Leakage treatment method for vertical expansion joint of reservoir dam under non-drainage condition
By drilling holes on both sides of the vertical expansion joint of the reservoir dam and constructing enclosing joints, a triple barrier and seepage prevention system was formed by pouring concrete barriers, which solved the problem of dam leakage under conditions of no water release and achieved a rapid and low-cost seepage control effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WATER RESOURCES RES INST OF SHANDONG PROVINCE
- Filing Date
- 2023-08-31
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies are insufficient to effectively address leakage problems at vertical expansion joints of reservoir dams without releasing water. Conventional methods are time-consuming, labor-intensive, and unsuitable, especially in situations where water cannot be released.
Without releasing water, a triple barrier seepage prevention system is formed by drilling holes on both sides of the expansion joint, constructing a sealing joint, and pouring concrete barrier walls. This system includes a sandwich structure of a concrete base and side retaining walls. The design of the insert plate and barrier plate optimizes the grouting injection port to ensure a sealing effect.
It achieves rapid and low-cost treatment of expansion joint leakage without water discharge. The construction is simple, saves construction time, has a good barrier effect, and has a significant anti-leakage effect. Moreover, the construction process is time-saving and labor-saving.
Smart Images
Figure CN117248501B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of water conservancy engineering technology, specifically relating to a method for treating leakage at vertical expansion joints of reservoir dams under conditions of no water release. Background Technology
[0002] Expansion joints, also known as temperature joints, are designed to prevent damage to buildings caused by deformation due to changes in ambient temperature. Since buildings are constructed within the natural environment, temperature variations inevitably have a direct impact, resulting in thermal expansion and contraction. Generally, the greater the length of a building and the greater the temperature difference, the more accumulated deformation occurs, thus increasing the need for expansion joints. In reservoir dams, expansion joints reduce damage and destruction to the dam structure during expansion and contraction. The width of expansion joints in ordinary concrete wall dams is typically around 30mm, while those in masonry gravity dams and arch dams are usually between 60mm and 130mm. Dam expansion joints are a crucial part of dam engineering. During dam design and construction, relevant specifications and standards must be followed, and the installation and treatment of expansion joints must be strictly controlled. This not only ensures the safe operation of the dam but also improves its seismic performance and ability to withstand natural disasters, thus providing fundamental protection for people's lives and property. After a period of operation, the dam body expands and contracts under temperature stress, causing fatigue and damage to the water-stopping material in the expansion joints. This leads to leakage, and if left untreated for a long time, the damage to the expansion joint water-stopping material will become more serious, and the leakage will gradually increase, endangering the safety of the dam.
[0003] Because these types of expansion joints have pressure head, repairs are relatively difficult. A common method is to first drain the water and then excavate the silt deposited in front of the dam (see attached document). Figures 1-2 The solution involves repairing the vertical expansion joints, which is relatively time-consuming and labor-intensive. Moreover, this method cannot be used for dams that cannot be excavated without releasing water. Based on the above principles, it is necessary to further study how to treat leakage in vertical expansion joints without releasing water. Summary of the Invention
[0004] To address the problems existing in the prior art, a method for treating leakage at vertical expansion joints of reservoir dams without releasing water is provided. This construction process is relatively simple, requires no water release or excavation, has low cost, short construction period, saves time and labor, and can quickly treat leakage at expansion joints.
[0005] The technical solution adopted by this invention to solve its technical problem is:
[0006] This technical solution proposes a method for treating seepage at vertical expansion joints of a reservoir dam under conditions of no water release. The method involves an expansion joint installed on the dam body, with silt deposited on one side of the dam to cover the bottom of the expansion joint. The method includes the following steps:
[0007] S1: Drilling the channel
[0008] Holes are drilled from top to bottom on both sides of the expansion joint, extending from the top of the dam to the bottom of the dam.
[0009] S2: Structural enclosure joint;
[0010] S3: Construct a barrier wall to form an expansion joint leakage control system and block the leakage point.
[0011] Preferably, the specific method for constructing the enclosing joint in S2 is as follows:
[0012] The structure of the sealing joint is constructed using an insert plate, the insert plate including a first plate body, the first plate body being a U-shaped structure formed by bending, the two ends of the first plate body being respectively fixed with first pipe piles along the length direction of the first plate body; a middle pipe pile is fixedly connected to the middle position of the first plate body along the length direction; both the first pipe pile and the middle pipe pile are hollow structures.
[0013] The insert plate is lifted up, the first pipe pile is inserted into the duct, and then the insert plate is hammered downwards until the bottom end of the insert plate is inserted into the silt in front of the dam. When the design depth is reached, the hammering is stopped. Then the insert plate is lifted out as a whole, and after being lifted out, a sealing joint is formed in the silt in front of the dam. At the same time, a hole is formed at the position of the middle pipe pile, which is the grouting injection port.
[0014] Preferably, the specific method of S3 is as follows:
[0015] A barrier wall is constructed using a barrier plate, the barrier plate including a second plate body, the second plate body also being a U-shaped structure formed by bending, and second pipe piles being fixed at both ends of the second plate body along the length direction of the second plate body; the thickness of the second plate body is less than the thickness of the first plate body, the width of the second plate body is the same as that of the first plate body, and the length of the second plate body is less than that of the first plate body; the pipe diameter of the second pipe pile is the same as that of the first pipe pile.
[0016] S31: Lift the barrier plate, insert the bottom of the second pipe pile into the duct, and then press down the barrier plate. The bottom end of the barrier plate falls along the pre-constructed enclosing joint until the bottom end of the barrier plate reaches the designated design position. Keep the barrier plate in this position and form a cavity between the bottom end of the barrier plate and the bottom of the enclosing joint.
[0017] S32: The gap between the second pipe pile and the inner wall of the duct is sealed with adhesive.
[0018] S33: Concrete is injected into the enclosing joint through the grouting inlet. The concrete is poured from the bottom of the enclosing joint upwards until it reaches the top line of the silted soil in front of the dam. The concrete below the barrier plate forms a concrete base. The concrete above the bottom surface of the barrier plate forms side retaining walls on both sides of the barrier plate. The side retaining walls and the barrier plate in the middle form a sandwich structure, forming a triple barrier seepage prevention system, referred to as the lower seepage prevention system. Above the top line of the silted soil in front of the dam, the barrier plate and sealant form a seepage prevention system, referred to as the upper seepage prevention system. The upper seepage prevention system and the lower seepage prevention system together form the expansion joint leakage control system.
[0019] Preferably, step S33 also includes pouring concrete into the second pipe pile to form a steel pipe pile structure.
[0020] Preferably, the channel is divided into an open channel section and a closed channel section. The channel located above the silt in front of the dam is the open channel section, and the channel located inside the silt in front of the dam is the closed channel section.
[0021] Preferably, the channel is formed by drilling.
[0022] Preferably, the open trench section has an opening, the diameter of which is smaller than the diameter of the second pipe pile.
[0023] Compared with the prior art, the present invention has the following advantages:
[0024] 1. This method can address leakage at expansion joints without releasing water. Holes are drilled on both sides of the expansion joint to serve as sliding channels. A concrete barrier wall is constructed by pouring concrete into the silted soil in front of the dam through a sealing joint. The concrete barrier wall consists of a concrete base and side retaining walls. The concrete base serves both load-bearing and barrier functions, while the side retaining walls and barrier panels form a sandwich structure, creating a triple-barrier seepage prevention system with excellent barrier effect and superior seepage control.
[0025] 2. This method has a relatively simple construction process, requiring no watering or excavation, saving construction time and quickly achieving leakage control of expansion joints. The insert plates and barrier plates used in the construction process can be prefabricated and customized according to design requirements. The height of the concrete base can be determined directly by the height difference between the insert plates and barrier plates, eliminating the need for measurement during pouring. The elevation of the concrete base can be predetermined during fabrication, saving time and effort, and making the fabrication convenient and simple.
[0026] 3. In this method, an intermediate pipe pile is set on the insert plate. When the intermediate pipe pile is pulled out, it can be used to construct the insertion hole. This insertion hole can be used as the grout injection port during subsequent grouting. This facilitates the subsequent concrete pouring. Otherwise, it is more difficult and harder to control to pour concrete based solely on the gap between the enclosure joint and the barrier plate. This structural form can effectively solve this problem.
[0027] 4. The duct is formed by drilling and the open section has an opening. The diameter of the opening is smaller than the diameter of the second pipe pile. This design makes the duct have a certain limiting effect to prevent the barrier plate from falling out. At the same time, the drilled duct facilitates the subsequent sealing with glue, which tightly fills the space between the barrier plate and the inner wall of the duct, forming a good seal, ensuring the sealing effect, and effectively blocking water penetration. Attached Figure Description
[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:
[0029] Figure 1 This is a schematic diagram of the expansion joint structure of the existing dam.
[0030] Figure 2 This is a side view of the dam body and the siltation soil structure in front of the dam.
[0031] Figure 3 This is a front view of the dam body and the siltation soil structure in front of the dam.
[0032] Figure 4 This is a schematic diagram of the channel structure in this invention.
[0033] Figure 5 This is a 3D diagram of the insert structure.
[0034] Figure 6 yes Figure 5 Top view of the middle insert plate structure.
[0035] Figure 7 This is a 3D diagram of the barrier plate structure.
[0036] Figure 8 This is a schematic diagram of the structure after the enclosure seam is constructed.
[0037] Figure 9 This is a schematic diagram of the structure after the barrier plate is installed.
[0038] Figure 10 yes Figure 9 Enlarged schematic diagram of the structure of region A in the middle.
[0039] Figure 11 It is a structural cross-sectional view along the BB direction.
[0040] Figure 12 yes Figure 11 Side view of the structure in conjunction with the central barrier plate, concrete base, and side retaining walls.
[0041] Figure 13 This is a flowchart of the method of the present invention.
[0042] Explanation of reference numerals in the attached figures:
[0043] 1-Dam body; 2-Expansion joint; 3-Silt in front of the dam; 4-Drainage channel; 5-First slab; 6-First pipe pile; 7-Intermediate pipe pile; 8-Second slab; 9-Second pipe pile; 10-Enclosure joint; 11-Grouting inlet; 12-Concrete barrier wall; 121-Side retaining wall; 122-Concrete base; 13-First concrete pile; 14-Second concrete pile; 15-Sealing adhesive layer. Detailed Implementation
[0044] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0045] like Figures 1-2 As shown, after years of operation, silt 3 will accumulate on one side of dam 1. This silt 3 will bury the expansion joint 2 near the bottom. If the water-stopping material in this expansion joint 2 fails due to fatigue, leakage will occur. The conventional approach to treating this leakage is to first drain the water and then excavate the silt 3 in front of the dam, which results in a large amount of work and is time-consuming and labor-intensive. Sometimes, due to poor coordination and lack of conditions for draining water, there is no good solution to the leakage problem.
[0046] Based on this, such as Figures 1-13 As shown, this embodiment proposes a method for treating leakage at vertical expansion joint 2 under conditions of no water release. Expansion joint 2 is provided on dam body 1, and silt 3 is accumulated on one side of dam body 1, covering the bottom of expansion joint 2. The treatment method under this technical environment mainly includes the following steps:
[0047] S1: Drilling 4 holes
[0048] Holes 4 are drilled from top to bottom on both sides of the expansion joint 2, extending from the top of the dam to the bottom. As a feasible solution, the holes 4 are formed by drilling, with drilling extending downwards from the top of the dam. Within the area from the top line of the silt 3 in front of the dam to the dam top line, the holes 4 have a "channel" type structure, forming a "vertical channel" structure on the outer wall of the dam body 1. Specifically, the holes 4 are divided into open channel sections and closed channel sections. The holes 4 located above the silt 3 in front of the dam are open channel sections, while the holes 4 located within the silt 3 in front of the dam are closed channel sections.
[0049] S2: Constructing the enclosure joint 10; The enclosure joint 10 is constructed in the silt 3 in front of the dam. Its main purpose is to connect the ducts 4 on both sides of the expansion joint. The enclosure joint 10 and the ducts 4 enclose the expansion joint 2.
[0050] S3: Construct a barrier wall to form a leakage control system for expansion joint 2, blocking the leakage point; use the opened channel 4 and the enclosing joint 10 to construct a barrier wall, and perform further sealing treatment to form a barrier structure, which can effectively prevent water from seeping into expansion joint 2.
[0051] The key points of each construction stage will be explained in detail below:
[0052] The specific method for constructing the enclosing joint 10 in S2 above is as follows:
[0053] The enclosure joint 10 is constructed using an insert plate, employing an "integral downward pressing joint construction" method to form the enclosure joint 10 as a whole. The specific structural form of the insert plate is as follows:
[0054] The insert plate includes a first plate body 5, which is a U-shaped structure formed by bending. First pipe piles 6 are fixed at both ends of the first plate body 5 along the length direction of the first plate body 5. A middle pipe pile 7 is fixedly connected at the middle position of the first plate body 5 along the length direction. The first pipe pile 6 and the middle pipe pile 7 are both hollow structures and are of equal length.
[0055] The purpose of adopting a hollow structure for the first pipe pile 6 and the intermediate pipe pile 7 is twofold: firstly, the thin-walled tubular structure has a small stress area, making it easy to press into the soil; secondly, when the first pipe pile 6 and the intermediate pipe pile 7 are pulled out, they can bring out the silted soil, thereby forming a hole.
[0056] The purpose of the intermediate pipe pile 7 is as follows: the intermediate pipe pile 7 is set on the insert plate. When the intermediate pipe pile 7 is pulled out, it can be used to construct the insertion hole. The insertion hole can be used as the grout injection port 11 for subsequent grouting. This facilitates the subsequent concrete pouring. Otherwise, it is more difficult and harder to control to pour concrete based solely on the gap between the enclosure joint 10 and the barrier plate. This structural form can effectively solve this problem.
[0057] The specific construction method of the enclosing joint 10 is as follows:
[0058] The insert plate is lifted, and the first pipe pile 6 is inserted into the duct 4. Then, the insert plate is hammered downwards, which can be done using a pile driver. The first pipe pile 6 can slide up and down along the duct 4 and be completely contained within the duct 4. The bottom end of the insert plate moves down until it is inserted into the silt 3 in front of the dam. When the insertion depth of the insert plate reaches the design depth, the hammering is stopped. Then, the insert plate is lifted out as a whole. After being lifted out, a retaining joint 10 is formed in the silt 3 in front of the dam (this retaining joint 10 is formed by the bottom end of the insert plate squeezing the silt). At the same time, an insertion hole is formed at the position of the middle pipe pile 7 (this insertion hole is formed by bringing out the silt). This insertion hole is the grouting injection port 11. Grouting will be carried out through this grouting injection port 11 in the future.
[0059] The specific construction method for the barrier wall in S3 is as follows:
[0060] The barrier wall is constructed using barrier panels. The specific structural form of the barrier panels is as follows:
[0061] The barrier plate includes a second plate 8, which is processed in the same way as the first plate 5, forming a U-shaped structure by bending. Second pipe piles 9 are fixed at both ends of the second plate 8 along its length. It should be noted that the thickness of the second plate 8 is less than that of the first plate 5, the width of the second plate 8 is the same as that of the first plate 5, and the length of the second plate 8 is less than that of the first plate 5. The second pipe piles 9 have the same diameter as the first pipe piles 6. The purpose of this design is that the thickness of the second plate 8 being less than that of the first plate 5 is twofold: firstly, it facilitates insertion into the enclosing joint 10; secondly, it leaves a gap between the second plate 8 and the inner wall of the enclosing joint 10, facilitating subsequent grouting and the formation of a protective layer.
[0062] The purpose of the second plate 8 being shorter than the first plate 5 is to facilitate control of the height of the concrete to be poured. For example, if the overall height of the concrete pouring is 1 meter according to the design requirements and the length of the first plate is 5 meters, then the length of the second plate 8 can be 4 meters. This setting is intended to facilitate control of the pouring height.
[0063] It should be noted that the open channel section has an opening, the diameter of which is smaller than the diameter of the second pipe pile 9. This design allows the channel 4 to have a certain limiting effect, preventing the barrier plate from falling out. At the same time, the drilled channel 4 facilitates subsequent sealing with adhesive, tightly filling the space between the barrier plate and the inner wall of the channel 4 to form a good seal, ensuring the sealing effect and effectively blocking water penetration.
[0064] As a preferred option, a base ring (not shown in the figure) can be welded around the bottom of the second plate 8 in the circumferential direction. The base ring is made of I-beams or channel steel, which can increase the area with the concrete foundation and achieve better connection.
[0065] The specific construction method for the barrier board is as follows:
[0066] S31: The barrier plate is lifted up, and the bottom of the second pipe pile 9 is inserted into the channel 4. The channel 4 acts as a guide, allowing the second pipe pile 9 to move down along the channel 4. Then, the barrier plate is pressed down using appropriate equipment. The bottom end of the barrier plate falls down along the pre-constructed enclosing joint 10 until the bottom end of the barrier plate reaches the designated design position. The position of the barrier plate is kept still at this time, and a cavity is formed between the bottom end of the barrier plate and the bottom of the enclosing joint 10.
[0067] S32: The gap between the second pipe pile 9 and the inner wall of the duct 4 is sealed with adhesive, and after curing, a sealant layer 15 is formed.
[0068] S33: Concrete is injected into the enclosing joint 10 through the grouting inlet 11. The concrete is poured from the bottom of the enclosing joint 10 upwards until it reaches the top line of the silted soil 3 in front of the dam; the concrete below the barrier plate forms the concrete base 122 (see attached). Figure 12 The height difference between H0 and H1 is the height of the concrete base 122; the concrete above the bottom surface of the barrier plate forms side retaining walls 121 on both sides of the barrier plate (see attached). Figure 12 The height difference between H1 and H2 is the height of the side retaining wall 121. The side retaining wall 121 and the middle barrier plate form a sandwich structure, forming a triple barrier seepage prevention system, referred to as the lower seepage prevention system. The seepage prevention system is composed of the barrier plate and sealant located above the top line of the silt 3 in front of the dam. The concrete base and the side retaining wall 121 together form a concrete barrier wall. The upper seepage prevention system and the lower seepage prevention system together form a combined barrier wall system, forming the expansion joint 2 leakage treatment system.
[0069] Note that the first concrete pile 13 is formed after the concrete inside the grouting inlet 11 solidifies.
[0070] It should be noted that if the grouting inlet 11 is not designed and grouting is carried out solely through the gap between the barrier plate and the enclosure joint 10, the construction difficulty will be greatly increased due to the small gap. If the barrier plate is not placed first and grouting is carried out, it cannot be guaranteed that the grouting can accurately reach the specified height to form the concrete base 122 of the required height. Secondly, the space is small, making it inconvenient to measure, and even if measurement is performed, the pouring height of the concrete base 122 cannot be well controlled. However, this construction method can perfectly solve this technical problem. Grouting is carried out using the grouting inlet 11, which increases the grouting diameter and facilitates operation. The height difference between the first plate 5 and the second plate 8 is used as the preset height value of the concrete base 122, which can effectively control the elevation of the concrete base 122 and ensure good consolidation between the concrete base 122 and the barrier plate.
[0071] To improve overall stability, S33 also includes pouring concrete into the second pipe pile 9, which solidifies to form the second concrete pile column 14. Together, they form a steel pipe pile structure, namely an external steel pipe-internal concrete composite structure.
[0072] Construction efficiency:
[0073] Using this method, leakage at expansion joint 2 can be treated without releasing water. Holes 4 are drilled on both sides of expansion joint 2 to serve as sliding tracks. By constructing enclosing joint 10, a concrete barrier wall can be poured into the silt 3 in front of the dam. The concrete barrier wall consists of a concrete base 122 and side retaining walls 121. The concrete base 122 serves as a load-bearing and barrier function, while the side retaining walls 121 and the barrier plate form a sandwich structure, thus constructing a triple barrier and seepage prevention system with good barrier effect and excellent seepage prevention treatment effect.
[0074] This method has a relatively simple construction process, requiring no watering or excavation, resulting in low cost, short construction period, and saving time and effort. It can quickly achieve leakage control at expansion joint 2. The insert plates and barrier plates used in the construction process can be prefabricated and customized according to design requirements. The height of the concrete base 122 can be determined directly from the height difference between the insert plates and barrier plates, eliminating the need for measurement during pouring. The elevation of the concrete base 122 can be pre-determined during fabrication, saving time and effort and making the fabrication convenient and simple.
[0075] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims
1. Methods for controlling leakage at vertical expansion joints of reservoir dams under conditions of no water release, including: The dam body is equipped with expansion joints, and silt is piled up on one side of the dam body, covering the bottom of the expansion joints; its characteristic is that it includes the following steps: S1: Drilling the channel Holes are drilled from top to bottom on both sides of the expansion joint, extending from the top of the dam to the bottom of the dam. S2: Structural enclosure joint; S3: Construct a barrier wall to form an expansion joint leakage control system and block the leakage point; The specific method for constructing the enclosing joint in S2 is as follows: The structure of the sealing joint is constructed using an insert plate, the insert plate including a first plate body, the first plate body being a U-shaped structure formed by bending, the two ends of the first plate body being respectively fixed with first pipe piles along the length direction of the first plate body; a middle pipe pile is fixedly connected to the middle position of the first plate body along the length direction; both the first pipe pile and the middle pipe pile are hollow structures. The insert plate is lifted up, the first pipe pile is inserted into the duct, and then the insert plate is hammered downwards until the bottom end of the insert plate is inserted into the silt in front of the dam. When the design depth is reached, the hammering is stopped. Then the insert plate is lifted out as a whole, and after being lifted out, a sealing joint is formed in the silt in front of the dam. At the same time, a hole is formed at the position of the middle pipe pile, which is the grouting injection port.
2. The method for treating leakage at vertical expansion joints of a reservoir dam under non-water release conditions as described in claim 1, characterized in that, The specific method for S3 is as follows: A barrier wall is constructed using a barrier plate, the barrier plate including a second plate body, the second plate body also being a U-shaped structure formed by bending, and second pipe piles being fixed at both ends of the second plate body along the length direction of the second plate body; the thickness of the second plate body is less than the thickness of the first plate body, the width of the second plate body is the same as that of the first plate body, and the length of the second plate body is less than that of the first plate body; the pipe diameter of the second pipe pile is the same as that of the first pipe pile. S31: Lift the barrier plate, insert the bottom of the second pipe pile into the duct, and then press down the barrier plate. The bottom end of the barrier plate falls along the pre-constructed enclosing joint until the bottom end of the barrier plate reaches the designated design position. Keep the barrier plate in this position and form a cavity between the bottom end of the barrier plate and the bottom of the enclosing joint. S32: The gap between the second pipe pile and the inner wall of the duct is sealed with adhesive. S33: Concrete is injected into the enclosing joint through the grouting inlet. The concrete is poured from the bottom of the enclosing joint upwards until it reaches the top line of the silted soil in front of the dam. The concrete below the barrier plate forms a concrete base. The concrete above the bottom surface of the barrier plate forms side retaining walls on both sides of the barrier plate. The side retaining walls and the barrier plate in the middle form a sandwich structure, forming a triple barrier seepage prevention system, referred to as the lower seepage prevention system. Above the top line of the silted soil in front of the dam, the barrier plate and sealant form a seepage prevention system, referred to as the upper seepage prevention system. The upper seepage prevention system and the lower seepage prevention system together form the expansion joint leakage control system.
3. The method for treating leakage at vertical expansion joints of a reservoir dam under non-water release conditions as described in claim 1, characterized in that, S33 also includes pouring concrete into the second pipe pile to form a steel pipe pile structure.
4. The method for treating leakage at vertical expansion joints of a reservoir dam under non-water release conditions as described in claim 1, characterized in that, The channel is divided into open channel section and closed channel section. The channel located above the silt in front of the dam is the open channel section, and the channel located inside the silt in front of the dam is the closed channel section.
5. The method for treating leakage at vertical expansion joints of a reservoir dam under non-water release conditions as described in claim 1, characterized in that, The channel is formed by drilling.
6. The method for treating leakage at vertical expansion joints of a reservoir dam under non-water release conditions as described in claim 4, characterized in that, The open trench section has an opening, the diameter of which is smaller than the diameter of the second pipe pile.