Multi-stage sinking construction method for assembled caisson

Abstract

This invention relates to a multi-stage sinking construction method for prefabricated caissons. Based on conventional caisson construction, a steel base with active telescopic and active steering functions is installed at the bottom of the caisson, and a support mechanism with active telescopic function is installed between the caisson sections. The method is characterized by the following steps: S1, Soil excavation: excavating the soil at the bottom of the caisson to a set depth. This application, by installing a steel base with active telescopic and active steering functions at the bottom of the caisson and a support mechanism with active telescopic function between the caisson sections, enables the caisson to have three different sinking control modes. Different control modes can be selected to adapt to different sinking resistance levels to ensure normal sinking construction. Furthermore, the combination of different control modes can achieve multi-stage sinking while simultaneously ensuring the sinking posture of the caisson. This solves the technical problems of difficult sinking and poor structural posture control caused by high sinking resistance in traditional prefabricated caisson construction methods.

Description

Technical Field

[0001] This invention relates to the field of caisson construction technology, and specifically to a method for multi-stage sinking of prefabricated caissons. Background Technology

[0002] Caisson technology is widely used in deep-buried projects such as bridge foundations and underground structures. Precise control of its sinking attitude is the core challenge to ensure structural safety and construction efficiency.

[0003] In traditional construction, caissons are easily affected by factors such as uneven geology, excavation disturbance, and external forces, leading to problems such as tilting, deviation, or even "getting stuck" and loss of posture control. Existing correction methods such as unilateral over-excavation, weighting, and water jetting often have lag, large disturbance, and limited effect, especially in deep and large-section caissons.

[0004] Therefore, realizing the active steering and correction of the caisson base, actively counteracting the unbalanced torque caused by the caisson's attitude deviation, improving the caisson's self-adaptive ability and attitude stability when traversing complex strata, and reducing disturbance to the surrounding soil is an important research direction for realizing intelligent and high-precision construction of prefabricated caissons. It has significant theoretical value and broad engineering application prospects. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-stage sinking construction method for prefabricated caissons, which solves the problems of sinking difficulties and poor structural posture control caused by the large sinking resistance in the traditional prefabricated caisson construction method.

[0006] To achieve the above objectives, this invention provides a multi-stage sinking construction method for prefabricated caissons. Based on conventional prefabricated caisson construction, a steel base with both active telescopic and active steering functions is installed at the bottom of the caisson, and a support mechanism with active telescopic function is installed between the caisson sections. The construction method includes the following steps:

[0007] S1. Soil excavation: Excavate the soil at the bottom of the caisson to the set depth;

[0008] S2. Segment splicing: Assemble new segments at the top of the caisson;

[0009] S3. Sinking Control: Apply downward pressure to the caisson using a pressing mechanism, while simultaneously monitoring the offset of the lower end center plane of the steel base and the magnitude of the downward pressure applied by the pressing mechanism, and selecting one of the following control modes based on the monitoring results:

[0010] Control Mode 1: When the current pressure is less than the set threshold, the pressing mechanism is continuously controlled to press down while the steel base is adjusted to maintain the caisson's posture until the pressing stroke of the pressing mechanism on the caisson is equal to the width of one ring of segments.

[0011] Control Mode 2: When the current pressure exceeds the set threshold and the caisson cannot sink, adjust the steel base to maintain the caisson's posture while controlling its lower end to actively extend until the lower end of the steel base extends a distance equal to the width of one ring of segments. Then control the pressing mechanism to press down the caisson and simultaneously control the steel base to retract until the pressing stroke of the pressing mechanism on the caisson is equal to the width of one ring of segments.

[0012] Control Mode 3: When the pressing mechanism in Control Mode 2 still cannot sink, the support mechanism is extended and the steel base is retracted simultaneously until the extension distance of the support mechanism is equal to the width of one ring of segments. Then the pressing mechanism is pressed down on the caisson and the support mechanism is retracted simultaneously until the pressing stroke of the pressing mechanism on the caisson is equal to the width of one ring of segments.

[0013] S4. Cyclic construction: Repeat steps S2-S3 above until the caisson sinks to the design elevation.

[0014] By adopting this technical solution, based on the installation of a steel base with active telescopic and active steering functions at the bottom of the caisson and the installation of a support mechanism with active telescopic function between the caisson sections, the caisson has three different sinking control modes. It can adapt to different sinking resistance levels by selecting different control modes to ensure the normal sinking construction of the caisson. It can also achieve multi-stage sinking by coordinating different control modes, and simultaneously ensure the sinking posture of the caisson. This solves the technical problems of difficult sinking and poor structural posture control caused by high sinking resistance in traditional caisson construction methods.

[0015] Furthermore, the steel base, which combines active extension and active steering functions, includes a steel pipe section, a steel cutting edge, and a steering jack; wherein,

[0016] The steel pipe section is connected to the lower end of the caisson;

[0017] The steel cutting edge is located below the steel pipe section;

[0018] The steering jacks are evenly distributed in the circumferential direction between the steel pipe section and the steel cutting foot, and each of the steering jacks can be controlled independently.

[0019] The base of the steering jack is fixedly connected to the bottom surface of the steel pipe section, and the piston rod end of the steering jack is hinged to the top surface of the steel blade foot.

[0020] By adopting this technical solution, when multiple steering jacks located between the steel pipe section and the steel cutting edge are controlled independently, the angle of the steel cutting edge relative to the steel pipe section can be changed. This allows the caisson to continue sinking and achieve a steering effect, thus realizing the corresponding steering capability. Moreover, the steering control only needs to overcome the soil pressure around the steel cutting edge, requiring low control pressure, making it safe and quick. When multiple steering jacks located between the steel pipe section and the steel cutting edge are controlled together, the steering jacks can push the steel cutting edge vertically downward to achieve the extension and retraction function. Furthermore, the caisson can sink one step ahead of the steel cutting edge by moving downward, and the subsequent sinking of the caisson does not need to overcome the soil resistance at the bottom surface. This reduces the downward pressure required for the caisson to sink and solves the problem of sinking difficulties caused by excessive sinking resistance.

[0021] Furthermore, the steel base, which combines active extension and active steering functions, also includes an inner ring plate, an outer ring plate, and a double-layer sealing ring; wherein,

[0022] The inner ring plate and the outer ring plate are respectively connected to the inner and outer sides of the top surface of the steel cutting foot, and the upper ends of the inner ring plate and the outer ring plate extend to the outer periphery of the top of the steel pipe section.

[0023] The double-layer sealing rings are respectively installed on the inner ring plate and the outer ring plate on the side of the steel pipe section away from the steel cutting edge.

[0024] By adopting this technical solution, the double-layer sealing rings can achieve sealing between the inner ring plate and the steel pipe section, as well as between the outer ring plate and the steel pipe section, thereby preventing external water and soil from entering the interior of the steel base.

[0025] Furthermore, the steel base, which combines active extension and active steering functions, also includes an oil chamber and a grease pump; wherein,

[0026] The oil cavity is formed between the inner ring plate and the inner wall of the steel pipe section and between the outer ring plate and the outer wall of the steel pipe section by double sealing rings;

[0027] The grease pump is connected to the oil chamber via a grease injection pipe.

[0028] By adopting this technical solution, the oil cavity is formed and the grease pump is installed. During the caisson operation, the pressure inside the oil cavity can be adjusted by the grease pump, thereby improving the resistance to external water and soil intrusion and achieving the purpose of protecting the internal structure.

[0029] Furthermore, the support mechanism with active telescopic function includes a lower sleeve, an upper sleeve, and a relay jack; wherein,

[0030] The lower sleeve section has an inverted U-shaped vertical cross section and is fixedly connected to the lower end of the upper sleeve section;

[0031] The upper sleeve section has a U-shaped vertical cross section and is fixedly connected to the upper end of the lower sleeve section, and the upper sleeve section and the lower sleeve section are nested together.

[0032] The relay jacks are evenly distributed in the circumferential direction between the lower sleeve section and the upper sleeve section, and the relay jacks evenly distributed in the circumferential direction are jointly controlled.

[0033] The relay jack base is fixedly connected to the inner top surface of the lower sleeve section, and the piston rod end of the relay jack is fixedly connected to the inner bottom surface of the upper sleeve section.

[0034] By adopting this technical solution, the connection between the lower and upper sleeve sections allows them to move relative to each other. With the addition of intermediate jacks, the lower and upper sleeve sections can be extended and retracted by controlling the intermediate jacks, thereby achieving the purpose of applying pressure to the middle of the caisson.

[0035] Furthermore, the pressing mechanism includes a rotatable reaction frame and a pressing jack; wherein,

[0036] The rotatable reaction frame includes a column fixed to the ground and a horizontal frame rotatably connected to the top of the column.

[0037] The base of the downward jack is connected to the bottom surface of the horizontal frame and can move to the top of the caisson as the horizontal frame rotates.

[0038] By adopting this technical solution, the rotatable reaction frame can be set up to change the position of the pressure jacks used for applying pressure, adapting to the needs of caisson sinking construction and new pipe section assembly. Specifically, when the pressure jacks are moved to the top of the caisson under the action of the rotatable reaction frame, they can apply pressure to the caisson for sinking operations. When the pressure jacks are moved outside the caisson under the action of the rotatable reaction frame, the assembly of new pipe sections can be carried out normally.

[0039] Furthermore, the pressing mechanisms are evenly distributed around the periphery of the top of the caisson, and the evenly distributed pressing mechanisms are jointly controlled.

[0040] By adopting this technical solution, the evenly distributed and jointly controlled pressing mechanism can provide stable pressing pressure during caisson construction, which is beneficial to improving the attitude control effect of the caisson.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] By installing a steel base with active telescopic and active steering functions at the bottom of the caisson and a support mechanism with active telescopic function between the caisson sections, the caisson has three different sinking control modes. The different control modes can be selected to adapt to different sinking resistance levels to ensure the normal sinking construction of the caisson. The different control modes can also be combined to achieve multi-stage sinking and simultaneously ensure the sinking posture of the caisson. This solves the technical problems of traditional prefabricated caisson construction methods, which are difficult to sink and have poor structural posture control due to high sinking resistance. Attached Figure Description

[0043] Figure 1 This is a flowchart illustrating the multi-stage sinking construction method for prefabricated caissons in this invention.

[0044] Figure 2 This is a schematic diagram of the overall construction elevation of the prefabricated caisson multi-stage sinking construction method in this invention;

[0045] Figure 3 This is a schematic diagram of soil excavation for the multi-stage sinking construction method of prefabricated caissons in this invention.

[0046] Figure 4 This is a schematic diagram of the segment splicing in the multi-stage sinking construction method of the prefabricated caisson in this invention;

[0047] Figure 5 This is a schematic diagram of the control mode of the multi-stage sinking construction method for prefabricated caissons in this invention before sinking construction.

[0048] Figure 6 This is a schematic diagram of the control mode of the multi-stage sinking construction method for prefabricated caissons in this invention after sinking construction.

[0049] Figure 7 This is a schematic diagram of the control mode two of the prefabricated caisson multi-stage sinking construction method in this invention before sinking construction;

[0050] Figure 8 This is a schematic diagram of the control mode two of the prefabricated caisson multi-stage sinking construction method in this invention after sinking construction;

[0051] Figure 9 This is a schematic diagram of the control mode three before sinking construction in the multi-stage sinking construction method of the prefabricated caisson in this invention;

[0052] Figure 10 This is a schematic diagram of the control mode three of the prefabricated caisson multi-stage sinking construction method in this invention after sinking.

[0053] Explanation of reference numerals in the attached diagram: 1. Steel pipe section; 2. Steel cutting edge; 3. Steering jack; 4. Double sealing ring; 5. Inner ring plate; 6. Outer ring plate; 7. Oil chamber; 8. Grease pump; 9. Intermediate jack; 10. Rotatable reaction frame; 11. Downward jack. Detailed Implementation

[0054] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0055] Please see the appendix Figure 2 This invention provides a multi-stage sinking construction method for prefabricated caissons. Based on conventional prefabricated caisson construction, a steel base with both active telescopic and active steering functions is installed at the bottom of the caisson; an active telescopic support mechanism is installed between the caisson sections; and the existing pressing mechanism is improved. Specifically:

[0056] The steel base with active telescopic and active steering functions includes a steel pipe section 1, a steel cutting foot 2, and a steering jack 3. The steel pipe section 1 is connected to the lower end of the caisson. The steel cutting foot 2 is located below the steel pipe section 1. The steering jacks 3 are evenly distributed in a circumferential direction between the steel pipe section 1 and the steel cutting foot 2, and each steering jack 3 can be controlled independently. The base of the steering jack 3 is fixedly connected to the bottom surface of the steel pipe section 1, and the piston rod end of the steering jack 3 is hinged to the top surface of the steel cutting foot 2.

[0057] The above structure, its connection, and coordination, when independently controlled by multiple steering jacks 3 located between steel pipe section 1 and steel cutting foot 2, can change the angle of steel cutting foot 2 relative to steel pipe section 1, thereby cooperating with the continued sinking of the caisson to achieve the steering effect and realize the corresponding steering capability. Moreover, the steering control only needs to overcome the soil pressure on the outer periphery of steel cutting foot 2, requiring low control pressure, making it safe and quick. When multiple steering jacks 3 located between steel pipe section 1 and steel cutting foot 2 are controlled together, the steering jacks 3 can push steel cutting foot 2 vertically downward to achieve the extension and retraction function. Furthermore, the caisson can sink one step ahead of the steel cutting foot 2 by moving downward, and the subsequent sinking of the caisson does not need to overcome the soil resistance at the bottom surface, thereby reducing the downward pressure required for the caisson to sink and solving the problem of sinking difficulties caused by excessive sinking resistance.

[0058] Furthermore, the steel base, which combines active telescopic and active steering functions, also includes an inner ring plate 5, an outer ring plate 6, and a double-layer sealing ring 4; wherein, the inner ring plate 5 and the outer ring plate 6 are respectively connected to the inner and outer sides of the top surface of the steel cutting foot 2, and the upper ends of the inner ring plate 5 and the outer ring plate 6 extend to the outer periphery of the top of the steel pipe section 1; the double-layer sealing ring 4 is respectively installed on the side of the inner ring plate 5 and the outer ring plate 6 away from the steel cutting foot 2 and close to the steel pipe section 1.

[0059] The above structure, connection, and fit together enable the double-layer sealing ring 4 to achieve sealing between the inner ring plate 5 and the steel pipe section 1, as well as between the outer ring plate 6 and the steel pipe section 1, thereby preventing external water and soil from entering the interior of the steel base.

[0060] Furthermore, the steel base, which combines active telescopic and active steering functions, also includes an oil chamber 7 and a grease pump 8; wherein, the oil chamber 7 is formed between the inner ring plate 5 and the inner wall of the steel pipe section 1 and between the outer ring plate 6 and the outer wall of the steel pipe section 1 respectively through double-layer sealing rings 4; the grease pump 8 is connected to the oil chamber 7 through a grease injection pipe;

[0061] The above structure, its connection, and its coordination allow the pressure inside the oil chamber 7 to be adjusted by the grease pump 8 during the caisson operation, thereby improving the resistance to external water and soil intrusion and achieving the purpose of protecting the internal structure.

[0062] The support mechanism with active telescopic function includes a lower sleeve section, an upper sleeve section, and intermediate jacks 9. The lower sleeve section has an inverted U-shaped vertical cross section and is fixedly connected to the lower end of the upper sleeve section. The upper sleeve section has a regular U-shaped vertical cross section and is fixedly connected to the upper end of the lower sleeve section. The upper and lower sleeve sections are interlocked. The intermediate jacks 9 are evenly distributed circumferentially between the lower and upper sleeve sections, and the intermediate jacks 9 are controlled by a common mechanism. The base of the intermediate jack 9 is fixedly connected to the inner top surface of the lower sleeve section, and the piston rod end of the intermediate jack 9 is fixedly connected to the inner bottom surface of the upper sleeve section.

[0063] The above structure is designed, connected and coordinated, and the lower and upper sleeve sections have the ability to move relative to each other. With the addition of the intermediate jack 9, the lower and upper sleeve sections can be extended and retracted relative to each other by controlling the intermediate jack 9, so as to achieve the purpose of applying pressure in the middle of the caisson.

[0064] Furthermore, the support structure can be selectively installed during actual construction based on the sinking depth and soil conditions, rather than being installed between every adjacent pipe section, thereby reducing operating costs.

[0065] The pressing mechanism includes a rotatable reaction frame 10 and a pressing jack 11; wherein, the rotatable reaction frame 10 includes a column fixed to the ground and a horizontal frame rotatably connected to the top of the column; the base of the pressing jack 11 is connected to the bottom surface of the horizontal frame and can move directly above the top of the caisson as the horizontal frame rotates.

[0066] The above structure is set up, connected and coordinated so that the rotatable reaction frame 10 can change the position of the pressure jack 11 used for applying pressure, adapting to the needs of caisson sinking construction and new pipe section assembly. Specifically, when the pressure jack 11 moves to the top of the caisson under the action of the rotatable reaction frame 10, it can apply pressure to the caisson for sinking operation. When the pressure jack 11 moves outside the caisson under the action of the rotatable reaction frame 10, it can normally assemble new pipe sections.

[0067] Furthermore, the pressure-down mechanisms are evenly distributed around the top of the caisson, and these evenly distributed pressure-down mechanisms are jointly controlled. The evenly distributed and jointly controlled pressure-down mechanisms can provide stable downward pressure during caisson construction, which is beneficial to improving the attitude control effect of the caisson.

[0068] Please see the appendix Figure 1 The construction method includes the following steps:

[0069] S1. Soil Excavation: Please refer to the appendix. Figure 3 The grab bucket is used to excavate the soil at the bottom of the caisson until the soil surface is near the bottom of the steel blade foot.

[0070] S2. Segment splicing: Please refer to the appendix. Figure 4 A new ring of pipe sections was assembled at the top of the caisson;

[0071] S3, Sinking Control: Please refer to the appendix. Figure 5 The rotatable reaction frame 10 is used to adjust the downward jack 11 to be directly above the top of the new ring pipe section. The downward jack 11 is then activated to apply the caisson downward pressure from the top of the new ring pipe section. At the same time, the offset of the lower center plane of the steel cutting edge 2 and the magnitude of the downward pressure applied by the downward jack 11 are monitored, and one of the following control modes is selected based on the monitoring results:

[0072] Control Mode 1: Please refer to the appendix Figure 6 When the downward pressure applied by the downpressure jack 11 is less than the set threshold, the relay jack 9 is locked, and the downpressure jack 11 is continuously controlled to press down. At the same time, the center of the bottom surface of the steel blade foot 2 is kept at the design center by the fine adjustment steering jack 3 to maintain the caisson posture until the downpressure stroke of the downpressure jack 11 on the caisson is equal to the width of the new ring segment.

[0073] Control Mode 2: Please refer to the appendix Figure 7-8When the downward pressure applied by the downpressure jack 11 exceeds the set threshold and the caisson cannot sink, the downpressure jack 11 and the relay jack 9 are locked. The fine-tuning swivel jack 3 is used to keep the bottom center of the steel cutting foot 2 at the design center to maintain the posture of the steel cutting foot 2. Then, multiple swivel jacks 3 are simultaneously controlled to extend, so that the steel cutting foot 2 sinks relative to the steel pipe section 1 until the extension distance of the steel cutting foot 2 is equal to the width of the new ring segment. Then, the downpressure jack 11 is controlled to press down the caisson and multiple swivel jacks 3 are simultaneously controlled to retract until the downward stroke of the downpressure jack 11 on the caisson is equal to the width of the new ring segment.

[0074] In this control mode, it should be noted that there may be a situation where the downward jack 11 has been pressed down for a certain stroke but is not enough to cover the width of the new ring segment. In this case, the distance by which the multiple directional jacks 3 extend and the cutting edge 2 sinks should be the width of the new ring segment minus the stroke already pressed down by the downward jack 11. Accordingly, after the downward control of the cutting edge 2 is completed, the downward stroke of the downward jack 11 is the same as the distance already sunk by the cutting edge 2.

[0075] Control Mode 3: Please refer to the appendix Figure 9-10 When the caisson cannot be controlled to sink by the lowering jack 11 after the steel blade foot 2 sinks using control mode 2, the lowering jack 11 should be locked first, and then the extension of the relay jack 9 should be controlled and the retraction of the steering jack 3 should be controlled simultaneously. At this time, the part of the caisson below the relay jack 9 should sink first until the extension distance of the relay jack 9 is equal to the width of the new ring segment. Then, the lowering jack 11 should be controlled to press down the part of the caisson above the relay jack 9 and the retraction of the relay jack 9 should be controlled simultaneously until the lowering stroke of the lowering jack 11 on the caisson is equal to the width of the new ring segment.

[0076] In this control mode, it should be noted that, similar to control mode two, there is a situation where the downward jack 11 is pressed down for a certain stroke but does not cover the width of the new ring segment. In this case, after the steel cutting foot 2 is controlled to sink, the extension length of the relay jack 9 should be the same as the sinking distance of the steel cutting foot 2. Correspondingly, after the caisson section below it controlled by the relay jack 9 sinks, the stroke of the downward jack 11 should be the same as the extension length when the caisson section below it is controlled to sink.

[0077] S4. Cyclic construction: Move the downward jack 11 to outside the top of the caisson using the rotatable reaction frame 10, and repeat steps S2-S3 until the caisson sinks to the design elevation.

[0078] In the above construction method, the offset of the lower end center plane of the steel blade foot 2 and the magnitude of the downward pressure applied by the downward jack 11 are monitored using corresponding standard monitoring equipment, such as position sensors and pressure sensors.

[0079] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A multi-stage sinking construction method for prefabricated caissons, comprising, based on conventional prefabricated caisson construction, installing a steel base with both active telescopic and active steering functions at the bottom of the caisson, and installing a support mechanism with active telescopic function between the caisson sections; characterized in that, The construction method includes the following steps: S1. Soil excavation: Excavate the soil at the bottom of the caisson to the set depth; S2. Segment splicing: Assemble new segments at the top of the caisson; S3. Sinking Control: Apply downward pressure to the caisson using a pressing mechanism, while simultaneously monitoring the offset of the lower end center plane of the steel base and the magnitude of the downward pressure applied by the pressing mechanism, and selecting one of the following control modes based on the monitoring results: Control Mode 1: When the current pressure is less than the set threshold, the pressing mechanism is continuously controlled to press down while the steel base is adjusted to maintain the caisson's posture until the pressing stroke of the pressing mechanism on the caisson is equal to the width of one ring of segments. Control Mode 2: When the current pressure exceeds the set threshold and the caisson cannot sink, adjust the steel base to maintain the caisson's posture while controlling its lower end to actively extend until the lower end of the steel base extends a distance equal to the width of one ring of segments. Then control the pressing mechanism to press down the caisson and simultaneously control the steel base to retract until the pressing stroke of the pressing mechanism on the caisson is equal to the width of one ring of segments. Control Mode 3: When the pressing mechanism in Control Mode 2 still cannot sink, the support mechanism is extended and the steel base is retracted simultaneously until the extension distance of the support mechanism is equal to the width of one ring of segments. Then the pressing mechanism is pressed down on the caisson and the support mechanism is retracted simultaneously until the pressing stroke of the pressing mechanism on the caisson is equal to the width of one ring of segments. S4. Cyclic construction: Repeat steps S2-S3 above until the caisson sinks to the design elevation.

2. The prefabricated caisson multi-stage sinking construction method according to claim 1, characterized in that: The steel base, which combines active extension and active steering functions, includes a steel pipe section, a steel cutting edge, and a steering jack; wherein, The steel pipe section is connected to the lower end of the caisson; The steel cutting edge is located below the steel pipe section; The steering jacks are evenly distributed in the circumferential direction between the steel pipe section and the steel cutting foot, and each of the steering jacks can be controlled independently. The base of the steering jack is fixedly connected to the bottom surface of the steel pipe section, and the piston rod end of the steering jack is hinged to the top surface of the steel blade foot.

3. The prefabricated caisson multi-stage sinking construction method according to claim 2, characterized in that: The steel base, which combines active telescopic and active steering functions, also includes an inner ring plate, an outer ring plate, and a double-layer sealing ring; wherein, The inner ring plate and the outer ring plate are respectively connected to the inner and outer sides of the top surface of the steel cutting foot, and the upper ends of the inner ring plate and the outer ring plate extend to the outer periphery of the top of the steel pipe section. The double-layer sealing rings are respectively installed on the inner ring plate and the outer ring plate on the side of the steel pipe section away from the steel cutting edge.

4. The prefabricated caisson multi-stage sinking construction method according to claim 3, characterized in that: The steel base, which combines active extension and active steering functions, also includes an oil chamber and a grease pump; wherein, The oil cavity is formed between the inner ring plate and the inner wall of the steel pipe section and between the outer ring plate and the outer wall of the steel pipe section by double sealing rings; The grease pump is connected to the oil chamber via a grease injection pipe.

5. The prefabricated caisson multi-stage sinking construction method according to claim 1, characterized in that: The support mechanism with active telescopic function includes a lower sleeve, an upper sleeve, and a relay jack; wherein, The lower sleeve section has an inverted U-shaped vertical cross section and is fixedly connected to the lower end of the upper sleeve section; The upper sleeve section has a U-shaped vertical cross section and is fixedly connected to the upper end of the lower sleeve section, and the upper sleeve section and the lower sleeve section are nested together. The relay jacks are evenly distributed in the circumferential direction between the lower sleeve section and the upper sleeve section, and the relay jacks evenly distributed in the circumferential direction are jointly controlled. The relay jack base is fixedly connected to the inner top surface of the lower sleeve section, and the piston rod end of the relay jack is fixedly connected to the inner bottom surface of the upper sleeve section.

6. The prefabricated caisson multi-stage sinking construction method according to claim 1, characterized in that: The pressing mechanism includes a rotatable reaction frame and a pressing jack; wherein... The rotatable reaction frame includes a column fixed to the ground and a horizontal frame rotatably connected to the top of the column. The base of the downward jack is connected to the bottom surface of the horizontal frame and can move to the top of the caisson as the horizontal frame rotates.

7. The prefabricated caisson multi-stage sinking construction method according to claim 6, characterized in that: The pressing mechanisms are evenly distributed around the top of the caisson, and these evenly distributed pressing mechanisms are controlled together.

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