Energy support pile system and construction method thereof

Abstract

The present application provides an energy support pile system, comprising: a plurality of energy support piles, each of which is provided with a pile inner heat exchange pipe, and a pile foundation reinforcement cage is arranged in each of the energy support piles, the pile foundation reinforcement cage has a pile side part and a pile end part; a corbel beam is fixedly connected with the plurality of energy support piles; wherein a water collecting pipe is arranged in the corbel beam, an interface pipe is arranged on the water collecting pipe, and the pile inner heat exchange pipe is communicated with the water collecting pipe. The present application also provides a construction method of the energy support pile system. The energy support pile system and the construction method thereof can solve the technical problem that the existing foundation pit support pile can only be used as a temporary structure and cannot be effectively used in long-term ground heat exchange.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering foundation pit support technology, specifically to an energy support pile system and its construction method. Background Technology

[0002] The development and utilization of shallow geothermal energy has enormous practical demand and application prospects. As a conventional technology for utilizing shallow geothermal energy, ground source heat pumps typically bury underground heat exchange pipes within a depth of 200 meters in the soil. The heat pump system extracts energy from the soil through a heat transfer medium and exchanges this energy with indoor air to achieve heating and cooling. In the 1980s, Austrian engineers first proposed and applied energy pile technology. Energy piles replace the buried pipes of the traditional ground source heat pump primary loop, embedding the heat exchange pipes within the pile body. While bearing the load, they also exchange heat with the surrounding soil, extracting shallow geothermal energy, achieving "one pile, two uses." Due to the excellent thermal conductivity of concrete, energy piles can achieve higher heat exchange efficiency and also save on drilling and backfilling procedures, thus exhibiting significant technical and economic advantages.

[0003] Domestic and international research and application of energy piles mainly focus on conventional compression piles with lengths of 20-40m. However, with the accelerated pace of large-scale public infrastructure construction in my country and the increasing scarcity of urban land, the development of underground space is intensifying, leading to a surge in deep foundation pit projects, particularly for commercial complexes, office buildings, high-rise buildings, and subway stations. Support piles (with additional anchors and supports) are the most common support method for large-scale deep foundation pit projects. Generally, foundation pit support piles are temporary structures, serving only during excavation and underground structure construction. Once the pit is backfilled, the support piles cease to function and become "solid waste" in the soil. Because deep foundation pit support piles are generally reinforced concrete structures, and due to the large number and length of piles involved, their cost is inherently very high. Treating them merely as temporary structures would result in a huge waste of resources and contradict the concept of modern sustainable development. On the other hand, due to the extremely tight land resources within the building red line in first-tier cities such as Beijing, there is very little space available for traditional ground source heat pumps and energy piles, which limits the energy supply of the primary loop in the development of ground source heat pump systems, often making the entire shallow geothermal resource utilization plan infeasible. Summary of the Invention

[0004] The purpose of this invention is to provide an energy support pile system and its construction method, which solves the technical problem that existing foundation pit support piles can only be used as temporary structures and cannot be effectively utilized in geothermal heat exchange for a long time.

[0005] To achieve the above objectives, the present invention provides an energy support pile system, comprising: multiple energy support piles, each of which is provided with an internal heat exchange pipe, and a pile foundation reinforcement cage is provided within the energy support pile, the pile foundation reinforcement cage having a pile side portion and a pile end portion; a capping beam, the capping beam being fixedly connected to the multiple energy support piles; wherein, a water collection pipe is provided within the capping beam, the water collection pipe is provided with an interface pipe, and the internal heat exchange pipe is connected to the water collection pipe.

[0006] This invention also provides a construction method for an energy support pile system, comprising the following steps: Step 1, constructing a high-slope soil nailing wall; Step 2, after the soil nailing wall reaches the required curing time and strength, constructing the pile hole for the energy support pile on-site using rotary drilling technology, and laying the heat exchange pipe inside the pile inside the pile foundation reinforcement cage and pressurizing the heat exchange pipe; Step 3, lowering the heat exchange pipe inside the pile into the pile hole under pressure, rotating and adjusting the pile foundation reinforcement cage so that the heat exchange pipe inside the pile is attached to the soil outside the foundation pit; Step 4, pouring pile body concrete to form an energy support pile; Step 5, connecting the heat exchange pipe inside the pile to the water collection pipe, and pouring cap beam concrete to form a cap beam.

[0007] Preferably, the energy support pile system further includes a high-slope soil nailing wall, which includes soil nails, a cross-sectional steel mesh, and a facing; the soil nails are fixedly connected to the cross-sectional steel mesh, the facing is attached to the cross-sectional steel mesh, and the soil nails and the facing are set perpendicular to each other; the soil nails have an inclination angle of 5~20° in the horizontal plane.

[0008] Preferably, the energy support pile system also includes ordinary support piles, wherein no heat exchange pipes are installed inside the ordinary support piles, the ordinary support piles are fixedly connected to the cap beam, and the ordinary support piles and the energy support piles are arranged at intervals.

[0009] Preferably, the energy support pile system further includes a waist beam and multiple anchor bodies. The waist beam is fixedly connected to the multiple energy support piles. The waist beam is arranged along the entire length of the multiple energy support piles. One end of the anchor body is fixedly connected to the waist beam.

[0010] Preferably, the energy support pile system further includes multiple anchor body heat exchange tubes, each anchor body heat exchange tube including a heat exchange section and a connecting section, the heat exchange section extending within at least a portion of the anchor body, and the connecting section extending outward from one end of the heat exchange section near the waist beam, the multiple anchor body heat exchange tubes being connected to the water collection pipe through the connecting section.

[0011] Preferably, step 1 specifically includes: step 11, excavating the surface soil within the foundation pit area, with the excavation angle of the foundation pit slope being 70~85°; step 12, drilling holes and driving soil nails into the slope, and grouting into the soil nail holes; step 13, laying a cross-sectional steel mesh on the slope surface, and welding the soil nails to the cross-sectional steel mesh using reinforcing bars; step 14, repeating steps 11 to 13 until the preset foundation pit depth, and then performing concrete spraying treatment on the slope surface to form the protective surface of the soil nail wall.

[0012] Preferably, the water collection pipe is provided with an interface pipe; after completing step 5, a temporary plug is used to temporarily seal the opening of the interface pipe.

[0013] Preferably, in step 5, after connecting the heat exchange pipe inside the pile to the water collection pipe, before pouring the cap beam concrete, a connecting pipe and joint for connecting to the heat exchange pipe of the anchor body are reserved on the water collection pipe, and the anchor body and waist beam are constructed.

[0014] Preferably, the construction of the anchor body and the waist beam specifically includes: Step 51, drilling holes for the energy anchor bolts, with the heat exchange pipes of the anchor body being installed obliquely inside the energy anchor bolt holes along with the construction of the energy anchor bolts; Step 52, grouting the energy anchor bolt holes; Step 53, after the grout strength in the energy anchor bolt holes reaches the required level, installing the waist beam on the energy support piles; Step 54, applying prestress to the energy anchor bolts and locking the prestress.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] The energy support pile system of this invention not only provides support during deep foundation pit excavation but also functions as an underground heat exchanger for building air conditioning and heating systems after backfilling. While ensuring the traditional functions of the support system, it fully explores and develops its value potential, thus achieving "one pile, two uses, turning waste into treasure." This invention can significantly reduce the overall cost and construction difficulty of energy piles while ensuring the construction efficiency and quality of the heat exchange pipe system, promoting the further dissemination and application of this technology.

[0017] This invention proposes a deep foundation pit support method using a soil nailing wall with high slope and composite energy pile anchors. The upper soil nailing wall serves as both the top soil support structure and reduces the cost of pile anchor support. At the same time, it ensures that the energy support pile anchors are located deep within the natural ground surface, eliminating the influence of the surface temperature variation layer on the heat exchange pipeline.

[0018] The heat exchange pipe inside the support pile of this invention can be W-shaped and laid inside the pile foundation reinforcement cage on the side close to the soil. PVC protective pipes are installed at the inlet and outlet to prevent damage to the heat exchange pipe during pile head cleaning. At the same time, the anchor solid heat exchange pipe is installed in the anchor bolt hole along with the steel strand, forming a primary loop together with the energy support pile, expanding the scale of the underground heat exchange pipe and improving the overall heat exchange capacity.

[0019] Multiple energy support piles and energy anchors are connected in parallel within the water collection / distribution pipeline inside the capping beam. Inlet / outlet pipes are pre-installed for connection to the heat pump unit and HVAC system, thus achieving modular encapsulation and ensuring the entire pipeline is protected from damage during construction and operation. Drilling to a certain depth below the pile bottom allows grout to penetrate, split, and compact the soil at the pile bottom and sides, increasing pile end resistance and side friction, thereby improving pile bearing capacity and reducing pile settlement. Attached Figure Description

[0020] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a front view of the energy support pile system of the present invention;

[0022] Figure 2 This is a front view of the energy support pile system of the present invention;

[0023] Figure 3 This is a top view of the energy support pile system of the present invention;

[0024] Figure 4 This is a side view of the energy support pile system of the present invention;

[0025] Figure 5 This is a front view of the internal support structure and heat exchange pipe circuit of the energy support pile system of the present invention.

[0026] Figure 6 This is a front view of the internal support structure and heat exchange pipe circuit of the energy support pile system of the present invention.

[0027] Figure 7 This is a top view of the internal support structure and heat exchange pipe circuit of the energy support pile system of the present invention.

[0028] Figure 8 This is a side view of the internal support structure and heat exchange pipe circuit of the energy support pile system of the present invention.

[0029] Figure 9 This is a front view of the heat exchanger pipe circuit in the energy support pile system of the present invention;

[0030] Figure 10 This is a front view of the heat exchanger pipe circuit in the energy support pile system of the present invention;

[0031] Figure 11This is a top view of the heat exchanger pipe circuit in the energy support pile system of the present invention;

[0032] Figure 12 This is a side view of the heat exchange pipe circuit in the energy support pile system of the present invention.

[0033] Among them, 1. facing, 2. soil nail, 3. cross-sectional steel mesh, 4. capping beam, 5. capping beam steel cage, 6. energy support pile, 7. ordinary support pile, 8. pile foundation steel cage, 9. waist beam, 10. energy anchor, 11. anchor, 12. anchor body heat exchange pipe, 13. elbow joint, 14. connecting pipe, 15. reserved joint, 16. reserved connecting pipe, 17. pile heat exchange pipe, 18. U-shaped joint, 19. energy pile connecting pipe, 20. PVC protective pipe, 21. sealing sleeve, 22. water collection pipe, 23. tee joint, 24. interface pipe, 25. temporary plug. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] like Figures 1-12 As shown, the present invention discloses an energy support pile system, comprising: multiple energy support piles 6, each energy support pile 6 having an internal heat exchange pipe 17, and a pile foundation reinforcement cage 8 having a pile side and a pile end; a capping beam 4, which is fixedly connected to the multiple energy support piles 6; wherein, a water collection pipe 22 is provided inside the capping beam 4, and an interface pipe 24 is provided on the water collection pipe 22, and the internal heat exchange pipe 17 is connected to the water collection pipe 22.

[0036] In one specific implementation, the building's air conditioning system utilizes a ground-source heat pump system for energy supply. The underground heat exchange pipeline mainly consists of a traditional ground-source heat pump and energy pile anchors. Each heat exchange unit of the energy pile anchor consists of heat exchange pipes installed in three energy support piles and four sets of energy anchor rods. The heat exchange pipes 17 inside a single energy support pile 6 are made of PE material, with an effective inner diameter of 20-35mm, preferably 32mm. They form a W-shaped series heat exchange pipeline through three 32mm inner diameter U-shaped joints 18. The total length of the buried pipes in a single pile is 84m, with the inlet and outlet pipes protruding 1.0m above the designed pile top. The heat exchange pipes inside the pile are laid on the side of the pile foundation reinforcement cage close to the soil, and can be fixed using plastic cable ties. To prevent damage to the heat exchange pipes inside the pile during pile head treatment, 40mm diameter PVC protective pipes 20 are installed at the pile head inlet and outlet positions of the heat exchange pipes inside the pile, ensuring that the middle section of the PVC pipe is flush with the designed pile top elevation. In addition, waterproof tape must be used to seal the two ends where the PVC pipe contacts the heat exchange tube 17 inside the pile to ensure that mud or concrete does not enter the gap during construction.

[0037] In one specific implementation, the capping beam 4 is equipped with inlet / outlet water collectors / distributors for the energy pile anchors. These are primarily composed of four 5m long, 80mm inner diameter PE material water collection pipes 22, welded together via two tee joints 23 and four sealing sleeves 21. The water collection pipes 22, with an inner diameter of 80mm, are connected to the inlet / outlet pipes of the heat exchange pipes 17 extending from the top of the energy pile via energy pile connecting pipes 19. Since the energy anchor rods 10 are installed after the capping beam 4 concrete is poured, joints 15 and connecting pipes 16 are pre-installed in the capping beam 4. These joints should be buried in the soil at the bottom of the capping beam 4 to avoid being encased by the poured concrete.

[0038] Specifically, the energy support pile system also includes a high-slope soil nailing wall, which includes soil nails 2, cross-sectional steel mesh 3, and a facing 1; the soil nails 2 are fixedly connected to the cross-sectional steel mesh 3, the facing 1 is attached to the cross-sectional steel mesh 3, and the soil nails 2 and the facing 1 are set perpendicular to each other; the soil nails 2 have an inclination angle of 5~20° in the horizontal plane.

[0039] The high-slope soil nailing wall of this invention has two main functions: first, to support the upper soil; and second, to eliminate the influence of the temperature-changing soil layer on the heat exchange efficiency of the energy pile anchors. Soil nailing walls are simple, quick, and low-cost to construct, making them suitable for foundation pit support with depths below 12m. Therefore, in this invention, soil nailing walls are used to support the upper soil layer. Furthermore, since the ground temperature is a temperature-changing layer within 6-10m, it is greatly affected by air temperature and climate, while the ground temperature remains stable year-round up to 200m, representing the depth range for shallow geothermal development. Therefore, the height of the soil nailing wall in this technical solution should not be less than 6.0m to ensure that all energy support pile anchor heat exchangers can operate below the temperature-changing layer, thereby improving heat exchange efficiency. In the soil nailing wall support, the soil nails (2) are generally steel bars with a diameter of 20-35mm, a horizontal inclination angle of 5-20°, and a horizontal and vertical spacing of 1.0-2.0m in cross-section. After the soil nail 2 is inserted into the borehole, it is reinforced with ordinary silicate cement grout. After the soil nail is constructed, it should form a good connection with the cross-sectional steel mesh 3. The cross-sectional steel mesh 3 can use steel bars with a diameter of 6~10mm, and the mesh size should be 150~250mm. Reinforcing bars should be set at the connection with the soil nail 2. After the cross-sectional steel mesh 3 and soil nail 2 are constructed, shotcrete is used to form the facing 1. The surface layer thickness is generally 100~200mm, and the concrete grade should not be lower than C20.

[0040] In one specific implementation, the total excavation depth of the deep foundation pit using a soil nailing wall with high slope and composite energy pile anchors is 18m. The strata within the excavation area are mainly silty clay and sand, with relatively good geological conditions. According to calculations and relevant specifications, the soil nailing wall height is 6m. The soil nails 2 are made of 24mm diameter steel bars, arranged in the soil at a horizontal angle of 15° and a horizontal and vertical spacing of 1.5m, and reinforced with ordinary silicate cement grout. The cross-sectional steel mesh 3 is made of 8mm diameter steel bars with a mesh spacing of 200mm, laid on the surface, with 20mm diameter reinforcing bars at the connection points with the soil nails 2. The concrete facing 1 of the soil nailing wall is generally 150mm thick, with a concrete strength grade of C20, and constructed using shotcrete technology.

[0041] During the construction of the high-slope soil nailing wall, the surface soil is first excavated to a depth of 2m within the foundation pit area, with the excavation angle of the foundation pit slope being 75°. Then, soil nails 2 are drilled and driven into the slope, grout is injected into the soil nail holes, and a cross-sectional steel mesh 3 is laid on the slope surface. Reinforcing bars are then welded to the soil nails 2 and the cross-sectional steel mesh 3. Subsequently, the soil is excavated to depths of 4m and 6m, and the processes of driving soil nails, grouting reinforcement, and laying steel mesh are repeated. Finally, the slope surface is treated with shotcrete finishing 1. Once the soil nailing wall surface layer has reached the required curing time and strength, the support pile anchors can be constructed. The pile foundation reinforcement cage of the energy support pile 6 is exactly the same as that of the ordinary support pile 7. During the construction of the energy support pile, the heat exchange pipe is first laid in the pile foundation reinforcement cage 8 and pressurized to 0.8MPa. This serves two purposes: firstly, to check the airtightness of the pipeline, and secondly, to balance the external concrete pressure during concrete pouring. In addition, PVC protective pipes 20 are installed at the inlet and outlet of the heat exchange pipes of the energy support piles and at the designed pile top elevation. After the pile foundation reinforcement cage is ready, the pile position can be determined at the bottom of the soil nailing wall according to the design drawings. Then, a 1.0m diameter rotary drill bit is used to drill a hole on site, and bentonite slurry is poured into the borehole for wall protection. When the drilling depth reaches the designed depth, the drilling rig is withdrawn, a concrete pouring auxiliary device is installed at the borehole opening, and a large crawler crane is used to lift and lower the pile foundation reinforcement cage 8 (containing the pressure-holding pile internal heat exchange pipe 17). During the lowering of the pile foundation reinforcement cage 8, it is necessary to rotate and adjust the pile foundation reinforcement cage 8 so that the pile internal heat exchange pipe 17 is attached to the side close to the external soil of the foundation pit. After the pile foundation reinforcement cage 8 is lowered, before concrete pouring, the airtightness of the pile internal heat exchange pipe 17 is checked again and the pile end sediment is cleaned. Then, the concrete pouring operation is carried out through the guide pipe, thereby completing the construction of a single energy support pile 6. The same method can be used to construct other energy support piles 6 and ordinary support piles 7. After the support piles have reached their curing time, the excess soil on the pile tops is first cleared and the pile heads are repaired to the design elevation. Despite the protection of the PVC protective pipes 20, careful work must be done when chiseling away the pile heads to avoid damaging the inlet and outlet pipes of the energy support piles 6.

[0042] In some preferred embodiments, the drilling tool is used to drill to a depth of 0.3 to 0.5 m below the pile bottom soil layer, so that the grout can penetrate, split, and compact the soil at the pile bottom and on the pile side to a larger area, increasing the pile end resistance and pile side friction, thereby improving the bearing capacity of the foundation pile and reducing the settlement of the foundation pile.

[0043] After all the support pile heads are processed, a cap beam reinforcement cage 5 is constructed at the pile top. Simultaneously, a water distribution unit consisting of a sealing sleeve 21, a water collection pipe 22, a tee joint 23, and an interface pipe 24 is fixed in a suitable position within the cap beam reinforcement cage 5 and connected to the three sets of energy support piles 6 via the energy pile connecting pipe 19. Since the anchor bolt construction occurs after the cap beam concrete is completed, a pre-installed connecting pipe 16 and a pre-installed joint 15 must be installed in advance. The pre-installed joint 15 must be embedded in the soil below the cap beam 4 to avoid being encased in concrete. Once the above work is completed and the pipeline airtightness check is passed, the cap beam concrete can be poured. The interface pipe 24 must extend 10cm above the top surface of the cap beam 4 to facilitate subsequent connection to the heat pump unit pipeline.

[0044] After the strength of the capping beam 4 meets the requirements, the soil inside the foundation pit is excavated, first to 0.5m below the anchor bolt position. Then, water drilling is performed to reach the designed depth. The energy anchor bolts 10 and the anchor body heat exchange pipes 12 are then inserted into the borehole and grouting is performed. After grouting, the four sets of anchor body heat exchange pipes 12 are connected to the reserved joints 15 via connecting pipes 14, thus integrating the energy anchor bolts into the water collector / distributor inside the capping beam 4. Once the grout strength inside the anchor bolts reaches the required level, the installation of the waist beam, the application of anchor bolt prestress, the prestress locking, and further excavation of the foundation pit can be completed. During the construction of the underground structure, the energy pile anchor system only serves as traditional foundation pit support. During foundation pit backfilling and the construction of the upper HVAC system, the energy pile anchor units or other underground heat exchangers are connected to the geothermal pump unit through a horizontal pipeline system, forming an HVAC system based on the primary loop of the energy pile anchor. This enables the energy pile anchor to perform the dual functions of retaining soil support during foundation pit excavation and heat exchange during building commissioning.

[0045] Specifically, the energy support pile system also includes ordinary support piles 7, which do not have internal heat exchange pipes 17 installed. The ordinary support piles 7 are fixedly connected to the cap beam 4, and the ordinary support piles 7 and energy support piles 6 are arranged at intervals.

[0046] The concrete strength grade of the energy support piles 6 and ordinary support piles 7 is generally C30 or C40, and they can form a deep foundation pit lower soil support system together with the cap beam 4, waist beam 9, energy anchor 10, and anchorage 11. Based on the foundation pit depth and design calculations, the diameter of the energy support piles 6 and ordinary support piles 7 is generally 0.8~1.2m. To protect the heat exchange tubes inside the pile foundation reinforcement cage, the energy support piles 6 need to be constructed on-site using rotary drilling technology, while the ordinary support piles 7 can also be constructed using spiral drilling followed by reinforcement cage insertion. To reduce mutual interference during energy pile operation, the energy support piles 6 and ordinary support piles 7 are arranged alternately. The pile foundation reinforcement cage 8 inside the ordinary support piles 7 and energy support piles 6 has the same configuration, mainly serving to bear force and fix the heat exchange tubes. It is generally composed of steel bars with a diameter of about 32mm, formed by reinforcing bars and stirrups. The reinforcing bars are welded at equal intervals to the main reinforcement bars of the pile foundation reinforcement cage, and the stirrups are arranged spirally on the outside of the pile foundation reinforcement cage. To facilitate the lowering of the pile foundation reinforcement cage and protect the heat exchange pipelines, the reinforcing bars at the bottom of the pile foundation reinforcement cage are tapered to form a pile end guide section. Grinding wheels are installed on the pile side reinforcing bars to prevent direct friction between the pile foundation reinforcement cage and the borehole wall. The pile top cap beam 4 and its internal cap beam reinforcement cage 5 connect all the support piles (including energy support piles 6 and ordinary support piles 7) to make them a unified whole for shared stress. Furthermore, to reduce foundation pit deformation and distribute earth pressure, multiple layers of anchor bolt support can be installed below the pile top. The anchor bolt stress system mainly consists of a girder beam 9, energy anchor bolts 10, and anchorages 11. The girder beam 9 can be an I-beam or channel steel, and the energy anchor bolt 10 is a steel strand that is inserted into the borehole and grouted to form an anchor body. Once the anchor body has reached sufficient strength and meets the required curing time, it is tensioned using jacks and the prestress of the anchor bolts is locked through the anchorages 11.

[0047] In one specific implementation, the ordinary support piles 7 and the energy pile support piles 6 are 22m long, 1.0m in diameter, spaced 2.0m apart, and embedded 10m into the soil. A prestressed anchor rod is installed 3m below the top of the support piles. The energy anchor rod 10 uses two strands of steel wire, each 25m long. The waist beam is made of channel steel and is arranged along the entire length of the support piles. According to the design specifications, the total length of the pile foundation reinforcement cage 8 is 22.5m, and the main reinforcement consists of 14 28mm diameter HRB400 main reinforcing bars. The reinforcing bars are 20mm diameter steel bars, arranged in a ring every 1m along the pile foundation reinforcement cage. The stirrups are 8mm diameter and arranged in a 200mm spiral along the pile foundation reinforcement cage, with a density of 100mm within the top 2m of the pile foundation reinforcement cage. The cap beam 4 has a cross-sectional area of ​​1.2×0.4m (length×height), and the internal reinforcing bars are configured according to structural requirements. The main reinforcement bars of the support piles penetrate 0.35m into the cap beam.

[0048] Specifically, the energy support pile system also includes a waist beam 9 and multiple anchor bodies. The waist beam 9 is fixedly connected to multiple energy support piles 6. The waist beam 9 is arranged along the entire length of the multiple energy support piles 6. One end of the anchor body is fixedly connected to the waist beam 9.

[0049] Specifically, the energy support pile system also includes multiple anchor body heat exchange pipes 12. Each anchor body heat exchange pipe 12 includes a heat exchange section and a connecting section. The heat exchange section extends within at least a portion of the anchor body. The connecting section extends outward from the anchor body from one end of the heat exchange section near the waist beam 9. The multiple anchor body heat exchange pipes 12 are connected to the water collection pipe 22 through the connecting section.

[0050] In one specific implementation, the anchor heat exchange tube 12 is a single U-shape with an inner diameter of 32m. The length of the embedded tube in a single anchor borehole is 48m, and it is connected to the water collector / distributor system in the capping beam 4 via a bend joint 13 and a reserved connecting pipe 16. The effective total length of the unit energy pile anchor heat exchange tube connected to the water collector / distributor in the capping beam 4 is approximately 450 meters (including the connecting pipe). Multiple energy pile anchor units or other buried pipe systems can be collected through the interface pipe 24 extending from the top of the capping beam to form the underground primary loop system of the building ground source heat pump. Since the air conditioning and heating system has not been constructed during the foundation pit support, in order to avoid internal contamination of the heat exchange pipeline system during construction and to test the pipeline's airtightness, after the construction of each source pile anchor unit is completed, a certain air pressure needs to be maintained in the pipeline, and the pipeline interface needs to be temporarily sealed with a temporary plug 25. After the capping beam concrete is poured and the foundation pit is excavated, the anchor heat exchange tube 12 is integrated into the water collector / distributor system in the capping beam 4 through the connecting pipe 14, thereby forming the underground energy pile anchor loop system of the ground source heat pump system.

[0051] The working principle of the energy pile anchor heat exchange is as follows: Before backfilling the foundation pit, the energy pile anchor heat exchanger, heat pump unit system, and building indoor air conditioning are connected through the ground source heat pump horizontal pipeline system and the interface pipe 24 reserved on the top of the crown beam 4 for water inlet / outlet. In summer, the ground temperature is higher than the underground temperature. The air conditioning and heat pump system of the upper building drives the high-temperature heat transfer fluid through the interface reserved on the crown beam 4, so that the high-temperature heat transfer fluid circulates inside the energy pile anchor. During this process, due to the temperature difference between the heat transfer medium inside the pipe and the surrounding soil and rock, heat exchange between the energy pile anchor and the surrounding soil can be achieved. The temperature of the high-temperature heat transfer fluid will also drop to form a low-temperature fluid, thereby transferring the building's redundant heat to the ground to achieve a cooling effect. Conversely, in winter, the ground temperature is lower than the underground temperature. The air conditioning and heat pump system of the upper building drives the low-temperature fluid through the interface on the crown beam 4 to achieve heat exchange between the building and the soil, and the low-grade heat is converted into high-grade heat and stably input into the building interior by the heat pump unit. The heat pump unit and indoor air conditioning system are existing technologies in this field, and will not be described in detail here.

[0052] Compared with traditional buried pipes and energy piles, energy support piles have the following characteristics that deserve attention: (1) Compared with traditional ground source heat pump drilling (diameter of about 100-150mm), the diameter of general support piles can reach 0.8-1.2m. The buried pipes of large-diameter energy support piles are diverse, and various buried pipe forms such as U-shaped, spiral and W-shaped can be adopted; (2) During the operation of general energy piles, special attention needs to be paid to their mechanical response under thermo-coupling. Existing research results show that the additional stress caused by temperature change can even be greater than the internal force of the pile body under structural load. However, energy support piles do not need to support the superstructure during operation and completely act as heat exchangers. Therefore, it is not necessary to pay attention to their thermo-coupling characteristics, but the heat transfer characteristics and capacity are the focus of design. (3) Energy support piles are generally distributed along the building red line. The pile spacing, surrounding soil and basement are important factors affecting their heat transfer characteristics. (4) Foundation pit support engineering is generally designed and constructed by geotechnical companies, while energy pile technology involves multiple disciplines such as geotechnical, architecture, structure and HVAC, and therefore has certain technical difficulties. At the same time, special attention should be paid to the design and construction issues such as heat exchange pipe connection, pressure maintenance and horizontal pipeline routing during the construction of energy support piles.

[0053] Shallow geothermal energy, as a renewable energy source, boasts large reserves, wide distribution, high utilization efficiency, and low application costs. Furthermore, it is unaffected by external factors such as seasons, climate, and diurnal variations, making it a realistic and highly competitive new energy source. Unlike pressure-resistant energy piles that simultaneously bear the load of the superstructure and exchange heat, energy-supported piles embed heat exchange pipes within the piles, providing support during underground structure construction. During the building's service life, they act as underground heat exchangers for the ground source heat pump system, supplementing the primary loop system via horizontal pipelines, thus achieving "dual-purpose" operation of the support piles at different service stages. Moreover, there is no need to consider the adverse effects of thermal coupling on its bearing capacity, making the comprehensive technical and economic advantages of energy-supported piles even more pronounced.

[0054] In order to maximize the potential of the support piles and enhance the heat exchange capacity of the primary loop of the traditional ground source heat pump, it is necessary to upgrade the traditional support piles into energy support piles, so that they can act as underground heat exchangers for the ground source heat pump during the building's use phase, thereby realizing the "dual purpose" of the support piles.

[0055] This invention aims to upgrade and transform building support piles during the construction of underground structures into energy piles. Based on this, it proposes a composite energy pile anchor structure design for soil nailing walls on high slopes and a corresponding construction method. The energy support pile system of this invention not only provides support during deep foundation pit excavation but also functions as an underground heat exchanger for the building's air conditioning and heating system after backfilling. While ensuring the traditional functions of the support system, it fully explores and develops its value potential, thus achieving "one pile, two uses, turning waste into treasure." This invention can significantly reduce the overall cost and construction difficulty of energy piles while ensuring the construction efficiency and quality of the heat exchange pipe system, promoting the further dissemination and application of this technology.

[0056] Accordingly, the present invention also discloses a construction method for an energy support pile system, comprising the following steps:

[0057] Step 1: Construct the high-slope soil nailing wall;

[0058] Step 2: After the soil nailing wall has reached the required curing time and strength, the pile holes of the energy support piles are constructed on site using rotary drilling technology, and the heat exchange pipes inside the pile are laid inside the pile foundation reinforcement cage and pressurized.

[0059] Step 3: Lower the heat exchange tube inside the pile into the pile hole along with the pile foundation reinforcement cage under pressure, and rotate and adjust the pile foundation reinforcement cage so that the heat exchange tube inside the pile is attached to the soil outside the foundation pit.

[0060] Step 4: Pour the concrete for the pile body to form the energy support pile;

[0061] Step 5: Connect the heat exchange pipe inside the pile to the water collection pipe, and pour the cap beam concrete to form the cap beam.

[0062] Specifically, step 1 includes:

[0063] Step 11: Excavate the surface soil within the foundation pit area, with the excavation angle of the foundation pit slope being 70~85°;

[0064] Step 12: Drill holes and drive soil nails into the slope, and then inject grout into the soil nail holes;

[0065] Step 13: Lay a cross-sectional steel mesh on the slope surface and weld the soil nails to the cross-sectional steel mesh using reinforcing bars;

[0066] Step 14: Repeat steps 11 to 13 until the preset foundation pit depth is reached, and then perform concrete spraying treatment on the slope surface to form the protective surface of the soil nailing wall.

[0067] Specifically, the water collection pipe is equipped with an interface pipe; after completing step 5, a temporary plug is used to temporarily seal the opening of the interface pipe.

[0068] Specifically, in step 5, after connecting the heat exchange pipe inside the pile to the water collection pipe, before pouring the cap beam concrete, a connecting pipe and joint for connecting to the heat exchange pipe of the anchor body are reserved on the water collection pipe, and the anchor body and waist beam are constructed.

[0069] Specifically, the construction of the anchor body and the lintel includes:

[0070] Step 51: Drill holes for the energy anchor bolts, and install the anchor heat exchange tubes at an angle inside the energy anchor bolt holes as the energy anchor bolts are being constructed.

[0071] Step 52: Grouting is performed on the drilled holes for the energy anchor bolts;

[0072] Step 53: After the cement grout in the energy anchor hole reaches the required strength, install the waist beam on the energy support pile.

[0073] Step 54: Apply prestress to the energy anchor bolts and lock the prestress.

[0074] The foregoing description of various embodiments of the invention is provided for the purpose of description to those skilled in the art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, various alternatives and variations of the invention will be apparent to those skilled in the art to which the foregoing pertains. Therefore, while some alternative embodiments have been specifically discussed, other embodiments will be obvious or readily apparent to those skilled in the art. The invention is intended to include all alternatives, modifications, and variations of the invention already discussed herein, as well as other embodiments falling within the spirit and scope of the foregoing claims.

[0075] Although the invention has been described by way of embodiments, those skilled in the art will recognize that the invention has many variations and modifications without departing from its spirit, and it is intended that the appended claims cover such variations and modifications without departing from the spirit of the invention.

Claims

1. An energy support pile system, applied to deep foundation pit projects where the superstructure requires ground source heat pump energy supply, characterized in that, include: Multiple energy support piles, each of which is equipped with a pile foundation steel cage and an internal heat exchange pipe, wherein the internal heat exchange pipe is laid on the side of the pile foundation steel cage near the external soil of the foundation pit. The capping beam is fixedly connected to the multiple energy support piles. A water collection pipe is installed inside the capping beam, and the water collection pipe is connected to the heat exchange pipe inside the pile. A joint and a connecting pipe are reserved in the capping beam. The joint is buried in the soil at the bottom of the capping beam. The anchor heat exchange pipe is connected to the reserved joint through the connecting pipe. An interface pipe extending out of the top surface of the capping beam is provided at the top of the capping beam for connecting the ground source heat pump unit. A high-slope soil nailing wall, the height of which is not less than 6.0m, comprises soil nails, a cross-sectional steel mesh, and a facing; the soil nails are fixedly connected to the cross-sectional steel mesh, the facing is attached to the cross-sectional steel mesh, and the soil nails and the facing are set perpendicular to each other; the soil nails have an inclination angle of 5~20° in the horizontal plane.

2. The energy support pile system as described in claim 1, characterized in that, It also includes ordinary support piles, which do not have internal heat exchange pipes. The ordinary support piles are fixedly connected to the cap beam. The ordinary support piles and the energy support piles are arranged at intervals to form a heat exchange unit.

3. The energy support pile system as described in any one of claims 1 to 2, characterized in that, It also includes a waist beam and multiple anchor bodies. The waist beam is fixedly connected to the multiple energy support piles. The waist beam is arranged along the entire length of the multiple energy support piles. One end of the anchor body is fixedly connected to the waist beam.

4. The energy support pile system as described in claim 3, characterized in that, It also includes multiple anchor body heat exchange tubes, each of which includes a heat exchange section and a connecting section. The heat exchange section extends within at least a portion of the anchor body, and the connecting section extends outward from the anchor body from one end of the heat exchange section near the waist beam. The multiple anchor body heat exchange tubes are connected to the water collection pipe inside the crown beam through the connecting section.

5. The construction method of the energy support pile system as described in claim 3, comprising the following steps: Step 1: Construct the high-slope soil nailing wall; Step 2: After the soil nailing wall has reached the required curing time and strength, the pile holes of the energy support piles are constructed on site using rotary drilling technology, and the heat exchange pipes inside the pile are laid inside the pile foundation reinforcement cage and pressurized. Step 3: Lower the heat exchange tube inside the pile into the pile hole along with the pile foundation reinforcement cage under pressure, and rotate and adjust the pile foundation reinforcement cage so that the heat exchange tube inside the pile is attached to the soil outside the foundation pit. Step 4: Pour the concrete for the pile body to form the energy support pile; Step 5: Connect the heat exchange pipe inside the pile to the water collection pipe inside the capping beam, and reserve joints and connecting pipes. Pour the capping beam concrete to form the capping beam, and excavate the foundation pit soil to construct the anchor body and waist beam. Step 6: Connect the anchor body heat exchange pipe to the water collection pipe inside the crown beam through connecting pipes and joints to form a complete heat exchange unit; before backfilling the foundation pit, connect the heat exchange unit to the ground source heat pump unit through a horizontal pipeline system.

6. The construction method of the energy support pile system as described in claim 5, characterized in that, Step 1 specifically includes: Step 11: Excavate the surface soil within the foundation pit area, with the excavation angle of the foundation pit slope being 70-85°; Step 12: Drill holes and drive soil nails into the slope, and then inject grout into the soil nail holes; Step 13: Lay a cross-sectional steel mesh on the slope surface and weld the soil nails to the cross-sectional steel mesh using reinforcing bars; Step 14: Repeat steps 11 to 13 until the preset foundation pit depth is reached, and then perform concrete spraying treatment on the slope surface to form the protective surface of the soil nailing wall.

7. The construction method of the energy support pile system as described in claim 5, characterized in that, The water collection pipe is equipped with an interface pipe; after completing step 5, a temporary plug is used to temporarily seal the opening of the interface pipe.

8. The construction method of the energy support pile system as described in claim 5, characterized in that, Step 5, the construction of the anchor body and the wainscoting, specifically includes: Step 51: Drill holes for the energy anchor bolts, and install the anchor heat exchange tubes at an angle inside the energy anchor bolt holes as the energy anchor bolts are being constructed. Step 52: Grouting is performed on the drilled holes for the energy anchor bolts; Step 53: After the cement grout in the energy anchor hole reaches the required strength, install the waist beam on the energy support pile. Step 54: Apply prestress to the energy anchor bolts and lock the prestress.

Images