥10 m, that is, the upstream rockfill area 1.2 starts filling at a position 10 m or more downstream of the second upstream soft rock filling area 3.3; The slope of the downstream face of the downstream rockfill area 1.7 is 1:1.75. The distance between the bottom of the downstream face of the downstream rockfill area 1.7 and the top of the downstream face of the second downstream soft rock fill area 3.6 is... L 2 ≥20 m, meaning the bottom of the downstream face of the downstream rockfill area 1.7 is located more than 20 m upstream of the second downstream soft rock filling area 3.6; The bottom width of the upper dam body 1 is much smaller than the top width of the lower dam body 3. The lower dam body 3 provides a large foundation support for the upper dam body 1 and is conducive to proper slope, thereby reducing uneven settlement.

[0025] Combination Figure 2 It can be seen that the upstream face of the upstream rockfill area 1.2 also has an upstream slope protection 1.8, and the downstream face of the downstream rockfill area 1.7 also has a downstream slope protection 1.9. The slope of the upstream slope protection 1.8 is the same as the slope of the upstream face of the upstream rockfill area 1.2, and the slope of the downstream slope protection 1.9 is the same as the slope of the downstream face of the downstream rockfill area 1.7. The slope protection effectively prevents the instability of the upstream and downstream dam slopes. In actual engineering, the upstream slope protection 1.8 and the downstream slope protection 1.9 can be made of concrete or hard rock blocks, etc.

[0026] The lower dam body 3 of this invention is mainly constructed using soft rock as fill material. The lower dam body 3 and bedrock 2 combine to form a composite dam foundation, which greatly improves the utilization rate of soft rock, making full use of on-site materials and reducing dam investment. The concrete cutoff wall 3.1 of this invention can effectively improve the seepage prevention effect of the lower dam body 3. The lower filter layer 3.5 on the downstream side of the first downstream soft rock filling area 3.4 can effectively prevent it from being carried out by seepage force, thereby preventing the concrete cutoff wall 3.1 from tilting and improving the stability of the lower dam body 3.

[0027] Finally, it should be emphasized that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A core-wall earth-rock dam based on a soft rock composite foundation, comprising a composite foundation and an upper dam body constructed on the composite foundation, characterized in that: The composite dam foundation includes bedrock and a lower dam body built on the bedrock. The lower dam body has a concrete cutoff wall, the lower part of which extends downward into the bedrock. The lower dam body also includes a first upstream soft rock filling zone and a second upstream soft rock filling zone, which are sequentially filled from upstream to downstream on the upstream side of the concrete cutoff wall. The lower dam body also includes a first downstream soft rock filling zone, a lower filter layer, and a second downstream soft rock filling zone, which are sequentially filled from upstream to downstream on the downstream side of the concrete cutoff wall. A drainage prism is provided at the toe of the second downstream soft rock filling zone.

2. The core-wall earth-rock dam based on soft rock composite foundation according to claim 1, characterized in that: The upper dam body includes an upper core wall. The upstream side of the upper core wall is filled with an upstream rockfill area, an upstream drainage layer, a second upstream filter layer and a first upstream filter layer from upstream to downstream. The downstream side of the upper core wall is filled with a first downstream filter layer, a second downstream filter layer and a first downstream drainage layer and a downstream rockfill area from downstream to downstream. The first downstream drainage layer has a first horizontal section extending horizontally from its bottom to downstream. The lower dam body also includes a second downstream drainage layer filled between the lower filter layer and the second downstream soft rock filling area. The second downstream drainage layer has a second horizontal portion extending horizontally downstream from its bottom to the drainage prism. The upper part of the second downstream drainage layer is filled in integrally with the first horizontal portion.

3. The core-wall earth-rock dam based on soft rock composite foundation according to claim 2, characterized in that: The upstream rockfill area of ​​the upper dam body is filled with sandstone or limestone from the lower reservoir, and the distance between the bottom of its upstream face and the top of the upstream face of the second upstream soft rock filling area is ≥10 m; the downstream rockfill area is filled with limestone from the upper reservoir, limestone from the lower reservoir, or excavated material, and the distance between the bottom of its downstream face and the top of the downstream face of the second downstream soft rock filling area is ≥20 m.

4. The core-wall earth-rock dam based on soft rock composite foundation according to claim 2, characterized in that: The slope of the upstream face of the first downstream drainage layer is 1: The slope of the downstream face of the first horizontal section is 1:0.4, and the filling height of the first horizontal section is 4 m to 8 m; the slope of the downstream face of the second downstream drainage layer is 1:0.5, and the filling thickness of the second downstream drainage layer is 8 m to 15 m.

5. The core-wall earth-rock dam based on soft rock composite foundation according to claim 1, characterized in that: The slope of the upstream face of the upstream rockfill area of ​​the upper dam body is 1:2 to 1:3, and the slope of the downstream face of the downstream rockfill area of ​​the upper dam body is 1:1.5 to 1:

2.

6. The core-wall earth-rock dam based on soft rock composite foundation according to claim 2, characterized in that: The upper part of the concrete anti-seepage wall extends into the upper core wall.

7. The core-wall earth-rock dam based on soft rock composite foundation according to claim 1, characterized in that: The lower dam body also includes the formwork enhancement zone filled on both sides of the concrete anti-seepage wall.

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