W-shaped energy pile buried pipe structure suitable for cast-in-situ bored pile and construction method

Abstract

The invention discloses a W-shaped energy pile buried pipe structure suitable for a cast-in-situ bored pile and a construction method, which are suitable for the condition of large pile length and expand the application range of an energy pile. Meanwhile, according to the scheme, the exhaust device and the loop are arranged at the top elbow of the W-shaped heat exchanger, the long-term heat exchange efficiency of the energy pile group is improved, and stable operation of the system is guaranteed. In addition, the invention further provides another reasonable energy pile group spacing calculation method, and the energy pile group spacing calculation method can be used for calculating the energy pile spacing so as to obtain the optimal energy pile arrangement.

Description

Technical Field

[0001] The invention relates to the technical field of construction engineering, and in particular to a W-shaped energy pile buried pipe structure suitable for bored cast-in-place piles and a construction method. Background Art

[0002] Bored piles are a common type of pile foundation for large infrastructure, with characteristics of large pile diameter and length, prefabricated steel cage and then poured concrete. Energy piles, as an energy-saving and carbon-reducing construction technology that combines ground-source heat pumps with pile foundation buried pipes, have been increasingly widely used in recent years.

[0003] Energy piles are mainly used in prefabricated piles, and single U-shaped heat exchange tubes are mostly buried. The construction is simple, but the heat exchange efficiency is low. The W-shaped buried pipe scheme is mostly used for ground source heat pump buried pipes. There is less research on the buried pipe scheme for heat exchange tubes in energy piles, and there is no effective solution to the problem of excessive water resistance caused by gas accumulation at the top elbow.

[0004] The present invention proposes a W-shaped heat exchange tube burying scheme suitable for bored cast-in-place energy piles with large volume and high heat exchange rate, and adjusts the gas blockage problem during the operation of the energy pile group by reserving an exhaust device and an exhaust loop. Summary of the invention

[0005] In view of the technical problem that the existing W-type heat exchange tube burying scheme of bored cast-in-place energy piles has low reliability, the purpose of the present invention is to provide a W-type energy pile buried pipe structure suitable for bored cast-in-place piles, which adjusts the gas blockage problem during the operation of the energy pile group by reserving an exhaust device and an exhaust loop, thereby effectively overcoming the problems existing in the prior art.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a W-shaped energy pile buried pipe structure suitable for bored piles, which includes an exhaust device arranged at the top elbow of the W-shaped heat exchanger for discharging stagnant gas.

[0007] Furthermore, the exhaust device includes a tee, an exhaust pipeline and an exhaust circuit. The tee is arranged at the top elbow of the W-type heat exchanger, and its two ends are respectively connected to the elbows of the W-type heat exchanger, and the other end is connected to one end of the exhaust pipeline. The other end of the exhaust pipeline is connected to the exhaust circuit, and the gas accumulated at the top elbow of the W-type heat exchanger is discharged through the exhaust pipeline.

[0008] Furthermore, an exhaust valve is provided on the exhaust pipeline, and the exhaust valve can be used to control the exhaust pipeline to be opened or closed.

[0009] Furthermore, the W-shaped energy pile buried pipe structure also includes a protection component, and the protection component is respectively sleeved on the pile head part at both ends of the W-shaped heat exchanger.

[0010] Furthermore, the protection component includes a protection sleeve and thermal insulation cotton. The protection sleeve is sleeved on the top of the pile, and thermal insulation cotton is added inside the protection sleeve.

[0011] Furthermore, a tube cap is provided on the upper part of the protective sleeve and is sealed with tape.

[0012] Furthermore, the protective sleeve and the lower part of the pile top are injected with foam glue, which is sealed with tape after solidification.

[0013] In order to achieve the above object, the present invention provides a construction method for W-type energy pile pipe embedding suitable for bored cast-in-place piles, and the W-type energy pile pipe embedding method comprises the following steps:

[0014] S1: Energy pile buried pipe form selection

[0015] Select the W-type energy pile heat exchanger according to the performance, and tie the W-type energy pile heat exchanger to the main reinforcement of the steel cage with a tie;

[0016] S2: Installation of W-type energy pile exhaust device

[0017] A tee is added to the top elbow of the W-shaped heat exchanger in the energy pile, and the upper part is connected to an exhaust pipeline, so that the gas accumulated in the top elbow of the W-shaped heat exchanger can be discharged through the exhaust pipeline; at the same time, thermal insulation cotton is added inside the protective sleeve and integrally sleeved on the pile heads at both ends of the energy pile and sealed;

[0018] S3: The split energy pile prefabricated in S2 is hoisted and lowered in sections, and each section of the energy pile is connected by setting an electric fusion joint. After the connection, a pressure pump is used to inject water and pressurize the heat exchange pipeline of the energy pile and pour concrete;

[0019] S4: Based on the actual thermal conductivity parameters of the soil around the piles, the thermal conductivity coefficient of the energy piles, and the buried depth of the energy piles, calculate the relationship between the heat exchange of the energy pile group and time, and calculate the optimal energy pile arrangement spacing.

[0020] Furthermore, after pouring is completed, the heat exchange tube at the head of the energy pile is cut off and the cut section of the heat exchange tube is sealed with a hot-melt pipe cap to prevent other debris from entering the heat exchange tube.

[0021] Furthermore, the calculation of the optimal energy pile arrangement spacing includes the following steps:

[0022] S41: Heat transfer model establishment

[0023] The steps are used to establish a heat transfer model between energy pile groups and rock and soil around the piles;

[0024] S42: Data Collection

[0025] This step is used to collect data on the thermal physical parameters of the soil around the pile and the thermal conductivity of the energy pile;

[0026] Thermophysical parameters of soil around pile: measured by in-situ soil thermal response test (thermophysical test); Thermal conductivity of energy pile: measured by single pile thermal response test of energy pile;

[0027] S43: Calculation of temperature rise curves of energy pile groups and surrounding rock and soil

[0028] According to the S42 soil in-situ thermal response test + energy pile thermal response test, the thermal physical parameters of the soil and a single energy pile can be obtained. Then, the obtained thermal physical parameters are brought into the heat transfer model established in S41 for calculation, and the temperature rise curve of the energy pile group and the rock and soil around the piles can be obtained.

[0029] The W-shaped energy pile buried pipe structure and construction method applicable to bored cast-in-place piles provided by the present invention are applicable to situations where the pile length is relatively large, thus expanding the application scope of the energy piles.

[0030] At the same time, this solution is equipped with an exhaust device and a loop, which improves the long-term heat exchange efficiency of the energy pile group and ensures the stable operation of the system.

[0031] In addition, the present invention provides another reasonable method for calculating the spacing between energy pile groups, which can calculate the spacing between energy piles to obtain the optimal energy pile arrangement. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0033] Figure 1 This is a schematic diagram of the assembly of the exhaust device in the W-type energy pile buried pipe structure applicable to bored piles;

[0034] Figure 2 This is a schematic diagram of the exhaust pipe assembly in the W-type energy pile buried pipe structure applicable to bored piles;

[0035] Figure 3 This is a schematic diagram of the overall structure of the W-type energy pile buried pipe structure suitable for bored piles;

[0036] Figure 4 This is a schematic diagram of the location of the energy pile heat exchange pipe in the W-type energy pile pipe embedding method applicable to bored piles;

[0037] Figure 5 Schematic diagram of the energy pile connection structure in the W-type energy pile pipe embedding method applicable to bored cast-in-place piles;

[0038] Figure 6This is a schematic diagram of the structure of the pressure pump injecting water and pressurizing the heat exchange pipeline of the energy pile in the W-type energy pile burying method applicable to bored piles;

[0039] Figure 7 The present invention is a schematic diagram of the process of burying pipes of W-type energy piles suitable for bored cast-in-place piles.

[0040] The following is a description of the components in the accompanying drawings:

[0041] 1. W-type heat exchanger 2. Tee 3. Exhaust pipe 4. Exhaust valve 5. Exhaust circuit 6. Protective sleeve 7. Insulation cotton DETAILED DESCRIPTION

[0042] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific diagrams.

[0043] The W-type energy pile pipe embedding device suitable for bored cast-in-place piles provided by the present invention includes an exhaust device, which is used to discharge the gas accumulated at the top elbow of the W-type heat exchanger 1, and includes a tee head 2, an exhaust pipeline 3, an exhaust valve 4 and an exhaust circuit 5.

[0044] This solution adds an exhaust loop 5 on the basis of the original water inlet and return water, and the exhaust loop 5 is connected to the manifold to deal with the risk of gas accumulation at the top elbow of the W-type heat exchanger 1.

[0045] A single W-shaped energy pile has an elbow, and a tee 2 is arranged at the top elbow of the W-shaped heat exchanger 1. Its two ends are respectively connected to the elbows of the W-shaped heat exchanger 1, and the other end is connected to one end of the exhaust pipe 3. The other end of the exhaust pipe 3 is connected to the exhaust circuit 5. The gas accumulated at the top elbow of the W-shaped heat exchanger 1 is discharged through the exhaust pipe 3.

[0046] An exhaust valve 4 is provided on the exhaust pipeline 3, and the exhaust valve 4 can be used to control the exhaust pipeline 3 to be opened or closed.

[0047] Furthermore, since the pile head needs to be chiseled off and subsequent construction is carried out after the energy pile construction is completed, protective components are respectively provided at the pile heads at both ends of the W-shaped heat exchanger 1, which play the role of protecting the heat exchange tube from being damaged when the pile top is chiseled off. The protective component includes a protective sleeve 6 and a thermal insulation cotton 7.

[0048] The protective sleeve 6 is sleeved on the pile top, and a cap is provided on the upper part of the protective sleeve 6 and sealed with tape. Foam glue is injected into the protective sleeve and the lower part of the pile top, and after solidification, it is sealed with tape to effectively isolate the concrete and prevent the concrete from entering the protective sleeve during the pouring process, causing the concrete-bonded heat exchange pipe to be broken during the pile head chiseling and pulling out process. Here, the protective sleeve 6 is preferably a steel pipe to ensure its hardness and rigidity.

[0049] Since the temperature of the pile top is close to the ambient temperature, thermal insulation material needs to be set at the top of the pile. Therefore, this solution adds thermal insulation cotton inside the protective sleeve, and the thermal insulation cotton plays a role of sealing and heat preservation.

[0050] It should be noted here that the center position of the protective sleeve 6 and the thermal insulation cotton 7 structure should be set at the pile head chiseling elevation to ensure that the chiseling tool will not damage the heat exchange tube even if there is an error in the control of the pile head chiseling elevation (≤1m).

[0051] The W-type energy pile pipe embedding device suitable for bored cast-in-place piles based on the above scheme improves the long-term heat exchange efficiency of the energy pile group and ensures the stable operation of the system by equipping the exhaust device and the loop. On this basis, the scheme also provides a W-type energy pile pipe embedding method suitable for bored cast-in-place piles, which includes the following steps:

[0052] S1: Energy pile buried pipe form selection

[0053] There are five main ways to arrange the heat exchange pipes of energy piles: single U, double U, parallel double U, triple U, and W type, among which single U is more commonly used. According to the test, the heat exchange efficiency of W or double U is about 30% higher than that of single U. The bored pile has a larger diameter, and the pile concrete has better thermal conductivity than the bored filler of the ground source heat pump. Therefore, the double-row pipe arrangement in the energy pile has a better heat exchange effect.

[0054] The existing double-row piping methods include double U type and W type. The double U type has four joints at the top of the pile, and the W type has two joints. Therefore, the W type energy pile heat exchanger has better integrity and avoids joint leakage.

[0055] In large-diameter bored piles, the heat exchange pipes of the energy piles should be laid on the side close to the soil to obtain better heat exchange effect. The heat exchange pipes are tied to the main reinforcement of the steel cage with cable ties, and 0.5m should be reserved at the bottom of the pile to prevent contact with the sediment at the bottom of the pile.

[0056] S2: Installation of exhaust device for W-type energy pile

[0057] This step is used to install the exhaust device on the W-type energy pile so as to exhaust the U-shaped elbow on the top of the pile to avoid the problem of excessive water resistance.

[0058] Specifically, although the W-type buried pipe method has a better heat exchange effect, the U-shaped elbow on the top of the pile has the risk of gas collection. According to GB50366-2005 "Technical Specifications for Ground Source Heat Pump System Engineering", the flow rate in the buried pipe heat exchanger is recommended to be no less than 0.4m / s. It can be calculated that the minimum flow rate of De32 pipe at this time is 1.147m3 / h. According to the pipeline circulation test, the pressure head required to exceed this flow rate is large, and there is a large resistance to the operation of the system.

[0059] In order to eliminate the gas accumulation at the top elbow of the W-type heat exchanger when the unit is in operation, this scheme adds a tee to the top elbow of the W-type heat exchanger, and connects the exhaust pipeline to the upper part, the exhaust pipeline is connected to the exhaust circuit, the exhaust circuit is connected to the manifold, and an automatic exhaust valve is arranged on the exhaust pipeline to open and close the exhaust pipeline through the exhaust valve to remove the gas accumulated at the top elbow of the W-type heat exchanger.

[0060] The thermal insulation cotton is added inside the protective sleeve and is integrally mounted on the pile heads at both ends of the energy pile and sealed to achieve thermal insulation and effectively isolate the concrete.

[0061] The exhaust device provided by the above solution, as well as the protective sleeve and the thermal insulation cotton are prefabricated together with the energy pile and can be directly assembled at the construction site, thereby improving the construction efficiency.

[0062] S3: Energy column connection process

[0063] This step is used to install and connect the split energy pile.

[0064] When existing large-volume concrete bored piles are used as energy pile carriers, due to the large length of the piles, the steel cages are often prefabricated in sections for easy transportation and lifting.

[0065] The energy pile heat exchanger is prefabricated with the steel cage as a split type. The energy heat exchanger is set in the steel cage and the exhaust device and protection components are installed according to S2 for split connection. Thus, the heat exchanger connection and the steel cage connection are carried out simultaneously, which improves the construction efficiency. The specific connection includes the following steps:

[0066] S31: Firstly, one section of the split steel cage is hoisted and lowered, and then another section of the split steel cage is hoisted and lowered, and the upper and lower sections of heat exchange tubes are connected by setting electric fusion joints at the heat exchangers corresponding to the two steel cages.

[0067] S32: After the connection is completed, use a pressure pump to inject water and pressurize the energy pile heat exchange pipeline.

[0068] Before pouring concrete, the water pressure inside the heat exchange tube needs to be maintained. This solution uses a pressure pump to inject water and pressurize the heat exchange pipeline of the energy pile to prevent the heat exchange tube from being damaged or deformed due to the pressure of concrete pouring.

[0069] S33: After pouring is completed, the heat exchange tube at the head of the energy pile is cut off and the cut section of the heat exchange tube is sealed with a hot-melt pipe cap to prevent other debris from entering the heat exchange tube.

[0070] After the energy pile construction is completed, the pile head needs to be chiseled off and subsequent construction is carried out. In the process of chiseling off the pile head, the rock breaking tool should be prevented from penetrating the protective sleeve and damaging the energy pile heat exchanger. After the pile head is exposed, the heat exchange tube should be connected as soon as possible and the pipe cap should be hot-melted for plugging.

[0071] S4: Energy pile layout spacing

[0072] Large-volume energy piles have better heat exchange performance, and the appropriate connection method can be selected according to the actual burial depth, pile diameter and geothermal properties. The overall series connection should be avoided, and it is appropriate to select 4 to 8 energy piles in series and then connect them in parallel to the loop.

[0073] This step is used to calculate the spacing between energy pile groups to obtain the optimal energy pile arrangement. The specific calculation includes the following steps:

[0074] S41: Heat transfer model establishment

[0075] This step is used to establish a heat transfer model between the energy pile group and the rock and soil around the piles. It can be used to simulate the changes in soil temperature field under different energy pile group arrangements to obtain the optimal energy pile arrangement.

[0076] The actual heat transfer process between the energy pile group and the pile head soil is relatively complex, which is related to the energy pile diameter, burial depth, steel cage and concrete characteristics, geological characteristics around the pile, groundwater seepage, buried pipe spacing and layout method.

[0077] Assuming that the soil around the pile is an infinite heat transfer medium, the initial temperature field is uniform, the energy pile is a columnar heat transfer structure, and the groundwater seepage effect and surface heat exchange are ignored, the temperature rise curve of any point in the energy pile group can be described by step load and superposition process:

[0078]

[0079] Based on the above formula 1, a heat transfer model can be established, where Δθ a is the temperature rise at any point in the heat transfer space; n and i are the total number of energy piles and the i-th pile respectively; m and j are the total time action point and the time action point of a certain load respectively; qi,j is the heat flow per unit tube length at the j-th moment of the i-th energy pile (W / m); h and h0 are the integral differential of the heat exchange tube height and the heat exchange tube height respectively; λ s and a are the thermal conductivity and thermal diffusion coefficient of the soil medium around the pile, respectively; ri is the distance from any point to the ith energy pile (m); tm and tj-1 are the total time (s) and the time of the j-1th moment, respectively.

[0080] S42: Data Collection

[0081] The heat transfer model established in S41 (temperature rise at any point in the space between the pile group and the soil around the pile) is a set of differential equations related to multiple variables. It can calculate the temporal relationship of regional heat exchange in the energy pile group based on the actual thermal conductivity parameters of the soil around the pile, the thermal conductivity coefficient of the energy pile, and the buried depth of the energy pile to obtain the optimal energy pile arrangement. Therefore, this step is used to collect data on the thermal physical parameters of the soil around the pile and the thermal conductivity coefficient of the energy pile.

[0082] Here, the thermal physical parameters of the soil around the pile are measured by the in-situ thermal response test of the soil (thermal physical test); the thermal conductivity coefficient of the energy pile is measured by the single pile thermal response test of the energy pile.

[0083] Specifically, the thermophysical parameters of the soil (volume specific heat of soil / (J·m-3·K-1), soil thermal conductivity (J·m-3·K-1), initial soil temperature (℃)) are obtained according to the soil in-situ thermal response test (thermophysical property test)

[0084] During the energy pile design phase, the heat transfer capacity per meter (W / m) and the heat transfer power (kW) of a single pile are obtained through the energy pile thermal response test.

[0085] S43: Calculation of temperature rise curves of energy pile groups and surrounding rock and soil

[0086] Therefore, the thermal physical parameters of the soil and a single energy pile can be obtained based on the S42 soil in-situ thermal response test + the thermal response test of the energy pile. Then, the obtained thermal physical parameters are brought into the heat transfer model established in S41 for calculation, and the temperature rise curve of the energy pile group and the rock and soil around the piles can be obtained.

[0087] Based on the above-mentioned scheme, the W-shaped energy pile buried pipe structure and construction method suitable for bored cast-in-place piles are constructed. The following examples illustrate the working process in specific applications. It should be noted that the working process here is only an example and does not constitute a limitation to this scheme.

[0088] (1) Split energy pile prefabrication

[0089] The split energy pile is prefabricated at the steel cage processing site, and the heat exchange tube is fixed to the main reinforcement of the steel cage with cable ties. If necessary, thermal insulation cotton is used at the stress concentration point to protect the heat exchanger from friction damage. After fixing, the heat exchanger interface is sealed with a pipe cap.

[0090] (2) Lifting and lowering of split energy piles

[0091] Lift and lower each section of the steel cage in turn, and perform electric fusion connection on the heat exchange tube when connecting the steel cage. Avoid quality risks caused by uneven temperature or stress at the interface during connection. After checking that the joint is fused and qualified, connect the next section of the steel cage and the heat exchange tube until all the split energy piles are connected.

[0092] (3) Pressure pump water injection and pressure

[0093] When the energy pile is connected and lowered, use a pressure water pump to inject water and pressurize it. The pressure should be the pressure value of the concrete at the bottom of the pile. Check the connection quality of the energy pile joint. If the pressure drops within 15 minutes, the steel cage should be lifted and the energy pile heat exchange tube should be inspected.

[0094] (4) Energy pile casting under pressure

[0095] After confirming that the water pressure test is qualified, the energy pile is poured. Confirm that the heat exchange tube is poured under pressure. The heat exchange tube needs to maintain internal and external pressure balance to avoid damage to the heat exchange tube due to excessive concrete pressure.

[0096] (5) After pouring, the heat exchange tubes on the top of the pile are sealed

[0097] After pouring is completed, cut off the heat exchange pipe on the top of the pile, seal it with hot-melt pipe caps, and take protective measures.

[0098] The W-shaped energy pile buried pipe structure and construction method suitable for bored cast-in-place piles formed by the above scheme are suitable for situations where the pile length is relatively long, thus expanding the application scope of the energy piles.

[0099] At the same time, this solution is equipped with an exhaust device and a loop, which improves the long-term heat exchange efficiency of the energy pile group and ensures the stable operation of the system.

[0100] In addition, the present invention provides another reasonable method for calculating the spacing between energy pile groups, which can calculate the spacing between energy piles to obtain the optimal energy pile arrangement.

[0101] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A W-shaped energy pile buried pipe structure suitable for bored piles, characterized in that: It includes an exhaust device arranged at the top elbow of the W-type heat exchanger, which is used for discharging the stagnant gas.

2. A W-shaped energy pile buried pipe structure suitable for bored piles according to claim 1, characterized in that: The exhaust device includes a tee, an exhaust pipeline and an exhaust circuit. The tee is arranged at the top elbow of the W-type heat exchanger, and its two ends are respectively connected to the elbows of the W-type heat exchanger, and the other end is connected to one end of the exhaust pipeline. The other end of the exhaust pipeline is connected to the exhaust circuit, and the gas accumulated at the top elbow of the W-type heat exchanger is discharged through the exhaust pipeline.

3. A W-shaped energy pile buried pipe structure suitable for bored piles according to claim 2, characterized in that: The exhaust pipeline is provided with an exhaust valve, through which the exhaust pipeline can be controlled to be opened or closed.

4. A W-shaped energy pile buried pipe structure suitable for bored piles according to claim 1, characterized in that: The W-shaped energy pile buried pipe structure also includes a protection component, and the protection component is respectively sleeved on the pile head parts at both ends of the W-shaped heat exchanger.

5. A W-shaped energy pile buried pipe structure suitable for bored piles according to claim 4, characterized in that: The protection component comprises a protection sleeve and thermal insulation cotton. The protection sleeve is sleeved on the top of the pile, and thermal insulation cotton is added inside the protection sleeve.

6. A W-shaped energy pile buried pipe structure suitable for bored piles according to claim 5, characterized in that: A tube cap is arranged on the upper part of the protective sleeve and is sealed with an adhesive tape.

7. A W-shaped energy pile buried pipe structure suitable for bored piles according to claim 5, characterized in that: The protective sleeve and the lower part of the pile top are injected with foam glue, which is sealed with adhesive tape after solidification.

8. A construction method for W-type energy pile buried pipe suitable for bored piles, characterized in that: The W-type energy pile buried pipe construction method comprises the following steps: S1: Energy pile buried pipe form selection Select the W-type energy pile heat exchanger according to the performance, and tie the W-type energy pile heat exchanger to the main reinforcement of the steel cage with a tie; S2: Installation of W-type energy pile exhaust device A tee is added to the top elbow of the W-shaped heat exchanger in the energy pile, and the upper part is connected to an exhaust pipeline, so that the gas accumulated in the top elbow of the W-shaped heat exchanger can be discharged through the exhaust pipeline; at the same time, thermal insulation cotton is added inside the protective sleeve and integrally sleeved on the pile heads at both ends of the energy pile and sealed; S3: The split energy pile prefabricated in S2 is hoisted and lowered in sections, and each section of the energy pile is connected by setting an electric fusion joint. After the connection, a pressure pump is used to inject water and pressurize the heat exchange pipeline of the energy pile and pour concrete; S4: Based on the actual thermal conductivity parameters of the soil around the piles, the thermal conductivity coefficient of the energy piles, and the buried depth of the energy piles, calculate the relationship between the heat exchange of the energy pile group and time, and calculate the optimal energy pile arrangement spacing.

9. A construction method for W-type energy pile pipe embedding suitable for bored piles according to claim 8, characterized in that: After pouring is completed, the heat exchange tube at the head of the energy pile is cut off and the cut section of the heat exchange tube is sealed with a hot-melt pipe cap to prevent other debris from entering the heat exchange tube.

10. A construction method for W-type energy pile pipe embedding suitable for bored piles according to claim 8, characterized in that: The calculation of the optimal energy pile arrangement spacing includes the following steps: S41: Heat transfer model establishment The steps are used to establish a heat transfer model between energy pile groups and rock and soil around the piles; S42: Data Collection This step is used to collect data on the thermal physical parameters of the soil around the pile and the thermal conductivity of the energy pile; Thermophysical parameters of soil around pile: measured by in-situ soil thermal response test (thermophysical test); Thermal conductivity of energy pile: measured by single pile thermal response test of energy pile; S43: Calculation of temperature rise curves of energy pile groups and surrounding rock and soil According to the S42 soil in-situ thermal response test + energy pile thermal response test, the thermal physical parameters of the soil and a single energy pile can be obtained. Then, the obtained thermal physical parameters are brought into the heat transfer model established in S41 for calculation, and the temperature rise curve of the energy pile group and the rock and soil around the piles can be obtained.

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