A method for controlling the sinking of a caisson

Abstract

This application relates to the technical field of the foundation construction of beam bridges, and specifically relates to a method for controlling the sinking of a caisson, which includes the following steps: obtaining the actual conditions of each soil layer through geological exploration tests, including the maximum and minimum values of the internal friction angle and cohesion of the soil layer, and establishing a finite element model for the sinking of the caisson according to the actual conditions of the soil layer and the caisson; for each soil layer, obtaining the first critical sinking state and the second critical sinking state of the caisson; carrying out soil extraction construction according to the first critical sinking state, measuring the inclination angle and sinking amount of the caisson on site after the caisson sinks, finding the optimal critical sinking state, and continuing the soil extraction construction until the caisson sinks through the current soil layer under the optimal critical sinking state. The method for controlling the sinking of the caisson in this application solves the technical problems of unstable sinking, poor safety performance, and slow sinking and low efficiency during the sinking process of the caisson.

Description

Technical Field

[0001] The present invention relates to the technical field of beam bridge construction foundation, and particularly relates to a method for controlling the sinking of a caisson. Background Art

[0002] At present, the caisson foundation is a relatively common foundation form and is widely used in the foundation of long-span bridges. With the increase of bridge span and load, the scale of the foundation increases sharply, and the difficulty of controlling the sinking of the caisson foundation increases. When the caisson is sinking, it is necessary to ensure a stable attitude, and adverse situations such as sudden sinking and inclination should be avoided.

[0003] In related technologies, in the traditional method for controlling the sinking of a caisson, the caisson mainly sinks by excavating soil in the well holes. During the actual sinking process, once the caisson inclines, on the side where the inclination is larger, more soil is excavated on the other side in the following time to guide the caisson to incline to the other side; in this way, it inclines on one side and excavates soil on the other side, and adjusts repeatedly to achieve the purpose of keeping the caisson as vertical as possible.

[0004] However, in the method of repeatedly adjusting the inclination during the sinking process like this, the whole sinking process is not stable, the safety performance is poor, and it needs to be monitored at all times to prevent accidents of excessive inclination. At the same time, the sinking is slow and the efficiency is low. Summary of the Invention

[0005] The present application provides a method for controlling the sinking of a caisson to solve the technical problems of unstable sinking, poor safety performance, and low sinking speed and efficiency during the sinking process of the caisson.

[0006] An embodiment of the present application provides a method for controlling the sinking of a caisson, including the following steps:

[0007] Obtain the actual situation of each soil layer through geological exploration tests, including the maximum and minimum values of the internal friction angle and cohesion of the soil layer, and establish a finite element model for the sinking of the caisson according to the actual situation of the soil layer and the caisson;

[0008] For each soil layer, based on the finite element model, obtain the first critical sinking state of the caisson according to the minimum values of the internal friction angle and cohesion of this soil layer; obtain the second critical sinking state of the caisson according to the maximum values of the internal friction angle and cohesion of this soil layer;

[0009] Carry out soil excavation construction according to the first critical sinking state. After the caisson sinks, measure the inclination angle and sinking amount of the caisson on site. If both are within their respective set threshold ranges, recognize the first critical sinking state as the optimal one; otherwise, refine the soil excavation state between the first critical sinking state and the second critical sinking state until both the inclination angle and the sinking amount are within their respective set threshold ranges. At this time, the corresponding critical sinking state is the optimal one; under the optimal critical sinking state, continue the soil excavation construction until the caisson sinks through the current soil layer.

[0010] Based on the above technical solution, in one embodiment, for multi-layer soil layers, the first critical sinking state and the second critical sinking state of the open caisson corresponding to each layer of soil layer are obtained, and the optimal critical sinking state of the open caisson in each layer of soil layer is obtained between the first critical sinking state and the second critical sinking state;

[0011] The open caisson maintains the optimal critical sinking state in each layer of soil layer, and the soil-taking construction is carried out on each layer of soil layer in sequence starting from the first layer of soil layer until the open caisson sinks to the bottom.

[0012] Based on the above technical solution, in one embodiment, the judgment of whether the inclination angle and the sinking amount are both within their respective set threshold ranges includes:

[0013] The threshold range of the inclination angle is less than or equal to the previously set inclination value;

[0014] The sinking amount is greater than or equal to the previously set sinking value.

[0015] Based on the above technical solution, in one embodiment, the outer side walls of the open caisson are separated into several well holes by several partition walls; during the process of obtaining the first critical sinking state, obtaining the second critical sinking state, carrying out actual soil-taking construction according to the first critical sinking state, or maintaining the optimal critical sinking state to continue soil-taking construction, the soil-taking principle of first in the middle and then around, first in the well holes and then in the blind areas is followed for soil-taking.

[0016] Based on the above technical solution, in one embodiment, the soil-taking principle further includes symmetric soil-taking centered on the axis of the open caisson.

[0017] Based on the above technical solution, in one embodiment, the critical sinking state represents the remaining soil layer form when the open caisson is vertical and has a sinking depth greater than the set depth.

[0018] Based on the above technical solution, in one embodiment, the refinement of the soil-taking state between the first critical sinking state and the second critical sinking state includes:

[0019] Gradually approaching from the first critical sinking state to the second critical sinking state, and during the process, the soil-taking area is preferentially expanded, and then the depth is expanded.

[0020] Based on the above technical solution, in one embodiment, when the cross-section of the open caisson is circular, the refinement of the soil-taking state between the first critical sinking state and the second critical sinking state includes:

[0021] Gradually approaching from the first critical sinking state to the second critical sinking state, centered on the axis of the open caisson, maintaining a circular soil-taking area, and taking soil according to the soil-taking principle of first in the middle and then around, first in the well holes and then in the blind areas.

[0022] Based on the above technical solution, in one embodiment, when the cross-section of the open caisson is square, the soil-taking state between the refined first critical sinking state and the second critical sinking state includes:

[0023] Gradually approaching from the first critical sinking state to the second critical sinking state, with the axis of the open caisson as the center, maintaining a square soil-taking area, and taking soil according to the principle of taking soil in the middle first and then around, and taking soil in the well holes first and then in the blind areas.

[0024] Based on the above technical solution, in one embodiment, when an unexpected situation occurs and the inclination angle of the open caisson exceeds the set threshold range, first perform inclination rectification. After the rectification, re-obtain the optimal critical sinking state, and continue the construction of taking soil in the optimal critical sinking state until the open caisson sinks through the current soil layer.

[0025] The beneficial effects brought by the technical solution provided by the embodiments of the present application at least include:

[0026] 1. For the open caisson sinking control method of the present application, by establishing a finite element model of the open caisson sinking and simplifying the complex soil layer with the maximum value of the soil layer parameters and the minimum value of the soil layer parameters into a soil layer with a single soil layer parameter in two steps, the first critical sinking state corresponding to the minimum values of the internal friction angle and cohesion and the second critical sinking state corresponding to the maximum values of the internal friction angle and cohesion are obtained. Guided by these two critical sinking states for actual soil taking and being able to quickly obtain the optimal critical sinking state according to actual measurement, the remaining soil layer of this optimal critical sinking state can well support the open caisson to maintain a vertical state. By maintaining the optimal critical sinking state and continuing the construction of taking soil until it sinks through the current soil layer, it can effectively avoid the phenomena of immovable sinking or sudden sinking during the sinking process of the open caisson. The open caisson sinking control method combines theoretical calculation, on-site implementation and real-time measurement, and can more accurately grasp the critical state during the sinking process of the open caisson, ensure the stable and controllable sinking of the open caisson, and has good safety performance.

[0027] 2. For the open caisson sinking control method of the present application, the soil layer is divided into multiple layers according to the geological exploration test, and construction is carried out layer by layer starting from the first layer. For each layer, it is necessary to obtain the optimal critical sinking state according to the first critical sinking state and the second critical sinking state, and repeat the construction of taking soil while maintaining the optimal critical sinking state until the open caisson penetrates the current soil layer. Since the soil quality of each soil layer is different, each soil layer has a different optimal critical sinking state. The open caisson sinking control method of the present application can quickly obtain the optimal critical sinking state during the construction of each soil layer for stable and efficient soil-taking construction, greatly improving the construction efficiency of the open caisson sinking.

[0028] 3. The well - sinking control method of the present application, whether it is obtaining the first critical sinking state and the second critical sinking state, or during the actual soil - taking construction, follows the soil - taking principle of first the middle and then the periphery, and first the well holes and then the blind areas, which can ensure the stable and vertical sinking of the well - sinking to the greatest extent, ensure smooth and controllable sinking and greatly improve the sinking efficiency.

[0029] 4. The well - sinking control method of the present application, even if an unexpected situation occurs during soil - taking and the inclination angle exceeds the set threshold range, can quickly respond and re - obtain the optimal critical sinking state after rectification, and can also quickly restore the state, maintain the optimal critical sinking state, and carry out soil - taking construction until the well - sinking passes through the current soil layer. The well - sinking is stable and the construction efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 is the flow chart of the well - sinking control method provided by the embodiment of the present application;

[0032] Figure 2 is the schematic diagram of the first critical sinking state of a certain soil layer provided by the embodiment of the present application;

[0033] Figure 3 is the schematic diagram of the second critical sinking state of a certain soil layer provided by the embodiment of the present application;

[0034] Figure 4 is the schematic diagram of the intermediate state between the first critical sinking state and the second critical sinking state of a certain soil layer provided by the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] In order to enable those skilled in the art to better understand the solutions of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0036] The present application provides a well - sinking control method to solve the technical problems of unstable sinking, poor safety performance, and slow and low - efficiency sinking during the well - sinking process; the present application uses the maximum values of soil layer parameters (φ max and cmax ), and the minimum value (φ min and c min ), the critical sinking state of the open caisson sinking construction is obtained, and by always maintaining the critical sinking state, the sinking state of the open caisson can be more accurately grasped, ensuring the smooth, controllable and efficient sinking of the open caisson.

[0037] As Figure 1 shown, the present application discloses a method for controlling the sinking of an open caisson, comprising the following steps:

[0038] S1: Through geological exploration tests, the actual conditions of each soil layer are obtained, including the maximum and minimum values of the internal friction angle and cohesion of the soil layer. According to the actual conditions of the soil layer and the open caisson, a finite element model for the sinking of the open caisson is established.

[0039] Specifically, through geological exploration tests, the actual conditions of each soil layer are obtained. The actual conditions of the soil layer include the maximum value φ max and c max of the soil layer parameters, as well as the minimum value φ min and c min ; wherein, φ max and φ min respectively represent the maximum internal friction angle and the minimum internal friction angle of the soil layer, and c max and c min respectively represent the maximum cohesion and the minimum cohesion of the soil layer; a finite element model for the sinking of the open caisson is established according to the actual conditions of the soil layer and the open caisson. Specifically, the actual conditions of the soil layer include the soil layer depth and soil layer parameters, and the actual conditions of the open caisson include the open caisson material, shape and volume.

[0040] S2: During the construction of each soil layer, based on the finite element model, according to the minimum values of the internal friction angle and cohesion of the soil layer, the first critical sinking state of the open caisson is obtained; according to the maximum values of the internal friction angle and cohesion of the soil layer, the second critical sinking state of the open caisson is obtained.

[0041] Specifically, the soil layer parameters of a certain soil layer in the finite element model are set to φ min and c min . The soil layer parameters in the finite element model for the sinking of the open caisson are adjustable. The complex soil layer sandwiched between the maximum value and the minimum value of the soil layer parameters is simplified into a soil layer with a single minimum soil layer parameter, simplifying the scenario conditions to obtain the first critical sinking state of the open caisson. Among them, the critical sinking state represents the remaining soil layer form when the open caisson is vertical and has a sinking depth greater than the set depth sinking amount (such as Figure 2 , Figure 3 or Figure 4 ). The soil layer parameters of the same soil layer in the finite element model for the sinking of the open caisson are set to φ max and c max to obtain the second critical sinking state of the open caisson.

[0042] S3: Carry out soil extraction construction according to the first critical sinking state. After the caisson sinks, measure the inclination angle and sinking amount of the caisson on-site. If both are within their respective set threshold ranges, the first critical sinking state is determined to be the optimal one; otherwise, refine the soil extraction state between the first critical sinking state and the second critical sinking state until both the inclination angle and the sinking amount are within their respective set threshold ranges. At this time, the corresponding critical sinking state is the optimal one; under the optimal critical sinking state, continue the soil extraction construction until the caisson sinks through the current soil layer.

[0043] Specifically, carry out actual soil extraction construction according to the first critical sinking state. When the soil layer reaches the first critical sinking state, after the caisson sinks, measure the inclination angle and sinking amount of the caisson on-site, and judge whether both the inclination angle and the sinking amount are within their respective set threshold ranges. Use the inclination angle and the sinking amount to define whether it is an ideal sinking. If it is within the range, it means it is an ideal sinking; if it is not within the range, it means it is not an ideal sinking. If so (that is, both the inclination angle and the sinking amount are within their respective set threshold ranges), it means that the first critical sinking state is the optimal critical sinking state, indicating that the remaining soil layer in this state can well support the caisson without skew. Maintain the first critical sinking state and continue the soil extraction construction until it sinks through the current soil layer. If not (that is, the inclination angle and the sinking amount are not both within their respective set threshold ranges), it means that the first critical sinking state is not the optimal critical sinking state. Refine the soil extraction state between the first critical sinking state and the second critical sinking state, and conduct multiple actual soil extraction tests. If, when extracting soil to a certain intermediate state, both the inclination angle and the sinking amount are within their respective set threshold ranges, then the intermediate state is determined to be the optimal critical sinking state. Maintain the optimal critical sinking state and continue the soil extraction construction until the caisson sinks through the current soil layer.

[0044] The caisson sinking control method of this application simplifies the complex soil layer with the maximum value of soil layer parameters and the minimum value of soil layer parameters into a soil layer with a single soil layer parameter according to the finite element model of caisson sinking, and simplifies it in two times to obtain the first critical sinking state corresponding to the minimum values of the internal friction angle and cohesion and the second critical sinking state corresponding to the maximum values of the internal friction angle and cohesion. Guide the actual soil extraction according to these two critical sinking states and can quickly obtain the optimal critical sinking state according to actual measurement. The remaining soil layer in the optimal critical sinking state can well support the caisson to maintain a vertical state. Maintain the optimal critical sinking state and continue the soil extraction construction until it sinks through the current soil layer, which can effectively avoid the phenomena of immovable sinking or sudden sinking during the caisson sinking process. The caisson sinking control method combines theoretical calculation, on-site implementation and real-time measurement, and can more accurately grasp the critical state during the caisson sinking process, ensure the stable and controllable sinking of the caisson, and has good safety performance.

[0045] In one embodiment, for multi-layer soil layers, the first critical sinking state and the second critical sinking state of the open caisson corresponding to each layer of soil layer are obtained, and the optimal critical sinking state of the open caisson in each layer of soil layer is obtained between the first critical sinking state and the second critical sinking state;

[0046] The open caisson maintains its respective optimal critical sinking state in each layer of soil layer, and soil is taken layer by layer starting from the first layer of soil layer until the open caisson sinks to the bottom.

[0047] Specifically, for the n layers of soil layers obtained from geological exploration tests, where n is a positive integer greater than or equal to 1, each layer of soil layer has soil layer parameters φ max , c max , φ min and c min .

[0048] The open caisson sinking control method includes:

[0049] According to the four parameters of the first layer of soil layer, the first critical sinking state and the second critical sinking state of the open caisson in the first layer of soil layer are obtained; actual soil taking construction is carried out to obtain the optimal critical sinking state of the open caisson in the first layer of soil layer, and repeated soil taking construction is carried out while maintaining the optimal critical sinking state until the open caisson penetrates the first layer of soil layer;

[0050] Continue to repeat the above steps respectively according to the four parameters of the second layer to the nth layer of soil layer until the open caisson sinks to the bottom.

[0051] In one example, according to the four parameters of a certain soil layer, the obtained first critical sinking state is as Figure 2 shown, the obtained second critical sinking state Figure 3 shown, and the obtained optimal critical sinking state is as Figure 3 shown.

[0052] For the open caisson sinking control method of the present application, the soil layer is divided into n layers according to geological exploration tests, and construction is carried out layer by layer from the first layer to the nth layer. For each layer, the optimal critical sinking state needs to be obtained according to the first critical sinking state and the second critical sinking state, and repeated soil taking construction is carried out while maintaining the optimal critical sinking state until the open caisson penetrates the current soil layer. Since the soil quality of each layer of soil layer is different, each layer of soil layer has a different optimal critical sinking state. The open caisson sinking control method of the present application can quickly obtain the optimal critical sinking state for stable and efficient soil taking construction during the construction of each layer of soil layer, greatly improving the construction efficiency of the open caisson sinking.

[0053] In one embodiment, determining whether the inclination angle and the sinking amount are both within their respective set threshold ranges includes:

[0054] The threshold range of the inclination angle is less than or equal to the preset inclination value, aiming to always ensure the verticality of the open caisson; the sinking amount is greater than or equal to the preset sinking value, aiming to ensure that there is a sinking amount and it is vertical.

[0055] In one embodiment, the outer side walls of the open caisson are separated by several partition walls into several well holes;

[0056] During the processes of obtaining the first critical sinking state, obtaining the second critical sinking state, actually excavating soil according to the first critical sinking state, or maintaining the optimal critical sinking state to continue excavating soil, the soil excavation is carried out in accordance with the principle of excavating soil from the middle to the periphery first and from the well holes to the blind areas first.

[0057] Specifically, the blind area refers to directly below the bottom end face of the partition wall.

[0058] For the open caisson sinking control method of the present application, whether it is in the process of obtaining the first critical sinking state and the second critical sinking state, or during the actual soil excavation construction, the soil excavation is carried out in accordance with the principle of excavating soil from the middle to the periphery first and from the well holes to the blind areas first, which can ensure the most stable vertical sinking of the open caisson to the greatest extent, ensure stable and controllable sinking and greatly improve the sinking efficiency.

[0059] Furthermore, the soil excavation principle also includes symmetric soil excavation centered on the axis of the open caisson. Symmetric soil excavation centered on the axis of the open caisson further ensures the stability of soil excavation and the stability of the open caisson sinking.

[0060] In one embodiment, the critical sinking state represents the remaining soil layer form of the sinking depth of the open caisson that is vertical and has a sinking amount greater than the set depth. It only needs to ensure that the open caisson can be vertically supported by this remaining soil layer form of this soil layer.

[0061] In one embodiment, the soil excavation steps between the first critical sinking state and the second critical sinking state are refined, including:

[0062] Gradually approaching from the first critical sinking state to the second critical sinking state, and during this process, the soil excavation area is preferentially expanded, and then the depth is expanded. During this process, until a certain intermediate state is obtained, the inclination angle and the sinking amount of the open caisson are both within their respective set threshold ranges, which means that this intermediate state is the optimal critical sinking state.

[0063] In one embodiment, when the cross-section of the open caisson is circular, the refined soil excavation state between the first critical sinking state and the second critical sinking state includes:

[0064] Gradually approaching from the first critical sinking state to the second critical sinking state, centered on the axis of the open caisson, maintaining a circular soil excavation area, and excavating soil in accordance with the principle of excavating from the middle to the periphery first and from the well holes to the blind areas first.

[0065] When the cross-section of the open caisson is circular, maintaining the circular soil-taking area can ensure the stability of the open caisson.

[0066] In one embodiment, when the cross-section of the open caisson is square, the refined soil-taking state between the first critical sinking state and the second critical sinking state includes:

[0067] Gradually approaching from the first critical sinking state to the second critical sinking state, with the axis of the open caisson as the center, maintaining the square soil-taking area, and taking soil according to the principle of taking soil in the middle first and then around, and taking soil in the well hole first and then in the blind area.

[0068] When the cross-section of the open caisson is square, maintaining the square soil-taking area can ensure the stability of the open caisson.

[0069] In one embodiment, when an unexpected situation occurs and the inclination angle of the open caisson exceeds the set threshold range, first use inclination correction. After the correction, re-obtain the optimal critical sinking state and continue the optimal critical sinking state, and take soil until the open caisson sinks through the current soil layer.

[0070] For the open caisson sinking control method of the present application, even if an unexpected situation occurs during soil taking and the inclination angle exceeds the set threshold range, after the correction, it can quickly respond, re-obtain the optimal critical sinking state, quickly restore the state, maintain the optimal critical sinking state, take soil until the open caisson sinks through the current soil layer, the open caisson is stable, and the construction efficiency is high.

[0071] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application 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 to the present application. Unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0072] It should be noted that in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0073] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for controlling the sinking of a caisson, characterized in that, It includes the following steps: Through geological exploration tests, obtain the actual conditions of each soil layer, including the maximum and minimum values of the internal friction angle and cohesion in the soil layer. Based on the actual conditions of the soil layer and the actual conditions of the open caisson, establish a finite element model for the sinking of the open caisson; For each soil layer, based on the finite element model, according to the minimum values of the internal friction angle and cohesion in this soil layer, obtain the first critical sinking state of the open caisson; according to the maximum values of the internal friction angle and cohesion in this soil layer, obtain the second critical sinking state of the open caisson; Carry out soil extraction construction according to the first critical sinking state. After the open caisson sinks, measure the inclination angle and sinking amount of the open caisson on-site. If both are within their respective set threshold ranges, recognize the first critical sinking state as the optimal one; otherwise, refine the soil extraction state between the first critical sinking state and the second critical sinking state until both the inclination angle and the sinking amount are within their respective set threshold ranges. At this time, the corresponding critical sinking state is the optimal one; under the optimal critical sinking state, continue the soil extraction construction until the open caisson sinks through the current soil layer; For multiple soil layers, obtain the first critical sinking state and the second critical sinking state corresponding to the open caisson in each soil layer, and obtain the optimal critical sinking state of the open caisson in each soil layer between the first critical sinking state and the second critical sinking state; The open caisson maintains the optimal critical sinking state in each soil layer, and starts from the first soil layer to carry out soil extraction construction on each soil layer in turn until the open caisson sinks to the bottom; The refinement of the soil extraction state between the first critical sinking state and the second critical sinking state includes: Gradually approach from the first critical sinking state to the second critical sinking state. During the process, first expand the soil extraction area, and secondly expand the depth.

2. The control method for the sinking of a caisson according to claim 1, characterized in that: Judging whether both the inclination angle and the sinking amount are within their respective set threshold ranges includes: The threshold range of the inclination angle is less than or equal to the pre-set inclination value; The sinking amount is greater than or equal to the pre-set sinking value.

3. The control method for the sinking of a caisson according to claim 1, wherein: The space between the outer side walls of the open caisson is divided into several well holes by several partition walls; During the process of obtaining the first critical sinking state, obtaining the second critical sinking state, carrying out actual soil extraction construction according to the first critical sinking state, or maintaining the optimal critical sinking state to continue the soil extraction construction, the soil extraction is carried out in accordance with the soil extraction principle of first in the middle and then around, first in the well holes and then in the blind areas.

4. The control method for the sinking of a caisson according to claim 3, wherein: The soil extraction principle also includes symmetric soil extraction centered on the axis of the open caisson.

5. The control method for the sinking of a caisson according to claim 1, characterized in that: The critical sinking state represents the remaining soil layer form in which the open caisson is vertical and has a sinking depth greater than the set depth.

6. The control method for the sinking of a caisson as described in claim 5, wherein: When the cross-section of the open caisson is circular, the refinement of the soil extraction state between the first critical sinking state and the second critical sinking state includes: Gradually approach from the first critical sinking state to the second critical sinking state. Centered on the axis of the open caisson, maintain a circular soil extraction area, and carry out soil extraction according to the soil extraction principle of first in the middle and then around, first in the well holes and then in the blind areas.

7. The control method for the sinking of a caisson according to claim 5, wherein: When the cross-section of the open caisson is square, the refinement of the soil extraction state between the first critical sinking state and the second critical sinking state includes: Gradually approach from the first critical sinking state to the second critical sinking state. Centered on the axis of the open caisson, maintain a square soil extraction area, and carry out soil extraction according to the soil extraction principle of first in the middle and then around, first in the well holes and then in the blind areas.

8. A method for controlling the sinking of a caisson according to any one of claims 1 to 7, characterized in that: When an unexpected situation occurs and the inclination angle of the caisson exceeds the set threshold range, inclination correction is first performed. After the correction, the optimal critical sinking state is re-obtained, and the optimal critical sinking state is continued, and soil excavation construction is carried out until the caisson sinks through the current soil layer.

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