A prefabricated plain concrete thin-wall dam and a construction method thereof
By using a prefabricated plain concrete thin-walled dam structure, and utilizing a plain concrete arch ring and anchor force transmission system, combined with a hydraulic membrane and underground seepage prevention body, the problems of complex construction and difficult maintenance of traditional pier-supported arch dams have been solved, achieving rapid and low-cost lightweight dam construction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- POWER CHINA KUNMING ENG CORP LTD
- Filing Date
- 2025-06-10
- Publication Date
- 2026-07-07
AI Technical Summary
Traditional arch dams with piers are complex to construct, have high requirements for geological conditions, have long construction periods, are prone to stress concentration, are difficult to maintain, and are costly.
The prefabricated plain concrete thin-walled dam structure is adopted. Through the force transmission system between the plain concrete arch ring and the anchor, combined with the hydraulic membrane and underground seepage prevention body, a lightweight, anti-sliding and stable dam structure is formed. The pressure is transmitted by cables, which simplifies the construction process and reduces the requirements for the foundation.
It reduces construction difficulty and cost, improves anti-slip stability and durability, is highly adaptable, can be built quickly and is easy to maintain, and reduces overall construction and use costs.
Smart Images
Figure CN120401423B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of municipal water conservancy engineering technology, specifically relating to a prefabricated plain concrete thin-walled dam and its construction method. Background Technology
[0002] Aspen dams are a type of lightweight dam with a sophisticated structure, saving 20% to 60% of concrete compared to gravity dams. They are particularly suitable for areas with wide valleys, favorable geological conditions, and poor transportation infrastructure. Traditional aspen dams utilize the weight of water on the inclined panels to stabilize the dam body and experience less uplift pressure at the aspen foundation, resulting in a significantly reduced dam volume. However, the aspen supports must possess extremely high compressive and anti-sliding capabilities, placing high demands on the foundation, which must be constructed on a rock foundation. Aspen dams are lightweight and use less material, but require a large amount of steel reinforcement, making their structure and construction complex. Aspen dams incorporate supporting structures at the dam foundation and abutments to withstand water pressure and other external forces, making them suitable for areas with good foundation conditions.
[0003] The existing pier dams have the following problems:
[0004] (1) Traditional arch dams with piers are constructed by on-site casting, which is complex, has high requirements for geological conditions, long construction period, low efficiency and poor adaptability, and is difficult to meet the needs of projects with complex geological conditions.
[0005] (2) When traditional arch dams with piers are used under complex conditions, stress concentration is likely to occur in local areas of the dam body. Stress concentration may cause cracking or deformation of the dam body. Local structural damage affects the overall stability and durability, and may lead to overall structural instability, resulting in high safety risks.
[0006] (3) Traditional arch dams with piers are difficult to repair and take a long time to repair after partial damage, and the construction and use costs are high.
[0007] With technological advancements, the cost of concrete materials has decreased, and their ease of on-site preparation has made it common practice to directly use regularly shaped concrete to replace natural stone in the construction of concrete block dams. The widespread adoption of hydraulic membrane products has also led to the successful application of laying flexible hydraulic membranes in dam construction to form independent waterproof layers. In modern architecture, the use of anchors and cables can efficiently provide strong tensile strength to building components, and this technology is widely used in bridges and long-span structures. In dam construction, the integration of these technologies can potentially lead to the creation of new dam structures that are simpler and lighter in size. Summary of the Invention
[0008] To address the aforementioned problems, this invention proposes a novel prefabricated plain concrete thin-walled dam and its construction method. A force transmission system is established between the plain concrete arch and the anchorage to transmit the pressure borne by the plain concrete arch to the anchorage, thereby maintaining the anti-sliding stability of the dam body.
[0009] A prefabricated plain concrete thin-walled dam, characterized by: a dam body, cables, anchors, and a seepage prevention system; the dam body consists of columns and plain concrete arches; the plain concrete arches are convex, upstream-facing, semi-circular upright columns formed by stacked plain concrete blocks; the columns are reinforced concrete, steel-concrete composite, or steel trusses; the columns are evenly arranged along the dam axis and fixed to column foundations; the column foundations are cast-in-place concrete anti-sliding piles; scissor bracing is used between adjacent columns, and horizontal struts are installed at their tops for connection; a ring beam foundation is installed at the bottom of the plain concrete arches; the columns and plain concrete arches are spaced apart and connected laterally to form the dam body; each plain concrete block on the inner ring of the plain concrete arches has one or more hanging hooks on one side; steel wire ropes are used to connect the hanging hooks on the same layer of concrete blocks and fix their ends to the two sides of the rear end of the column; the steel wires of each layer are vertically connected to form a net on the backwater side of adjacent columns.
[0010] The anchorages are set on the riverbanks on both sides of the upstream of the dam, above the check flood level. The top of the column is connected to the anchorage by a cable. The resultant force of the cable tension on each column is opposite to the resultant force of the water pressure on the column. The resultant force is perpendicular to the dam axis and points upstream.
[0011] The seepage prevention system consists of a hydraulic membrane and an underground seepage barrier. The underground seepage barrier is located on the upstream face of the dam, and a seepage barrier wall is installed at the top of the underground seepage barrier. The hydraulic membrane is sealed to the seepage barrier wall using a water-stop joint plate. The hydraulic membrane covers the water-facing side of the dam and the bottom of the reservoir between the dam and the underground seepage barrier. The top of the hydraulic membrane is suspended from the top of the dam, forming a continuous and closed seepage prevention base. A protective layer is installed under the hydraulic membrane. In steep areas, hydraulic fabric is laid, and in gentle areas, fine river sand is laid.
[0012] A method for constructing a prefabricated plain concrete thin-walled dam, characterized by the following steps:
[0013] S1. Based on the reservoir's scale, topography, and geological conditions, design the reservoir dam. Anchorages are installed on the riverbanks on both upstream sides of the dam at locations higher than the reservoir's high water level, perpendicular to the dam axis where the columns are located. If no suitable location is available in front of the dam, anchorages are installed on both banks in front of the dam, and tensioned with cables. The two cables tensioning the same column are symmetrical. If no suitable location is available on either bank, anchorages are installed at the reservoir bottom in front of the dam using tension piles. Water intake and flood discharge facilities are installed on the riverbanks or other dam sections outside the concrete thin-walled dam section, and dam components are prefabricated according to design specifications.
[0014] S2, an anti-seepage system is arranged upstream of the dam axis of the plain concrete thin-walled dam section, a reinforced concrete anti-seepage wall is set at the top of the anti-seepage system, and a water-stop joint plate is embedded at the top of the anti-seepage wall.
[0015] S3, excavate the dam foundation to solid bedrock or a foundation that meets the requirements for dam construction after reinforcement treatment, shape the cross-section of the foundation into a vertical slope step shape, pour concrete column foundations on the foundation, and arrange the column foundations evenly along the dam axis; pour arch ring beams between adjacent columns.
[0016] S4, erect supports and scaffolding, use post-pouring strips to fix the columns to the column foundation, and connect the columns and column foundations into one piece; the column at the end is directly poured and connected to the column foundation on the side of the vertical face of the bank or the stepped rock foundation, and the plain concrete arch ring adjacent to other dam sections is directly set on the arch foot of the other dam section.
[0017] S5, install struts and scissor braces; install cables, and gradually tighten the cables in a cycle after all connections are made; assemble the arch ring with blocks on the arch ring beam, using only plain concrete blocks of the same specification for each layer of the arch ring, and using different specifications of blocks for adjacent layers of the arch ring; connect the blocks with each other and with the columns using dowel bars to limit relative displacement; build all the arch rings in a step-by-step symmetrical cycle, keeping them rising synchronously, and connect the backwater side hanging buckles and install the mesh during the construction process to prevent the blocks or baffles from slipping off to the water-facing side; then dismantle and remove the supports and scaffolding;
[0018] S6. A fine-grained river sand cushion layer is laid on the reservoir bottom between the front side of the thin-walled dam and the water-stop joint, with the layer being thickened at the corners; a hydraulic fabric is laid on the steep water-facing side of the thin-walled dam and on the top surface of the fine-grained river sand, and a hydraulic membrane is laid on the hydraulic fabric. The hydraulic membrane is connected to the surrounding water-stop joint and is suspended and fixed; the protruding parts of the substructures under the hydraulic membrane that come into contact with the hydraulic membrane are rounded.
[0019] Furthermore, the distance between the arch feet of the two arch rings on the water-facing side of the column is greater than 0.4m, which facilitates construction and ensures that the arc segment of the concrete arch ring in contact with the water is a complete and strictly semi-circular shape. This ensures that there is only a positive pressure perpendicular to the contact surface between the column and the arch ring, and between the arch ring blocks. All major load-bearing components are connected without hinges. Controllable mutual displacement eliminates local stress concentration, avoids component damage, and thus improves the overall safety and durability of the dam.
[0020] Furthermore, the joints of adjacent plain concrete blocks in the same plain concrete arch ring are staggered, and dowel rod holes are opened on the four connecting surfaces of each plain concrete block. Dowel rods are inserted between adjacent plain concrete blocks and between columns and plain concrete blocks for connection.
[0021] The beneficial effects of this invention are as follows:
[0022] Compared with existing dam types, the prefabricated plain concrete thin-walled dam described in this invention has the advantages of lightweight and material-saving structure and low uplift pressure of the dam foundation, as well as the following advantages: (1) This dam type reduces the requirements for the geological conditions of the dam foundation and has strong adaptability. The water-retaining surface of the dam is inclined and bears the heavy pressure of the upper water body, and the pressure of the pier foundation is high; the connection surface between the thin shell dam surface and the dam foundation is thin, and the pressure difference of the foundation seepage prevention is large; the traditional arch dam has high requirements for the compressive and seepage resistance of the dam foundation; the water-retaining surface of the dam type described in this invention is upright, and the dam foundation only bears the weight of the thin-walled dam body itself. The distance between the underground seepage prevention body located upstream and the dam axis is large, and the pressure difference per unit length of the seepage prevention body is small, which reduces the requirements for the compressive and seepage resistance of the dam foundation. (2) The construction is less difficult and faster. The water-retaining surface of the pier-arch dam is a thin-shell curved surface. The formwork construction process is demanding and difficult. The curing period of cast-in-place reinforced concrete is long. The underground seepage prevention body and the water-retaining dam are located on the same cross section. Construction proceeds from bottom to top and gradually unfolds, resulting in a long construction period. The dam body and dam foundation of this type of dam do not bear the weight of the water. The load on the components and dam foundation is small. The material and process requirements are low. The dam body components are connected in series with force transmission rods and assembled without adhesive. The support and fixing are easy, the installation accuracy is high, and the construction speed is fast. On the main river channel, the underground seepage prevention body and the water-retaining dam are staggered, which facilitates the organization of parallel construction and speeds up the overall construction speed. (3) The construction and use costs are low. The equal-diameter and equal-depth columns and thin-walled arches have completely consistent load characteristics and identical shapes and specifications, which facilitates standardization, precise design, and mass production. The dam body is thin and the components are lightweight, which facilitates rapid assembly of the dam body and reduces the use of large construction machinery and equipment. Plain concrete is inexpensive, and the independent anti-seepage structure ensures that the load-bearing structural components of the dam are not submerged in water, resulting in excellent working conditions, significantly improved weather resistance, and enhanced resistance to freezing and corrosion. This reduces the requirements for dam construction materials and processes, and extends the service life. All components of this dam type are connected by movable joints, and the flexible splicing can flexibly adapt to local deformation, avoid stress concentration, and reduce component damage. Each assembled component is independent of the others, and in case of damage, it can be quickly replaced and repaired at low cost, which can further reduce the total life cycle cost of this type of dam.
[0023] Compared to traditional dams that rely on high-strength materials or complex reinforcement measures, the force transmission system design in this invention, consisting of cables, columns, and a geonet, is simpler and more efficient, offering significant technical advantages. Using plain concrete blocks and hydraulic membranes as the main materials results in low material costs and ease of mass production and transportation. Furthermore, the prefabricated structure reduces the complexity of on-site construction and labor costs, further lowering the overall cost. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the plan layout of a prefabricated plain concrete thin-walled dam.
[0025] Figure 2 This is a schematic diagram of the dam along the river in Example 1.
[0026] Figure 3 This is a schematic diagram of the dam's cross-section along the river in Example 2.
[0027] Figure 4 This is a schematic diagram of the axial section of a prefabricated plain concrete thin-walled dam.
[0028] Figure 5 This is a partial top view of a prefabricated plain concrete thin-walled dam.
[0029] Figure 6 This is a schematic diagram of a plain concrete block structure.
[0030] Among them: 1-anchor seat, 2-cable, 3-column, 31-column foundation, 4-strut, 5-plain concrete arch, 51-arch ring beam, 52-first block, 53-second block, 6-hydraulic membrane, 61-waterstop joint, 62-hydraulic fabric, 7-fine river sand, 8-dowel bar, 81-dowel bar insertion hole, 9-bedrock, 10-hanging buckle, 11-netting, 12-underwater anchor seat, 13-tension pile, 14-seepage barrier wall, 15-underground seepage barrier, 16-dam axis, 17-gravity dam, 18-spillway. Detailed Implementation
[0031] Example 1: A certain river is a wide and shallow river with a steep right bank and a relatively gentle left bank. The alluvial layer of the riverbed is thin and the bedrock on both sides is exposed. A hybrid dam is designed and constructed. The main channel section adopts a plain concrete thin-walled dam with a total of 7 plain concrete arch rings of equal diameter. The two banks are concrete gravity dams. The prefabricated plain concrete thin-walled dam includes a dam body, cables 2, anchors 1, and a seepage prevention system. The dam body consists of columns 3 and plain concrete arch rings 5. The plain concrete arch rings 5 are upright, semi-circular columns convex upstream, constructed from layers of plain concrete blocks. The columns 3 are reinforced concrete trusses, evenly arranged along the dam axis and fixed to column foundations 31, which are cast-in-place concrete anti-sliding piles. Scissor bracing is used between adjacent columns 3, and horizontal bracing 4 is installed at their tops for apical connection. A ring beam foundation is installed at the bottom of the plain concrete arch rings 5. The columns 3 and plain concrete arch rings 5 are spaced apart and connected laterally to form the dam body. Each plain concrete block on the plain concrete arch ring 5 has one or more hanging hooks 10 on one side of its inner ring surface. Steel wire ropes are used to connect the hanging hooks 10 on the same layer of concrete blocks and fix their ends to the two sides of the rear end of the column 3. The steel wires of each layer are vertically connected to form a net 11 on the backwater side of adjacent columns 3.
[0032] Anchor 1 is set on the riverbanks on both sides of the upstream of the dam at a position higher than the high water level of the reservoir. The top of the column 3 is connected to the anchor 1 by a cable 2. The resultant force of the cable 2 on each column 3 is opposite to the resultant force of the water pressure on the column 3. The resultant force is perpendicular to the dam axis and points upstream.
[0033] The seepage prevention system consists of a hydraulic membrane 6 and an underground seepage barrier 15. The underground seepage barrier 15 is located on the upstream face of the dam. A seepage barrier wall 14 is installed at the top of the underground seepage barrier 15. The hydraulic membrane 6 is sealed to the seepage barrier wall 14 using a water-stop joint plate 61. The hydraulic membrane 6 covers the water-facing side of the dam and the bottom of the reservoir between the dam and the underground seepage barrier 15. The top of the hydraulic membrane 6 is suspended from the top of the dam, and the remaining peripheral edges are sealed to the water-stop joint plate 61 at the top of the seepage barrier wall 14, thus forming a continuous and closed seepage prevention base. A protective layer is installed under the hydraulic membrane 6. A hydraulic fabric 62 is laid on steep areas, and fine river sand 7 is laid on gentle areas. At the parts where the structures under the membrane contact the hydraulic membrane 6, the protruding corners are rounded and wrapped with flexible materials to ensure a smooth contact surface.
[0034] This prefabricated plain concrete thin-walled dam was constructed according to the following steps:
[0035] S1, Anchor 1 is set at the upstream bank slopes where it is higher than the check flood level. The left bank anchors are combined into a single anchor, and five anchors are set on the right bank respectively. Both banks are connected to the riverbank by concrete gravity dams 17. A spillway 18 is set on the open concrete dam section on the left bank. The bank slope is gentle and stable, and the water flow returns to the channel well.
[0036] S2, prefabricated plain concrete thin-walled dam components according to design specifications and quantities, column 3 is a variable cross-section T-shaped column with a web that is wider at the bottom and narrower at the top, and is prefabricated with reinforced concrete, plain concrete blocks include two specifications, first block 52 and second block 53, and are prefabricated with lightweight aggregate concrete.
[0037] S2, an underground seepage barrier 15 is arranged upstream of the axis of the plain concrete thin-walled dam. A reinforced concrete seepage barrier wall 14 is set at the top of the underground seepage barrier 15, and a water-stop joint plate 61 is buried on the top of the seepage barrier wall 14.
[0038] S3, excavate the dam foundation to solid bedrock or a foundation that meets the requirements for dam construction after reinforcement treatment, pour gravity dam 17 on both banks, divide the plain concrete thin-walled dam section into sections of different depths, and shape the cross-section foundation into a vertical bank slope step type, pour concrete column foundation 31 on the foundation, the column foundation 31 is an anti-sliding pile that meets the requirements for both anti-sliding and bearing capacity, and is arranged at equal intervals along the dam axis; pour arch ring beam 51 between the columns 3.
[0039] S4, erect supports and scaffolding, install columns 3 on column foundation 31, fix columns 3 on column foundation 31 using post-pouring strip method, connect columns 3 and column foundation 31 into one; the end column 3 is directly poured and connected to the foundation on the side near the bank or near the stepped rock foundation facade, and the plain concrete arch ring 5 adjacent to the gravity dam 17 is directly built on the gravity dam 17 at the arch foot of the end near the gravity dam 17.
[0040] S5, the top of the adjacent columns are supported by bracing rods 4, and scissor bracing is used between columns 3 using bracing rods 4; install the tension cable 2, and after all the tension cables 2 are connected, tighten them gradually in a cycle; the arch ring is assembled with blocks on the arch ring beam 51, and only plain concrete blocks of the same specification are used for each layer of the arch ring, while the upper and lower adjacent layers of the arch ring must use first blocks 52 and second blocks 53 of different specifications, and the first blocks 52 and second blocks 53 are used alternately from bottom to top; between the blocks and between the blocks and the columns, the transmission rods 8 are connected to each other by inserting transmission rods 8 into the reserved transmission rod insertion holes 81 to limit relative displacement; all the arch rings are built in a step-by-step symmetrical cycle, keeping synchronous rise. During the construction, the hanging hooks 10 are installed synchronously, and steel wire ropes are pulled to form a net 11 to prevent the water-facing surface of the blocks from slipping off; dismantle and remove the supports and scaffolding.
[0041] S6. A fine-grained river sand 7 cushion layer is laid at the bottom of the reservoir between the water-retaining dam body and the top of the underground seepage prevention body 15 at the top of the water-stop plate 61. The layer is thickened at corners such as the dam toe and foundation steps. A hydraulic fabric 62 is laid on the water-facing side of the thin-walled dam and on top of the fine-grained river sand 7 cushion layer. A hydraulic membrane 6 is laid on the hydraulic fabric 62. The hydraulic membrane is sealed to the water-stop plate 61 and the hydraulic membrane 6 is suspended and fixed. All protruding parts of the substructure that come into contact with the hydraulic membrane 6 must be rounded or padded for protection of the hydraulic membrane.
[0042] Example 2: In a wide and shallow river channel, the river widens upstream of the dam site, the terrain is gentle, and the riverbanks are far apart and low in elevation, making it difficult to find suitable anchorage points. Therefore, anti-tension piles 13 are driven into the bedrock 9 under the riverbed in the upstream channel, underwater anchorages 12 are installed, and anchor cables 2 are installed one-to-one with the columns 3. Underwater anchorages 12 are installed directly above the columns. The remaining construction methods are the same as in Example 1.
Claims
1. A prefabricated plain concrete thin-walled dam, characterized in that: The system includes a dam body, cables, anchorages, and a seepage prevention system. The dam body consists of columns and plain concrete arches. The plain concrete arches are upright, semi-circular columns convex upstream, constructed from layers of plain concrete blocks. The columns are made of reinforced concrete, steel-concrete composite, or steel trusses. The columns are evenly distributed along the dam axis and fixed to column foundations, which are cast-in-place concrete anti-sliding piles. Adjacent columns are supported by scissor bracing, with horizontal struts connecting them at their tops. A ring beam foundation is installed at the bottom of the plain concrete arches. The columns and plain concrete arches are spaced apart and connected laterally to form the dam body. Each plain concrete block on the arch has one or more hanging hooks on one side of its inner ring. Steel wire ropes are used to connect the hanging hooks on the same layer of concrete blocks and fix their ends to the two sides of the rear end of the column. The steel wires of each layer are vertically connected to form a net on the back side of adjacent columns. The anchorages are set on the riverbanks on both sides of the upstream of the dam, above the check flood level. The top of the column is connected to the anchorage by a cable. The resultant force of the cable tension on each column is opposite to the resultant force of the water pressure on the column. The resultant force is perpendicular to the dam axis and points upstream. The seepage prevention system consists of a hydraulic membrane and an underground seepage barrier. The underground seepage barrier is located on the upstream face of the dam, and a seepage barrier wall is installed at the top of the underground seepage barrier. The hydraulic membrane is sealed to the seepage barrier wall using a water-stop joint plate. The hydraulic membrane covers the water-facing side of the dam and the bottom of the reservoir between the dam and the underground seepage barrier. The top of the hydraulic membrane is suspended from the top of the dam, forming a continuous and closed seepage prevention base. A protective layer is installed under the hydraulic membrane. In steep areas, hydraulic fabric is laid, and in gentle areas, fine river sand is laid.
2. A prefabricated plain concrete thin-walled dam as described in claim 1, characterized in that... The distance between the arch feet of the two arch rings on the water-facing side of the column is greater than 0.4m.
3. A prefabricated plain concrete thin-walled dam as described in claim 1, characterized in that... The joints of adjacent plain concrete blocks in the same plain concrete arch are staggered. Each plain concrete block has dowel bar holes on its four connecting surfaces (top, bottom, left, and right). Dowel bars are inserted between adjacent plain concrete blocks and between columns and plain concrete blocks for connection.
4. A method for constructing a prefabricated plain concrete thin-walled dam, characterized in that... Includes the following steps: S1. Design the reservoir dam according to the reservoir size, topography, and geological conditions; anchorages are installed on the riverbanks on both sides upstream of the dam at locations higher than the reservoir's high water level; if there is no suitable location in front of the dam, anchorages are installed on both banks in front of the dam and the columns are tensioned by cables, with the two cables tensioning the same column being symmetrical to the vertical line of the dam axis of that column; if there is no suitable location on both banks, anchorages are installed at the reservoir bottom in front of the dam using pull-out piles, and the protection measures for the cables are strengthened; water intake and flood discharge facilities are installed on the riverbanks or other dam sections outside the concrete thin-walled dam section, and dam components are prefabricated according to the design specifications. S2, an anti-seepage system is arranged upstream of the dam axis of the plain concrete thin-walled dam section, a reinforced concrete anti-seepage wall is set at the top of the anti-seepage system, and a water-stop joint plate is embedded at the top of the anti-seepage wall. S3, excavate the dam foundation to solid bedrock or a foundation that has been reinforced to meet the requirements for dam construction, pour concrete gravity dams on both banks, divide the plain concrete thin-walled dam sections into segments of different depths, shape the cross-section foundation into a stepped shape with vertical bank slopes, pour concrete column foundations on the foundation, the column foundations are anti-sliding piles that meet the requirements for both anti-sliding and bearing capacity, and are evenly distributed along the dam axis; pour arch ring beams between adjacent columns; S4, erect supports and scaffolding, use post-pouring strips to fix the columns to the column foundation, and connect the columns and column foundations into one piece; the column at the end is directly poured and connected to the column foundation on the side of the vertical face of the bank or the stepped rock foundation, and the plain concrete arch ring adjacent to other dam sections is directly set on the arch foot of the other dam section. S5, install struts and scissor bracing between adjacent columns; install cables, and gradually tighten them in a cycle after all connections are made; assemble the arch ring with blocks on the arch ring beam, using only plain concrete blocks of the same specification for each layer of arch ring, and using different specifications of blocks for adjacent layers of arch ring; connect blocks with each other and with columns using dowel bars to limit relative displacement; build all arch rings in a step-by-step symmetrical cycle, maintaining synchronous rise, and connect backwater-side hanging buckles and install mesh nets during the construction process to prevent blocks or baffles from slipping onto the water-facing side; then dismantle and remove the supports and scaffolding; S6. A fine-grained river sand cushion layer is laid on the reservoir bottom between the front side of the thin-walled dam and the water-stop joint plate, with the layer being thickened at the corners; a hydraulic fabric is laid on the steep water-facing side of the thin-walled dam and on the top surface of the fine-grained river sand, and a hydraulic membrane is laid on the hydraulic fabric. The hydraulic membrane is connected to the water-stop joint plate and is suspended and fixed; the protruding parts of the substructures under the hydraulic membrane that come into contact with the hydraulic membrane are rounded.