UHPC (Ultra High Performance Concrete) photovoltaic pipe pile with flange plate body and construction method of UHPC photovoltaic pipe pile

Abstract

The invention relates to the technical field of photovoltaic pipe pile structure systems, and discloses a UHPC photovoltaic pipe pile with a flange plate body and a construction method thereof.The UHPC photovoltaic pipe pile comprises a columnar hollow pile body, the flange plate body is fixedly arranged outside the pile body, and the flange plate body is fixed to the pile body through a limiting device arranged on the pile body; the pile body is formed by pouring UHPC (Ultra High Performance Concrete); the flange plate body is located at the junction of the buried part and the exposed part and used for positioning and restraining cracking of a soil body. The flange plate body is used for restraining a sludge soft soil foundation or loose desert sand, the pile periphery resistance of a sludge or loose soil layer is improved, the length of the photovoltaic pipe pile can be shortened, so that the construction cost is reduced, or the capacity of resisting horizontal effects such as wind wave loads is greatly improved under the condition that the pile length is not reduced, and the construction cost is reduced. The device is suitable for photovoltaic construction in seabed or desert areas.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic pipe pile structure system and preparation thereof, and in particular to a UHPC photovoltaic pipe pile with a flange body and a construction method thereof. Background Art

[0002] At present, all photovoltaic pipe piles on the market are prestressed concrete pipe piles, which are mainly manufactured according to the national building standard design drawing 23G409 "Prestressed Concrete Pipe Piles". The most popular photovoltaic pipe pile model is PHC300Ф70, and the main material of the pipe pile is C80 concrete. However, in the long-term use of photovoltaic pipe piles, it is found that the above-mentioned ordinary pipe piles are prone to the following problems during service:

[0003] (1) The main reason is that C80 concrete needs two curing cycles to reach the design strength. The first curing cycle is 8 to 12 hours of high-temperature steam curing, and the second curing cycle is high-pressure and high-temperature curing.

[0004] (2) In most areas of Xinjiang, the soil sulfate content exceeds the standard, and ordinary concrete pipe piles are easily corroded, and their service life is difficult to reach the designed life of 25 years.

[0005] (3) When building a photovoltaic power station on the muddy surface soil of the seabed or the loose sand layer on the surface of the desert, due to the strong wind in the ocean and desert areas and the large windward surface of the photovoltaic panel, the pile body of the muddy surface soil of the seabed or the loose sand layer on the surface of the desert area will produce lateral compressive stress on the soil around the pile under the horizontal action of wind load, causing the soil structure to crack. Figure 1 shown.

[0006] In further research, the existing disclosed technologies of ultra-high performance concrete (UHPC) photovoltaic pipe piles are as follows:

[0007] Prior art 1

[0008] There is a Chinese patent with publication number CN114575335A, which provides an ultra-high performance concrete photovoltaic pipe pile, which includes a pile body, the material of the pile body is ultra-high performance concrete, and a plurality of convex rings are arranged on the outer wall of the pile body, and the plurality of convex rings are distributed along the axial direction of the pile body.

[0009] Prior art 2

[0010] The existing Chinese patent with publication number CN111364451A provides a non-reinforced ultra-high performance concrete prefabricated pipe pile and construction method. The pipe pile is a thin-walled prefabricated tubular structure and is made of ultra-high performance concrete. The specific steps are as follows: Step 1, mix the ultra-high performance concrete that meets the requirements; Step 2, use the centrifugal method to make the pipe pile; Step 3, transport to the construction, set a resonance-free hydraulic device at the upper end of the pipe pile, and use a high-frequency resonance-free hydraulic method to sink the pile.

[0011] The defects of the prior art 1 and 2 are: both are unreinforced UHPC piles, which are prone to shear failure under the action of horizontal forces. In order to improve the shear bearing capacity, the cross-sectional size must be increased;

[0012] Prior art three

[0013] The existing Chinese patent with publication number CN116497798B provides a prefabricated assembled ultra-high performance concrete large-diameter pipe pile and construction process, including a third concrete pipe, the front end of the third concrete pipe is slidably installed with a second concrete pipe, and the front end of the second concrete pipe is slidably installed with a first concrete pipe, a flange is fixedly installed between the third concrete pipe, the second concrete pipe and the first concrete pipe, nuts are slidably installed inside the flange, and the nuts are distributed in an annular shape, the reinforcement structure includes positioning components, steel bars and stirrups, the stirrups are equidistantly welded on the outer ring of the steel bars, the positioning components are slidably installed on the steel bars, the positioning components include a support device and a locking group, the locking group is fixedly installed inside the support device and the locking group is distributed in an annular shape, and the support device includes a reinforcement support plate, a hollow groove, a circular hole, a limit ring, a through groove and a guide cavity. The defects of this technology are: the pile is mainly a long pile of large diameter of UHPC, which is prefabricated in 3 sections, and each prefabricated pile stage is connected by a flange, resulting in weak soil resistance to horizontal loads;

[0014] By analyzing the above published patents, we can get:

[0015] (1) The UHPC piles in existing patents are mainly unreinforced structures (existing technologies 1 and 2) and ordinary reinforced concrete structures, and there is no prestressed reinforced concrete structure.

[0016] (2) The existing unreinforced UHPC photovoltaic piles mainly provide tensile and shear bearing capacities through the tensile strength of the UHPC itself (existing technologies 1 and 2). Calculations show that they cannot provide sufficient tensile and shear bearing capacities under the same cross-sectional form as traditional PHC piles, and the cross-sectional area must be increased, which does not achieve the effect of reducing the deadweight of the structure and reducing costs.

[0017] (3) There is no mention of photovoltaic pipe piles that are suitable for environments such as silty soft soil foundations (ocean) or desert sand. Usually, the piles are not considered without considering the effects of silty soft soil foundations (ocean) or desert sand, resulting in very long piles and high costs. The existing technologies do not involve methods for considering the bearing capacity of foundations such as silt and desert sand in the ocean and desert; and the existing technologies only consider the bearing capacity of the pile itself, without considering the interaction between the pile and the soil. Summary of the invention

[0018] In order to overcome or alleviate one or more of the above technical problems, the present invention aims to provide a UHPC photovoltaic pipe pile with a flange body and a construction method thereof.

[0019] The present invention provides the following technical solutions:

[0020] A UHPC photovoltaic pipe pile with a flange body comprises a columnar hollow pile body, a flange body is fixedly arranged outside the pile body, and the flange body is fixed to the pile body by a limiting device arranged on the pile body; the pile body is cast by UHPC; the flange body is located at the junction of the buried part and the exposed part, and is used for positioning and restraining soil cracking.

[0021] According to some embodiments, the pile body is cast using prestressed steel bars and stirrups as a skeleton; and the flange body is prepared using reinforced UHPC.

[0022] According to some embodiments, the outer diameter of the flange body is 4 times or more than the diameter of the pile body, but does not exceed the clear distance between adjacent pile bodies.

[0023] According to some embodiments, the diameter d of the pile body is 300 mm to 500 mm, and the wall thickness is 40 mm to 70 mm; the radius r of the flange body is 900 mm to 1800 mm.

[0024] According to some embodiments, the strength grade of the UHPC is RPC100-RPC120, and a volume content of 0.5%-1.2% of fine steel fiber is added; when the centrifugal method is used for production, the initial setting time is controlled at 30min-40min, and the strength after 6h steam curing is not less than 80MPa.

[0025] According to some embodiments, the prestressed steel bars are made of stress-relieving steel wire with a diameter of 5mm to 8mm, an ultimate tensile strength of 1670MPa and 1860MPa, and a tension tensile control stress of 75% of the tensile strength; the spiral stirrups are made of cold-drawn steel wire with a diameter of 5mm to 8mm and a tensile strength of not less than 600MPa.

[0026] On the other hand, the present invention also provides a construction method of the above-mentioned UHPC photovoltaic pipe pile with a flange body, which comprises the following steps:

[0027] S1: The pile body is manufactured by centrifugal method, wherein the pile body uses prestressed steel bars and stirrups as a skeleton and is manufactured by centrifugal method;

[0028] S2: Flange body prefabrication, using reinforced UHPC to prepare the flange body;

[0029] S3: On-site installation, including the following steps:

[0030] S31: Install the pile to the designed elevation by extrusion or insertion after drilling, and ensure that the limit device is not less than 1 cm into the soil;

[0031] S32: Pass the flange through the top of the pile and drop it to the surface of the soil;

[0032] S33: The gap between the flange body and the pile body is appropriately filled with epoxy resin, UHPC or underwater cement.

[0033] According to some embodiments, the method of making a pile body by the centrifugal method comprises the following steps:

[0034] S11: To make a steel cage, first straighten the prestressed steel bars and thicken the ends, then install them on a roll welding machine. The roll welding machine automatically roll welds the spiral stirrups on the prestressed steel bars according to the designed spacing, and hoists the made steel cage into an open mold;

[0035] S12: pouring and laying concrete, mixing UHPC and transporting it to the formwork location for pouring. The slump of the mixed UHPC is 40cm-50cm. The UHPC is arranged in the mold within 30min-40min.

[0036] S13: Close the mold, hoist the top mold, and tighten the nuts around the mold;

[0037] S14: Centrifugal molding, hoist the mold after mold closing onto the centrifuge, centrifugation is divided into two stages, the first stage is a slow stage, the centrifugal time is 1min~3min, the centrifugal acceleration is 0.8g~1.2g, the UHPC is evenly arranged in the mold; the second stage is a fast stage, the centrifugal time is 5min~8min, the centrifugal acceleration is 5g~8g, the UHPC is compacted;

[0038] S15: Static stop: hoist the UHPC into the steam curing tank with the lid opened and stop it. The ambient temperature during the static stop should be above 10℃ and the relative humidity should be above 60%. The static stop time should not be less than 1h.

[0039] S16: Steam curing, the heating rate should not be greater than 20℃ / h, and the constant temperature (90℃±5℃) should be maintained for 2h until the compressive strength of the specimen under the same curing conditions reaches 80MPa; then the temperature should be lowered at a rate not exceeding 25℃ / h to a temperature range where the difference between the component surface temperature and the ambient temperature is no more than 20℃. The relative humidity of the environment during the curing process should be maintained above 95%;

[0040] S17: Remove the mold to obtain the finished pile body.

[0041] According to some embodiments, prefabricating the flange body comprises the following steps:

[0042] S21: Making a steel cage, first making HRB400 steel bars into discs according to design requirements, and placing the made steel cage in the mold according to the designed position;

[0043] S22: pouring concrete, mixing UHPC and transporting it to the formwork location for pouring. The slump expansion of the mixed UHPC is not less than 550mm. Since it is self-flowing and compacted, no vibration is required;

[0044] S23: Static stop: hoist the UHPC into the open steam curing tank and stop it. The ambient temperature during the static stop should be above 10℃ and the relative humidity should be above 60%. The static stop time should not be less than 1h.

[0045] S24: Steam curing, the heating rate should not be greater than 20℃ / h, and the constant temperature (90℃±5℃) should be maintained for 2h until the compressive strength of the specimen under the same curing conditions reaches 80Mpa; then the temperature should be lowered at a rate not exceeding 25℃ / h to a temperature range where the difference between the component surface temperature and the ambient temperature is no more than 20℃. The relative humidity of the environment during the curing process should be maintained above 95%;

[0046] S25: Remove the mold to obtain the finished flange body.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1. The UHPC photovoltaic pipe pile with flange body provided by the present invention is constructed by centrifugal method. The strength can reach the design strength after one conventional steam treatment. No additional process measures such as secondary and high pressure are required. The quality of UHPC pipe piles produced by the existing production line is reliable and controllable, and the cost is not higher than that of ordinary concrete pipe piles. The excellent durability of UHPC makes the photovoltaic pipe piles maintenance-free in marine chloride salt or desert sulfate environment.

[0049] 2. The UHPC photovoltaic pipe pile with flange body provided by the present invention is different from the existing technology 3 that uses flange to connect prefabricated piles. The present invention uses flange body to constrain silty soft soil foundation (ocean) or loose desert sand to improve the pile circumference impedance of silty or loose soil layer, so that the length of photovoltaic pipe pile can be shortened to reduce construction cost or greatly improve the ability to resist horizontal effects such as wind (wave) load without reducing pile length. It is suitable for photovoltaic construction in seabed or desert areas. In addition, the flange body can also reduce seabed scouring and surface sand fixation in desert areas;

[0050] 3. The flange body and the UHPC pile body are prefabricated separately and then assembled. The position of the flange body is ensured by the limit device of the pile body and the soil is well restrained. In addition, the split structure is also very convenient for transportation and installation;

[0051] 4. UHPC piles are made by centrifugal method, and the equipment of existing common concrete pile factories can be used. However, the initial setting time of UHPC must be strictly controlled to 30-40 minutes so that the factory does not need to adjust the production line and production equipment. In order to make full use of the production equipment of existing pile factories, the existing photovoltaic piles are all constructed by centrifugal method. From adding water and stirring to centrifugal molding and autoclaving, the time is controlled at 30-40 minutes. The initial setting time of normal UHPC is more than 2 hours, so it is necessary to add 18-20kg / m 3 Alkali-free accelerator is used. This material makes the initial setting time of UHPC strictly controlled to 30min~40min, so that existing factories do not need to change the production line and can directly use existing equipment for production.

[0052] 5. UHPC piles use less concrete, thus saving resources and reducing waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A front view of a UHPC photovoltaic pipe pile with a flange body provided in an embodiment of the present invention.

[0054] Figure 2 A cross-sectional view of a UHPC photovoltaic pipe pile with a flange body provided in an embodiment of the present invention.

[0055] Figure 3 A plan view of a flange body provided in an embodiment of the present invention.

[0056] Figure 4 for Figure 3 AA cross-section diagram.

[0057] Figure 5 A plan view of the flange body reinforcement provided in an embodiment of the present invention.

[0058] Figure 6A cross-sectional view of the flange body reinforcement provided in an embodiment of the present invention.

[0059] In the figure:

[0060] 1-pile body, 2-flange body; 3-limiting device; 4-UHPC; 5-prestressed steel bars, 6-spiral stirrups. DETAILED DESCRIPTION

[0061] The present invention adopts UHPC to prepare photovoltaic pipe piles. Ultra-high performance concrete (UHPC) is a new type of cement-based composite material with the characteristics of high strength, high toughness and excellent durability. Therefore, it is an ideal material for making photovoltaic pipe piles. It has high strength and good toughness. Compared with ordinary photovoltaic pipe piles, it can greatly improve the service life of the pipe piles. The durability meets the service life requirements of harsh environments such as freeze-thaw cycles, saline-alkali, and oceans. Moreover, under the same bearing capacity, the prestressed ultra-high performance concrete (UHPC) photovoltaic pipe pile structure is lighter and thinner, which is more conducive to reducing transportation costs.

[0062] When building photovoltaic power stations on the muddy surface soil of the ocean floor or the loose surface sand layer in the desert, if the horizontal bearing capacity of the muddy surface soil of the ocean floor or the loose surface sand layer in the desert can be fully utilized, the length of the photovoltaic piles can be shortened to reduce the construction cost or significantly improve the ability to resist horizontal forces such as wind loads without reducing the pile length.

[0063] The present invention is described in detail below in conjunction with the embodiments and drawings, but it should be understood that the embodiments and drawings are only used to exemplify the present invention and do not constitute any limitation on the protection scope of the present invention. All reasonable changes and combinations within the scope of the inventive concept of the present invention fall within the protection scope of the present invention.

[0064] The present invention will be further described below in conjunction with the accompanying drawings.

[0065] Example 1

[0066] This embodiment provides a UHPC photovoltaic pipe pile with a flange body, and its structure is as follows: Figures 1-2 As shown, it includes a cylindrical hollow pile body 1 and a flange body 2 arranged at a certain height below the pile body 1. The flange body 2 is fixed to the pile body 1 through a limit device 3 (thickness 20CM) arranged on the pile body 1. The pile body 1 is fixed with prestressed steel bars 5 and spiral stirrups 6 as a skeleton and cast using UHPC4. The function of the flange body 2 is to constrain the silty soft soil foundation (ocean) or loose desert sand, increase the pile perimeter impedance of the silty or loose soil layer, so that the pile can be better stressed to reduce the pile length or increase the bearing capacity.

[0067] Flange body 2 is reinforced UHPC, with the same material and performance as the pile body;

[0068] like Figure 2-Figure 3 , the outer diameter of the pile body 1 is d, the outer diameter of the flange body 2 (d+2r) is 4 times or more of the diameter of the pile body 1, but does not exceed the clear distance between the pile bodies 1;

[0069] After the part above the soil surface is subjected to horizontal loads transmitted by wind, water flow, etc., the horizontal loads are dispersed and transmitted to the surrounding area through the friction between the flange body 2 and the soil surface. Since the contact area between the flange body 2 and the soil surface is 1125 times the contact area between the pile body and the silt (taking 1m thick silt or desert sand, 300mm diameter pipe pile, r = 900mm as an example), the stress generated by the horizontal load directly borne by the silt or desert sand is reduced by 1125 times, thereby restraining the cracking of the soil and further improving the pile periphery impedance of the silt or loose soil layer. In this way:

[0070] ① If the pile length remains unchanged, the horizontal bearing capacity of the UHPC pile with flange body 2 can be increased by 25-38%, thereby improving the ability to resist extreme environments;

[0071] ② After considering the contribution of flange body 2, the pile length can be shortened. Taking 1m thick desert sand as an example, after considering the pile side impedance of sand, the pile length can be reduced by 0.38m / pile, thereby reducing investment;

[0072] ③ The flange body 2 is made of UHPC material, which has guaranteed durability and is maintenance-free within the design life period.

[0073] The aperture error of the flange body 2 is ±2mm. To control the error, a mold is used to ensure accuracy. During installation, ensure that the flange body 2 can smoothly pass through the pile body and reach the designed position.

[0074] The main technical requirements of this embodiment are as follows:

[0075] (1) The overall diameter d of the pile body 1 is 300 mm to 500 mm, and the wall thickness is 40 mm to 70 mm. The pile body is divided into an underground part (underground part) and an exposed part (above ground part), and the length is determined according to the project requirements.

[0076] (2) Flange body 2: used to locate and restrain soil cracking, located at the junction of the buried part and the exposed part, such as Figure 3 and Figure 4 The top surface of the flange body 2 is flush with the soil surface, the radius r of the flange body is 900mm-1800mm, and it is prefabricated separately.

[0077] (3) Limiting device 3: Limiting the excessive downward displacement of flange body 2, so that flange body 2 can restrain the surface muddy or loose soil layer to improve the pile surrounding impedance of the soil. Limiting device 3 can be prefabricated together with pile body 1, and is a corbel surrounding pile body 1 and located at the designed height of pile body 1.

[0078] (4) UHPC4, strength grade RPC100~RPC120, add 0.5%~1.2% volume content of fine steel fiber, the initial setting time is strictly controlled to 30min~40min when using centrifugal method, and the strength after 6h steam curing is not less than 80MPa;

[0079] (5) The prestressed steel bar 5 is made of stress-relieving steel wire with a diameter of 5 mm to 8 mm, an ultimate tensile strength of 1670 MPa and 1860 MPa, and a tension control stress of 75% of the tensile strength;

[0080] (6) The spiral stirrup 6 is made of cold-drawn steel wire with a diameter of 5 mm to 8 mm and a tensile strength of not less than 600 MPa.

[0081] The UHPC photovoltaic pipe pile with flange body provided in this embodiment can widely replace ordinary concrete photovoltaic pipe piles and can be used in harsh environments such as freeze-thaw cycles, saline-alkali, and oceans. The excellent durability of UHPC can ensure that the pipe piles will not have quality problems within the design period. The existing pipe pile design life is 25 years. After adopting UHPC, its service life exceeds 25 years and can reach 50 years.

[0082] Example 2

[0083] This embodiment provides a construction method of the UHPC photovoltaic pipe pile with a flange body provided in Embodiment 1, comprising the following steps:

[0084] Step 1: Make the pile body by centrifugal method:

[0085] The prestressed ultra-high performance concrete (UHPC) photovoltaic pipe pile body is mainly made by centrifugal method. The specific implementation method is as follows:

[0086] (1) Making steel cage

[0087] First, the prestressed steel wire is straightened and the ends are thickened, and then installed on the roll welding machine. The roll welding machine automatically roll welds the stirrups on the prestressed steel bars according to the designed spacing, and the prepared steel cage is hoisted and placed in the open mold;

[0088] (2) Pouring and laying of concrete

[0089] Mix UHPC and transport it to the formwork location for casting. The slump of the mixed UHPC is 40cm to 50cm. The UHPC needs to be arranged in the mold within 30min-40min (including the mixing time). This process is best carried out using an automatic or semi-automatic placing machine.

[0090] (3) Mold closing

[0091] Lift the top mold onto the cover and tighten the nuts around the mold.

[0092] (4) Centrifugal Forming

[0093] The mold after mold closing is hoisted onto the centrifuge. The centrifugation is mainly divided into two stages. The first stage is the slow stage. The centrifugal time is 1min~3min and the centrifugal acceleration is 0.8g~1.2g. The main function is to evenly arrange the UHPC in the mold. The second stage is the fast stage. The centrifugal time is 5min~8min and the centrifugal acceleration is 5g~8g. The main function is to compact the UHPC.

[0094] (5) Static stop

[0095] Hoist the UHPC into an open steam curing tank and place it in a static state. The ambient temperature should be above 10°C and the relative humidity should be above 60%. The static state time should not be less than 1 hour.

[0096] (6) Steam curing

[0097] The heating rate should not exceed 20℃ / h, and the constant temperature (90℃±5℃) should be maintained for 2h until the compressive strength of the specimen under the same curing conditions reaches 80MPa. Then the temperature should be lowered at a rate not exceeding 25℃ / h to a temperature range where the difference between the component surface temperature and the ambient temperature is no more than 20℃. The relative humidity of the environment during the curing process should be maintained above 95%.

[0098] (7) Demolding

[0099] (8) Surface coding

[0100] The specified codes are sprayed on the surface of the pipe piles, including: model, production time, manufacturer and other information.

[0101] (9) Finished product inspection

[0102] (10) Finished product storage

[0103] Step 2: Flange body prefabrication

[0104] The UHPC flange body is prefabricated by prefabrication method. The specific implementation method is as follows:

[0105] (1) Making steel cage

[0106] like Figure 5 and Figure 6 First, make the HRB400 steel bar into a disc according to the design requirements, and place the prepared steel cage in the mold according to the designed position;

[0107] (2) Pouring concrete

[0108] Mix UHPC and transport it to the formwork location for pouring. The slump expansion of the mixed UHPC should not be less than 550mm. Since it is self-flowing and does not require vibration, this process is best carried out using an automatic or semi-automatic placing machine.

[0109] (3) Static stop

[0110] Hoist the UHPC into an open steam curing tank and place it in a static state. The ambient temperature should be above 10°C and the relative humidity should be above 60%. The static state time should not be less than 1 hour.

[0111] (4) Steam curing

[0112] The heating rate should not exceed 20℃ / h, and the constant temperature (90℃±5℃) should be maintained for 2h until the compressive strength of the specimen under the same curing conditions reaches 80MPa. Then the temperature should be lowered at a rate not exceeding 25℃ / h to a temperature range where the difference between the component surface temperature and the ambient temperature is no more than 20℃. The relative humidity of the environment during the curing process should be maintained above 95%.

[0113] (5) Demolding

[0114] (6) Surface coding

[0115] Spray the specified code on the surface of the flange body, including: model, production time, manufacturer and other information.

[0116] (7) Finished product inspection

[0117] (8) Finished product storage

[0118] Step 3: On-site installation

[0119] (1) Install the UHPC pile body to the designed elevation by extrusion or insertion after opening a hole, and ensure that the limit device 3 is not less than 1 cm in the soil;

[0120] (2) Pass the flange body 2 through the top of the pile body 1 and drop it to the surface of the soil;

[0121] (3) The gap between the flange body 2 and the pile body 1 can be appropriately filled with epoxy resin, UHPC or underwater cement.

[0122] The characteristics of the preparation method provided in this embodiment are as follows:

[0123] 1. Centrifugal method for making pile body: The factory's existing equipment can produce UHPC piles, with mature technology and no need for high temperature and high pressure;

[0124] 2. Flange body prefabrication: mature technology;

[0125] 3. On-site installation: The -2mm tolerance of the inner hole of the flange body can ensure that the flange body passes through the pile body to the designed position.

[0126] The construction techniques provided in this embodiment are basically mature processes, which can reduce costs and ensure construction quality.

[0127] Example 3

[0128] This embodiment provides a numerical simulation process to illustrate that the UHPC photovoltaic pipe pile with a flange body based on Example 1 has the effect of saving raw materials and reducing costs.

[0129] The diameter of the pile body is d = 300mm, the flange is r = 900mm (take 3d), h = 300, and the thickness of the desert sand is 1000mm. According to the design documents of photovoltaic pipe piles in a certain area of ​​Xinjiang provided by the design institute, without considering the effect of sand, the pile diameter is d = 300mm, and the pile length is 5m (1.5m above the ground, 3.5m underground, and the bearing layer is siltstone). According to this design document, it can be calculated that when considering the effect of 1m thick desert sand on the horizontal bearing capacity of the pile, the length of the siltstone pile entering the lower part of the desert sand can be reduced by 0.38m. 350,000 piles for 1GW photovoltaic is the general data of photovoltaic in my country.

[0130] Taking the 1m thick desert sand in the area as an example, after considering the pile side impedance of the sand, the pile length can be reduced by 0.38m. For 1GW photovoltaic power generation, 350,000 piles are needed, and a total of 133,000m of piles are reduced, saving about 18.62 million yuan in investment and greatly saving resources.

[0131] The above embodiments are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A UHPC photovoltaic pipe pile with a flange body, comprising a columnar hollow pile body, characterized in that: A flange body is fixed outside the pile body, and the flange body is fixed to the pile body through a limiting device arranged on the pile body; the pile body is cast by UHPC; the flange body is located at the junction of the buried part and the exposed part, and is used for positioning and restraining soil cracking.

2. The UHPC photovoltaic pipe pile with flange body according to claim 1, characterized in that: The pile body is cast using prestressed steel bars and stirrups as a skeleton; the flange body is prepared using reinforced UHPC.

3. The UHPC photovoltaic pipe pile with flange body according to claim 2, characterized in that: The outer diameter of the flange body is 4 times or more than the diameter of the pile body, but does not exceed the clear distance between adjacent pile bodies.

4. The UHPC photovoltaic pipe pile with flange body according to claim 3, characterized in that: The diameter d of the pile body is 300mm-500mm, and the wall thickness is 40mm-70mm; the radius r of the flange body is 900mm-1800mm.

5. The UHPC photovoltaic pipe pile with flange body according to claim 4, characterized in that: The strength grade of the UHPC is RPC100-RPC120, and a volume content of 0.5%-1.2% of fine steel fiber is added; When the centrifugal method is used, the initial setting time is controlled at 30min to 40min, and the strength after 6h steam curing is not less than 80MPa.

6. The UHPC photovoltaic pipe pile with flange body according to claim 5, characterized in that: The prestressed steel bars are made of stress-relieving steel wire with a diameter of 5mm to 8mm, an ultimate tensile strength of 1670MPa and 1860MPa, and a tension tensile control stress of 75% of the tensile strength; the spiral stirrups are made of cold-drawn steel wire with a diameter of 5mm to 8mm and a tensile strength of not less than 600MPa.

7. A construction method for a UHPC photovoltaic pipe pile with a flange body according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: The pile body is manufactured by centrifugal method, wherein the pile body uses prestressed steel bars and stirrups as a skeleton and is manufactured by centrifugal method; S2: Flange body prefabrication, using reinforced UHPC to prepare the flange body; S3: On-site installation, including the following steps: S31: Install the pile to the designed elevation by extrusion or insertion after drilling, and ensure that the limit device is not less than 1 cm into the soil; S32: Pass the flange through the top of the pile and drop it to the surface of the soil; S33: The gap between the flange body and the pile body is appropriately filled with epoxy resin, UHPC or underwater cement.

8. The construction method according to claim 7, characterized in that: The method of making a pile body by the centrifugal method comprises the following steps: S11: To make a steel cage, first straighten the prestressed steel bars and thicken the ends, then install them on a roll welding machine. The roll welding machine automatically roll welds the spiral stirrups on the prestressed steel bars according to the designed spacing, and hoists the made steel cage into an open mold; S12: pouring and laying concrete, mixing UHPC and transporting it to the formwork location for pouring. The slump of the mixed UHPC is 40cm-50cm. The UHPC is arranged in the mold within 30min-40min. S13: Close the mold, hoist the top mold, and tighten the nuts around the mold; S14: Centrifugal molding, hoist the mold after mold closing onto the centrifuge, centrifugation is divided into two stages, the first stage is a slow stage, the centrifugal time is 1min~3min, the centrifugal acceleration is 0.8g~1.2g, the UHPC is evenly arranged in the mold; the second stage is a fast stage, the centrifugal time is 5min~8min, the centrifugal acceleration is 5g~8g, the UHPC is compacted; S15: Static stop: hoist the UHPC into the steam curing tank with the lid opened and stop it. The ambient temperature during the static stop should be above 10℃ and the relative humidity should be above 60%. The static stop time should not be less than 1h. S16: Steam curing, the heating rate should not be greater than 20℃ / h, and the constant temperature (90℃±5℃) should be maintained for 2h until the compressive strength of the specimen under the same curing conditions reaches 80Mpa; then the temperature should be lowered at a rate not exceeding 25℃ / h to a temperature range where the difference between the component surface temperature and the ambient temperature is no more than 20℃. The relative humidity of the environment during the curing process should be maintained above 95%; S17: Remove the mold to obtain the finished pile body.

9. The construction method according to claim 7, characterized in that: Prefabrication of the flange body comprises the following steps: S21: Making a steel cage, first making HRB400 steel bars into discs according to design requirements, and placing the made steel cage in the mold according to the designed position; S22: pouring concrete, mixing UHPC and transporting it to the formwork location for pouring. The slump expansion of the mixed UHPC is not less than 550mm. Since it is self-flowing and compacted, no vibration is required; S23: Static stop: hoist the UHPC into the open steam curing tank and stop it. The ambient temperature during the static stop should be above 10℃ and the relative humidity should be above 60%. The static stop time should not be less than 1h. S24: Steam curing, the heating rate should not be greater than 20℃ / h, and the constant temperature (90℃±5℃) should be maintained for 2h until the compressive strength of the specimen under the same curing conditions reaches 80MPa; then the temperature should be lowered at a rate not exceeding 25℃ / h to a temperature range where the difference between the component surface temperature and the ambient temperature is no more than 20℃. The relative humidity of the environment during the curing process should be maintained above 95%; S25: Remove the mold to obtain the finished flange body.

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