Dewatering and drainage construction method for foundation pit of high-water-level fan foundation in desert windy and sandy area

Abstract

The embodiment of the invention provides a dewatering and drainage construction method for a high-water-level fan foundation pit in a desert windy and sandy area. According to the method, the fan foundation pit is excavated in a layered excavation mode. In the excavation process of the foundation pit, every time the foundation pit is excavated downwards by one layer, an annular drainage ditch extending along the edge line of the bottom of the foundation pit and a water collecting well communicating with the annular drainage ditch are arranged at the bottom of the current foundation pit, and accumulated water collected in the water collecting well is pumped and drained through drainage equipment so as to conduct dewatering and drainage on the current foundation pit; and when the underground water level at the bottom of the current foundation pit meets the preset dryness requirement through dewatering and drainage, downward digging is further conducted on the basis of the current foundation pit, dewatering and drainage are conducted on the basis of the same principle, and then downward digging continues to continue dewatering and drainage till the elevation of the bottom of the foundation pit reaches the designed elevation through downward digging. According to the method, the foundation pit is effectively dewatered and drained in the construction process of the wind turbine foundation pit, and the construction safety during wind turbine foundation construction in a high underground water level area can be improved.

Description

Technical Field

[0001] This application relates to the field of building construction technology, and in particular to a dewatering construction method for high-water-level wind turbine foundation pits in desert and sandy areas. Background Technology

[0002] With the continuous advancement of national carbon peaking and carbon neutrality efforts, the wind power industry, as a core engine of green energy, has become increasingly prominent in its strategic position and has become a core pillar of global energy transition. Guided by the "dual carbon" goals, my country's wind power industry has continued to develop rapidly, with wind turbines widely distributed in mountains, plains, plateaus, Gobi deserts, coastal areas, and desert and marginal regions. Furthermore, as the country has clearly proposed prioritizing desert, Gobi, and arid regions to accelerate the construction of large-scale wind power bases, wind power projects are continuously extending into the western and northern desert areas, making the environmental conditions for project construction more complex and unique.

[0003] In desert regions, the foundation soil is mostly sandy soil and silty soil. A high groundwater level can significantly increase the soil saturation, reducing the internal friction angle and cohesion of the sandy soil, thus lowering the bearing capacity of the foundation. This can lead to uneven or overall settlement of the wind turbine foundation. Furthermore, wind turbine foundation construction in desert areas requires the excavation of deep foundation pits. When there is a high groundwater level at the construction site, the aforementioned characteristics of the foundation soil make the foundation pit extremely prone to collapse, posing a significant safety risk.

[0004] Therefore, how to avoid the adverse effects of high groundwater levels and precipitation on the construction progress and safety of wind turbine foundations has become a key technical direction for wind power projects in desert areas. Summary of the Invention

[0005] The purpose of this application is to provide a dewatering construction method for high-water-level wind turbine foundation pits in arid and sandy areas, so as to achieve effective dewatering of the foundation pit during the construction process, thereby improving the construction safety of wind turbine foundations in areas with high groundwater levels. The specific technical solution is as follows: This application provides a method for dewatering construction of high-water-level wind turbine foundation pits in desert and sandy areas, including: Within the selected site, excavate to a certain depth along the top edge of the pit to form a foundation pit; at a predetermined distance from the toe of the slope at the bottom of the pit, construct a ring-shaped drainage ditch extending along the edge of the bottom of the pit; construct multiple collection wells evenly distributed along the edge of the bottom of the pit and connected to the ring-shaped drainage ditch; use drainage equipment to extract and drain the accumulated water in the collection wells until the groundwater level at the bottom of the pit meets the predetermined dryness requirements; further excavate to a certain depth based on the current foundation pit, and return to the step of constructing a ring-shaped drainage ditch extending along the edge of the bottom of the pit at a predetermined distance from the toe of the slope at the bottom of the pit, until the elevation of the bottom of the pit reaches the design elevation; once the elevation of the bottom of the pit reaches the design elevation and the pit passes the inspection, construct the wind turbine foundation within the pit.

[0006] Optionally, after excavating downwards to the bottom elevation of the foundation pit to reach the design elevation, and before constructing the wind turbine foundation within the foundation pit, the dewatering construction method for high-water-level wind turbine foundation pits in desert and sandy areas also includes: Multiple simple drainage ditches are set at the bottom of the foundation pit, extending from the center of the foundation pit to the edge of the foundation pit and connecting with the annular drainage ditch at the bottom of the foundation pit; the bottom of the simple drainage ditch has a slope, and the height of the bottom of the simple drainage ditch gradually decreases along a first direction, which is the direction from the center of the foundation pit to the edge of the foundation pit.

[0007] Optionally, after setting up multiple simple drainage ditches at the bottom of the pit, extending from the center of the pit to the edge and connecting with the annular drainage ditch at the bottom of the pit, before carrying out the construction of the wind turbine foundation inside the pit, the dewatering construction method for high-water-level wind turbine foundation pits in desert and sandy areas also includes: A waterproof geotextile is placed at the bottom of the foundation pit; the waterproof geotextile covers the first area, which is the area formed by the first edge line of the annular drainage ditch at the bottom of the foundation pit, and the first edge line is the edge line of the annular drainage ditch on the side closest to the center of the bottom of the foundation pit.

[0008] Optionally, after setting up a ring-shaped drainage ditch extending along the edge line of the bottom of the foundation pit, and setting up multiple water collection wells evenly distributed along the edge line of the bottom of the foundation pit and connected to the ring-shaped drainage ditch, and before pumping out and discharging the accumulated water in the water collection wells by drainage equipment, the dewatering construction method for high-water-level wind turbine foundation pits in desert and sandy areas also includes: Geotextile is laid on the inner wall of the circular drainage ditch and the inner wall of the collection well; after laying the geotextile, a certain thickness of crushed stone is laid at the bottom of the collection well to form a filter layer.

[0009] Optionally, the inner wall of the annular drainage ditch is a filter layer constructed using pebbles.

[0010] Optionally, the drainage equipment includes multiple submersible pumps respectively installed in the aforementioned multiple sump pits, and multiple drainage pipes with one end connected to each of the multiple submersible pumps and the other end extending to the outside of the foundation pit; the aforementioned process of extracting and discharging the accumulated water in the sump pits through the drainage equipment until the groundwater level at the bottom of the foundation pit meets the preset dryness requirements includes: after the sump pit construction is completed, starting the submersible pumps to extract and discharge the accumulated water in the sump pits; periodically monitoring the groundwater level at preset water level observation points to determine whether the groundwater level at the bottom of the foundation pit meets the dryness requirements, the water level observation points including multiple water level observation points respectively set at the center and edge of the bottom of the foundation pit; if it is determined that the groundwater level at the bottom of the foundation pit meets the dryness requirements, retrieving the submersible pumps and the drainage pipes, and performing the step of further excavating downwards to a certain depth based on the current foundation pit.

[0011] Optionally, the total daily drainage capacity of the aforementioned submersible pumps shall not be less than the first water volume, which is 1.5 times the estimated seepage volume of the foundation pit within the foundation site.

[0012] Optionally, before excavating a certain depth downward along the top edge of the foundation pit to form the foundation pit within the selected foundation site, the dewatering construction method for the foundation pit of high-water-level wind turbines in desert and sandy areas also includes: setting up an annular water-retaining platform extending along the top edge of the foundation pit and having a certain distance between it and the top edge of the foundation pit on the outside of the top edge of the foundation pit; and forming a drainage slope on the outside of the annular water-retaining platform.

[0013] Optionally, after the construction of the wind turbine foundation is completed, the dewatering construction method for the foundation pit of high-water-level wind turbines in desert and sandy areas also includes: backfilling the foundation pit with earth and removing the submersible pump and drainage pipe installed in the foundation pit; after the earth backfilling is completed, removing the annular water-retaining platform.

[0014] Optionally, when excavating further downwards to a certain depth based on the current foundation pit, the certain depth shall not exceed 1.5 meters.

[0015] Beneficial effects of the embodiments in this application: The dewatering construction method for high-water-level wind turbine foundation pits in desert and sandy areas provided in this application adopts a layered excavation method for excavating the wind turbine foundation pits. During the excavation of the pit, a ring-shaped drainage ditch extending along the bottom edge of the pit and a collection well connected to the ring-shaped drainage ditch are set at the bottom of the current pit. The water collected in the collection well is pumped out and discharged by drainage equipment to dewater the current pit. Only when the groundwater level at the bottom of the current pit meets the preset dryness requirements will the pit be further excavated and dewatered based on the same principle. Then, the excavation continues and the dewatering continues until the elevation of the bottom of the pit reaches the design elevation.

[0016] It can be seen that the aforementioned dewatering construction method for high-water-level wind turbine foundation pits in arid and sandy areas can effectively dewater the foundation pit during the construction of the wind turbine foundation, thereby improving the construction safety of wind turbine foundations in areas with high groundwater levels. Furthermore, this dewatering construction method optimizes the drainage equipment and path by using a path of ring drainage ditch → sump well → drainage equipment → outside the site for dewatering the foundation pit after each deep excavation. Compared with single dewatering methods such as dewatering wells, this method effectively improves dewatering efficiency. Moreover, this dewatering construction method effectively connects the dewatering process with the foundation pit excavation process. Compared with the traditional dewatering method using professional dewatering teams, it reduces a large number of redundant procedures, shortens the construction cycle, and effectively reduces construction costs. Therefore, this dewatering construction method not only achieves effective dewatering but also has the advantages of high construction safety, controllable construction period, convenient implementation, and economical cost, making it highly valuable for widespread application.

[0017] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0019] Figure 1 A schematic flowchart illustrating a dewatering construction method for a high-water-level wind turbine foundation pit in a desert and sandy area, provided in an embodiment of this application. Figure 2 A plan view of the simplified drainage ditch, the base drainage ditch, and the base collection well provided in the embodiments of this application; Figure 3 A cross-sectional view of a temporary drainage ditch and a temporary water collection well provided in an embodiment of this application; Figure 4 A cross-sectional view of the base drainage ditch and base water collection well provided for embodiments of this application; Figure 5 A layout diagram of the submersible pump and drain pipe provided in an embodiment of this application; Figure 6 Detailed diagram of the temporary water collection well provided in the embodiments of this application; Figure 7 Detailed view of the base water collection well provided in the embodiments of this application; Figure 8This is another schematic diagram of the dewatering construction method for high-water-level wind turbine foundation pits in desert and sandy areas, provided in an embodiment of this application.

[0020] Figure label: 1- Circular drainage ditch, 1a- Temporary drainage ditch, 1b- Base drainage ditch, 2- Sump well, 2a- Temporary sump well, 2b- Base sump well, 3- Simple drainage ditch, 4- Waterproof geotextile, 5- Geotextile, 6- Filter layer, 7- Circular water retaining platform, 8- Drainage equipment, 81- Submersible pump, 82- Drainage pipe. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0022] As noted in the background section of this application, a key technical direction is how to avoid the adverse effects of high groundwater levels and precipitation on the construction progress and safety of wind turbine foundations in high groundwater levels in desert areas. To address this issue, effective dewatering of the construction site is required during the construction of the wind turbine foundation pit.

[0023] However, in desert areas, the bearing capacity of foundation soil is easily reduced under high water levels, making foundation pits highly susceptible to collapse and posing significant challenges for dewatering. Furthermore, the slope stability of sandy foundation pits is generally poor, and dewatering can easily trigger settlement of surrounding soil, thus increasing safety risks.

[0024] Furthermore, the efficiency and effectiveness of dewatering at high groundwater levels directly impact the excavation progress of the foundation pit. If groundwater resources are abundant and the groundwater level remains high for an extended period, the construction cycle will increase, thus affecting the overall progress. Therefore, balancing dewatering with construction efficiency is a challenging task.

[0025] In view of this, this application provides a dewatering construction method for high-water-level wind turbine foundation pits in desert and sandy areas, based on the following... Figures 1-7 The method will be described in conjunction with specific embodiments. See [link to documentation]. Figure 1 In one embodiment of this application, the method specifically includes the following steps: Step S101: Within the selected foundation site, excavate downwards to a certain depth along the top edge of the foundation pit to form the foundation pit.

[0026] This application embodiment employs a layered excavation method for foundation pit excavation. Specifically, based on the original site, a certain depth is first excavated along the top edge of the foundation pit to form the initial foundation pit. Following steps S102-S104, the initial foundation pit is dewatered. If the groundwater level at the bottom of the initial foundation pit meets the preset dryness requirements, the foundation pit is further excavated to a deeper level, and again, following steps S102-S104, dewatering is performed on this deeper level. If the groundwater level at the bottom of this deeper level meets the preset dryness requirements, the foundation pit is further excavated to an even deeper level, and again, following steps S102-S104, dewatering is performed on this deeper level. This process is repeated until the bottom elevation of the foundation pit reaches the design elevation, and again, following steps S102-S104, dewatering is performed on the foundation pit where the elevation reaches the design elevation.

[0027] In one example, during the excavation of a foundation pit using the layered excavation method described above, if the groundwater level at the bottom of the current foundation pit meets the preset dryness requirements, the depth of further excavation on the current foundation pit can be controlled to not exceed 1.5 meters before the next dewatering operation based on steps S102-S104. In other words, the depth of a single layer of excavation is controlled to not exceed 1.5 meters.

[0028] Step S102: At a predetermined distance from the bottom of the foundation pit to the slope toe, set up a ring-shaped drainage ditch 1 extending along the edge line of the bottom of the foundation pit.

[0029] For ease of distinction, the annular drainage ditch 1 set at the bottom of the foundation pit before the excavation reaches the design elevation will be referred to as temporary drainage ditch 1a, and the annular drainage ditch 1 set at the bottom of the foundation pit after the excavation reaches the design elevation will be referred to as base drainage ditch 1b.

[0030] The layout of the base drainage ditch 1b in the top view of the foundation pit can be found in [reference needed]. Figure 2 As shown in the diagram, the foundation drainage ditch 1b is installed around the bottom edge line (slope bottom line) of the foundation pit. The temporary drainage ditch 1a is installed in the same way and will not be shown here.

[0031] For details on the installation of temporary drainage ditch 1a across the foundation pit cross-section, please refer to [link / reference needed]. Figure 3 The diagram shows the layout of the foundation drainage ditch 1b across the foundation pit cross-section. Figure 4 The illustration is shown in the image.

[0032] When setting up a ring-shaped drainage ditch 1 at the bottom of the current foundation pit, the preset distance between the ring-shaped drainage ditch 1 and the toe of the slope (that is, the location of the bottom line of the slope) can be set according to actual needs. In one example, the distance between the ring-shaped drainage ditch 1 and the toe of the slope can be set to 1 meter.

[0033] The dimensions of the temporary drainage ditch 1a and the base drainage ditch 1b can be set according to actual needs. In one example, the width of the temporary drainage ditch 1a can be set to 500 mm and the depth to 500 mm; the width of the base drainage ditch 1b can be set to 500 mm and the depth to 500 mm.

[0034] In one example, the bottom of the base drainage ditch 1b can be set with a certain slope (the slope can be set according to actual needs, for example, 0.3%-0.5%). By setting this slope, the bottom of the base drainage ditch 1b tilts towards the nearest base collection well 2b. Therefore, for the drainage path within the base drainage ditch 1b corresponding to a specific base collection well 2b (among all base collection wells 2b, each point of the base drainage ditch 1b on this drainage path is closest to that specific base collection well 2b), the bottom height of the location closer to the specific base collection well on this drainage path is lower, so that water accumulated in the base drainage ditch 1b can collect in the base collection well 2b. Figure 2 Taking this as an example, the section between position A in the base drainage ditch 1b and the collection well 1 is the drainage path corresponding to the collection well 1. Therefore, in this drainage path, the bottom height decreases as the distance from the collection well 1 increases. Similarly, the bottom of the temporary drainage ditch 1a can also be designed with a certain slope, which will not be elaborated here.

[0035] Step S103: Set up multiple water collection wells 2 that are evenly distributed along the edge line of the bottom of the foundation pit and connected to the annular drainage ditch 1.

[0036] For ease of distinction, the sump 2 set at the bottom of the foundation pit before the excavation reaches the design elevation will be referred to as temporary sump 2a, and the sump 2 set at the bottom of the foundation pit after the excavation reaches the design elevation will be referred to as base sump 2b.

[0037] The number of water collection wells 2 set at the bottom of the foundation pit formed after each downward excavation can be selected according to actual needs, and this application embodiment does not limit this. In one example, four water collection wells 2 can be set at the bottom of the foundation pit formed after each downward excavation.

[0038] The location of the foundation sump 2b in the top view of the foundation pit can be found in [reference needed]. Figure 2 The illustration is shown in the image. Figure 2In the illustration, four foundation sump wells 2b are set at the bottom of the foundation pit (in actual applications, the number of foundation sump wells 2b is not limited to this). It can be seen that each sump well 2b is evenly distributed along the bottom line of the slope and is connected to the foundation drainage ditch 1b. The temporary sump well 2a is set up in the same way and will not be shown here.

[0039] The layout of temporary sump 2a on the excavation pit cross-section can be found in [reference needed]. Figure 3 The diagram shows the layout of the foundation sump 2b across the foundation pit cross-section. Figure 4 The illustration is shown in the image.

[0040] In one example, a water collection well 2 can be set up 1 meter away from the toe of the current foundation pit slope.

[0041] The dimensions of the temporary collection well 2a and the base collection well 2b can be set according to actual needs. In one example, the temporary collection well 2a can be set to a length of 1000mm, a width of 1000mm, and a depth of 2000mm; the base collection well 2b can be set to a length of 1000mm, a width of 1000mm, and a depth of 1000mm.

[0042] Step S104: Extract and drain the accumulated water in the collection well 2 using the drainage device 8 until the groundwater level at the bottom of the pit meets the preset dryness requirements.

[0043] Specifically, the annular drainage ditch 1 set at the bottom of the current foundation pit based on the aforementioned step S102 can be used to collect seepage water and rainwater from the foundation pit, and the accumulated water collected by the annular drainage ditch 1 can flow into the collection well 2 set at the bottom of the current foundation pit based on step S103. Thus, in this embodiment of the application, by using the drainage equipment 8 to extract and discharge the accumulated water collected in the collection well 2, rainwater, groundwater, and construction wastewater in the current foundation pit can be discharged to ensure that the base layer (bottom of the foundation pit) is dry.

[0044] In one example, the drainage device 8 may include multiple submersible pumps 81 respectively installed in each sump 2 at the bottom of the current foundation pit, and multiple drainage pipes 82 connected at one end to each of the multiple submersible pumps 81 and extending to the outside of the foundation pit at the other end. For example, if four evenly distributed sump 2 are installed at the bottom of the current foundation pit, a submersible pump 81 may be installed in each sump 2, and the four submersible pumps 81 may be connected to one end of each of the four drainage pipes 82, with the other ends of the four drainage pipes 82 extending to the outside of the foundation pit.

[0045] For details regarding the arrangement of the submersible pump 81 and the drain pipe 82, please refer to Figure 5 The illustration is shown in the image. Based on... Figure 5When the drainage equipment 8 is arranged as shown in the diagram, the specific drainage path during the drainage process is as follows: seepage / rainwater from the foundation pit → ring drainage ditch 1 → collection well 2 → submersible pump 81 → drainage pipe 82 → discharge outside the site.

[0046] In this step, the method for determining whether the groundwater level at the bottom of the current foundation pit meets the preset dryness requirements can be selected according to actual needs. This application embodiment does not make specific limitations on this. In one example, the preset dryness requirement can be set as follows: the groundwater level at the bottom of the current foundation pit is stable at 0.5 meters below the foundation.

[0047] In one example, after the construction of the sump 2 at the bottom of the current foundation pit is completed, the submersible pump 81 in the drainage equipment 8 can be started to extract and discharge the water collected in the sump 2; and the groundwater level at the preset water level observation point can be checked regularly to determine whether the groundwater level at the bottom of the foundation pit meets the preset dryness requirements.

[0048] The water level observation points include multiple points located at the center and edges of the bottom of the foundation pit. For example, three water level observation points can be set at the center and four corners of the bottom of the foundation pit.

[0049] For example, in practical applications, groundwater levels at observation points can be measured using a water level measuring rope. For instance, a water level measuring rope with an accuracy of ±50mm can be used.

[0050] Step S105: Excavate further downwards to a certain depth based on the current foundation pit, and return to the aforementioned step S102 until the elevation of the bottom of the foundation pit reaches the design elevation.

[0051] After dewatering the current foundation pit based on steps S102-S104 above, and confirming that the groundwater level at the bottom of the current foundation pit meets the preset dryness requirements, the foundation pit can be further excavated to a certain depth. Then, based on steps S102-S104 above, the excavated foundation pit can be dewatered, and so on, until the elevation of the bottom of the foundation pit reaches the design elevation.

[0052] Step S106: Once the elevation at the bottom of the foundation pit reaches the design elevation and the foundation pit passes inspection, proceed with the construction of the wind turbine foundation within the foundation pit.

[0053] Specifically, after the excavation reaches the design elevation at the bottom of the foundation pit, and after dewatering the pit according to steps S102-S104, the foundation pit can be inspected. If the foundation pit passes inspection, construction of the wind turbine foundation can begin within the pit. For details on how to inspect the foundation pit and how to determine if it has passed inspection, please refer to relevant technical documents.

[0054] As can be seen from the above, the dewatering construction method for high-water-level wind turbine foundation pits in desert and sandy areas provided in this application adopts a layered excavation method for excavating the wind turbine foundation pits. During the excavation of the pit, each time the pit is excavated to the bottom, a ring-shaped drainage ditch 1 extending along the bottom edge of the pit and a collection well 2 connected to the ring-shaped drainage ditch 1 are set up at the bottom of the current pit. The water collected in the collection well 2 is pumped out and discharged by the drainage equipment 8 to dewater the current pit. Only when the groundwater level at the bottom of the current pit meets the preset dryness requirements will the pit be further excavated and dewatered based on the same principle. Then, the excavation continues and the dewatering continues until the elevation of the bottom of the pit reaches the design elevation.

[0055] It can be seen that the aforementioned dewatering construction method for high-water-level wind turbine foundation pits in desert and sandy areas can effectively dewater the foundation pit during the construction of wind turbine foundations, thereby improving the construction safety of wind turbine foundations in areas with high groundwater levels. Furthermore, this dewatering construction method optimizes the drainage equipment 8 and drainage path by using a ring-shaped drainage ditch 1 → sump well 2 → drainage equipment 8 → outside the site for dewatering the foundation pit after each deep excavation. Compared with single dewatering methods such as dewatering wells, this method effectively improves dewatering efficiency. Moreover, this dewatering construction method effectively connects the dewatering process with the foundation pit excavation process. Compared with the traditional dewatering method using professional dewatering teams, it reduces a large number of redundant processes, shortens the construction cycle, and effectively reduces construction costs. Therefore, this dewatering construction method not only achieves effective dewatering but also has the advantages of high construction safety, controllable construction period, convenient implementation, and economical cost, making it highly valuable for widespread application.

[0056] In one embodiment of this application, after excavating downwards to the design elevation of the bottom of the foundation pit, before constructing the wind turbine foundation in the foundation pit according to the aforementioned step S106, multiple simple drainage ditches 3 can be set at the bottom of the foundation pit, extending from the center of the foundation pit to the edge of the foundation pit and connected to the annular drainage ditch 1 (base drainage ditch 1b) at the bottom of the foundation pit.

[0057] The layout of the simple drainage ditch 3 in the top view of the foundation pit can be found in [reference needed]. Figure 2 The illustration in the image. Figure 2 In the illustration, eight simple drainage ditches 3 (in actual applications, the number of simple drainage ditches 3 is not limited to this) are evenly distributed in a star shape and extend from the center of the foundation pit to the edge of the foundation pit. All eight simple drainage ditches 3 are connected to the base drainage ditch 1b.

[0058] The bottom of the simple drainage ditch 3 has a certain slope, and the height of the bottom of the simple drainage ditch 3 gradually decreases along a first direction, which is the direction from the center of the pit to the edge of the pit. Simply put, the bottom of the simple drainage ditch 3 is higher near the center of the pit than it is far from the center of the pit, so that water in the middle of the pit can flow into the base drainage ditch 1b along the simple drainage ditch 3.

[0059] Specifically, in construction sites rich in groundwater, the bottom of the foundation pit may experience multiple small surges of groundwater due to pressure. If this water is not drained, it may affect the subsequent construction of the wind turbine foundation. In this embodiment, by setting up a simple drainage ditch 3 extending from the center of the foundation pit to its edge, the surged groundwater can be introduced into the base drainage ditch 1b and then flow into the collection well 2 along the base drainage ditch 1b, thereby preventing the groundwater from affecting the construction of the wind turbine foundation.

[0060] In addition, during the construction of the wind turbine foundation, the accumulated water in the foundation sump 2b should be promptly extracted and drained through the drainage equipment 8 to prevent the foundation pit from being soaked in water.

[0061] The dimensions of the simple drainage ditch 3 can be set according to actual needs. In one example, the simple drainage ditch 3 can be set to be 15cm wide and 15cm deep.

[0062] In one embodiment of this application, after setting up the simple drainage ditch 3 at the bottom of the foundation pit, and before carrying out the construction of the wind turbine foundation in the foundation pit according to the aforementioned step S106, a waterproof geotextile 4 can also be covered at the bottom of the foundation pit.

[0063] The area covered by the waterproof geotextile 4 is the first region. The first region is the area formed by the first edge line of the base drainage ditch 1b, which is the edge line of the base drainage ditch 1b on the center side near the bottom of the foundation pit. In other words, the first region is the area formed by the inner edge line of the base drainage ditch 1b.

[0064] For details on the installation of waterproof geotextile 4 on the foundation pit cross-section, please refer to [link / reference needed]. Figure 4 The illustration is shown in the image. Based on... Figure 4 As can be seen from the diagram, the waterproof geotextile 4 covers the area within the base drainage ditch 1b in a circular arrangement, and its edge overlaps with one side of the base drainage ditch 1b.

[0065] In this embodiment of the application, by setting waterproof geotextile 4 at the bottom of the foundation pit, it is possible to prevent the subsequent wind turbine foundation construction process from damaging the simple drainage ditch 3 and affecting the drainage effect of the sudden water source at the bottom of the foundation pit, thereby helping to prevent the sudden water source at the bottom of the foundation pit from affecting the construction and quality control of the wind turbine foundation cushion layer.

[0066] In one embodiment of this application, during the process of setting up the water collection well 2 at the bottom of the foundation pit based on the aforementioned step S103, after excavating the water collection well 2, a layer of geotextile 5 (which can be ordinary geotextile 5) can be laid on the inner wall of the water collection well 2, and then a certain thickness of crushed stone can be laid at the bottom of the water collection well 2 to form a filter layer 6. This method can be used for both the temporary water collection well 2a and the base water collection well 2b. Details of the temporary water collection well 2a can be found in [reference needed]. Figure 6 The illustration shows the details of the base water collection well 2b. Figure 7 The illustration.

[0067] In addition, during the process of setting up the annular drainage ditch 1 at the bottom of the foundation pit based on the aforementioned step S102, a layer of geotextile 5 can also be laid on the inner wall of the annular drainage ditch 1 after it is excavated.

[0068] In one example, the geotextile 5 laid on the inner wall of the annular drainage ditch 1 and the collection well 2 can be 200g / m². 2 5. Geotextile (grams per square meter). The particle size of the crushed stone backfilled into the bottom of the collection well 2 can be 10-30mm.

[0069] In one example, a 50-100mm thick layer of gravel can be backfilled into the bottom of the temporary collection well 2a to form a reverse filter layer; a 200mm thick layer of gravel can be backfilled into the bottom of the base collection well 2b to form a reverse filter layer.

[0070] Specifically, seepage and rainwater inside the foundation pit may mix with the soil, containing a large amount of silt. If this silt clogs the submersible pump 81 and the drainage pipe 82, the drainage equipment 8 may be unable to smoothly pump out the water collected in the sump 2, thus preventing the foundation pit from being drained. In this embodiment, by laying geotextile 5 on the inner walls of the annular drainage ditch 1 and the sump 2, silt from the bottom of the foundation pit can be prevented from mixing into the water collected in the annular drainage ditch 1 and the sump 2. The filter layer 6 at the bottom of the sump 2 can also filter the water in the sump 2, thereby preventing the submersible pump 81 from sucking in silt during the water intake process, ensuring smooth water flow and preventing silt from clogging the submersible pump 81, thus ensuring the smooth operation of the foundation pit drainage work.

[0071] In one embodiment of this application, during the process of setting up annular drainage ditch 1 at the bottom of the foundation pit based on the aforementioned step S102, after excavating the annular drainage ditch 1, the inner wall of the annular drainage ditch 1 can be constructed with pebbles to form a reverse filter layer, so as to filter mud and sand and prevent mud and sand from clogging the drainage equipment 8.

[0072] In one embodiment of this application, before performing the aforementioned step S101, an annular water-retaining platform 7 may be provided outside the upper edge of the foundation pit, extending along the upper edge of the foundation pit and having a certain distance between it and the upper edge of the foundation pit.

[0073] The placement of the annular water-retaining platform 7 in the top view of the foundation pit can be referenced. Figure 2 The illustration is shown in the image.

[0074] The distance between the annular water-retaining platform 7 and the top edge of the foundation pit can be set according to actual needs. In one example, an annular water-retaining platform 7 can be set at a distance of 2 meters from the top edge of the foundation pit, along the top edge of the foundation pit.

[0075] The dimensions of the annular water-retaining platform 7 can also be set according to actual needs. In one example, the annular water-retaining platform 7 can be constructed using C25 (a concrete strength grade) concrete, with a width of 300mm and a height of 300mm.

[0076] In another example, for ecologically fragile areas or areas with high environmental protection requirements, considering factors such as environmental protection, site restoration, and construction costs, the construction materials for the annular water barrier 7 can be sourced locally, and the width of the annular water barrier 7 can be set at 800mm and the height at 400mm.

[0077] For example, the annular water-retaining platform 7 can be arranged along the natural slope of the site. In one possible implementation of this application, the ground elevation outside the site can be constructed at the same time as the annular water-retaining platform 7 to form a drainage slope, so as to prevent rainwater from eroding the slope of the foundation pit.

[0078] For ease of understanding, the following describes a possible construction process for wind turbine foundation construction using the dewatering construction method for high-water-level wind turbine foundation pits in desert and sandy areas provided in the above embodiments of this application. This construction process can be used to construct large wind turbine foundation pits with excavation depths of approximately 5-12 meters, and is suitable for geological conditions such as silt, sand, gravel layers, gravelly sand layers, rounded gravel layers, pebble layers, and weakly weathered rock, or other similar geological conditions. See [link to relevant documentation]. Figure 8 The construction process includes the following steps: Step S801: Construction preparation.

[0079] Specifically, this involves completing technical, site, material, and labor preparations, as well as drafting, reviewing, and submitting the construction plan for approval. It also includes organizing workers to familiarize themselves with construction drawings, geological survey reports, and other design documents, conducting technical briefings, and providing detailed explanations of all aspects of construction, including progress, organization, quality, safety, cost, environmental protection, and civilized construction practices. This ensures that site management and construction workers fully understand and strictly adhere to the design drawings, specifications, and the approved construction plan. Finally, it involves site leveling, clearing the construction area, arranging temporary power and water supplies, and setting up fencing, warning signs, and warning lights to ensure construction safety.

[0080] Step S802: Measure and lay out the lines.

[0081] Specifically, this involves accurately laying out the top line, zoning lines, and local foundation pit edge positions at different depths based on the control points and leveling points handed over.

[0082] Step S803: Level the site.

[0083] Site leveling should be carried out using machinery, and a dedicated person should be assigned to direct the construction process.

[0084] Step S804: Construction of the slope top water-retaining platform.

[0085] This refers to the construction of a circular water-retaining platform 7, as detailed in the previous text.

[0086] Step S805: Layered excavation.

[0087] This means excavating the foundation pit layer by layer from top to bottom, as detailed in the previous explanation of step S101. During layered excavation, indiscriminate and over-excavation is strictly prohibited. The excavation depth of each layer should not exceed 1.5 meters, and bottom excavation is strictly forbidden. Excavation operations must maintain slope stability, preventing the formation of "fairy soil," and must not damage or interfere with nearby structures and facilities. If ancient tombs, underground pipelines, cables, or other unidentified foreign objects, liquids, or gases are encountered during excavation, operations must be stopped immediately to prevent accidents and losses. The person in charge must be notified, and relevant units must be contacted. Excavation can only continue after the situation has been investigated and dealt with. Soil transport vehicles must travel on designated routes, and the loading height must be strictly controlled. The surface of soil and rocks in the truck bed must be compacted to prevent soil and rocks from rolling off, and overloading is strictly prohibited. Unwashed vehicles carrying mud are strictly prohibited from leaving the site. Before excavation of the foundation pit area, the surrounding site must be leveled to the ±0.000 elevation of the corresponding hoisting platform.

[0088] During the layered excavation process, temporary drainage ditch 1a and temporary sump 2a should be installed simultaneously with each excavation. After each layer is excavated, temporary drainage ditch 1a and temporary sump 2a should be immediately installed on the platform of that layer. Once the temporary drainage ditch 1a and temporary sump 2a are constructed, continuous dewatering of the current foundation pit can be carried out using drainage equipment 8. After ensuring that the foundation of that layer is dry and the groundwater level is stable at 0.5m below the foundation, excavation of the next layer can begin. This construction sequence should be followed until mechanical excavation reaches 300mm above the design elevation. At this point, to avoid disturbing the foundation soil, mechanical excavation should be stopped, and manual slope trimming and bottom inspection should be carried out.

[0089] In one example, when excavating a foundation pit, the excavation size can be increased by 2 meters compared to the original design, and the excavation slope ratio should meet the requirements of the design drawings.

[0090] In addition, the following matters should be noted during the layered excavation process: (1) Each time the foundation pit is further excavated to a certain depth, the middle part should be excavated first, and then the surrounding area should be excavated; and when the bottom layer of soil is excavated, about 30cm above the design elevation should be left for manual cleaning. The specific reserved thickness depends on the performance of the construction machinery. It is strictly forbidden to disturb the foundation soil; (2) During the excavation process, it is important to check frequently. If weak layers such as silt or quicksand are encountered, the designer, supervisor and relevant personnel must be asked to come to the site in time to solve the problem in order to meet the bearing capacity requirements of the foundation; (3) The foundation pit should be trimmed once every 1.5 meters or so; when trimming the edge, the slope should be checked and the deviation should be corrected by pulling a line along the slope; the length and width of the foundation pit should not be less than the design requirements, and the allowable deviation should be controlled within the range of 0 to +20mm (under-excavation is not allowed); (4) The excavation of the foundation pit should be carried out continuously and interspersed with the slope trimming, and completed as soon as possible; when encountering obstacles, the type and range of the obstacles should be investigated first, and they should be removed manually or mechanically. (5) If the geological conditions are found to be significantly different from those in the geological survey report after the foundation pit is excavated, the design should be notified in a timely manner. Construction can only proceed after confirmation by the geotechnical and design departments. For shallow general solution channels and troughs, after confirmation by the geotechnical and design departments, the soil, rocks or other impurities in the channels should be cleaned and replaced with graded sand and gravel. (6) During the construction process, deformation monitoring should be carried out on each slope. If the slope conditions in a local area do not match the survey conditions or there are obvious signs of deformation, the operation should be stopped immediately. After excavation, the foundation layer and pile cap should be poured in a timely manner; before the pile cap is poured, measures should be taken to protect the foundation trench; the foundation pit should not be exposed for a long time, and the foundation pit should not be exposed to the sun; prevent surface water from seeping in, and prevent the foundation pit from being soaked; (7) the foundation pit after excavation should not have water, loose soil and mud at the base, and the foundation soil at the bottom must maintain its original structure and should not be disturbed by construction; (8) during construction, measures should be taken to prevent surface water from flowing into the pit and to avoid slope collapse or damage to the foundation soil; (9) after the excavation of the site is completed, the roadway soil should be excavated layer by layer, and the slope protection work should be completed layer by layer.

[0091] Step S806: Slope protection.

[0092] First, edge protection should be implemented. For example, a 1.2m high guardrail can be installed at the top of the pit, with a dense safety net and red warning lights at night. The guardrail posts can be spaced 2 meters apart and can have two horizontal bars. The red warning lights can be spaced 10 meters apart.

[0093] When carrying out mechanical excavation, the thickness of the loose soil should be controlled, and the slope excavation of the foundation pit should meet the design requirements and relevant regulations. During construction, the stability of the pit walls should be checked frequently.

[0094] During construction, slope displacement monitoring should be carried out as required, using a total station to monitor the horizontal displacement at the top of the slope. Specifically, the warning value can be set at a daily slope horizontal displacement exceeding 3mm or a cumulative slope horizontal displacement exceeding 30mm. If the warning value is exceeded, backfilling and counter-pressure should be carried out immediately, and drainage should be checked for obstruction.

[0095] Step S807: Leveling the base.

[0096] Specifically, when excavating to the design elevation of the pit bottom, leveling should be carried out once, and the excavation depth should be controlled according to the leveling marks to avoid over-excavation.

[0097] In addition, it is necessary to ensure that the same set of foundations is located in a single bearing layer during the construction of the wind turbine foundation. Otherwise, over-excavation is required, and graded sand and gravel should be used to replace the foundation to the design elevation. The graded sand and gravel cushion layer should be made of hard, weather-resistant and water-softening-resistant sand and gravel. A combination of fine sand and silt should not be used.

[0098] Step S808: Excavate a simple drainage ditch 3.

[0099] Please refer to the explanation above for details.

[0100] Step S809: Cover with waterproof geotextile 4.

[0101] That is, waterproof geotextile 4 is installed in the area formed by the inner edge of the base drainage ditch 1b, as explained in the previous text.

[0102] Step S810: Construction of the base ring drainage ditch 1 and the base water collection well 2b.

[0103] Please refer to the explanation above for details.

[0104] Step S811: Drainage operation.

[0105] That is, the water collected in the base water collection well 2b is extracted and discharged through the drainage equipment 8.

[0106] For example, submersible pump 81 can be started immediately after the construction of the foundation sump 2b to dewater the foundation pit. The groundwater level at the bottom of the pit can be checked 24 hours after dewatering to determine if it has dropped to 0.5 meters below the foundation. Pumping can be carried out continuously for 24 hours, with the pumping volume and groundwater level recorded every 2 hours. In case of heavy rain, the pump can be checked before the rain and pumping can be resumed within 30 minutes after the rain to ensure that no water accumulation in the foundation pit exceeds 300mm.

[0107] In one example, if... Figure 2 The diagram shows that four foundation collection wells (2b) are set up on the foundation, which can be equipped with a total of six pumps with a head of 30 meters and a flow rate of not less than 10 m³ / h. 3 The submersible pumps have a capacity of 100 cubic meters per hour, with 4 pumps installed in 4 collection wells for pumping water, and 2 pumps as backup. Each submersible pump is equipped with a DN100 (one type of drainage pipe) drainage pipe of no less than 50 meters.

[0108] In one example, water level monitoring can be conducted regularly. For instance, three water level observation points can be set up at the center and four corners of the foundation pit, and the groundwater level can be measured at 8:00 AM and 6:00 PM every day to form a water level monitoring record table, ensuring that the groundwater level remains stable at 0.5m below the foundation.

[0109] In one possible implementation, the total daily drainage capacity of each submersible pump 81 installed in each base water collection well 2b at the bottom of the foundation pit can be designed to be no less than the first drainage capacity, which is 1.5 times the estimated seepage volume of the foundation pit within the predetermined foundation site.

[0110] To illustrate with a specific example, assuming four foundation sump wells (2b) are installed at the bottom of the foundation pit, and on-site measurements indicate a daily seepage volume of approximately 500-600 cubic meters, then if each submersible pump (81) has a flow rate of 10 m³ / s... 3 / h, and continuous pumping for 24 hours, the total daily drainage capacity of the four submersible pumps 81 in the four base sump wells 2b is 4 24 hours 10 cubic meters per hour = 960 cubic meters, which is 1.5 times (900 cubic meters) greater than the estimated maximum seepage of 600 cubic meters, thus meeting the requirements in the previous paragraph.

[0111] Step S812: Excavation pit inspection.

[0112] For example, an inspection can be organized after the excavation of the foundation pit is completed (the bottom elevation of the foundation pit reaches the design elevation) and after the excavated foundation pit has been drained for 24 hours using drainage equipment 8. The inspection can be conducted according to Appendix A of the "Standard for Acceptance of Construction Quality of Building Foundation Engineering" GB 50202-2018, specifically requiring that the foundation be free of standing water and soft mud, and that the bearing capacity meet the design requirements. During the inspection, if any inconsistencies are found between the geological conditions and the geological survey report and design documents, or if any abnormalities are encountered, the opinions on handling the situation should be determined jointly with the surveying, design, construction, supervision, and construction units.

[0113] After the foundation pit inspection is conducted, if the foundation pit passes the inspection, the wind turbine foundation construction can proceed according to the subsequent step S813. If the foundation pit fails the inspection due to excessive water content in the foundation, further dewatering can be carried out in step S811, and a new inspection can be organized subsequently.

[0114] Step S813: Construction of wind turbine foundation.

[0115] For example, the specific process of wind turbine foundation construction may include: foundation trench acceptance (power cable pipes need to be pre-embedded) → foundation concrete pouring (anchor bolt assembly support steel plate needs to be pre-embedded) → installation of anchor bolt assembly → horizontal and verticality verification → reinforcement binding → pre-embedded foundation drainage pipe → formwork erection → upper anchor plate horizontality verification → pre-embedded parts installation → foundation concrete pouring → formwork removal → foundation curing → acceptance → earthwork backfilling → upper anchor plate horizontality verification.

[0116] During the construction of the foundation layer (i.e., the pouring of foundation concrete), the base elevation should be controlled within +0.3m. Over-excavation or under-excavation is prohibited, and the excavated soil should not be used to fill the over-excavated portion; the natural soil quality of the base should be maintained. After cleaning the trench, the over-excavated portion should be leveled with C20 (a concrete strength grade) concrete to the design base elevation. According to the "Wind Turbine Foundation Plan," the bottom embedded parts should be evenly separated using a theodolite and installed. PVC-C (chlorinated polyvinyl chloride) cable conduits of type 23D1175+350 (a type of cable conduit) should be laid as required. After the wind turbine foundation trench is excavated to the foundation bottom elevation, the trench should be cleaned, and after joint acceptance, the foundation layer construction can begin. After the foundation layer formwork is erected, concrete should be poured using a concrete pump truck, and the surface smoothed with a wooden trowel. The foundation layer's planar dimensions should be 150mm larger than the foundation bottom planar dimensions around the perimeter, with the center of the foundation layer aligned with the wind turbine center; a difference of less than 10mm is acceptable.

[0117] When installing anchor bolt assemblies, the material specifications and models should be checked promptly upon arrival. Technical briefings should be conducted with the manufacturer's technicians before installation, and technical guidance should be provided during the installation process. During installation, the distance between the upper and lower anchor plates, their levelness, the exposed length of the anchor bolt, and concentricity should be strictly controlled. After installation, the anchors should be secured promptly. The specific construction process is as follows: preparation → installation of the lower anchor plate → installation of the upper anchor plate → insertion of the remaining anchor bolts → adjustment of the concentricity of the upper and lower anchor plates → adjustment of the level of the upper anchor plate → reinforcement with the anchor bolt assembly.

[0118] Step S814: Backfilling the foundation pit.

[0119] Backfilling of the foundation pit can only commence after the wind turbine foundation construction is completed, concrete curing is finished, and concealed works have passed inspection. Backfilling is carried out using a combination of manual labor and a loader, with each layer no more than 300mm thick, and mechanical compaction. According to design requirements, the compacted dry density should be greater than 18kN / m³. 3 (1,000 N / m³), density not less than 0.94.

[0120] Step S815: Drainage system removal.

[0121] During the backfilling process, the area away from the water collection well 2 is backfilled first, and then the submersible pump 81 and drainage pipe 82 are removed in sequence until the entire wind turbine foundation is backfilled. Finally, the annular water retaining platform 7 is removed and the site is restored.

[0122] It can be seen that the above construction process adopts a three-stage dewatering system of "slope top water-blocking platform + base drainage ditch open drainage + collection well pumping" to dewater the foundation pit, which optimizes the drainage equipment and drainage path. Compared with the use of single dewatering methods such as dewatering pipe wells, it can effectively improve the dewatering efficiency.

[0123] Furthermore, in the aforementioned construction process, a circular drainage ditch and sump are installed at the bottom of each layer of the foundation pit before excavation. Drainage equipment is then used to dewater the current layer before further excavation and dewatering. This effectively connects the dewatering process with the foundation pit excavation process. Compared to traditional dewatering methods using specialized dewatering teams, this reduces numerous redundant steps, shortens the construction cycle, and effectively lowers construction costs, thereby improving the overall economic benefits of the project. Moreover, real-time dewatering during the layered excavation process helps avoid the need for continuous slope repairs due to slope collapse, reducing the impact of external factors on on-site construction and enhancing safety.

[0124] Especially for wind turbine foundations in sites with shallow groundwater depth, groundwater replenishment from external rivers, and abundant groundwater, a three-stage dewatering system of "slope top water-blocking platform + base drainage ditch open drainage + sump pumping" can continuously dewater until the end of the wind turbine foundation curing period, ensuring that the groundwater level remains stable at 0.5m below the base, solving the problem of surrounding soil settlement that is easily caused during dewatering, and reducing safety risks.

[0125] In summary, the construction process described in this application can achieve efficient dewatering in wind turbine foundation construction in arid areas with high groundwater levels. It offers high construction safety, controllable construction period, convenient implementation, and economical cost, making it highly valuable for widespread application. This lays a solid foundation for the subsequent construction of large-scale wind farms with high groundwater levels in arid areas and for the application of wind turbine foundations in complex groundwater-rich environments.

[0126] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0127] The various embodiments in this specification are described in a related manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0128] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A method for dewatering construction of high-water-level wind turbine foundation pits in desert and sandy areas, characterized in that, include: Within the selected foundation site, excavate to a certain depth along the top edge of the foundation pit to form the foundation pit; At a predetermined distance from the bottom of the foundation pit to the toe of the slope, a ring-shaped drainage ditch extending along the edge line of the bottom of the foundation pit is set. Multiple water collection wells are set up, evenly distributed along the edge line of the bottom of the foundation pit and connected to the annular drainage ditch; The accumulated water in the sump is extracted and discharged through drainage equipment until the groundwater level at the bottom of the pit meets the preset dryness requirements. Further excavate to a certain depth based on the current foundation pit, and return to the step of setting a ring-shaped drainage ditch extending along the edge line of the foundation pit at a preset distance from the bottom of the foundation pit to the slope, until the elevation of the bottom of the foundation pit reaches the design elevation; Once the bottom elevation of the foundation pit reaches the design elevation and the foundation pit passes inspection, the construction of the wind turbine foundation can proceed within the foundation pit.

2. The method according to claim 1, characterized in that, After excavating downwards to the bottom elevation of the foundation pit reaches the design elevation, and before constructing the wind turbine foundation within the foundation pit, the method further includes: Multiple simple drainage ditches are set at the bottom of the foundation pit, extending from the center of the foundation pit to the edge of the foundation pit and connecting with the annular drainage ditch at the bottom of the foundation pit; the bottom of the simple drainage ditch has a slope, and the height of the bottom of the simple drainage ditch gradually decreases along a first direction, which is the direction from the center of the foundation pit to the edge of the foundation pit.

3. The method according to claim 2, characterized in that, After constructing multiple simple drainage ditches at the bottom of the foundation pit, extending from the center of the pit to the edge and connecting with the annular drainage ditch at the bottom of the pit, the method further includes the following steps before constructing the wind turbine foundation within the pit: A waterproof geotextile is placed at the bottom of the foundation pit; the waterproof geotextile covers a first area, which is the area formed by the first edge line of the annular drainage ditch at the bottom of the foundation pit, and the first edge line is the edge line of the annular drainage ditch on the side closest to the center of the bottom of the foundation pit.

4. The method according to claim 1, characterized in that, After setting up a ring-shaped drainage ditch extending along the edge line of the bottom of the foundation pit, and setting up multiple collection wells evenly distributed along the edge line of the bottom of the foundation pit and connected to the ring-shaped drainage ditch, before pumping out and discharging the accumulated water in the collection wells using drainage equipment, the method further includes: Geotextile is laid on the inner wall of the annular drainage ditch and the inner wall of the water collection well. After laying the geotextile, a certain thickness of crushed stone is laid at the bottom of the collection well to form a filter layer.

5. The method according to claim 1 or 4, characterized in that, The inner wall of the annular drainage ditch is a filter layer constructed using pebbles.

6. The method according to claim 1 or 4, characterized in that, The drainage equipment includes multiple submersible pumps respectively installed in the multiple water collection wells, and multiple drainage pipes with one end connected to each of the multiple submersible pumps and the other end extending to the outside of the foundation pit; The process of extracting and draining the accumulated water in the sump through drainage equipment until the groundwater level at the bottom of the pit meets the preset dryness requirements includes: After the water collection well is constructed, the submersible pump is started to extract and discharge the water collected in the water collection well. The groundwater level at the preset water level observation points is periodically monitored to determine whether the groundwater level at the bottom of the foundation pit meets the dryness requirements; the water level observation points include multiple water level observation points respectively set at the center and edge of the bottom of the foundation pit; If the groundwater level at the bottom of the foundation pit meets the dryness requirements, the submersible pump and the drainage pipe are retrieved, and the step of further excavating to a certain depth based on the current foundation pit is performed.

7. The method according to claim 6, characterized in that, The total daily drainage capacity of the plurality of submersible pumps shall not be less than the first water volume, which is 1.5 times the estimated seepage volume of the foundation pit within the foundation site.

8. The method according to claim 6, characterized in that, Before excavating a certain depth downwards along the top edge of the foundation pit within the selected foundation site to form the foundation pit, the method further includes: An annular water-retaining platform is set outside the upper edge of the foundation pit, extending along the upper edge of the foundation pit and having a certain distance between it and the upper edge of the foundation pit. A drainage slope is formed on the outside of the annular water-retaining platform.

9. The method according to claim 8, characterized in that, After the construction of the wind turbine foundation is completed, the method further includes: Backfill the foundation pit with earth and remove the submersible pump and drainage pipe installed in the foundation pit; After the earthwork backfilling is completed, the annular water-retaining platform is removed.

10. The method according to claim 1, characterized in that, When excavating further downwards to a certain depth based on the existing foundation pit, this certain depth shall not exceed 1.5 meters.

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