Inclined micro-pile energy pile thermal-mechanical response test system and test method

Abstract

The present application provides a kind of inclined micro pile energy pile thermal-mechanical response test system and test method, including micro pile energy pile, model box, load loading device, circulating temperature control device, pile top displacement testing device, data acquisition equipment and drainage system.Micro pile energy pile is inclined in model box, model box is equipped with drainage system and pore pressure gauge, can carry out saturated or unsaturated soil test;Model box is equipped with circulating temperature control device outside, heat exchange tube is transported to micro pile energy pile to realize energy pile system simulation;Micro pile energy pile in pile and pile surface are equipped with thermocouple and strain gauge, surrounding soil is buried with thermocouple, and pile top is equipped with displacement meter, and temperature, strain and displacement data can be collected by combining data acquisition system.The present application can be based on saturated or unsaturated soil, inclined axial force is applied to inclined micro pile energy pile, and the temperature stress distribution of pile body and surrounding soil temperature can be tested, which can be used for testing the thermal-mechanical response of micro pile energy pile system.

Description

Technical Field

[0001] This invention relates to the field of new energy building structure testing technology, and specifically to a thermal-mechanical response testing system and method for inclined micropile energy piles. Background Technology

[0002] An energy pile is a special type of ground-source heat pump system, a novel energy-saving technology combining geothermal energy utilization with building bearing foundations. It works by installing heat exchangers within the pile foundation, with the heat pump driving liquid within the heat exchange tubes to flow through the pile and back at a specific speed. In summer, the liquid injects heat energy into the ground during its flow, causing the liquid temperature inside the tubes to drop, thus providing cooling. In winter, the liquid extracts heat energy from the ground during its flow, causing the liquid temperature inside the tubes to rise, thus providing heating. The energy pile uses the building's underground foundation piles as the geothermal energy harvesting element, utilizing the widely distributed heat energy in the soil to provide energy for building heating / cooling and domestic heating, resulting in significant and continuous energy savings. Simultaneously, the energy pile integrates heating / cooling facilities with the building structure, eliminating the drilling costs required for similar geothermal installations and achieving economic benefits.

[0003] In recent years, micropile energy piles, as a novel application of energy piles, have attracted widespread attention from researchers both domestically and internationally. Compared to traditional energy piles, micropile energy piles have a pile diameter of less than 30cm and a larger slenderness ratio. They are often used in the form of pile groups and inclined piles for structural reinforcement and building functional applications. Compared to traditional energy piles, they offer advantages such as convenient construction and resistance to sliding and overturning. Currently, energy pile model test devices are all vertically placed, with few model test designs considering the inclined pile configuration of micropile energy piles. For micropile energy piles, due to their inclined placement in the model box, there is currently a lack of effective devices to simulate the inclined axial forces they experience. Most model test devices use dry sand to simulate the soil environment where the energy piles are located, without a drainage system, resulting in discrepancies between the simulated working conditions and actual saturated soil conditions.

[0004] Currently, no descriptions or reports of technologies similar to this invention have been found, and no similar information has been collected domestically or internationally. Summary of the Invention

[0005] To address the aforementioned shortcomings in the existing technology, this invention provides a thermal-mechanical response testing system and method for inclined micropile energy piles.

[0006] According to one aspect of the present invention, a thermo-mechanical response testing system for inclined micropile energy piles is provided, comprising: a micropile energy pile, a model box, a load loading device, a cyclic temperature control device, a pile top displacement testing device, a data acquisition device, and a drainage system; wherein:

[0007] The model box is used to simulate the soil environment. The micropile energy pile is buried in the model box at a set angle to the vertical direction, and the top of the micropile energy pile is exposed in the soil environment.

[0008] The inlet and outlet of the micro pile energy pile and the inlet and outlet of the circulating temperature control device are connected by heat exchange pipes. The heat exchange fluid of the circulating temperature control device flows out of the outlet of the circulating temperature control device and into the inlet of the micro pile energy pile. It flows from the top of the micro pile energy pile to the bottom and then back to the top. Finally, it flows back to the inlet of the circulating temperature control device through the outlet of the micro pile energy pile, forming a heat exchange cycle.

[0009] The data acquisition device is used to acquire in real time the temperature data of the soil environment, the temperature data during the heat exchange cycle, and the surface and internal temperature and stress data of the micropile energy pile.

[0010] The load loading device is used to apply a corresponding load to the micropile energy pile;

[0011] The pile top displacement testing device is used to measure the pile top displacement of the micropile energy pile;

[0012] The drainage system is connected to the model box and is used to drain the water stored in the model box.

[0013] Preferably, the model box includes: a box body with an open top formed by splicing 4 side plates and 1 bottom plate; the interior of the box body is set as soil, the bottom of the box body is laid with a sand cushion layer, a wooden stick is inserted into the soil, the bottom of the wooden stick is located on top of the sand cushion layer, and the top of the wooden stick protrudes from the soil body to simulate the soil environment.

[0014] Preferably, drainage holes are provided at a set distance from the center of the four side panels to the bottom edge; a wooden pad is laid on the bottom of the outer side of the box; limiting frames are provided on the two inner side walls of the box at a first set distance from the top and a second set distance from the bottom; and a pressure gauge is also embedded in the bottom of the box.

[0015] Preferably, the load loading device includes: a horizontal loading device and a vertical loading device; wherein:

[0016] The vertical loading device includes a loading disk and a weight, and vertical loading is performed by placing the loading disk on the top of the micro pile energy pile and placing the weight on the loading disk.

[0017] The horizontal loading device includes a nylon rope, a slider, and a weight. A horizontal load is applied to the micropile energy pile by horizontally tying one end of the nylon rope to the top of the micropile energy pile, passing the nylon rope through the slider, and tying the other end of the nylon rope to the weight.

[0018] Preferably, the circulating temperature control device includes: an electric pump, a heater, a cooler, a constant temperature water tank, and an indicator; wherein:

[0019] The electric pump is located at the bottom of the constant temperature water tank and is connected to the constant temperature water tank via an electric wire. The heat exchange fluid in the constant temperature water tank flows out from the outlet of the constant temperature water tank, flows through the micro-pile energy pile, and then flows back to the constant temperature water tank from the inlet. The heater and the cooler are used to heat and cool the heat exchange fluid, respectively. The indicator is located at the top of the constant temperature water tank and is used to display the current temperature in the constant temperature water tank and to set the temperature of the constant temperature water tank.

[0020] Preferably, the data acquisition device includes: a first thermocouple, a second thermocouple, a third thermocouple, a strain gauge, a multi-channel recorder, a strain data acquisition unit, and a computer terminal; wherein:

[0021] The first thermocouple is placed in the soil environment to obtain the temperature of the soil environment;

[0022] The second thermocouple is installed at the front end of the inlet and outlet of the micro-pile energy pile to obtain the temperature during the heat exchange cycle.

[0023] The third thermocouple and the strain gauge are installed as a set of data acquisition components on the internal main reinforcement and the corresponding external concrete of the micropile energy pile, respectively, to acquire the surface and internal temperature stress data of the micropile energy pile.

[0024] The first thermocouple, the second thermocouple, and the third thermocouple are respectively connected to the multi-channel recorder via wires, the strain gauge is connected to the strain data acquisition device via wires, and the multi-channel recorder and the strain data acquisition device are respectively connected to the computer terminal.

[0025] Preferably, the drainage system includes: a drainage pipe and a main shut-off valve; wherein:

[0026] The drainage pipe is connected to the drainage hole on the side plate of the model box, and the convergence point of the drainage pipe is connected to one end of the main stop valve.

[0027] According to another aspect of the present invention, a method for testing the thermal-mechanical response of inclined micropile energy piles is provided, comprising:

[0028] According to the test conditions, apply the corresponding load using the load loading device, inject water into the model box according to the required soil properties to form a soil environment, turn on the data acquisition equipment, and detect the pore pressure at the bottom of the model box until the pore pressure reaches the theoretical value or water overflows from the soil surface. Cover the top of the model box with a layer of plastic wrap to prevent soil moisture evaporation, and let it stand for a set time to wait for the pile stress to balance.

[0029] Turn on the power and inject heat exchange fluid into the constant temperature water tank of the circulating temperature control device until the liquid level is a set distance from the top of the constant temperature water tank. Set the temperature of the circulating temperature control device according to the test conditions and wait for the heat exchange fluid in the constant temperature water tank to reach the preset temperature.

[0030] First, turn on the multi-channel recorder and strain data acquisition device of the data acquisition equipment, then turn on the electric pump. The heat exchange fluid in the constant temperature water tank flows through the micro pile energy pile, and the flow rate of the heat exchange fluid reaches the value specified by the working condition.

[0031] When the operation ends, turn off the electric pump of the circulating temperature control device, stop the heater or cooler from working, turn on the computer terminal, check and save the data, turn off the data acquisition equipment, and drain the heat exchange fluid remaining in the constant temperature water tank.

[0032] By adopting the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art:

[0033] The present invention provides a thermo-mechanical response testing system and method for inclined micropile energy piles, belonging to a thermo-mechanical response testing technology for inclined micropile energy piles. It allows for the application of axial loads to the piles in saturated or unsaturated soil, monitoring the temperature stress changes of the inclined micropile energy piles, and testing the building reinforcement and load-bearing heat transfer effects of the micropile energy piles under the coupled action of temperature and mechanical loads. Energy piles represent a new form of geothermal energy utilization, and inclined micropiles are often used for building reinforcement. Micropile energy piles are a combination of these two methods, and this invention provides conditions for model testing of micropile energy piles.

[0034] The present invention provides a thermo-mechanical response testing system and method for inclined micropile energy piles. The micropile energy piles are embedded in the soil at an incline to simulate the position and stress conditions of the micropile energy piles during building reinforcement. The model box is equipped with a drainage system and a pore pressure gauge, allowing for testing in saturated or unsaturated soil. During use, the micropile energy piles are located below the ground surface and at a certain angle to the horizontal. The force loading device in this invention solves the problem of simulating the stress state of the micropile energy piles under inclined conditions.

[0035] The present invention provides a thermo-mechanical response test system and method for inclined micropile energy piles. The model box is equipped with a constant-temperature water tank, through which heat exchange fluid is supplied to the micropile energy piles via heat exchange pipes, thus simulating the energy pile system. The constant-temperature water tank serves to restore the initial temperature of the heat exchange fluid after heat exchange, simulating the temperature state of the heat exchange fluid before heating / cooling in actual engineering.

[0036] This invention provides a thermo-mechanical response testing system and method for inclined micropile energy piles. The micropile energy pile is equipped with thermocouples and strain gauges both inside and on its surface, with thermocouples embedded in the surrounding soil. A displacement gauge is installed at the top of the pile. Combined with a data acquisition system, temperature, strain, and displacement data can be collected. Thermocouples and strain gauges are essential sensors for collecting temperature and strain data. This invention symmetrically deploys sensors both inside and outside the energy pile, improving measurement accuracy and preventing the impact of partial sensor malfunction on the measurement results.

[0037] The thermo-mechanical response testing system and method for inclined micropile energy piles provided by this invention can apply an inclined axial force to inclined micropile energy piles based on saturated or unsaturated soil, and test the temperature stress distribution of the pile body and the temperature of the surrounding soil. This system can be used to test the thermo-mechanical response of micropile energy pile systems. The inclined loading device and temperature stress sensor of this invention work together to monitor the temperature stress changes of the micropile energy pile under stress, thereby analyzing the heat transfer and bearing characteristics of the micropile energy pile under loading. Attached Figure Description

[0038] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0039] Figure 1 This is a schematic diagram of the thermal-mechanical response test system for inclined micropile energy piles in a preferred embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram of the pile structure of a micropile energy pile in a preferred embodiment of the present invention.

[0041] Figure 3 This is a schematic diagram showing the positional relationship between the micropile energy pile test box and the pile body in a preferred embodiment of the present invention.

[0042] Figure 4 This is a schematic diagram showing the deployment location of the micro-pile energy pile sensor in a preferred embodiment of the present invention.

[0043] In the diagram, 1 is the model box, 2 is the micro-pile energy pile, 3 is the weight, 4 is the wooden stick, 5 is the loading plate, 6 is the pulley, 7 is the limiting frame, 8 is the drainage pipe, 9 is the wooden pad, 10 is the displacement gauge, 11 is the drainage hole, 12 is the orifice pressure gauge, 13 is the nut, 14 is the water inlet of the micro-pile energy pile, 15 is the water outlet of the micro-pile energy pile, 16 is the flow meter, 17 is the throttle valve, 18 is the heat exchange tube, 19 is the indicator, and 20 is the thermostat. 21 is the outlet of the water tank, 22 is the inlet of the constant temperature water tank, 23 is the electric pump, 24 is the chiller, 25 is the heater, 26 is the constant temperature water tank, 27 is the caster wheel, 28 is the multi-channel recorder, 29 is the strain data acquisition device, 30 is the computer terminal, 31 is the concrete pad, 32 is the main reinforcement, 33 is the stirrup, 34 is the soil, 35 is the bolt, 36 is the side plate, 37 is the thermocouple, 38 is the strain gauge, and 39 is the base plate. Detailed Implementation

[0044] The embodiments of the present invention are described in detail below: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0045] To address the issues that existing technologies rarely consider model test designs for inclined micropile energy piles, lack effective devices for simulating the inclined axial force they experience, and have discrepancies between simulated working conditions and actual saturated soil conditions, an embodiment of the present invention provides a thermo-mechanical response test system for inclined micropile energy piles. This system can apply an inclined axial force to the inclined micropile energy pile based on saturated or unsaturated soil, test the temperature and stress distribution of the pile body and the temperature of the surrounding soil, and can be used to test the thermo-mechanical response of the inclined micropile energy pile system.

[0046] Specifically, such as Figure 1 As shown, the inclined micropile energy pile thermal-mechanical response test system provided in this embodiment may include: a micropile energy pile, a model box, a load loading device, a cyclic temperature control device, a pile top displacement testing device, data acquisition equipment, and a drainage system; wherein:

[0047] The model box is used to simulate saturated or unsaturated soil environments. The micropile energy piles are buried in the model box at a set angle to the vertical direction, with the top of the micropile energy piles exposed in the soil environment.

[0048] The inlet and outlet of the micro pile energy pile and the inlet and outlet of the circulating temperature control device are connected by heat exchange pipes. The heat exchange liquid of the circulating temperature control device flows out of the outlet of the circulating temperature control device and into the inlet of the micro pile energy pile. It flows from the top of the micro pile energy pile to the bottom and then back to the top. It then flows back to the inlet of the circulating temperature control device through the outlet of the micro pile energy pile, forming a heat exchange cycle.

[0049] Data acquisition equipment is used to acquire real-time temperature data of the soil environment, temperature data during the heat exchange cycle, and surface and internal temperature and stress data of the micropile energy pile;

[0050] The load loading device applies an inclined axial force along the axial direction to apply a corresponding load to the micropile energy pile;

[0051] The pile top displacement testing device is used to measure the pile top displacement of micropile energy piles.

[0052] The drainage system is connected to the model box and is used to drain the water stored inside the model box.

[0053] In some preferred embodiments, the model box includes: a box body with an open top formed by splicing 4 side panels and 1 bottom panel; further, the panel material used is preferably acrylic; the interior of the box body is set as soil, the bottom of the box body is laid with a sand cushion layer, and wooden sticks are inserted into the soil body, with the bottom of the wooden sticks located on top of the sand cushion layer and the top of the wooden sticks protruding from the soil body to simulate the soil environment.

[0054] In some preferred embodiments, drainage holes are provided at a set distance from the center of the four side plates to the bottom edge; a wooden pad is laid on the bottom of the outer shell; limiting frames are provided on the two side walls inside the shell at a first set distance from the top and a second set distance from the bottom, respectively. Further, the limiting frames are preferably made of two side channel steels fixed by bolts; a pressure gauge is also embedded in the bottom of the shell.

[0055] In some preferred embodiments, the surface of the heat exchange tube is covered with a heat insulation sleeve.

[0056] In some preferred embodiments, the outer sides of the four walls of the model box are covered with heat-insulating cotton.

[0057] In some preferred embodiments, a flow meter and a throttling valve are provided in the middle section of the heat exchange pipe connected to the outlet of the circulating temperature control device; after the heat exchange liquid of the circulating temperature control device flows out from the outlet of the circulating temperature control device, it flows through the flow meter and the throttling valve and then flows into the inlet of the micro pile energy pile.

[0058] In some preferred embodiments,

[0059] The load loading device includes: a horizontal loading device and a vertical loading device; wherein:

[0060] The vertical loading device includes a loading disk and weights, and vertical loading is performed by placing the loading disk on the top of the micropile energy pile and placing weights on the loading disk.

[0061] The horizontal loading device includes a nylon rope, a slider, and a weight. A horizontal load is applied to the micropile energy pile by horizontally tying one end of the nylon rope to the top of the micropile energy pile, passing the nylon rope through the slider, and tying the other end of the nylon rope to the weight.

[0062] In some preferred embodiments, the circulating temperature control device includes: an electric pump, a heater, a cooler, a constant temperature water tank, and an indicator; wherein:

[0063] The electric pump is located at the bottom of the constant temperature water tank and is connected to the constant temperature water tank by an electric wire. The heat exchange fluid in the constant temperature water tank flows out from the outlet of the constant temperature water tank, flows through the micro-pile energy pile, and then flows back to the constant temperature water tank from the inlet. The heater and the cooler are used to heat and cool the heat exchange fluid, respectively. The indicator is located at the top of the constant temperature water tank and is used to display the current temperature in the constant temperature water tank and to set the temperature of the constant temperature water tank.

[0064] In some preferred embodiments, the circulating temperature control device further includes: casters; the casters are installed at the bottom of the constant temperature water tank.

[0065] In some preferred embodiments, the data acquisition device includes: a first thermocouple, a second thermocouple, a third thermocouple, a strain gauge, a multi-channel recorder, a strain data acquisition unit, and a computer terminal; wherein:

[0066] The first thermocouple is placed in the soil environment to obtain the temperature of the soil environment;

[0067] The second thermocouple is installed at the front end of the inlet and outlet of the micro-pile energy pile to obtain the temperature during the heat exchange cycle.

[0068] The third thermocouple and strain gauge, as a set of data acquisition components, are installed on the internal main reinforcement and the corresponding external concrete of the micropile energy pile to obtain surface and internal temperature stress data of the micropile energy pile.

[0069] The first, second, and third thermocouples are connected to the multi-channel recorder via wires, and the strain gauges are connected to the strain data acquisition unit via wires. The multi-channel recorder and the strain data acquisition unit are respectively connected to the computer terminal.

[0070] In some preferred embodiments, the drainage system includes: a drainage pipe and a main shut-off valve; wherein:

[0071] The drainage pipes are connected to the drainage holes on the side panels of the model box, and the drainage pipe confluence is connected to one end of the main stop valve. All drainage pipe connections are coated with a gap sealant.

[0072] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0073] The technical solution provided by the above-described embodiment of the present invention will be further described in detail below with reference to a preferred embodiment and the accompanying drawings.

[0074] Please also refer to Figures 1 to 4 .

[0075] The preferred embodiment provides an inclined micropile energy pile thermal-mechanical response testing system, such as... Figure 1As shown, the system includes micropile energy piles 2, a model box 1, a load loading device, a circulating temperature control device, a pile top displacement testing device, a data acquisition device, and a drainage system. The bottom of the model box 1 is covered with a 40cm thick sand cushion layer as a bearing layer. The micropile energy piles 2 are buried in the soil 33 of the model box at a 30° angle to the vertical direction. In this preferred embodiment, the micropile energy piles 2 are buried at an angle in the soil 33 to simulate the position and stress conditions of the micropile energy piles during building reinforcement. Approximately 20cm of the top of the micropile energy pile protrudes from the soil surface. A 1.5cm diameter wooden stick 4 is inserted into the soil of the model box. This stick is used to install thermocouples buried in the soil. After the thermocouples are installed on the sticks, the sticks are buried in the sand, thereby fixing the thermocouples. Thermocouples 36 are attached to the surface of the wooden stick 4 to monitor the temperature of the surrounding soil 33. The bottom of the wooden stick 4 is located on top of the sand cushion layer, and the top protrudes about 15cm from the soil. The four walls of the model box 1 are covered with aluminum foil rubber and plastic insulation cotton for heat insulation. The pile top displacement testing device uses a displacement gauge 10, which is installed on the top of the micro pile energy pile 2 to measure the pile top displacement of the micro pile energy pile 2. The inlet and outlet of the micro pile energy pile 2 are connected to the outlet 20 and inlet 21 of the constant temperature water tank of the circulating temperature control device through heat exchange tubes 18. The surface of the heat exchange tubes 18 is covered with rubber and plastic insulation sleeves for heat insulation. The middle section of the heat exchange tube connected to the outlet of the circulating temperature control device is equipped with a flow meter 16 and a throttle valve 17, which are used to monitor and regulate the flow rate, respectively. The heat exchange liquid flows out from the outlet of the circulating temperature control device, flows through the flow meter 16, the throttle valve 17 and the thermocouple 36, and then flows into the inlet 14 of the micro pile energy pile. The hydrothermal fluid flows from the top of the micro-pile energy pile to the bottom and back to the top, then flows out of the outlet 15 of the micro-pile energy pile and flows back to the circulating temperature control device via thermocouple 36. During this process, the heat exchange fluid exchanges heat with the micro-pile energy pile 2 and then with the soil 33 through the heat exchange pipe, thereby extracting / injecting heat into the soil 33. At the same time, thermocouples 36 monitor the temperature of the heat exchange fluid before it flows into the inlet 14 and outlet 15 of the micro-pile energy pile. The heat transfer rate q can be calculated according to formula (1):

[0076] q = C p vAρΔT (1)

[0077] Among them, C pρ is the specific heat capacity of the heat exchange fluid, v is the flow rate of the heat exchange fluid, A is the cross-sectional area of ​​the heat exchange tube, ρ is the density of the heat exchange fluid, and ΔT is the temperature difference between the outlet 15 and inlet 14 of the micropile energy pile. Thermocouples 36 and strain gauges 37 are installed at the midpoints of the main reinforcement bars 31 of adjacent stirrups 32 within the micropile energy pile to test the internal temperature stress changes of the pile body 2. Thermocouples 36 and strain gauges 37 are also installed on the pile surface corresponding to each sensor installation point on each main reinforcement bar 31 to test the surface temperature stress changes of the pile body 2. Thermocouples 36 and strain gauges 37 are connected to a multi-channel recorder 27 and a strain data acquisition device 28 via wires, respectively. The multi-channel recorder 27 and the strain data acquisition device 28 are connected to a computer terminal (computer) 29 to store data. A load loading device is installed at the top of the micropile energy pile, applying an inclined axial force along the axial direction to simulate the load during building reinforcement. The pile structure of the micropile energy pile 2 is as follows: Figure 2 As shown. The positional relationship between the micropile energy pile test chamber and the pile body is as follows. Figure 3 As shown. The locations of the micro-pile energy pile sensors are as follows. Figure 4 As shown.

[0078] The inclined micropile energy pile thermal-mechanical response test system provided in this preferred embodiment has a model box 1 composed of four side plates 35 and a bottom plate 38, all made of acrylic material with a thickness of 2cm, forming a box structure with an open top. Each of the four side plates 35 has a 2.5cm diameter circular drainage hole 11 located 1cm from the bottom edge. A 10cm thick wooden pad 9 is laid at the bottom of the model box 1 to ensure the model box 2 is level. Two limiting frames 7 are provided on both sides of the model box 1 at 30cm from the top and 12cm from the bottom to prevent excessive lateral displacement due to excessive soil pressure on the inner side of the side plates 35. The limiting frames 7 are composed of two side channel steels fixed by matching bolts 34 and nuts 13. A borehole pressure gauge 12 is embedded at the bottom of the model box 1. In a further preferred embodiment, a concrete pad 30 is also provided to stabilize the loading plate, ensuring full contact between the loading plate and the pile top.

[0079] The inclined micropile energy pile thermal-mechanical response test system provided in this preferred embodiment consists of a horizontal loading device and a vertical loading device. The combination of the two loading devices in different directions realizes the axial loading of the inclined micropile energy pile. The vertical loading device consists of a loading disk 5 and a weight 3. Vertical loading is performed by placing the loading disk 5 on the top of the pile and placing the weight 3 on the loading disk 5. The horizontal loading device consists of a nylon rope, a slider 6 and a weight 3. One end of the nylon rope is horizontally tied to the top of the pile, the nylon rope passes through the slider 6, and the other end is tied to the weight 3 to create a horizontal load applied to the micropile energy pile.

[0080] The inclined micropile energy pile thermal-mechanical response test system provided in this preferred embodiment has a circulating temperature control device consisting of an electric pump 22, a heater 24, a cooler 23, an indicator 19, a constant temperature water tank 25, and casters 26. The electric pump 22 is located at the bottom of the constant temperature water tank 25 and is connected to the constant temperature water tank 25 via an electric wire. It is used to drive the heat exchange fluid in the constant temperature water tank 25. The heat exchange fluid flows out from the outlet 20 of the constant temperature water tank, flows through the micropile energy pile 2, and then flows back to the constant temperature water tank 25 through the inlet 21. The heater 24 and the cooler 23 heat / cool the heat exchange fluid. The indicator 19 is located at the top of the constant temperature water tank 25 and displays the current temperature inside the constant temperature water tank 25. It is also used to set the temperature of the constant temperature water tank 25. The bottom of the constant temperature water tank 25 is equipped with casters 26, which serve as a moving device.

[0081] The preferred embodiment of the inclined micropile energy pile thermal-mechanical response test system comprises a data acquisition device consisting of a thermocouple 36, a strain gauge 37, a multi-channel recorder 27, a strain data acquisition device 28, and a computer terminal 29. The thermocouple 36 and strain gauge 37 are installed between the main reinforcement inside the micropile energy pile and the external concrete to monitor the internal and external temperature and stress of the micropile energy pile 2. The thermocouple 36 is connected to the multi-channel recorder 27 via a wire, and the strain gauge 37 is connected to the strain data acquisition device 28 via a wire. The multi-channel recorder 27 and the strain data acquisition device 28 are respectively connected to the computer terminal 29. The multi-channel recorder 27 receives and records the electrical signals from the thermocouple 36, and the strain data acquisition device 28 receives and records the electrical signals from the strain gauge 37. The computer terminal 29 is used for querying and storing data.

[0082] The inclined micropile energy pile thermal-mechanical response test system provided in this preferred embodiment has a drainage system consisting of drainage pipes 8 and a main stop valve. The drainage pipes 8 are connected to the drainage holes 11 on the side plate of the model box 1. There are a total of 4 drainage holes 11. Water stored in the model box 1 can be discharged through the bottom drainage holes 11. The drainage pipes 8 converge at one end and are connected to the main stop valve. The other end of the main stop valve is connected to the sewer, which plays a role in controlling the drainage conditions. All the joints of the drainage pipes 8 are coated with AB glue as a gap sealant to seal the gaps and prevent water leakage.

[0083] An embodiment of the present invention provides a method for testing the thermal-mechanical response of inclined micropile energy piles, the method comprising the following operations:

[0084] S1. According to the test conditions, operate the load loading device to apply the corresponding load, and inject water into the model box according to the required soil properties. Taking saturated soil as an example, turn on the data acquisition device and check the pore pressure at the bottom of the model box until the pore pressure reaches the theoretical value or water overflows from the soil surface. Cover the top of the model box with a layer of plastic wrap to prevent soil moisture evaporation, and let it stand for a set time (preferably 24 hours) to wait for the pile stress to balance.

[0085] S1. Turn on the power and inject heat exchange fluid into the constant temperature water tank of the circulating temperature control device until the liquid level is a set distance (preferably 1cm) from the top of the water tank. Set the temperature of the circulating temperature control device according to the test conditions and wait for the heat exchange fluid in the constant temperature water tank to reach the preset temperature.

[0086] S3: First, turn on the multi-channel recorder and strain data acquisition device of the data acquisition equipment, then turn on the electric pump. The heat exchange fluid in the constant temperature water tank flows through the micro pile energy pile. The flow rate of the heat exchange fluid can be adjusted to the value specified by the working condition by adjusting the throttle valve.

[0087] S4. When the working condition ends, turn off the electric pump of the circulating temperature control device, stop the heater / cooler, turn on the computer terminal (computer), check and save the data, close the recording software, turn off the data acquisition equipment, and drain the heat exchange fluid remaining in the constant temperature water tank.

[0088] It should be noted that the steps in the method provided by the present invention can be implemented using corresponding modules, devices, units, etc. in the system. Those skilled in the art can refer to the technical solution of the system to implement the steps and flow of the method. That is, the embodiments in the system can be understood as preferred examples of the method, and will not be elaborated here.

[0089] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0090] The above are merely specific embodiments of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

[0091] The inclined micropile energy pile thermo-mechanical response test system and method provided in the above embodiments of the present invention involves placing the micropile energy pile at an angle in a model box equipped with a drainage system and a borehole pressure gauge for testing saturated or unsaturated soil. An external constant-temperature water tank supplies heat exchange fluid to the micropile energy pile through heat exchange pipes, simulating the energy pile system. Thermocouples and strain gauges are installed inside and on the surface of the micropile energy pile, with thermocouples embedded in the surrounding soil. A displacement gauge is installed at the top of the pile. Combined with a data acquisition system, temperature, strain, and displacement data can be collected. The inclined micropile energy pile thermo-mechanical response test system and method provided in the above embodiments of the present invention can apply an inclined axial force to the inclined micropile energy pile based on saturated or unsaturated soil, testing the temperature and stress distribution of the pile body and the temperature of the surrounding soil, and can be used to test the thermo-mechanical response of the inclined micropile energy pile system.

[0092] Any matters not covered in the above embodiments of the present invention are well-known in the art.

[0093] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A thermo-mechanical response testing system for inclined micropile energy piles, characterized in that, include: Micropile energy piles, model boxes, load loading devices, circulating temperature control devices, pile top displacement testing devices, data acquisition equipment, and drainage systems; among which: The model box is used to simulate the soil environment. The micropile energy pile is buried in the model box at a set angle to the vertical direction, and the top of the micropile energy pile is exposed in the soil environment. The inlet and outlet of the micro pile energy pile and the inlet and outlet of the circulating temperature control device are connected by heat exchange pipes. The heat exchange fluid of the circulating temperature control device flows out of the outlet of the circulating temperature control device and into the inlet of the micro pile energy pile. It flows from the top of the micro pile energy pile to the bottom and then back to the top. Finally, it flows back to the inlet of the circulating temperature control device through the outlet of the micro pile energy pile, forming a heat exchange cycle. The data acquisition device is used to acquire in real time the temperature data of the soil environment, the temperature data during the heat exchange cycle, and the surface and internal temperature and stress data of the micropile energy pile. The load loading device is used to apply a corresponding load to the micropile energy pile; The pile top displacement testing device is used to measure the pile top displacement of the micropile energy pile; The drainage system is connected to the model box and is used to drain the water stored in the model box; The load loading device includes: a horizontal loading device and a vertical loading device; wherein: The vertical loading device includes a loading disk and a weight, and vertical loading is performed by placing the loading disk on the top of the micro pile energy pile and placing the weight on the loading disk. The horizontal loading device includes a nylon rope, a slider, and a weight. A horizontal load is applied to the micropile energy pile by horizontally tying one end of the nylon rope to the top of the micropile energy pile, passing the nylon rope through the slider, and tying the other end of the nylon rope to the weight. The data acquisition device includes: a first thermocouple, a second thermocouple, a third thermocouple, a strain gauge, a multi-channel recorder, a strain data acquisition unit, and a computer terminal; wherein: The first thermocouple is placed in the soil environment to obtain the temperature of the soil environment; The second thermocouple is installed at the front end of the inlet and outlet of the micro-pile energy pile to obtain the temperature during the heat exchange cycle. The third thermocouple and the strain gauge are installed as a set of data acquisition components on the internal main reinforcement and the corresponding external concrete of the micropile energy pile, respectively, to acquire the surface and internal temperature stress data of the micropile energy pile. The first thermocouple, the second thermocouple, and the third thermocouple are respectively connected to the multi-channel recorder via wires, the strain gauge is connected to the strain data acquisition device via wires, and the multi-channel recorder and the strain data acquisition device are respectively connected to the computer terminal.

2. The inclined micropile energy pile thermal-mechanical response test system according to claim 1, characterized in that, The model box includes: a box body with an open top, which is formed by splicing 4 side plates and 1 bottom plate; the interior of the box body is set as soil, the bottom of the box body is laid with a sand cushion layer, and wooden sticks are inserted into the soil body, with the bottom of the wooden sticks located on top of the sand cushion layer and the top of the wooden sticks protruding from the soil body, in order to simulate the soil environment.

3. The inclined micropile energy pile thermal-mechanical response test system according to claim 2, characterized in that, It also includes any one or more of the following: - Drainage holes are provided at a set distance from the bottom edge of the center of the four side panels; a wooden pad is laid on the bottom of the outer side of the box; limiting frames are provided on the two inner side walls of the box at a first set distance from the top and a second set distance from the bottom, respectively; - A perforated pressure gauge is also embedded in the bottom of the box body; - The four side panels are made of acrylic sheet material; - The limiting frame is composed of two side channel steels fixed by bolts.

4. The inclined micropile energy pile thermal-mechanical response test system according to claim 1, characterized in that, It also includes any one or more of the following: - The surface of the heat exchange tube is covered with a heat insulation sleeve; - The four outer walls of the model box are covered with heat insulation cotton; - The heat exchange tube connected to the outlet of the circulating temperature control device is equipped with a flow meter and a throttling valve in the middle section; the heat exchange fluid of the circulating temperature control device flows out from the outlet of the circulating temperature control device, flows through the flow meter and the throttling valve, and then flows into the inlet of the micro pile energy pile.

5. The inclined micropile energy pile thermal-mechanical response test system according to claim 1, characterized in that, The circulating temperature control device includes: an electric pump, a heater, a cooler, a constant temperature water tank, and an indicator; wherein: The electric pump is located at the bottom of the constant temperature water tank and is connected to the constant temperature water tank via an electric wire. The heat exchange fluid in the constant temperature water tank flows out from the outlet of the constant temperature water tank, flows through the micro-pile energy pile, and then flows back to the constant temperature water tank from the inlet. The heater and the cooler are used to heat and cool the heat exchange fluid, respectively. The indicator is located at the top of the constant temperature water tank and is used to display the current temperature in the constant temperature water tank and to set the temperature of the constant temperature water tank.

6. The inclined micropile energy pile thermal-mechanical response test system according to claim 5, characterized in that, The circulating temperature control device further includes: casters; the casters are installed at the bottom of the constant temperature water tank.

7. The inclined micropile energy pile thermal-mechanical response test system according to claim 1, characterized in that, The drainage system includes: a drainage pipe and a main shut-off valve; wherein: The drainage pipes are connected to the drainage holes on the side panel of the model box, and the drainage pipes converge at one end of the main stop valve. All connections of the drainage pipes are coated with a gap sealant.

8. A method for conducting a thermal-mechanical response test on an inclined micropile energy pile using the system described in any one of claims 1-7, characterized in that, include: According to the test conditions, apply the corresponding load using the load loading device, inject water into the model box according to the required soil properties to form a soil environment, turn on the data acquisition equipment, and detect the pore pressure at the bottom of the model box until the pore pressure reaches the theoretical value or water overflows from the soil surface. Cover the top of the model box with a layer of plastic wrap to prevent soil moisture evaporation, and let it stand for a set time to wait for the pile stress to balance. Turn on the power and inject heat exchange fluid into the constant temperature water tank of the circulating temperature control device until the liquid level is a set distance from the top of the constant temperature water tank. Set the temperature of the circulating temperature control device according to the test conditions and wait for the heat exchange fluid in the constant temperature water tank to reach the preset temperature. First, turn on the multi-channel recorder and strain data acquisition device of the data acquisition equipment, then turn on the electric pump. The heat exchange fluid in the constant temperature water tank flows through the micro pile energy pile, and the flow rate of the heat exchange fluid reaches the value specified by the working condition. When the operation ends, turn off the electric pump of the circulating temperature control device, stop the heater or cooler from working, turn on the computer terminal, check and save the data, turn off the data acquisition equipment, and drain the heat exchange fluid remaining in the constant temperature water tank.

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