A self-overflow cemented dam structure and construction method

Abstract

This invention relates to the field of water conservancy and hydropower engineering technology, specifically to a self-overflowing cemented dam structure, comprising: a dam body, a foundation cushion layer at the bottom of the dam body, a first surface structure and a second surface structure on the upstream slope of the dam body, an overflow orifice and a third surface structure on the downstream slope of the dam body, and a fourth surface structure on the remaining parts of the dam body; wherein, the first surface structure is located below the upstream dead water level, the second surface structure is located in the upstream water level variation zone, and the third surface structure is located below the downstream dead water level; the bottom plate and guide wall of the overflow orifice are paved with concrete, and the first surface structure and the third surface structure are paved with concrete or cemented gravel; the dam body, foundation cushion layer, second surface structure, and fourth surface structure are all paved with cemented gravel.

Description

Technical Field

[0001] This invention relates to the field of water conservancy and hydropower engineering technology, specifically to a cemented dam structure with self-overflowing dam body and its construction method. Background Technology

[0002] In hydropower projects, the lower reservoir dam of a pumped storage power station is generally built on a river to utilize the river's inflow for initial water storage and to replenish water lost due to seepage and evaporation later on. After the power station is completed, the lower reservoir also needs to have the designed flood discharge capacity. Face-faced rockfill dams are a common dam type for pumped storage lower reservoirs. Considering the settlement of the dam body during operation, a spillway is usually built on the dam bank. Constructing a spillway requires excavating the bank slope, often resulting in high slope problems. This presents significant engineering challenges, high safety risks, and large investment scale; the spillway investment can account for more than 30% of the total investment in the lower reservoir's main structure.

[0003] Cemented dam technology utilizes locally sourced materials such as cement, fly ash, admixtures, and unscreened, unwashed sand, gravel, or stone to construct dams with certain compressive, shear strength, and erosion resistance. Cemented dams are a new type of dam between earth-rock dams and roller-compacted concrete dams. Their design philosophy is "suitable structure and suitable materials," optimizing the dam's shape to fully utilize local materials and selecting appropriate materials for different parts of the dam to meet structural requirements. Cemented sand and gravel dams have relatively low requirements for aggregate particle size, gradation, and mud content, allowing for full utilization of local materials and reducing waste. They also require less cementitious material, resulting in lower hydration heat and eliminating the need for temperature control measures such as water cooling. Cemented sand and gravel dams offer advantages such as safety, reliability, low investment, short construction period, and environmental friendliness.

[0004] Cemented dam construction materials have certain compressive and shear strength, and the dam body settlement is very small. The safety risk of setting spillway orifices in the dam body is low. When applied to the lower reservoir dam of pumped storage power stations, the construction of bank-side spillways can be avoided. Summary of the Invention

[0005] This invention provides a self-overflowing cemented dam structure and construction method, which designs the lower reservoir dam of a pumped storage power station as a self-overflowing cemented dam structure, avoiding the high slope problem caused by excavating the spillway, reducing engineering difficulty, safety risks and saving engineering investment.

[0006] The technical solution of the present invention is: a cemented dam structure with self-overflow, comprising: a dam body, a foundation cushion layer set at the bottom of the dam body, a first surface structure and a second surface structure set on the upstream slope of the dam body, an overflow surface orifice and a third surface structure set on the downstream slope of the dam body, and a fourth surface structure set on the remaining parts of the dam body.

[0007] The first surface structure is set below the upstream dead water level, the second surface structure is set in the upstream water level change zone, and the third surface structure is set below the downstream dead water level.

[0008] The bottom plate and guide wall of the overflow orifice are paved with concrete, and the first surface structure and the third surface structure are paved with concrete or cemented gravel.

[0009] The dam body, foundation cushion layer, second surface layer structure, and fourth surface layer structure are all constructed using cemented gravel.

[0010] In a further embodiment, the cemented gravel in the foundation cushion layer must meet the requirements for strength and impermeability;

[0011] The cemented gravel in the dam body must meet the strength requirements;

[0012] The concrete or cemented gravel of the first and third surface layers must meet the requirements for strength and impermeability.

[0013] The cemented gravel of the second surface structure must meet the requirements of impermeability and frost resistance;

[0014] The cemented gravel of the fourth surface layer structure must meet the requirements for frost resistance and protection.

[0015] The concrete of the base plate and guide wall must meet the requirements for strength and impact resistance.

[0016] In a further proposed solution, cemented gravel requiring any of the following properties—impermeability, frost resistance, or abrasion resistance—is made from slurry-rich cemented gravel or slurry-compacted cemented gravel.

[0017] In a further proposed solution, concrete requiring any of the following properties—impermeability, frost resistance, or abrasion resistance—would be either conventional concrete or roller-compacted concrete.

[0018] In a further embodiment, the slope of the upstream slope of the dam body is in the range of 1:0.3 to 0.7, and the slope of the downstream slope of the dam body is in the range of 1:0.5 to 0.7.

[0019] Another technical solution of the present invention is: a construction method for constructing the above-mentioned cemented dam structure, comprising:

[0020] S1. Based on the design requirements and the dam structure layout and construction conditions, structural joints are defined for the cemented dam structure, and no longitudinal joints or induced joints are set.

[0021] S2. Excavate the overburden layer of the dam body down to the exposed bedrock surface, and treat the bedrock surface to meet the construction conditions;

[0022] S3. Construction of the foundation cushion layer on the dam foundation;

[0023] S4. Install a copper sheet and rubber waterstop at the structural joint. Before laying the cemented gravel, temporary protection should be set on both sides of the waterstop to ensure the integrity of the waterstop.

[0024] S5. Lay cemented sand and gravel to form the dam body, and at the same time, lay cemented sand and gravel on both sides of the dam body to form the first to fourth surface structures, and make the height of the surface structures lower than the height of the compacted layer inside the dam.

[0025] S6. Set joint filler on the cemented gravel material of the dam body. After leveling and before compaction, dig a trench and fill it with joint filler.

[0026] S7. Compact the cemented gravel material of the dam body and vibrate the cemented gravel material of the first to fourth surface structures.

[0027] S8. Roughen the layers of the first to fourth surface structures;

[0028] S9. Install overflow gauge reinforcement bars on the downstream side of the overflow dam section according to the design requirements, erect formwork and pour concrete to form the overflow gauge.

[0029] Repeat steps S4 to S9 until the entire dam construction is completed.

[0030] In a further proposed solution, after the cemented gravel has set, the surface is roughened and mortar is laid before the next layer of cemented gravel is constructed. The strength of the cement mortar should be at least one grade higher than that of the cemented gravel.

[0031] In a further scheme, during step S7, when the gravel is grouted and vibrated at the water-stop installation site, the water-stop material is protected, and large aggregates in this area are manually removed and fully vibrated to prevent the formation of seepage channels.

[0032] In a further proposed solution, during construction, the surface of the storage area should be kept moist. When the sunlight is strong or the wind is strong and the surface is dry, surface moisture should be compensated by spraying or covered with tarpaulin to keep the surface from turning white and to keep it moist. When the temperature is low, a curing mat should be used to cover the surface to prevent the cemented gravel from freezing.

[0033] In a further embodiment, in step S5, the paving material for the first surface structure and the third surface structure can be replaced with concrete.

[0034] Compared with the prior art, the present invention has the following advantages: (1) The cemented gravel dam uses less cementing material, has a low hydration heat temperature rise, and does not require temperature control measures such as water cooling; (2) The safety risk of setting an overflow outlet in the dam body is low. When applied to the lower reservoir dam of a pumped storage power station, it can avoid setting up a bank-side spillway, reduce the difficulty of engineering treatment, safety risks and save engineering investment; (3) The cemented gravel dam has relatively low requirements for aggregate particle size, gradation and mud content. It can make full use of local materials, reduce waste, and achieve the goal of green construction. Attached Figure Description

[0035] Figure 1 This is a plan view of an embodiment of the present invention.

[0036] Figure 2 This is a cross-sectional view of the overflow dam section in an embodiment of the present invention.

[0037] In the diagram: 1. Dam section; 2. Overflow dam section; 3. Overflow outlet; 4. Structural joint; 5. Foundation cushion layer; 6. Dam body; 7. First surface structure; 8. Third surface structure; 9. Second surface structure; 10. Fourth surface structure; 11. Bottom slab; 12. Guide wall. Detailed Implementation

[0038] To enable those skilled in the art to more clearly understand the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments.

[0039] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention 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 limiting this invention.

[0040] like Figures 1-2 As shown, the self-overflowing cemented dam structure provided in this embodiment is divided into a water-retaining dam section 1 and an overflow dam section 2 according to the dam structure layout and function, with structural joints 4 arranged between the dam sections. An overflow orifice 3 is arranged on the downstream dam face of the overflow dam section 2, and the overflow orifice 3 includes an overflow orifice bottom plate 11 and a guide wall 12.

[0041] The cemented dam structure includes a dam body 6, a foundation cushion layer 5 at the bottom of the dam body, a first surface structure 7 and a second surface structure 9 on the upstream slope of the dam body, a third surface structure 8 on the downstream slope of the dam body, and a fourth surface structure 10 (mainly the top of the dam body and the downstream slope excluding the overflow orifice 3 and the third surface structure) on the remaining parts of the dam body. The first surface structure 7 is located below the upstream dead water level, the second surface structure 9 is located in the upstream water level variation zone, and the third surface structure 8 is located below the downstream dead water level.

[0042] The bottom plate 11 and guide wall 12 of the overflow orifice are paved with concrete, and the first surface structure 7 and the third surface structure 8 are paved with concrete or cemented gravel; the dam body 6, foundation cushion 5, second surface structure 9 and fourth surface structure 10 are all paved with cemented gravel.

[0043] The cemented gravel in the foundation cushion layer 5 must meet strength and impermeability requirements; the cemented gravel in the dam body 6 must meet strength requirements; the concrete or cemented gravel in the first surface structure 7 and the third surface structure 8 must meet strength and impermeability requirements; the cemented gravel in the second surface structure 9 must meet impermeability and frost resistance requirements; the cemented gravel in the fourth surface structure 10 must meet frost resistance and protection requirements; and the concrete in the base slab 11 and guide wall 12 must meet strength and erosion resistance requirements. Furthermore, in this embodiment, cemented gravel requiring any one of impermeability, frost resistance, or erosion resistance is rich-slurry cemented gravel or slurry-compacted cemented gravel; concrete requiring any one of impermeability, frost resistance, or erosion resistance is normal concrete or roller-compacted concrete.

[0044] In this embodiment, the slope of the upstream slope of the dam body 6 is in the range of 1:0.3~0.7, and the slope of the downstream slope of the dam body is 1:0.5~0.7.

[0045] Cemented gravel dams are an innovative type of dam that has significant advantages over concrete dams. Concrete dams need to be built on weakly weathered bedrock, while cemented gravel dams can be built on strongly weathered bedrock. Furthermore, cemented gravel has low requirements for material sources; strongly weathered material excavated from the quarry can be used to build the dam, greatly reducing waste and excavation.

[0046] This embodiment also provides a construction method applied to the construction of the above-mentioned cemented dam structure with self-overflow, including the following steps:

[0047] S1. According to the design requirements and in combination with the dam structure layout and construction conditions, the cemented sand and gravel water-retaining dam section 1 and the overflow dam section 2 are divided. Structural joints 4 are set between the dam structure, but no longitudinal joints or induced joints are set.

[0048] S2. Excavate the overburden layer of the dam body to expose the bedrock surface, and remove steep slopes, sharp corners and loose rock blocks on the bedrock surface; clean the soil, rust spots, calcium film and other debris on the structural surface; if there are faults, fissures or weak interlayers, they must be removed and backfilled according to the design requirements.

[0049] S3. Construction of foundation cushion layer 5 on the dam foundation. Foundation cushion layer 5 can be constructed by using cemented sand and gravel with rich slurry for seepage prevention and compaction.

[0050] S4. A copper sheet and a rubber waterstop are installed at each of the four structural joints. Before laying the cemented gravel, temporary protection is required on both sides of the waterstop to ensure the integrity of the waterstop and leave enough cavity to fill the self-compacting concrete.

[0051] S5. The cemented sand and gravel material for paving the dam body 6 can be transported to various locations parallel to the dam axis by dump trucks. Then, the cemented sand and gravel material is transported to the upstream part by loaders arranged in the storage area. In the area about 1m away from the formwork, waterstop and other details, manual paving is required to avoid the impact of machinery on the formwork and waterstop. At the same time, the stone material is paved on both sides of the compacted layer inside the dam to form the first to fourth surface structure, and the height of the surface structure is lower than the height of the compacted layer inside the dam.

[0052] The paving materials for the first surface structure 7 and the third surface structure 8 can also be replaced with concrete;

[0053] S6. Set the joint filling material. Asphalt cedar wood boards can be used. After leveling and before compaction, an excavator can be used to dig a trench and fill it with asphalt cedar wood boards. The spacing at the joints should not be greater than 100mm, and the height should be 30mm~50mm lower than the compaction thickness.

[0054] S7. Compact the cemented gravel in dam body 6 and vibrate the first to fourth surface structures 7 to 10. The junction between the cemented gravel 6 and the first to fourth surface structures 7 to 10 should be laid crosswise (i.e., at the junction of the cemented gravel dam body and the surface structure, the two materials need to cross each other and rise synchronously layer by layer). Vibrate the cemented gravel in the dam body 6 where the compaction is insufficient. During the process of adding grout and vibrating the cemented gravel at the water-stopping location, protect the water-stopping material. Large aggregates in this area should be manually removed and fully vibrated to prevent seepage channels.

[0055] S8. Roughen the layers 7 to 10 of the first to fourth surface structures;

[0056] S9. On the downstream side of the overflow dam section 2, the overflow surface hole reinforcement is fabricated and installed according to the design requirements. The formwork is erected and the concrete of the bottom plate 11 and the guide wall 12 is poured to form the overflow surface hole.

[0057] Repeat steps S4 to S9 until the entire dam construction is completed.

[0058] During construction, after the cemented gravel has set, the surface is roughened and mortar is laid before the next layer of cemented gravel is applied. The strength of the cement mortar should be at least one grade higher than that of the cemented gravel. During construction, the surface must be kept moist. In cases of strong sunlight or dry winds, surface moisture should be compensated by spraying or covered with tarpaulins to keep the surface moist and prevent it from turning white. In low temperatures, use curing mats to cover the surface to prevent the cemented gravel from freezing.

[0059] The above description is merely a preferred embodiment of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cemented dam structure with self-overflowing dam body, characterized in that, include: The dam body includes a foundation cushion layer at the bottom of the dam body, a first surface structure and a second surface structure on the upstream slope of the dam body, an overflow orifice and a third surface structure on the downstream slope of the dam body, and a fourth surface structure on the remaining parts of the dam body. The first surface structure is set below the upstream dead water level, the second surface structure is set in the upstream water level change zone, and the third surface structure is set below the downstream dead water level. The bottom plate and guide wall of the overflow orifice are paved with concrete, and the first surface structure and the third surface structure are paved with concrete or cemented gravel. The dam body, foundation cushion, second surface structure, and fourth surface structure are all constructed using cemented gravel. The cemented gravel in the foundation cushion layer must meet the requirements for strength and impermeability. The cemented gravel in the dam body must meet the strength requirements; The concrete or cemented gravel of the first and third surface layers must meet the requirements for strength and impermeability. The cemented gravel of the second surface structure must meet the requirements of impermeability and frost resistance; The cemented gravel of the fourth surface layer structure must meet the requirements for frost resistance and protection. The concrete of the base plate and guide wall must meet the requirements for strength and impact resistance. Cemented gravel requiring any of the following properties—impermeability, frost resistance, and abrasion resistance—should be rich-slurry cemented gravel or slurry-mixed vibratory cemented gravel. Concrete requiring any one of the following properties—impermeability, frost resistance, or abrasion resistance—should be conventional concrete or roller-compacted concrete. The slope of the upstream slope of the dam body is in the range of 1:0.3~0.7, and the slope of the downstream slope of the dam body is in the range of 1:0.5~0.

7. The dam body overflows through the overflow orifice, which replaces the bank-type spillway of the lower reservoir of the pumped storage power station, avoiding the high slope problem caused by excavating the spillway.

2. A construction method for constructing the cemented dam structure as described in claim 1, characterized in that, include: S1. Based on the design requirements and the dam structure layout and construction conditions, structural joints are defined for the cemented dam structure, and no longitudinal joints or induced joints are set. S2. Excavate the overburden layer of the dam body down to the exposed bedrock surface, and treat the bedrock surface to meet the construction conditions; S3. Construction of the foundation cushion layer on the dam foundation; S4. Install a copper sheet and rubber waterstop at the structural joint. Before laying the cemented gravel, temporary protection should be set on both sides of the waterstop to ensure the integrity of the waterstop. S5. Lay cemented sand and gravel to form the dam body, and at the same time, lay cemented sand and gravel on both sides of the dam body to form the first to fourth surface structures, and make the height of the surface structures lower than the height of the compacted layer inside the dam. S6. Set joint filler on the cemented gravel material of the dam body. After leveling and before compaction, dig a trench and fill it with joint filler. S7. Compact the cemented gravel material of the dam body and vibrate the cemented gravel material of the first to fourth surface structures. S8. Roughen the layers of the first to fourth surface structures; S9. Install overflow gauge reinforcement bars on the downstream side of the overflow dam section according to the design requirements, erect formwork and pour concrete to form the overflow gauge. Repeat steps S4 to S9 until the entire dam construction is completed.

3. The construction method as described in claim 2, characterized in that: After the cemented gravel has set, roughen the surface and lay cement mortar before proceeding with the next layer of cemented gravel. The strength of the cement mortar should be at least one grade higher than that of the cemented gravel.

4. The construction method as described in claim 2, characterized in that: In step S7, during the construction of cemented gravel with grouting and vibration at the water-stop installation site, the water-stop material should be protected, and large aggregates in this area should be manually removed and fully vibrated to prevent the formation of seepage channels.

5. The construction method as described in claim 2, characterized in that: During construction, keep the surface of the storage area moist. When the sunlight is strong or the wind is strong and dry, use spraying to compensate for surface moisture or cover with tarpaulin to keep the surface from turning white and to keep it moist. When the temperature is low, cover with curing mats to prevent cemented gravel from freezing.

6. The construction method as described in claim 2, characterized in that: In step S5, the paving material for the first surface structure and the third surface structure can be replaced with concrete.

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