Cast-in-situ bored pile steel casing lifting device and method

Abstract

The invention belongs to the field of cast-in-situ bored piles, and relates to a cast-in-situ bored pile steel casing lifting device and method which can reduce the difficulty of taking out a steel casing and protect the steel casing. The cast-in-situ bored pile steel casing lifting device comprises a lifting unit and a vibration unit. The lifting unit is configured to lift the steel casing, and the vibration unit is configured to send high-frequency vibration waves to the steel casing. The cast-in-situ bored pile steel casing lifting method comprises the step that the upper end of a steel casing is fixedly connected with a lifting unit. The lifting unit applies upward lifting force to the steel casing, the lifting force is gradually increased, and when the lifting force is the same as the gravity of the steel casing, high-frequency vibration is applied to the steel casing located above the ground, so that the whole steel casing generates high-frequency vibration. And the lifting force is continuously and gradually increased, so that the steel casing is gradually lifted upwards.

Description

Technical Field

[0001] The invention belongs to the field of bored cast-in-place piles and relates to a bored cast-in-place pile steel casing lifting device and method. Background Art

[0002] Bored cast-in-place piles refer to piles made by forming pile holes in the foundation soil at the construction site through mechanical drilling, steel pipe squeezing or manual excavation, placing a steel cage inside and pouring concrete.

[0003] During the drilling process, in order to prevent accidents such as side wall collapse, steel casings are inserted into the borehole. The wall thickness of the steel casing is generally 4~10mm and the length is 2~3m. The maximum drilling depth of bored piles can reach about 20m, so there are multiple steel casings that are welded and inserted into the borehole. This causes the problem of the steel casing being difficult to remove after the drilling is completed. In some cases, the steel casing at the bottom of the borehole may break. On the one hand, the steel casing cannot be effectively recovered, resulting in increased construction costs. On the other hand, the steel casing may affect the strength and life of the poured concrete. Summary of the invention

[0004] In order to overcome the defects in the above-mentioned related technologies, on the one hand, the present invention proposes a bored cast-in-place pile steel casing lifting device, which can reduce the difficulty of removing the steel casing and provide protection for the steel casing.

[0005] In order to achieve the above technical objectives, the present invention provides a bored cast-in-place pile steel casing lifting device. The bored cast-in-place pile steel casing lifting device comprises: a lifting unit and a vibration unit. The lifting unit is configured to lift the steel casing, and the lifting unit comprises: a lifting bracket and a clamping member. The lifting bracket is a horizontally arranged square frame, and the lifting bracket is connected to the crane. A clamping member is fixed on the lower side of the lifting bracket, and the clamping member is fixedly connected to the upper end of the steel casing. The vibration unit is fixedly connected to the lifting unit, and the vibration unit comprises: a vibration ring and a vibrator. The vibration ring is fixed below the lifting bracket, and the vibration ring is a circular ring. A plurality of through holes are arranged on the side wall of the vibration ring, and the center line of each through hole passes through the center point of the vibration ring. A vibrator is fixed in each through hole, and the vibrator is configured to send high-frequency vibration waves, and the vibrator is in conflict with the outer wall of the steel casing.

[0006] Preferably, the bored pile steel casing lifting device further comprises a heating unit. The heating unit comprises: a heating wire and a temperature sensor. The heating wire is wound around the side wall of the steel casing below the vibration unit. The temperature sensor is arranged on the side wall of the steel casing.

[0007] Preferably, an internal thread is provided on the inner wall of the through hole. The vibrator comprises: a vibration shell, an ultrasonic transducer and a horn. The vibration shell is a cylindrical shell with openings at both ends, an external thread is provided on the outer wall of the vibration shell, and the vibration shell is fixed in the through hole. The ultrasonic transducer is fixed in the vibration shell. A horn is fixed on the ultrasonic transducer.

[0008] Preferably, a plurality of locking through holes are provided on the vibration ring, at least two locking through holes are provided on both sides of each through hole, and the at least two locking through holes are symmetrical about the center line of the through hole.

[0009] The vibrator also includes a clamping plate, which is a plate member. At least two clamping through holes are arranged on the clamping plate, and at least two of the clamping through holes are adapted to the two locking through holes. The clamping plate is arranged at one end of the vibration shell away from the vibration ring, and each clamping through hole has a threaded rod passing through it, and the threaded rods pass through the locking through holes accordingly. The clamping plate is fixedly connected to the vibration ring via the threaded rods, and the clamping plate presses the vibration shell onto the vibration ring.

[0010] Preferably, the lifting bracket includes: an annular frame, a track and a slider. The annular frame is a circular steel structure, and the diameters of the multiple annular frames are different, and the multiple annular frames are concentrically arranged in the same plane. The multiple tracks are fixedly connected to the multiple annular frames, and each track is arranged along the center line of the multiple annular frames, and the multiple tracks are evenly distributed. At least one slider is movably inserted on each track, and a clamping member is fixed on each slider. The slider includes a main slider and a sub-plate movably connected to the track, and the sub-plate is a plate member. The two sub-plates are fixed on both sides of the main slider, and the lower end surfaces of the main slider and the sub-plate are in the same horizontal plane.

[0011] Preferably, the clamping member includes a plurality of metal rods, the plurality of metal rods are arranged on the lower end surface of the slider, and the plurality of metal rods are arranged on both inner and outer sides of the wall of the steel casing, and the plurality of metal rods are respectively welded to the slider and the steel casing.

[0012] On the other hand, a method for lifting a bored cast-in-place pile steel casing is applicable to the above-mentioned bored cast-in-place pile steel casing lifting device. The bored cast-in-place pile steel casing lifting method comprises: fixing the upper end of the steel casing to a lifting unit. The steel casing located above the ground is heated, and the heating temperature is less than 150°C to 200°C. The steel casing stops heating and cools to 75°C to 100°C. The lifting unit applies an upward lifting force to the steel casing, and the lifting force gradually increases. When the lifting force is the same as the gravity of the steel casing, high-frequency vibration is applied to the steel casing located above the ground, so that the steel casing as a whole generates high-frequency vibration. The lifting force continues to be gradually increased to gradually lift the steel casing upward.

[0013] The beneficial effects of the present invention are: The applicant found that it is relatively easy to insert the steel casing into the drill hole, but it is more difficult to remove it after drilling is completed. After analysis, it is believed that during the operation, the mud and sand on the hole wall are squeezed towards the steel casing due to vibration, causing the friction force of the outer wall of the steel casing to increase, which in turn makes it difficult to remove the steel casing.

[0014] In the present application, during the lifting process, a vibration unit is used to make the wall of the steel casing vibrate at high frequency. When vibration occurs, a gap is generated between the wall of the steel casing and the mud and sand on the hole wall, which can reduce the friction of the hole wall on the steel casing and reduce the difficulty of removal.

[0015] The present application adopts a heating unit, which makes the steel casing expand under the action of thermal expansion and contraction, and can expand the hole wall outward. At the same time, the expansion coefficient of the solidified concrete is low. When the temperature of the steel casing drops, a small gap can be created between the steel casing and the hole wall and the concrete, further reducing the difficulty of removing the steel casing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A structural diagram of the present invention; Figure 2 Another structural diagram of the present invention; Figure 3 is a structural diagram of the vibration unit of the present invention; Figure 4 It is a side structural diagram of the vibration unit of the present invention; Figure 5It is a structural diagram of the lifting unit of the present invention; Figure 6 It is a top view of the lifting unit described in the present invention. DETAILED DESCRIPTION

[0018] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0019] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0020] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0021] like Figure 1 , Figure 3 and Figure 4As shown, some embodiments of the present invention provide a bored cast-in-place pile steel casing lifting device. The bored cast-in-place pile steel casing lifting device comprises: a lifting unit 1 and a vibration unit 2. The lifting unit 1 is configured to lift the steel casing 6, and the lifting unit 1 comprises: a lifting bracket 11 and a clamping member 12, the lifting bracket 11 is a horizontally arranged square frame, the lifting bracket 11 is connected to the crane, and the lower side of the lifting bracket 11 is fixed with a clamping member 12, and the clamping member 12 is fixedly connected to the upper end of the steel casing 6. The vibration unit 2 is fixedly connected to the lifting unit 1, and the vibration unit 2 includes: a vibration ring 21 and a vibrator 22. The vibration ring 21 is fixed below the lifting bracket 11. The vibration ring 21 is a circular ring. A plurality of through holes are arranged on the side wall of the vibration ring 21, and the center line of each through hole passes through the center point of the vibration ring 21. A vibrator 22 is fixed in each through hole, and the vibrator 22 is configured to send high-frequency vibration waves. The vibrator 22 conflicts with the outer wall of the steel casing 6.

[0022] In some examples, the lower part of the steel casing 6 is located in the borehole 5, and the upper part of the steel casing 6 protrudes 50 cm from the ground. The outer wall of the steel casing 6 is attached to the outer wall of the borehole 5, and concrete 4 is poured in the steel casing 6. At this time, it is difficult to pull out the steel casing 6.

[0023] A plurality of vibrators 22 are fixed on the outer wall of the steel casing 6 located on the ground. The vibrators 22 can output ultrasonic low-amplitude vibrations. The plurality of vibrators 22 fit the outer surface of the steel casing 6 and transmit high-frequency vibrations to the inner wall of the steel casing 6. Under the action of vibration, the steel casing 6 can loosen the soil compacted on the outer wall of the borehole 5, and the side wall of the steel casing 6 moves relative to the soil on the outer wall of the borehole 5 and the concrete 4 inside the steel casing 6, which reduces the pressure of the outer wall of the borehole 5 on the steel casing 6 on the one hand, and reduces the relative friction between the steel casing 6 and the outer wall of the borehole 5 and the concrete 4 on the other hand. The lifting force of the lifting unit 1 can be reduced, and the situation of breaking the steel casing 6 into the borehole 5 can be avoided.

[0024] In some embodiments, Figure 2 As shown, the bored pile steel casing lifting device further includes a heating unit 3. The heating unit 3 includes: a heating wire 31 and a temperature sensor 32. The heating wire 31 is wound around the side wall of the steel casing 6 below the vibration unit 2. The temperature sensor 32 is arranged on the side wall of the steel casing 6.

[0025] In some examples, the heating wire 31 can be a heating tape. When in use, the heating wire 31 is wound around the steel casing 6 protruding from the ground. The temperature sensor 32 is fixed on the steel casing 6 to collect the surface temperature of the steel casing 6.

[0026] Before pulling out the steel casing 6, the heating wire 31 can be used to heat the steel casing 6. The expansion coefficient of the steel casing 6 is greater than the inner wall of the borehole 5 and the concrete 4. Heating can cause partial separation of the steel casing 6 from the concrete 4, avoiding large areas of adhesion between the concrete 4 and the steel casing 6.

[0027] In addition, when the steel casing 6 expands, it can squeeze the outer wall of the borehole 5, thus expanding the outer wall of the borehole 5. When the temperature of the steel casing 6 decreases, the volume shrinks, which can facilitate the formation of a gap between the steel casing 6 and the outer wall of the borehole 5.

[0028] The present application adopts a heating unit 3, which can utilize the different expansion coefficients between the steel casing 6 and the outer wall of the borehole 5 and the concrete 4 to form a gap between the steel casing 6 and the outer wall of the borehole 5, and between the steel casing 6 and the concrete 4, thereby facilitating the lifting of the steel casing 6.

[0029] In some embodiments, Figure 3 and Figure 4 As shown, the inner wall of the through hole is provided with an internal thread. The vibrator 22 comprises: a vibration housing 221, an ultrasonic transducer 222 and a horn 223. The vibration housing 221 is a cylindrical shell with openings at both ends, and the outer wall of the vibration housing 221 is provided with an external thread. The vibration housing 221 is fixed in the through hole. The ultrasonic transducer 222 is fixed in the vibration housing 221. The horn 223 is fixed on the ultrasonic transducer 222.

[0030] In some examples, the vibration ring 21 is a cylindrical shell with a diameter larger than the steel casing 6. A plurality of through holes are provided on the side wall of the vibration ring 21. The center lines of the plurality of through holes point to the center point of the vibration ring 21. In order to prevent the amplitude of the vibration wave generated by the vibrator 22 provided in the plurality of through holes from being superimposed or offset on the side wall of the steel casing 6, the present application may require that the plurality of through holes be evenly distributed and the center lines of the plurality of through holes be not colinear. This can avoid the peaks or troughs of the plurality of vibration waves on the steel casing 6 from appearing at the same position point, can prevent the steel casing 6 from being torn by high-frequency vibration, or the peaks of the plurality of vibration waves and the troughs of several other vibration waves from appearing at the same position point, causing the surface vibration of the steel casing 6 to be unclear.

[0031] An internal thread is provided on the inside of each through hole, and the vibration housing 221 of the vibrator 22 can be screwed into the corresponding through hole until the end of the horn 223 contacts the side wall of the steel casing 6 .

[0032] In the present application, the horn 223 reduces the vibration frequency, increases the amplitude, and changes the vibration direction, that is, the amplitude direction of the output of the horn 223 is along the extension direction of the center line of the through hole.

[0033] In some embodiments, a plurality of locking through holes are disposed on the vibration ring 21 , at least two locking through holes are disposed on both sides of each through hole, and the at least two locking through holes are symmetrical about the center line of the through hole.

[0034] The vibrator 22 also includes a clamping plate 224, which is a plate member. At least two clamping through holes are arranged on the clamping plate 224, and at least two of the clamping through holes are adapted to the two locking through holes. The clamping plate 224 is arranged at one end of the vibration shell 221 away from the vibration ring 21, and each clamping through hole has a threaded rod passing through it, and the threaded rod passes through the locking through hole accordingly. The clamping plate 224 is fixedly connected to the vibration ring 21 via the threaded rod, and the clamping plate 224 presses the vibration shell 221 onto the vibration ring 21.

[0035] For example, the pressing plate 224 can press the vibrator 22 into the through hole, thereby preventing the vibrator 22 from being loosened or separated from the through hole due to vibration itself.

[0036] In some embodiments, Figure 5 and Figure 6 As shown, the lifting bracket 11 includes: an annular frame 111, a track 112 and a slider 113. The annular frame 111 is a circular steel structure, and the diameters of the multiple annular frames 111 are different, and the multiple annular frames 111 are concentrically arranged in the same plane. The multiple tracks 112 are fixedly connected to the multiple annular frames 111, and each track 112 is arranged along the center line of the multiple annular frames 111, and the multiple tracks 112 are evenly distributed. At least one slider 113 is movably inserted on each track 112, and a clamping member 12 is fixed on each slider 113. The slider 113 includes a main slider 113 movably connected to the track 112 and a sub-plate, and the sub-plate is a plate member. The two sub-plates are fixed on both sides of the main slider 113, and the lower end surfaces of the main slider 113 and the sub-plate are in the same horizontal plane.

[0037] In some examples, the diameters of the multiple annular frames 111 are different, the diameter of the largest annular frame 111 is larger than the outer diameter of the steel casing 6, and the multiple annular frames 111 are concentrically arranged, for example, 4 annular frames 111 are arranged in sequence from the inside to the outside, the diameter of the largest annular frame 111 is 2.1m, the diameter of the adjacent inner annular frame 111 is 1.6m, the diameter of the innermost annular frame 111 is 1.3m, and the diameter of the innermost annular frame 111 is 1m.

[0038] A plurality of tracks 112 are fixed to the lower side of the plurality of annular frames 111 , each track 112 is fixedly connected to the plurality of annular frames 111 in sequence, and the center line of each track 112 intersects with a vertical line passing through the center point of the annular frame 111 , and the plurality of tracks 112 are evenly arranged.

[0039] A slider 113 is slidably disposed on each track 112 . It can be understood that the slider 113 can reciprocate on the corresponding track 112 , and the track 112 has an upward lifting force on the slider 113 .

[0040] The slider 113 includes a main slider 113 and a sub-plate. The main slider 113 is provided with a slide groove adapted to the track 112. A sub-plate is fixed on each side of the main slider 113. The lower end surface of the sub-plate is coplanar and horizontal with the lower end surface of the main slider 113. In this way, the area of ​​the lower end surface of the slider 113 can be expanded, for example, to adapt to different steel casings 6.

[0041] In some embodiments, the clamping member 12 includes a plurality of metal rods, which are arranged on the lower end surface of the slider 113 and on the inner and outer sides of the wall of the steel casing 6, and are respectively welded to the slider 113 and the steel casing 6.

[0042] The clamping member 12 is a plurality of metal rods, which are arranged inside and outside the steel casing 6. It is understood that there is a gap between the upper end of the steel casing 6 and the slider 113. When the clamping member 12 is arranged, the plurality of metal rods can be welded to the lower end surface of the corresponding slider 113 according to the diameter of the steel casing 6. When the area of ​​the lower end surface of the slider 113 is large, there is more space for fixing the metal rods. Afterwards, the slider 113 descends, inserts the fixed metal rods into the steel casing 6, and welds the upper end of the steel casing 6 to the metal rods.

[0043] A metal rod is welded to the outside of the steel casing 6 , and the metal rod is welded to the lower end surface of the slider 113 .

[0044] On the other hand, some embodiments of the present invention further provide a method for lifting a bored cast-in-place pile steel casing, which is applicable to the above-mentioned bored cast-in-place pile steel casing lifting device. The method for lifting a bored cast-in-place pile steel casing comprises: S3. Fixedly connect the upper end of the steel casing to the lifting unit.

[0045] S4. The lifting unit applies an upward lifting force to the steel casing, and the lifting force gradually increases. When the lifting force is the same as the gravity of the steel casing 6, high-frequency vibration is applied to the steel casing above the ground, so that the steel casing as a whole generates high-frequency vibration.

[0046] S5. Continue to gradually increase the lifting force to gradually lift the steel casing upward.

[0047] In this embodiment, an upward lifting force is first applied to the steel casing, and then high-frequency vibration is performed and the steel casing is gradually lifted. The high-frequency vibration process of the steel casing can create a small gap between the steel casing and the side wall of the borehole and the side wall of the concrete, thereby reducing relative static friction and facilitating lifting.

[0048] In addition, the high-frequency vibration of the steel casing can cause the soil and gravel on the side wall of the borehole to move downward relatively. The steel casing is set with lifting force in advance to avoid the accumulation of soil and gravel at the lower part of the borehole before the steel casing moves upward, thereby preventing the soil and gravel from forming higher pressure and adhesion on the lower part of the steel casing.

[0049] In some embodiments, before applying high-frequency vibration to the steel casing located above the ground, the method for lifting the bored pile steel casing of the present invention further includes step S2 and step S3.

[0050] Wherein, step S2: heating the steel casing located above the ground, with the heating temperature being less than 150°C to 200°C.

[0051] Step S3: the steel casing stops heating and cools to 75°C-100°C.

[0052] In this embodiment, the steel casing is heated to 150°C~200°C. At this time, the steel casing has a strong expansion coefficient and the internal force characteristics of the steel casing are less affected. That is, the steel casing can form a large extrusion pressure on the drill hole and form a gap with the concrete. At the same time, the internal structure of the steel casing is less affected and the metal properties of the steel casing will not be changed.

[0053] After that, the heating of the steel casing is stopped and it is cooled to 75℃~100℃. The steel casing cools and contracts again, thus forming a small gap between the borehole and the concrete, which can reduce the squeezing pressure of the borehole and concrete on the steel casing and reduce the difficulty of lifting the steel casing.

[0054] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0055] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A bored pile steel casing lifting device, characterized in that: include: A lifting unit, the lifting unit is configured to lift the steel casing, the lifting unit comprises: a lifting bracket and a clamping member, the lifting bracket is a horizontally arranged square frame, the lifting bracket is connected to the crane, a clamping member is fixed on the lower side of the lifting bracket, and the clamping member is fixedly connected to the upper end of the steel casing; A vibration unit, the vibration unit is fixedly connected to the lifting unit, the vibration unit comprises: a vibration ring and a vibrator, the vibration ring is fixed below the lifting bracket, the vibration ring is a circular ring, a plurality of through holes are arranged on the side wall of the vibration ring, and the center line of each through hole passes through the center point of the vibration ring, a vibrator is fixed in each through hole, the vibrator is configured to send high-frequency vibration waves, and the vibrator is in conflict with the outer wall of the steel casing.

2. The bored pile steel casing lifting device according to claim 1 is characterized in that: The bored pile steel casing lifting device also includes a heating unit; The heating unit comprises: A heating wire, the heating wire being wound around a side wall of the steel casing below the vibration unit; A temperature sensor is arranged on the side wall of the steel casing.

3. The bored pile steel casing lifting device according to claim 2 is characterized in that: An internal thread is provided on the inner wall of the through hole; The vibrator comprises: A vibration shell, the vibration shell is a cylindrical shell with openings at both ends, an outer wall of the vibration shell is provided with external threads, and the vibration shell is fixed in the through hole; An ultrasonic transducer, wherein the ultrasonic transducer is fixed in the vibration housing; A horn is fixed on the ultrasonic transducer.

4. The bored pile steel casing lifting device according to claim 3 is characterized in that: The vibration ring is provided with a plurality of locking through holes, at least two locking through holes are provided on both sides of each through hole, and the at least two locking through holes are symmetrical about the center line of the through hole; The vibrator also includes a clamping plate, which is a plate member. At least two clamping through holes are arranged on the clamping plate, and at least two of the clamping through holes are adapted to the two locking through holes. The clamping plate is arranged at one end of the vibration shell away from the vibration ring, and each clamping through hole has a threaded rod passing through it, and the threaded rods pass through the locking through holes accordingly. The clamping plate is fixedly connected to the vibration ring via the threaded rods, and the clamping plate presses the vibration shell onto the vibration ring.

5. The bored pile steel casing lifting device according to claim 4, characterized in that: The lifting bracket comprises: The annular frame is a circular steel structure, wherein the diameters of the plurality of annular frames are different and the plurality of annular frames are concentrically arranged in the same plane; Tracks, wherein a plurality of the tracks are fixedly connected to the plurality of the annular frames, and each track is arranged along the center line of the plurality of the annular frames, and the plurality of the tracks are evenly distributed; A slider, at least one slider is movably inserted on each track, a clamping member is fixed on each slider, the slider includes a main slider and a sub-plate movably connected to the track, the sub-plate is a plate, the two sub-plates are fixed on both sides of the main slider, and the lower end surfaces of the main slider and the sub-plate are in the same horizontal plane.

6. The bored pile steel casing lifting device according to claim 5, characterized in that: The clamping member includes a plurality of metal rods, which are arranged on the lower end surface of the slider and on the inner and outer sides of the steel casing wall. The plurality of metal rods are respectively welded to the slider and the steel casing.

7. A method for lifting a bored pile steel casing, applicable to the bored pile steel casing lifting device according to any one of claims 1 to 6, characterized in that: The method for lifting the bored pile steel casing comprises: The upper end of the steel casing is fixedly connected to the lifting unit; The steel casing located above the ground is heated to a temperature less than 150°C to 200°C; The steel casing stops heating and cools to 75°C-100°C; The lifting unit applies an upward lifting force to the steel casing, and the lifting force gradually increases. When the lifting force is equal to the weight of the steel casing, high-frequency vibration is applied to the steel casing above the ground, so that the steel casing as a whole generates high-frequency vibration; Continue to gradually increase the lifting force to gradually lift the steel casing upward.

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