While-drilling pipe-following energy pile and construction method thereof

Abstract

The invention discloses a pipe-following-while-drilling energy pile. The pipe-following-while-drilling energy pile comprises a pipe-following-while-drilling pile body, a heat accumulator, a heat transfer medium, a heat transfer medium conveying system, a valve system and a heat exchange unit; the while-drilling pipe-following pile body is a hollow cylinder, the outer side face of the while-drilling pipe-following pile body is connected with peripheral soil through a cementing material, a sealed cavity is formed by the bottom and the inner side face of the while-drilling pipe-following pile body, and a grouting guide pipe is arranged in the side wall of the while-drilling pipe-following pile body. The heat accumulator is arranged in the closed cavity of the while-drilling pipe pile body; the heat exchange unit comprises a compressor, an evaporator, a condenser, an expansion valve and a pipeline system. The heat exchange unit is configured to achieve heat exchange between heat in the pile body and heat on the user side. The heat transfer medium conveying system is configured to communicate one or more while-drilling pipe pile bodies, and a fluid channel of the while-drilling pipe pile body, the valve system, the heat exchange unit, the valve system and the while-drilling pipe pile body is formed. The invention further discloses a construction method of the pipe-following-while-drilling energy pile. The energy pile and the construction method thereof are high in construction efficiency and heat exchange efficiency.

Description

Technical Field

[0001] The present application relates to the fields of building and energy integration and geothermal utilization, and particularly relates to a follow - the - drill pipe energy pile and its construction method. Background Technique

[0002] The geothermal energy stored in geological environments such as surface water, groundwater, and soil rocks is a large - scale clean and renewable energy source. The temperature of geothermal energy is lower than the outdoor temperature in summer and higher than the outdoor temperature in winter. Through the heat exchange of the ground - source heat pump system, the purposes of winter heating and summer cooling can be achieved. However, the traditional construction process of the ground - source heat pump system of "drilling first and then burying heat - exchange pipes" has disadvantages such as high initial investment, difficult installation, low return rate, and complex system, which restricts the large - area popularization and application of geothermal energy in the fields of building heating, ventilation, and air - conditioning. The pile - embedded ground - source heat pump technology, also known as the energy pile technology, directly buries the heat - exchange pipes in the piles, greatly reducing the cost of the main additional drilling of the ground - source heat pump system. The construction process is simple and the return rate is high, which promotes the application of geothermal energy in the building field.

[0003] According to different types of piles, the pile - embedded ground - source heat pump technology can be divided into the cast - in - place pile - embedded ground - source heat pump technology and the precast pile - embedded ground - source heat pump technology. Although the cast - in - place pile - embedded ground - source heat pump technology can be applied to hard strata, has high single - pile bearing capacity and good heat - exchange effect, the mud - wall protection is prone to cause hole collapse; the disturbance caused by the vibration compaction of cast - in - place concrete is likely to cause the heat - exchange pipes to bend, deform, or even break, and there may be leakage caused by the rupture of the heat - exchange pipes and joints.

[0004] The precast pile buried pipe ground source heat pump technology can be divided into three categories: The first category is that the heat exchange pipes are located in the inner cavity of the precast pile. This type of precast pile buried pipe ground source heat pump technology relies on small-diameter PHC pipe pile foundations (300 - 600 mm) constructed by the hammering method and the jacking method. After the pile is formed, heat exchange pipes are buried in the cavity of the pipe pile and backfilled with filling materials. The heat exchange pipes under this technology are not easily damaged, the connection is convenient, and the construction speed is fast. However, the pile diameter of the pile foundation is small, the bearing capacity is not high, the embedding depth in the soil body is uneven, it is difficult to effectively embed into the rock layer, and it is difficult to be applied in hard soil layers. When constructing by the hammering or jacking method, the inner cavity of the precast pile is often filled with soil plugs, and the depth of the soil plugs varies with the type of soil layer, and the embedding depth of the pile foundation in different soil layers is uneven, resulting in unequal lengths of the heat exchange pipes and making it difficult to mass-produce. Coupled with the small inner diameter of the pile and limited dimensions of the heat exchange pipes, the construction efficiency and heat transfer efficiency are greatly reduced. The second category is that the heat exchange pipes are located in the pipe wall of the precast pile. This type of precast pile buried pipe ground source heat pump technology still relies on small-diameter PHC pipe pile foundations (300 - 600 mm) constructed by the hammering method and the jacking method. During the production process of the precast pile, the heat exchange pipes are pre-embedded in the pipe wall of the precast pile, and then follow the pile foundation to the expected depth under the construction process of the hammering or jacking method. The heat exchange pipes under this technology are not easily damaged and there is no problem of easy disturbance of the heat exchange pipes. However, the pile diameter of this type of pile foundation is small, the bearing capacity is not high, it is difficult to be applied in hard soil layers, and the precast pile generally needs to be spliced. During the splicing process, the docking of the heat exchange pipes is relatively difficult. The volume of the heat exchange pipes occupies the concrete consumption of the pipe wall of the precast pile, resulting in a decrease in the strength of the pile body. Due to the limited wall thickness of the small-diameter PHC pipe pile foundation (300 - 600 mm) and to prevent a significant decrease in the strength of the pile body, generally the designed value of the diameter of the heat exchange pipe is small, resulting in a low heat exchange rate. The third category is that the heat exchange pipes are located on the outer side wall of the precast pile. This type of precast pile buried pipe ground source heat pump technology relies on the static drilling and root planting pile. That is, during the construction process of the static drilling and root planting pile, heat exchange pipes with different layout forms are tied to the outer side wall of the precast pile, and then follow the precast pile to sink to the designed soil layer depth. Since there is a large operating space on the outer side wall of the precast pile, the heat exchange pipes can achieve a large diameter, and the connection and tying process between the heat exchange pipes is simple, and the heat exchange efficiency is high. However, when the static drilling and root planting pile with heat exchange pipes sinks in the cement soil, it is easily disturbed by the soil body and undergoes torsional deformation, cracks, and even rupture, affecting the heat exchange quality of the precast pile buried pipe ground source heat pump technology. Coupled with the fact that the tying of the heat exchange pipes occurs before the pile sinking, it seriously affects the construction efficiency of the static drilling and root planting pile.

[0005] Therefore, developing an energy pile that can be constructed efficiently, has high heat extraction efficiency, and has long durability and high reliability is an urgent issue to be solved currently. Summary of the Invention

[0006] The purpose of this application is to provide a drilling - while - casing energy pile, which can improve the construction efficiency and enable the pile body to fully exchange heat with the surrounding rock and soil mass. Through the heat - conducting medium injected between the pile body and the soil, the heat energy is stored in the heat - storage material in the pile for later use.

[0007] This application discloses a drilling - while - casing energy pile, comprising: a drilling - while - casing pile body, a heat - storage body, a heat - transfer medium, a heat - transfer medium delivery system, an intelligent control system, a valve system, and a heat - exchange unit;

[0008] The drilling - while - casing pile body is a hollow cylinder, whose outer side is connected to the surrounding soil through a cementitious material. The bottom and the inner side form a sealed closed cavity, and a grouting conduit is configured inside the side wall;

[0009] The heat - storage body is arranged in the closed cavity of the drilling - while - casing pile body;

[0010] The heat - exchange unit includes a compressor, an evaporator, a condenser, an expansion valve, and a pipeline system, and is configured to realize the heat exchange between the pile body and its surrounding soil and the heat on the user side;

[0011] The heat - transfer medium delivery system is configured to connect one or more drilling - while - casing pile bodies, and forms a fluid path of drilling - while - casing pile body - valve system - heat - exchange unit - valve system - drilling - while - casing pile body;

[0012] The intelligent control system is configured to regulate and optimize the operation of the entire drilling - while - casing energy pile.

[0013] In an optional embodiment, the ways for the intelligent control system to regulate and optimize the operation of the entire drilling - while - casing energy pile include: temperature control, demand response, and predictive maintenance.

[0014] In an optional embodiment, the heat - transfer medium delivery system is configured to connect one or more drilling - while - casing pile bodies, wherein the arrangement mode of the heat - exchange tubes of the heat - transfer medium delivery system is selected from any one of the following: arranged in the inner cavity of the drilling - while - casing pile body, embedded in its side wall, and arranged along the outer - wall of the drilling - while - casing pile body.

[0015] In an optional embodiment, the cementitious material includes a heat - conduction - enhanced grouting body injected through the grouting conduit, and the heat - conduction - enhanced grouting body is selected from any one or a combination of the following: a cement - based phase - change - material grouting body, a mineral - based grouting body, and a microbial phase - change capsule grouting body.

[0016] In an optional embodiment, the heat - storage body is selected from any one or a combination of the following: water, a shaped phase - change material, and a phase - change material.

[0017] In an alternative embodiment, the valve system includes any one of the following: a four-way valve, an electronic expansion valve, a reversible cycle system.

[0018] In an alternative embodiment, in the fluid passage of the follow-the-drill pipe pile body - valve system - heat exchange unit - valve system - follow-the-drill pipe pile body, a flow meter is further included, and the flow meter is disposed in the valve system and / or the heat exchange unit.

[0019] In an alternative embodiment, the heat exchange tubes are arranged in segments, and each segment is formed in a spiral shape.

[0020] In an alternative embodiment, a support structure orthogonal to the extending direction of the heat exchange tubes is disposed inside the follow-the-drill pipe energy pile, and the support structure is connected to the heat exchange tubes and fixes and supports the heat exchange tubes.

[0021] In an alternative embodiment, the inner diameter din of the follow-the-drill pipe pile body has a value range of: 400 mm ≤ din ≤ 1600 mm.

[0022] In an alternative embodiment, the thickness of the column side wall of the follow-the-drill pipe pile body is t, and the value range of t is 50 mm ≤ t ≤ 250 mm.

[0023] In an alternative embodiment, the microbial phase change capsule grouting body is prepared by first mixing a phase change material and an emulsifier to form a microemulsion, and then mixing the microemulsion with a microbial solution producing urease and a mixed solution containing a calcium source and urea.

[0024] In an alternative embodiment, a sealing material is disposed at the connection between the follow-the-drill pipe pile bodies.

[0025] In an alternative embodiment, the sealing material is a sealing gasket or a sealing coating.

[0026] This application also discloses a construction method for a follow-the-drill pipe energy pile, including the following steps:

[0027] (S1) Constructing the lower pile foundation structure;

[0028] (S2) Conducting airtightness testing and inspection;

[0029] (S3) Arranging the heat storage body and the heat exchange tubes;

[0030] (S4) Constructing the upper pile foundation structure and arranging the heat transfer medium conveying system;

[0031] (S5) Installing the valve system, the heat exchange unit and the user-side equipment;

[0032] (S6) Commissioning and operation.

[0033] In an alternative embodiment, step (S1) specifically further includes the following steps:

[0034] (S1-1) Connect the telescopic drill bit to the auger stem;

[0035] (S1-2) Extend the auger stem together with the drill bit through the prefabricated hollow internal cavity;

[0036] (S1-3) Lift the auger stem, telescopic drill bit, and pipe pile simultaneously and place them at the pile position. Use a ground pile clamp to hold the pipe pile to prevent it from sinking and swaying;

[0037] (S1-4) Drive the auger stem to rotate, and at the same time, open the expansion wing plates of the telescopic drill bit to drill a hole. The diameter of the drilled hole is larger than the outer diameter of the pipe pile;

[0038] (S1-5) When the telescopic drill bit drills into the soil layer to a certain depth, release the pile clamp and continue drilling. At this time, the pipe pile follows the drill bit and sinks synchronously under the action of a smaller pile sinking resistance. The soil and rock debris generated by the drilling are discharged to the ground through the internal cavity of the pipe pile and the auger stem, thus ensuring that drilling, pile sinking, and soil discharge are carried out synchronously;

[0039] (S1-6) Perform pile side grouting through the grouting conduit embedded in the side of the pipe pile; and

[0040] While performing pile side grouting, arrange heat exchange pipes in sections through the internal cavity of the pipe pile, and each section of the heat exchange pipe is provided with a spiral structure.

[0041] This application also discloses a construction method for a pipe - following energy pile while drilling, including the following steps:

[0042] (1) During the production of large - diameter (800 - 1400 mm) pipe piles, embed a grouting pipe 1 for later pile side grouting, weld a pile shoe 12 at the pile end for soil discharge during pile sinking, and arrange a head plate 5 at the pile top for pile connection;

[0043] (2) Connect the expandable - contractible drill bit 9 in the contracted state to the long auger stem 6. Subsequently, the auger stem together with the contracted drill bit extends through the inner cavity of the pipe pile 7. Use a truck crane to lift the drill stem 6, drill bit 9, and pipe - following pile body 7 simultaneously and place them at the pile position. Use a ground pile clamp to hold the pipe pile 7 to prevent it from sinking and swaying;

[0044] (3) The pipe - following drilling rig drives the auger stem 6 to rotate clockwise while the expandable - contractible drill bit 9 opens the expansion wing plates to drill a hole. The diameter of the drilled hole is 2 cm larger than the outer diameter of the pipe pile. When the drill bit drills into the soil layer about 3 m, release the pile clamp and continue drilling. At this time, the pipe pile follows the drill bit and sinks synchronously under the action of a smaller pile sinking resistance. The soil and rock debris generated by the drilling are discharged to the ground through the spiral drill stem in the inner cavity of the pipe pile, thus ensuring that drilling, pile sinking, and soil discharge are carried out synchronously;

[0045] (4) During the drilling process, if the length of a single pile is insufficient, pile splicing is required. That is, the follow - the - drill pipe pile body 2 is spliced, and the end plates between the upper and lower two pipe piles are welded 5. During the welding process, the pile - side grouting pipes need to be butt - jointed and sealed. The sealing methods include installing sealing gaskets or applying sealing coatings; to prevent slurry leakage during subsequent pile - side grouting, resulting in the failure of pile - side grouting.

[0046] (5) When the drill pipe drills to the design elevation (generally embedded 0.5 m into the rock formation), stop drilling, rotate the drill pipe counterclockwise to contract the drill bit, and then pull out the contracted drill bit and drill pipe from the inner cavity of the pipe pile. After cleaning the soil at the pile end, pour 3 - m - high bottom - sealing concrete 13 into the pile end through the pipe pile, and then insert the pipe pile into the concrete to integrate the pile end with the rock formation 11, greatly improving the pile - end resistance.

[0047] (6) There is a pile - soil gap 3 of about 10 mm between the hole wall and the outer wall of the pipe pile due to the above - mentioned construction process. Pile - side grouting needs to be carried out through the grouting pipes 1 embedded in the pipe - pile wall to form a grouting body 20, thereby filling the "pile - soil gap" and bonding the surrounding soil of the pile, thus greatly improving the frictional resistance.

[0048] (7) While carrying out pile - side grouting, heat - exchange pipes 17 are arranged in sections through the inner cavity of the follow - the - drill pipe pile (the inner cavity has a relatively large diameter, generally greater than 600 mm). Each section of the heat - exchange pipe is provided with a spiral structure 16 to improve the heat - exchange effect. The heat - exchange pipes are connected and sealed with special joints 15. An inner support 14 is arranged in the inner cavity of the pipe pile corresponding to the spiral structure and is connected to the heat - exchange pipe to bear the weight of the heat - exchange pipe and fix the heat - exchange pipe.

[0049] (8) After the installation of the heat - exchange pipes is completed, anti - corrosion treatment is required. Then, the inner cavity of the follow - the - drill pipe pile is filled with a heat - exchange fluid 21 to improve the heat - exchange efficiency. The heat - exchange pipes 17 are connected to the ground - source heat - pump system. The ground - source heat - pump system injects water from the water inlet 18 of the heat - exchange pipe. The injected water undergoes sufficient heat exchange and is discharged from the water outlet 9 for indoor temperature regulation, thereby achieving the purpose of keeping warm in winter and cool in summer.

[0050] This application has at least the following beneficial technical effects:

[0051] (1) The follow - the - drill energy pile, as an energy storage medium, stores the external heat and the heat of the underground rock and soil mass into the heat storage body in the pipe pile through the heat - conduction enhanced grouting body, achieving the purpose of energy storage.

[0052] (2) The pipe - following energy pile while drilling uses a pipe - following rig for drilling construction and the pipe pile body for self - retaining wall. The heat - exchange pipes are installed in the inner cavity of the pipe pile with a large space. Therefore, the pipe - following energy pile while drilling has no environmental pollution caused by slurry retaining wall, no damage to the heat - exchange pipes caused by hole collapse and hammering static pressure, and the operation of the heat - exchange pipes is convenient. The heat - exchange pipes can be arranged in any shape as needed.

[0053] (3) The installation of the heat - exchange pipes and the side grouting of the pipe - following energy pile while drilling can be carried out simultaneously, with high construction efficiency. The heat - exchange pipes adopt a spiral structure and are in close contact with the heat - exchange liquid, with high heat - exchange efficiency. The heat - exchange pipes are fixed by internal supports and bear their own weight. The construction process causes zero damage to the pile body, and the pipe pile skeleton structure is not corroded or damaged during operation. The heat - exchange pipes are treated with anti - corrosion, with strong durability.

[0054] (4) The pipe - following energy pile while drilling has a fast construction speed, low unit bearing capacity cost, no slurry retaining wall, energy - saving and environmental - friendly, and can be assembled for integrated construction. The pile diameter is large and can be embedded in slightly weathered rock layers, with high single - pile bearing capacity (up to more than 2000 tons), and it is applicable in both hard and soft soil masses, breaking the limitation of traditional precast energy piles with low bearing capacity and only being applicable in soft soil layers.

[0055] A large number of technical features are recorded in the description of this application, distributed in various technical solutions. If all possible combinations of technical features (i.e., technical solutions) of this application are listed, the description will be too long. To avoid this problem, each technical feature disclosed in the above - mentioned invention content of this application, each technical feature disclosed in the following embodiments and examples, and each technical feature disclosed in the drawings can be freely combined with each other to form various new technical solutions (these technical solutions should all be regarded as having been recorded in this specification), unless the combination of such technical features is technically infeasible. For example, in one example, features A + B + C are disclosed, and in another example, features A + B + D + E are disclosed. Features C and D are equivalent technical means that play the same role, and only one of them can be used technically and they cannot be used simultaneously. Feature E can be combined with feature C technically. Then, the solution of A + B + C + D should not be regarded as having been recorded because it is technically infeasible, while the solution of A + B + C + E should be regarded as having been recorded. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is the sinking pile schematic diagram of the pipe - following energy pile while drilling according to this application;

[0057] Figure 2 is the heat - exchange pipe layout schematic diagram of the pipe - following energy pile while drilling according to this application;

[0058] Description of the reference numerals:

[0059] 1- grouting conduit; 2- first drilling follow-up pipe pile body; 3- pile-soil gap; 4- grouting outlet; 5- end plate; 6- auger rod; 7- second drilling follow-up pipe pile body; 8- grouting outlet; 9- telescopic drill bit; 10- soil layer; 11- rock layer; 12- pile shoe; 13- bottom sealing concrete; 14- supporting structure; 15- special joint; 16- spiral structure; 17- heat exchange tube; 18- water inlet; 19- water outlet; 20- grouting body; 21- heat exchange fluid. DETAILED DESCRIPTION

[0060] After extensive and in-depth research, the inventors of this application have proposed a drill-and-pipe energy pile that perfectly integrates a safe and reliable energy storage system with the pile foundation system of highways and viaduct buildings, innovatively solving the problem of space limitations of energy storage systems in transportation network construction, making space utilization more intensive. Drilling-pile sinking-soil discharge are constructed simultaneously, and there is no mud discharge, which is energy-saving and environmentally friendly. The borehole diameter is about 2 cm larger than the outer diameter of the pipe pile (that is, there is a 1 cm thick pile-soil gap). After the inner cavity at the end of the pipe pile is sealed with concrete, the pile end and the rock layer are integrated, which greatly improves the pile end resistance. The grouting pipe pre-buried in the pipe wall of the pipe pile is used for pile side grouting. The slurry fills the pile-soil gap and bonds the soil around the pile, thereby greatly improving the pile side friction resistance.

[0061] The advantages of drilling and pipe energy piles include but are not limited to:

[0062] 1. The pile diameter is large and can be embedded in slightly weathered rock layers. The single pile has a high bearing capacity (up to more than 2,000 tons) and is applicable to both hard and soft soils;

[0063] 2. The diameter of the inner cavity of the pipe pile is large, and the inner cavity has enough space to install heat exchange tubes of various forms and sizes, and can be backfilled with filling materials mainly composed of construction waste to improve the heat transfer coefficient;

[0064] 3. Fast construction speed, low unit bearing capacity cost, no mud wall protection, energy saving and environmental protection, and integrated assembly construction; the drilling and pipe piles adopt non-soil squeezing construction technology, and there is no soil plugging effect.

[0065] In the following description, many technical details are provided to help readers better understand the present application. However, those skilled in the art can understand that the technical solution claimed in the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0066] the term

[0067] As used herein, "energy pile", "pipe-following energy pile" and "pipe-following energy pile while drilling" can be used interchangeably, and all refer to the pipe-following energy pile while drilling of the present application.

[0068] The following briefly describes some innovative points of the embodiments of the present application:

[0069] The drill - pipe - following energy pile

[0070] The energy pile of the present application includes a drill - pipe - following pile body, a heat storage body, a heat transfer medium, a heat transfer medium delivery system, a valve system, and a heat exchange unit. The drill - pipe - following pile body is a large - diameter hollow cylinder, and its inner diameter d in The optional value range is 400mm ≤ d in ≤ 1600mm. Preferably, 800mm ≤ d in ≤ 1600mm. More preferably, 1000mm ≤ d in ≤ 1600mm.

[0071] The column - side wall thickness of the drill - pipe - following pile body is t, and the preferred value range of t is 50mm ≤ t ≤ 250mm; a grouting conduit is arranged inside the side wall. The grouting conduit can be an aluminum - plastic pipe with an inner diameter of 20mm and a wall thickness of 4mm.

[0072] The outer side surface of the drill - pipe - following pile body is connected to the surrounding soil through a gelling material. The gelling material includes a heat - conduction - enhanced grouting body injected through the grouting conduit. The heat - conduction - enhanced grouting body can be: a cement - based phase - change - material grouting body, a mineral - based grouting body, and a microbial phase - change - capsule grouting body, or a combination of one or more substances. In an alternative embodiment, the microbial phase - change - capsule grouting body is prepared by first mixing a phase - change material with an emulsifier to form a micro - emulsion, and then mixing the micro - emulsion with a microbial bacterial solution producing urease, and a mixed solution containing a calcium source and urea.

[0073] The bottom and the inner side surface of the drill - pipe - following pile body form a sealed closed cavity. In one embodiment, the sealing is achieved by installing a bottom seal at the bottom of the pile body.

[0074] The heat storage body is enclosed in the closed cavity of the drill - pipe - following pile body. The heat storage body can be water, a shaped phase - change material, or a phase - change material.

[0075] The heat exchange unit is configured to achieve heat exchange between the heat inside the pile and the heat in the external heat exchange unit, and includes a compressor, an evaporator, a condenser, an expansion valve, and a pipeline system. The heat transfer medium delivery system is configured to connect one or more down-the-hole casing pipes, and forms a fluid passage of down-the-hole casing pipe - valve system - heat exchange unit - valve system - down-the-hole casing pipe. The valve system may include a four-way valve. In an alternative embodiment, the arrangement of the heat exchange pipes of the heat transfer medium delivery system is selected from any of the following: arranged in the inner cavity of the down-the-hole casing pipe, embedded in its side wall, or arranged along the pipe wall on the outside of the down-the-hole casing pipe. The heat exchange pipes are arranged in sections in the pile, and each section is formed into a spiral shape. In a preferred embodiment, a support structure orthogonal to the extension direction of the heat exchange pipes is provided inside the down-the-hole energy pile, and the support structure is connected to the heat exchange pipes and fixes and supports the heat exchange pipes.

[0076] Construction method of down-the-hole energy pile

[0077] The construction method of the above energy pile is as follows: Figure 1 , Figure 2 The main components required during the construction process are shown, including: grouting conduit 1, end plate 5, down-the-hole casing pipe 7, and pile shoe 12. In an alternative embodiment, the grouting conduit 1 is buried in the side wall of the down-the-hole casing pipe for later side grouting of the pile. A pile shoe 12 is welded to the end of the down-the-hole casing pipe for soil discharge during pile sinking. In an advantageous embodiment, the pile shoe 12 is configured to direct the discharge of soil slag during pile sinking. An end plate 5 is arranged at the top of the down-the-hole casing pipe, and the end plate is used for pile connection between down-the-hole casing pipes. When pile connection is required, the end plates 5 between two down-the-hole casing pipes are welded. During the welding process, the side grouting conduits 1 of the pile need to be docked and sealed. In an advantageous embodiment, the contact part between the end plate 5 and the down-the-hole casing pipe is sealed; the pipes already arranged inside the pile are passed through the reserved holes of the end plate, and the reserved holes are sealed.

[0078] During the construction process, the auger drill rod 6 for drilling is passed through the inner cavity of the down-the-hole casing pipe, and the retractable drill bit 9 is connected to the auger drill rod 6 and can extend out of the down-the-hole casing pipe for drilling. The retractable drill bit has two states: when the retractable drill bit is in the first state, i.e., the retracted state, it retracts into the inner cavity of the down-the-hole casing pipe; when the retractable drill bit is in the second state, i.e., the working state, it extends out of the inner cavity of the down-the-hole casing pipe and opens the expansion wing plates for drilling. The diameter of the drilled hole is larger than the outer diameter of the down-the-hole casing pipe. In an advantageous embodiment, the diameter of the drilled hole is 2 cm larger than the outer diameter of the down-the-hole casing pipe.

[0079] The internal cavity of the drilling and pipe pile body is penetrated with a heat exchange tube. The heat exchange tube is arranged in sections, and each section is formed into a spiral shape to improve the heat exchange effect. The heat exchange tubes are connected and sealed with a special joint 15. In a preferred example, a support structure orthogonal to the extension direction of the heat exchange tube is arranged inside the drilling and pipe pile body, and the support structure is connected to the heat exchange tube, and fixes and supports the heat exchange tube. An internal support 14 is arranged in the internal cavity of the drilling and pipe pile body corresponding to the spiral structure, and it is connected to the heat exchange tube to bear the weight of the heat exchange tube and fix the heat exchange tube. After the installation of the heat exchange tube is completed, it needs to be treated with corrosion protection, and then the internal cavity of the drilling and pipe pile body is filled with heat exchange liquid 21 to improve the heat exchange efficiency. The heat exchange tube 17 is connected to the ground source heat pump system, and the ground source heat pump system is injected with water from the water inlet 18 of the heat exchange tube. After sufficient heat exchange, the injected water is discharged from the water outlet 9 to adjust the indoor temperature, thereby achieving the purpose of warm in winter and cool in summer.

[0080] In an optional embodiment, if Figure 1 The first drill-while-drilling pile body 2 and the second drill-while-drilling pile body 7 shown have large diameters and high bearing capacity, and the grouting conduit 1 is connected together by an end plate 5. The bottom grouting outlet 8 is a non-connecting port of the grouting conduit 1, which can be located at the bottom end of the bottom section of the drill-while-drilling pile body, or at the bottom end of a middle section of the drill-while-drilling pile body. The thermally conductive enhanced grouting body 20 passes through the grouting conduit 1 and is injected into the outside of the drill-while-drilling pile body from the bottom grouting outlet 8. The pile shoe is located at the bottom end of the bottom section of the drill-while-drilling pile body. The top cover plate is located at the top end of the top section of the drill-while-drilling pile body, and is provided with holes thereon for the grouting conduit to pass through.

[0081] In an advantageous embodiment, the main part of the heat transfer medium delivery pipeline can be arranged in the inner cavity of the while drilling pile body, or can be pre-buried in its side wall, or can be arranged along the outer wall of the pipe. The two ends of the heat transfer medium delivery pipeline are respectively connected to the two sides of the external heat exchange unit through the valve system, and the heat transfer medium is circulated in the heat transfer medium delivery pipeline by using a circulating pump, so as to realize the heat exchange between the periphery of the while drilling pile body and the heat in the external heat exchange unit.

[0082] In an advantageous embodiment, the diameter of the pile body can be greater than 800 mm, the inner wall is corrosion-resistant, and the bearing capacity can reach more than 1,000 tons, more advantageously, more than 1,500 tons. The top cover plate has corrosion-resistant properties and is provided with a hole for the heat transfer medium conveying pipe to pass through the hole.

[0083] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0084] Embodiment: Construction of drilling and pipe-based energy piles

[0085] ReferenceFigure 1 , Figure 2 , the implementation plan for the construction of the casing pipe energy pile while drilling is as follows:

[0086] (1) Select a large-diameter (for example, 1400 mm) casing pipe pile body. During the manufacturing process, embed the grouting conduit 1 in the side wall of the pile body for later side grouting of the pile.

[0087] Weld a pile shoe 12 at the pile end for soil discharge during pile sinking, and arrange a head plate 5 at the pile top for pile connection.

[0088] (2) Connect the retractable drill bit 9 in the retracted state to the long auger drill rod 6. Then, the drill rod together with the retracted drill bit extends through the inner cavity of the casing pipe pile body 7. Use a truck crane to lift the drill rod 6, the drill bit 9, and the casing pipe pile body 7 simultaneously and place them at the pile position. Use a ground pile clamp to clamp the second casing pipe pile body 7 to prevent the casing pipe pile body from sinking and swaying.

[0089] (3) The casing pipe pile body machine drives the auger drill rod 6 to rotate clockwise while the retractable drill bit 9 opens the expansion wing plates for drilling. The drilling diameter is 2 cm larger than the outer diameter of the casing pipe pile body. When the drill bit drills into the soil layer about 3 m, loosen the pile clamp and continue drilling. At this time, the casing pipe pile body sinks synchronously with the drill bit under the action of a smaller pile sinking resistance. The soil and rock debris generated by drilling are discharged to the ground through the auger drill rod in the inner cavity of the casing pipe pile body, thus ensuring that drilling, pile sinking, and soil discharge are carried out simultaneously.

[0090] (4) During the drilling process, if the single pile length is not enough, pile connection is required, that is, connect the first casing pipe pile body 2. Just weld the head plates 5 between the upper and lower casing pipe pile bodies. During the welding process, it is necessary to dock and seal the grouting conduits 1 on the pile side to prevent slurry leakage during later pile side grouting, resulting in the failure of pile side grouting.

[0091] (5) When the drill rod drills to the design elevation (generally embedded 0.5 m into the rock stratum), stop drilling, rotate the drill rod counterclockwise to make the drill bit contract, and then pull out the contracted drill bit and drill rod from the inner cavity of the casing pipe pile body.

[0092] After cleaning the soil at the pile end, pour 3 m high bottom-sealing concrete 13 into the pile end through the casing pipe pile body, and then insert the casing pipe pile body into the concrete to integrate the pile end with the rock stratum 11, greatly improving the pile end resistance;

[0093] (6) There is a pile-soil gap 3 of about 10 mm between the hole wall and the outer wall of the casing pipe pile body in the above construction process. It is necessary to carry out pile side grouting through the grouting conduits 1 embedded in the pipe wall of the casing pipe pile body to form a grouting body 20 to fill the "pile-soil gap" and bond the surrounding soil of the pile, thus greatly improving the frictional resistance.

[0094] (7) While performing pile side grouting, heat exchange pipes 17 are arranged in sections through the inner cavity of the pipe - following - drilling pile (the inner cavity has a relatively large diameter, generally greater than 600 mm). Each section of the heat exchange pipe is provided with a spiral structure 16 to improve the heat exchange effect. Special joints 15 are used to connect and seal between the heat exchange pipes. An internal support 14 is arranged in the inner cavity of the pipe - following - drilling pile corresponding to the spiral structure and is connected to the heat exchange pipe to bear the weight of the heat exchange pipe and fix the heat exchange pipe;

[0095] (8) After the installation of the heat exchange pipes is completed, anti - corrosion treatment is required. Then, the inner cavity of the pipe - following - drilling pile is filled with a heat exchange liquid 21 to improve the heat exchange efficiency. The heat exchange pipes 17 are connected to a ground - source heat pump system. The ground - source heat pump system injects water from the water inlet 18 of the heat exchange pipe. The injected water undergoes sufficient heat exchange and then is discharged from the water outlet 9 for indoor temperature regulation, thus achieving the purpose of keeping warm in winter and cool in summer.

[0096] It should be noted that in the application documents of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non - exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one" does not exclude the existence of another identical element in the process, method, article or device including the said element. In the application documents of this patent, if it is mentioned that a certain action is performed according to a certain element, it means at least performing the action according to the said element, including two cases: performing the action only according to the said element and performing the action according to the said element and other elements. Expressions such as multiple, many times, various, etc. include 2, 2 times, 2 kinds, as well as more than 2, more than 2 times, more than 2 kinds.

[0097] This specification includes combinations of various embodiments described herein. A separate reference to "an embodiment" or a specific embodiment, etc. does not necessarily refer to the same embodiment; however, unless indicated as mutually exclusive or clearly understood by those skilled in the art as mutually exclusive, these embodiments are not mutually exclusive. It should be noted that unless the context clearly indicates or requires otherwise, the word "or" is used in a non - exclusive sense in this specification.

[0098] All documents mentioned in this application are considered to be incorporated herein by reference in their entirety so as to be available as a basis for modification if necessary. In addition, it should be understood that after reading the above disclosure of this application, those skilled in the art can make various changes or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A drilling - while - casing energy pile, characterized in that, it includes: a drilling - while - casing pile body, a heat storage body, a heat transfer medium, a heat transfer medium delivery system, a valve system, and a heat exchange unit; The drilling - while - casing pile body is a hollow cylinder, whose outer side is connected to the surrounding soil through a cementitious material, and the bottom and inner side form a sealed enclosed cavity, and grouting ducts are arranged inside the side wall; The heat storage body is arranged in the enclosed cavity of the drilling - while - casing pile body; The heat exchange unit includes a compressor, an evaporator, a condenser, an expansion valve, and a pipeline system, and the heat exchange unit is configured to achieve heat exchange between the pile body and its surrounding soil and the heat on the user side; The heat transfer medium delivery system is configured to connect one or more drilling - while - casing pile bodies, and forms a fluid passage of drilling - while - casing pile body - valve system - heat exchange unit - valve system - drilling - while - casing pile body.

2. The drilling - while - casing energy pile according to claim 1, characterized in that, the heat transfer medium delivery system is configured to connect one or more drilling - while - casing pile bodies, wherein the arrangement mode of the heat exchange tubes of the heat transfer medium delivery system is selected from any one of the following: arranged in the inner cavity of the drilling - while - casing pile body, embedded in its side wall, and arranged along the pipe wall on the outer side of the drilling - while - casing pile body.

3. The drilling - while - casing energy pile according to claim 1, characterized in that, the cementitious material includes a heat - conduction - enhanced grouting body injected through the grouting duct, and the heat - conduction - enhanced grouting body is selected from any one or a combination of the following: a cement - based phase - change - material - containing grouting body, a mineral - based grouting body, and a microbial phase - change - capsule - containing grouting body.

4. The drilling - while - casing energy pile according to claim 1, characterized in that, the heat storage body is selected from any one or a combination of the following: water, a shaped phase - change material, and a phase - change material.

5. The drilling - while - casing energy pile according to claim 1, characterized in that, the valve system includes any one of the following: a four - way valve, an electronic expansion valve, and a reversible cycle system.

6. The drilling - while - casing energy pile according to claim 2, characterized in that, the heat exchange tubes are arranged in sections, and each section is formed in a spiral shape.

7. The drilling - while - casing energy pile according to claim 2 or 6, characterized in that, a support structure orthogonal to the extending direction of the heat exchange tubes is arranged inside the drilling - while - casing energy pile, and the support structure is connected to the heat exchange tubes and fixes and supports the heat exchange tubes.

8. The drilling - while - casing energy pile according to claim 1, characterized in that, The inner diameter of the drilling pile is d in The value range is: 400mm≤d in ≤1600mm.

9. The drilling - while - casing energy pile according to claim 1, characterized in that, the thickness of the column side wall of the drilling - while - casing pile body is t, and the value range of t is 50mm ≤ t ≤ 250mm.

10. The drilling - while - casing energy pile according to claim 3, characterized in that, the microbial phase - change - capsule - containing grouting body is prepared by first mixing a phase - change material and an emulsifier to form a micro - emulsion, and then mixing the micro - emulsion with a microbial bacterial solution producing urease, a mixed solution containing a calcium source and urea.

11. A construction method of a drilling - while - casing energy pile, characterized in that, it includes the following steps: (S1) Construction of the lower pile foundation structure; (S2) Sealing test and inspection; (S3) Arrangement of the heat storage body and the heat exchange tubes; (S4) Construction of the upper structure of the pile foundation and layout of the heat transfer medium conveying system; (S5) Installation of the valve system, heat exchange unit and user-side equipment; (S6) Commissioning and operation.

12. The construction method according to claim 11, characterized in that (S1) specifically further includes the following steps: (S1-1) Connect the retractable drill bit to the auger; (S1-2) Make the auger together with the drill bit extend through the internal cavity of the precast hollow; (S1-3) Lift the auger, retractable drill bit and pipe pile together and place them at the pile position, and use a ground pile clamp to clamp the pipe pile to prevent the pipe pile from sinking and shaking; (S1-4) Drive the auger to rotate, and at the same time the retractable drill bit opens the expansion wing plate to drill a hole, and the diameter of the drilled hole is larger than the outer diameter of the pipe pile; (S1-5) When the retractable drill bit drills into the soil layer to a certain depth, release the pile clamp and continue drilling. At this time, the pipe pile follows the drill bit and sinks synchronously under the action of a smaller pile sinking resistance, and the soil and rock slag generated by drilling are discharged to the ground through the internal cavity of the pipe pile and the auger, so as to ensure that drilling, pile sinking and soil discharge are carried out synchronously; (S1-6) Perform side grouting of the pile through the grouting conduit embedded on the side of the pipe pile; and While performing side grouting of the pile, heat exchange pipes are arranged in sections through the internal cavity of the pipe pile, and each section of heat exchange pipe is provided with a spiral structure.

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