A method for fully enclosed continuous construction of the core wall area of ​​a gravel-soil core rockfill dam

Abstract

This invention discloses a method for the fully enclosed continuous construction of the core wall area of ​​a gravel-soil core rockfill dam. The method includes arranging an inflatable canopy above the core wall area of ​​the gravel-soil core rockfill dam, fixing the edges of the inflatable canopy to the banks, upstream rockfill areas, and downstream rockfill areas, ensuring that at least the core wall filling area is within the covered area of ​​the inflatable canopy, and sealing the edges of the inflatable canopy; using an air supply device to supply air into the inflatable canopy, making the pressure inside the inflatable canopy greater than the external pressure, thus supporting the inflatable canopy and forming a closed construction space. The height of the closed construction space is greater than the predetermined height of the core wall of the gravel-soil core rockfill dam for this phase of construction. This invention uses a base fabric to construct the inflatable canopy and arranges a steel cable net on top, covering and enclosing the core wall filling area on the banks and upstream and downstream rockfill areas. The air supply device supplies air to the inside of the inflatable canopy, creating a closed space that provides shelter from wind and rain and insulation, allowing for normal construction even in winter and the rainy season, achieving continuous and safe construction throughout the year.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy and hydropower engineering construction technology, specifically relating to a method for fully enclosed continuous construction of the core wall area of ​​a gravel-soil core rockfill dam. Background Technology

[0002] A gravel-soil core rockfill dam comprises a gravel-soil core wall, an upstream filter zone, a downstream filter zone, an upstream transition zone, a downstream transition zone, an upstream rockfill zone, and a downstream rockfill zone. Specifically, an upstream transition zone and an upstream filter zone are established between the upstream rockfill zone and the core wall; similarly, a downstream transition zone and a downstream filter zone are established between the downstream rockfill zone and the core wall. The gravel-soil core wall, located in the middle of the dam, serves as the structure for seepage prevention and waterproofing. The construction of a gravel-soil core rockfill dam is a time-consuming and extensive project with a very long time span. The construction of the gravel-soil core wall is highly dependent on weather conditions. For example, heavy rainfall during the rainy season or excessively low temperatures in winter prevent construction. In southwestern my country, the rainy season and winter constitute a significant portion of the year, resulting in very short construction time for the gravel-soil core wall during the rainy season and / or winter. Construction must be based on weather conditions, significantly shortening the annual construction time for the gravel-soil core wall and contributing to the long construction period of gravel-soil core rockfill dams.

[0003] To address this issue, existing technologies for rainy season construction include: 1) using tarpaulins for covering, which are quickly laid before rainfall and quickly removed after rain; 2) smoothing and compacting the surface before rain, and then roughening and drying the soil before resuming construction. For winter construction, there are two approaches: 1) quickly laying insulation materials at freezing temperatures to maintain soil temperature, and then quickly removing and removing the covering the next day after the temperature rises; 2) loosening the soil at freezing temperatures and leaving it overnight, then loosening the soil and thawing it the next day after the temperature rises before resuming construction.

[0004] While the aforementioned methods can improve construction efficiency to some extent, they are time-consuming and labor-intensive, and their long duration limits their effectiveness in improving construction efficiency. Furthermore, they present greater challenges for dams with large spans. Therefore, effectively ensuring the construction period for large-span dams is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a method for the fully enclosed continuous construction of the core wall area of ​​a gravel-soil core rockfill dam.

[0006] This invention is achieved through the following technical solution:

[0007] A method for fully enclosed continuous construction of the core wall area of ​​a gravel-soil core rockfill dam, characterized by:

[0008] An inflatable canopy is installed above the core wall area of ​​the gravel-soil core rockfill dam. The edges of the inflatable canopy are fixed to both banks, the upstream rockfill area and the downstream rockfill area, so that the core wall filling area is at least within the area covered by the inflatable canopy, and the edges of the inflatable canopy are sealed.

[0009] An air supply device is used to supply air into the inflatable roof, so that the pressure inside the inflatable roof is greater than the external pressure, thus supporting the inflatable roof and forming a closed construction space. The height of the closed construction space is greater than the predetermined height of the core wall of the gravel-soil core rockfill dam in this phase of construction.

[0010] Gravel core wall filling was carried out within the enclosed construction space.

[0011] Furthermore, a steel cable net is arranged on the upper outer side of the inflatable canopy.

[0012] The inflatable canopy of the present invention is made of waterproof base fabric; the base fabric is woven from polyester fibers and has an anti-ultraviolet coating and / or an anti-aging coating on its surface.

[0013] The enclosed space formed by the inflatable roof is equipped with material passages and personnel passages at its edges for materials and personnel to enter and exit; the material passages are equipped with double-layered sealed doors.

[0014] When the height of the filled gravel-soil core wall reaches the preset height value of the core wall of the gravel-soil core rockfill dam for this construction phase, the inflatable roof fixing is removed, and the areas used to fix the edge of the inflatable roof are filled in layers to their respective target heights.

[0015] The air supply device uses multiple sets of centrifugal fans without volutes.

[0016] During construction, if the elevation difference between the connection point of the upstream rockfill area and the inflatable roof foundation and any one of the gravel-soil core wall, the upstream transition area, and the upstream rockfill area is the maximum allowable value in the design requirements, the connection point of the upstream rockfill area and the inflatable roof shall be changed, and then the original foundation location shall be filled and compacted. If the elevation difference between the connection point of the downstream rockfill area and the inflatable roof and any one of the gravel-soil core wall, the downstream transition area, and the downstream rockfill area is the maximum allowable value in the design requirements, the connection point of the downstream rockfill area and the inflatable roof shall be changed, and then the original foundation location shall be filled and compacted.

[0017] The method for fixing the inflatable roof described in this invention is as follows: concrete walls are set up in the upstream and downstream rockfill areas, and the edges of the inflatable roof are fixed to the concrete walls by angle steel and bolts; at the same time, the edges of the inflatable roof are fixed to the riverbank slopes on both sides by angle steel and bolts.

[0018] The steel cable net is anchored to the concrete wall and the bank slopes on both sides.

[0019] The inflatable canopy space is also equipped with a lighting system and a temperature and humidity control system.

[0020] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0021] (1) The present invention uses an inflatable roof made of base fabric to cover and wrap the core wall filling area in the rockfill areas on both sides and upstream and downstream. An air supply device is used to supply air to the inside of the inflatable roof. The inflatable roof can provide a closed space for the core wall filling area to be sheltered from wind and rain and keep warm, so that construction can still be carried out normally in winter and rainy season, so as to achieve continuous construction throughout the year and ensure the construction period.

[0022] (2) In this invention, a steel cable net is arranged above the enclosed space of the inflatable roof. On the one hand, the steel cable net can constrain the elongation of the base fabric, so that the air pressure in the enclosed space can be increased, thereby improving the ability of the enclosed space formed by the base fabric to resist storms and snow. On the other hand, the steel cable net can reduce the internal force on the inflatable roof and make the stress on the inflatable roof more uniform, thus extending the service life of the base fabric of the inflatable roof. Furthermore, it can also improve the safety factor of the overall structure.

[0023] (3) Compared with rainproof cloth and thermal insulation materials, the method of building an inflatable roof enclosure using the base fabric of the present invention has the advantages of high construction efficiency, no influence from terrain span, high ability to withstand wind and snow loads, and long service life. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the inflatable canopy construction in an embodiment of the present invention. Figure 1 ;

[0025] Figure 2 This is a schematic diagram of the inflatable canopy construction in an embodiment of the present invention. Figure 2 ;

[0026] Figure 3 This is a schematic diagram of a target gravel-soil core rockfill dam in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram illustrating the fixing method of the inflatable canopy base fabric in an embodiment of the present invention.

[0028] In the attached diagram: 100 - target gravel-soil core rockfill dam, 110 - gravel-soil core wall, 120 - upstream rockfill area, 130 - upstream transition area, 140 - downstream rockfill area, 150 - downstream transition area, 200 - inflatable roof, 210 - roof edge rope, 220 - cable net, 300 - both banks, 400 - concrete wall, 500 - angle steel, 600 - bolt. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments. These specific embodiments are further explanations of the principles of the present invention and are not intended to limit the present invention in any way. Any technology that is the same as or similar to the present invention does not exceed the scope of protection of the present invention.

[0030] Refer to the attached diagram.

[0031] The fully enclosed continuous construction method of the core wall area of ​​the gravel-soil core rockfill dam in this embodiment is described in detail using a gravel-soil core rockfill dam of a power station in China as an example. The elevation of the gravel-soil core rockfill is 2195m to 2510m (i.e., the dam height is 315m). Of course, different gravel-soil core rockfill dams have different elevations, and the present invention does not limit the elevation of the gravel-soil core rockfill dam. Based on the local meteorological environment, excluding the impact of the rainy season and winter on the construction of the gravel-soil core wall, the construction period for the gravel-soil core wall is only 6 months. The specific impacts of the rainy season on the construction of the gravel-soil core wall are as follows: rainfall (more than 3 mm) will cause the moisture content of the gravel-soil core wall filling material (gravel soil) to increase, making the filling surface muddy, which makes the construction of the gravel-soil core wall impossible, and the compaction will not be dense, forming springy soil, which directly affects its mechanical properties. The specific impacts of winter on the construction of the gravel-soil core wall are as follows: when the temperature is below 0 degrees Celsius, the surface of the gravel-soil core wall filling material and the unfilled parts will be frozen, affecting the mechanical properties and permeability coefficient of the gravel-soil core wall filling material.

[0032] To effectively extend the filling time of the gravel-soil core wall, such as Figure 1 , Figure 2 As shown, an inflatable canopy 200 is installed on the gravel-soil core wall filling area. The inflatable canopy 200 can not only prevent rain but also keep the soil warm. This increases the filling time of the gravel-soil core wall 110 from 6 months to 10-11 months, avoiding the impact of the rainy season and / or winter on the construction period and improving the filling time.

[0033] The following example, using a gravel-soil core rockfill dam of a power station as an illustration, details the fully enclosed continuous construction method for the core wall area of ​​a gravel-soil core rockfill dam according to the present invention.

[0034] The edges of the inflatable roof 200 are fixed to both banks, the upstream rockfill area 120, and the downstream rockfill area 140, ensuring that the core wall filling area is located within the inflatable roof 200, and the edges of the inflatable roof 200 are sealed. The inflatable roof 200 is made of waterproof base fabric. An air supply device is used to supply air to the inside of the inflatable roof 200, making the pressure inside the inflatable roof 200 greater than the external pressure, thus supporting the inflatable roof 200 and forming a closed space. The height of the closed space is greater than the predetermined height. Gravel and soil core wall filling is carried out within the closed space.

[0035] The predetermined height is the height that the core wall needs to be filled in at each stage. Those skilled in the art will understand that the inflatable canopy 200 needs to be pre-processed from the base fabric to a size that allows its height to be greater than the predetermined height when inflated. In order to make its sealing better, it can be pre-processed into a shape that matches the required layout space.

[0036] The base fabric constituting the inflatable canopy 200 is woven from polyester fibers. The specific weaving method is known to those skilled in the art and will not be described in detail here. In order to enable the base fabric to withstand severe cold, extreme heat, and blizzards, it is preferable to coat the base fabric with a fluorine surface coating, such as an anti-ultraviolet coating or an anti-aging coating.

[0037] In this embodiment, as Figure 3 As shown, a gravel-soil core rockfill dam generally includes an upstream rockfill zone 120, an upstream transition zone 130, an upstream filter zone, a gravel-soil core 110, a downstream filter zone, a downstream transition zone 150, and a downstream rockfill zone 140. Both banks 300 are generally slopes, meaning they are the two banks perpendicular to the gravel-soil core rockfill dam. The following is a breakdown by... Figure 3 As shown, the two banks 300 are referred to as the left bank and the right bank, and both banks 300 are rocks with a certain degree of hardness. When the inflatable roof 200 is set above the gravel soil core wall 110, the four edges are connected to the two banks 300, the upstream rockfill area 120 and the downstream rockfill area 140 by angle steel 500 and bolts 600. Because the rocks on both banks 300 are hard, the base fabric can be directly fixed to the left bank and the right bank by angle steel 500 and bolts 600. Of course, concrete can also be poured on the left bank and the right bank, and then the inflatable roof 200 can be fixed to the left bank and the right bank by angle steel 500 and bolts 600. Figure 4 This diagram illustrates the fixing of the inflatable roof 200 to the upstream and downstream rockfill areas 120 and 140. Concrete walls 400 are installed in both areas, and the inflatable roof 200 is then fixed to these walls using angle steel 500 and bolts 600. This fixing method ensures the airtightness of the inflatable roof 200's internal structure. Preferably, a roof edge rope 210 is installed at the edge of the inflatable roof 200. This edge rope 210 can be part of the inflatable roof 200 itself, but its thickness must be greater than the base fabric to provide better sealing within the inflatable roof 200. Anchor bars are installed within the concrete walls 400 to form a flat and sealed foundation.

[0038] The concrete wall 400 is set on the upstream rockfill area 120 and the downstream rockfill area 140, which can at least ensure that the gravel-soil core wall 110 filling area is located within the inflatable roof 200. Of course, depending on the specific situation, the upstream filter material area, the upstream transition area 130, the downstream filter material area, and the downstream transition area 150 can also be selectively set in the area enclosed by the inflatable roof 200. This invention does not limit this.

[0039] In order to improve the strength of the enclosed space structure formed by the inflatable roof 200 and its ability to resist strong winds and rain, after the inflatable roof 200 is fixed, a steel cable net 220 is built above the inflatable roof 200. The steel cable net 220 is also fixed to the concrete wall 400 and both banks 300.

[0040] The steel cable net 220 is anchored to the concrete wall 400 and both banks 300 via a connecting structure. The connecting structure includes a flange, embedded round steel bars, and connecting steel cables. The steel cable net 220 is connected to the flange, the flange is connected to the connecting steel cables, and the connecting steel cables are connected to the embedded round steel bars. Embedded round steel bars are fixedly connected to both the concrete wall 400 and both banks 300. Based on the description of this connecting structure and its specific connection method, it is feasible for those skilled in the art, so it will not be described in further detail.

[0041] The steel cable net 220 is connected to the ground after the inflatable canopy 200 is installed, and is positioned on the upper surface of the inflatable canopy 200. This allows the steel cable net 220 to restrain and reinforce the inflatable canopy 200 after it is inflated. After installation, the steel cable net 220 is distributed in a scattered manner on the base fabric that makes up the inflatable canopy 200, and rises along with it as the inflatable canopy 200 is inflated.

[0042] In this embodiment, the steel cable net 220 installed above the inflatable roof 200 has the following functions: 1. The steel cable net 220 can constrain the elongation of the inflatable roof 200, allowing the air pressure in the enclosed space to be increased, thereby improving the ability of the enclosed space formed by the inflatable roof 200 to resist storms and snow; 2. The steel cable net 220 can reduce the internal force on the inflatable roof 200, while making the force on the inflatable roof 200 more uniform and extending the service life of the base fabric; 3. The steel cable net 220 can also improve the safety factor of the overall structure.

[0043] After the inflatable canopy 200 and the mesh steel cable net 220 are installed, air can be supplied to the inflatable canopy 200 through the air supply device, so that the pressure inside the inflatable canopy 200 is greater than the external pressure, the inflatable canopy 200 is supported, and the mesh steel cable net 220 wraps the entire inflatable canopy 200 under it.

[0044] The air supply system uses volute-less centrifugal fans, which have the advantages of large air volume, stable pressure, slow air velocity, and low noise. Furthermore, multiple volute-less centrifugal fans are installed according to the size of the enclosed space to meet the required pressure values ​​within the enclosed space.

[0045] The air supply system uses a volute-less centrifugal fan, with a single unit supplying an air volume of 5000 m³ / h. 3 / h, the base fabric in this embodiment occupies an area of ​​approximately 100,000 m². 2 Calculations show that 50 fans are needed simultaneously to supply air to ensure sufficient internal pressure to support the inflatable ceiling 200. Of course, the number of fans may vary depending on the area of ​​the inflatable ceiling 200; this invention does not impose any limitations.

[0046] Once the inflatable canopy 200 and the cable net 220 are erected, the enclosed space formed inside can shelter the construction environment of the core wall filling surface from wind, rain and snow, and keep it warm in winter, so that it is not affected by external climate factors and construction can proceed normally inside.

[0047] During construction, if the elevation difference between the connection point of the upstream rockfill area and the inflatable roof foundation and any one of the following areas—the gravel-soil core wall, the upstream transition area, and the upstream rockfill area—is the maximum allowable value in the design requirements (15m in this example), then to meet the design requirements, the connection point of the upstream rockfill area and the inflatable roof needs to be changed, and the original foundation location needs to be filled and compacted. Similarly, if the elevation difference between the connection point of the downstream rockfill area and the inflatable roof and any one of the following areas—the gravel-soil core wall, the downstream transition area, and the downstream rockfill area—is the maximum allowable value in the design requirements (15m in this example), then to meet the design requirements, the connection point of the downstream rockfill area and the inflatable roof needs to be changed, and the original foundation location needs to be filled and compacted.

[0048] Specifically, to meet the design requirement that the height difference between the inner wall of the inflatable roof 200mm and the rockfill area of ​​the upstream and downstream foundation anchor points should not exceed 15m, the first foundation anchor point conversion for the air-supported membrane will be carried out when the dam is filled to a certain elevation. To avoid affecting the dam body filling, the conversion of foundation anchor points in the upstream and downstream directions will be conducted unilaterally. That is, when the upstream foundation conversion is carried out, the inner wall filling of the inflatable roof 200mm will enter from the downstream channel. The downstream foundation conversion will only proceed after the upstream foundation conversion is completed.

[0049] In this way, as the filling height increases during construction, the fixed position of the inflatable canopy 200 can be raised by changing its fixed position, thus making it suitable for the entire filling process.

[0050] Since the enclosed construction space created by the inflatable roof 200 requires the access of materials and personnel to meet on-site construction needs, material passages and personnel passages are also provided. The material passages should be suitable for vehicle access. As a preferred option, emergency passages can also be provided.

[0051] The material passage, also known as the vehicle passage, is equipped with two doors—an outer door and an inner door—to prevent excessive pressure loss within the base fabric during vehicle entry and exit. When a vehicle enters the passage, the outer door opens and the inner door closes; after the vehicle has entered, the inner door opens and the outer door closes. This ensures stable pressure within the base fabric. The same principle applies when the vehicle exits, so it will not be elaborated upon here.

[0052] Personnel access refers to the installation of two normally closed entrance doors at appropriate locations, serving as access for personnel to and from the construction site, and also as an emergency access route.

[0053] Meanwhile, to ensure smooth construction, a lighting system and a temperature control system are also installed in the enclosed space formed by the inflatable ceiling 200. The lighting system is used for illumination of the enclosed space, and the temperature control system is used to maintain the environment within the enclosed space within a preset temperature range suitable for construction.

Claims

1. A full-closed continuous construction method for a gravel soil core wall of a rock-fill dam, characterized in that: an air-supported roof is arranged above the gravel soil core wall of the rock-fill dam, the edges of the air-supported roof are fixed on the two banks, the upstream rock-fill area and the downstream rock-fill area, at least the core wall filling area is located within the air-supported roof covering area, and the edges of the air-supported roof are sealed; a steel cable net is arranged above the outer side of the air-supported roof; air supply devices are used to supply air into the air-supported roof, so that the pressure on the inner side of the air-supported roof is greater than the external pressure, the air-supported roof is supported, a closed construction space is formed, and the height of the closed construction space is greater than the predetermined height of the gravel soil core wall of the rock-fill dam in the current construction period; gravel soil core wall filling is carried out in the closed construction space; when the elevation difference between the connection position of the upstream rock-fill area and the foundation of the air-supported roof and the elevation of any one of the gravel soil core wall, the upstream transition area and the upstream rock-fill area is the maximum value allowed in the design requirement, the connection position of the upstream rock-fill area and the air-supported roof is replaced, and then the original foundation position is filled and rolled; when the elevation difference between the connection position of the downstream rock-fill area and the air-supported roof and the elevation of any one of the gravel soil core wall, the downstream transition area and the downstream rock-fill area is the maximum value allowed in the design requirement, the connection position of the downstream rock-fill area and the air-supported roof is replaced, and then the original foundation position is filled and rolled. The air-supported roof is made of waterproof base cloth; the base cloth is woven from polyester fibers, and an ultraviolet-proof coating and / or an anti-aging coating are arranged on the surface of the base cloth.

2. The method according to claim 1, wherein the method is characterized by: Material channels and personnel channels are arranged at the edges of the closed space formed by the air-supported roof for material and personnel to enter and exit; the material channels are provided with inner and outer double-layer sealing doors.

3. The method according to claim 2, wherein the method is characterized by: When the filling height of the gravel soil core wall reaches the preset height of the gravel soil core wall of the rock-fill dam in the current construction period, the air-supported roof is removed, and the areas used for fixing the edges of the air-supported roof are filled layer by layer to the target heights.

4. The method according to claim 2, wherein the method is characterized by: The air supply devices use multiple groups of volute-free centrifugal fans.

5. The method according to claim 2, wherein the method is characterized by: The air-supported roof is fixed in the following manner: concrete walls are arranged in the upstream rock-fill area and the downstream rock-fill area, the edges of the air-supported roof are fixed on the concrete walls through angle steel and bolts, and the edges of the air-supported roof are fixed on the two bank slopes through angle steel and bolts.

6. The method according to any one of claims 2 to 5, wherein the method is characterized in that: The steel cable net is anchored on the concrete walls and the two bank slopes.

7. The method according to claim 6, wherein the method is characterized by, An illumination system and a temperature and humidity control system are further arranged in the air-supported roof space.

8. The method according to claim 7, wherein the method is characterized by, ​

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