Large open caisson and soil taking and bottom sealing construction method thereof

Abstract

The invention relates to a large open caisson and a soil taking and bottom sealing construction method thereof.The large open caisson comprises an outer caisson wall, an inner caisson wall and an outer caisson wall, the inner well wall is arranged in the outer well wall, and an inner well wall blade foot is arranged on the bottom end face of the inner well wall; the zoning partition wall group comprises a plurality of zoning partition walls which are perpendicular to one another, the inner space of the outer well wall is divided into a plurality of areas, and zoning partition wall blade feet are arranged on the bottom end face of the zoning partition wall group; the connecting partition wall is used for connecting the outer well wall, the inner well wall and the partition partition wall, a connecting partition wall blade foot is arranged on the bottom end face of the connecting partition wall, and the bottom of the connecting partition wall is an inclined face which inclines downwards from the inner well wall blade foot to the outer well wall blade foot or the partition partition wall blade foot. And meanwhile, a partition wall group and a connecting partition wall are arranged, so that the single excavation depth can be increased, the soil sampling efficiency can be improved, the inclined connecting partition wall blade feet can enhance the structural strength, and a supporting foundation is provided for the large height difference of the blade feet.

Description

Technical Field

[0001] This application relates to the field of bridge foundation construction technology, and in particular to a large caisson and its soil extraction and bottom sealing construction method. Background Technology

[0002] In caisson construction, the sinking operation is the core step. Its core principle lies in using the caisson's own effective self-weight to overcome the end resistance of the foundation soil on the bottom of the caisson and the lateral resistance around the caisson walls, thereby achieving the sinking of the caisson. To facilitate the caisson's excavation and sinking process, the cutting edge of the caisson is designed with a downward slope to cut the soil. Specifically, the cutting edge of the outer caisson wall adopts a tread surface with a single-sided slope, while the cutting edge of the inner partition wall has a tread surface with double-sided slopes. In traditional designs, there is a certain height difference between the tread surfaces of the outer caisson wall cutting edge and the inner partition wall cutting edge. This height difference is usually taken as a minimum of 0.5m, which directly limits the depth of soil excavation, resulting in shallow excavation depths in a single operation, reducing construction efficiency, and making it difficult to meet the construction requirements of large caisson projects. If the height difference is larger, on the one hand, the outer caisson wall cutting edge contacts the soil first, causing the outer caisson wall cutting edge to form a cantilever bearing force. The external earth pressure cannot be effectively diffused to the inner well wall, causing stress concentration at the cutting edge of the outer well wall, which poses a serious risk of structural damage. On the other hand, after the caisson is lowered into place, it is necessary to first fill the middle hole with crushed stone to fill the bottom gap as a partition wall for sealing the bottom. However, due to the large height difference between the inside and outside, some of the crushed stone will fall into the outer ring hole. The outer ring hole should be filled with pure sealing concrete, but because the crushed stone falls in, the concrete mixes with the crushed stone during pouring, resulting in a significant reduction in strength. Summary of the Invention

[0003] This application provides a large caisson and its soil extraction and bottom sealing construction method to solve the problems in related technologies where the height difference between the tread surfaces of the outer well wall cutting edge and the inner partition wall cutting edge of the traditional caisson is small, resulting in low construction efficiency; while when the height difference is large, the structure is unable to bear the load and the bottom sealing pouring quality is poor.

[0004] Firstly, a large caisson is provided, comprising: The outer well wall has an outer well wall cutting edge on its bottom end face; An inner well wall is located inside the outer well wall, and its bottom end face is provided with an inner well wall cutting edge. The bottom elevation of the inner well wall cutting edge is higher than the bottom elevation of the outer well wall cutting edge by a first preset value. The partition wall group includes multiple partition walls arranged perpendicularly to each other, which divide the space inside the outer well wall into multiple areas. The bottom end face of the partition wall is provided with a partition wall cutting foot, and the bottom elevation of the partition wall cutting foot is higher than the bottom elevation of the outer well wall cutting foot by a second preset value, and the first preset value is greater than the second preset value. The connecting partition wall connects the outer well wall, the inner well wall, and the partition wall. Its bottom end face is provided with a connecting partition wall cutting foot. The connecting partition wall cutting foot is an inclined surface that slopes downward from the inner well wall cutting foot to the outer well wall cutting foot or the partition wall cutting foot.

[0005] In some embodiments, the first preset value may be calculated to be 2~8m based on the structure.

[0006] In some embodiments, the second preset value is 0.5-1.0m.

[0007] In some embodiments, the bottom end face of the inner well wall cutting foot is a tread surface.

[0008] In some embodiments, the bottom sides of the partition wall blade are sloped.

[0009] In some embodiments, the bottom of the outer well wall cutting edge is sloped on the side near the inner well wall.

[0010] Secondly, a method for soil extraction and construction of a large caisson is provided, including the following steps: S1: Complete the structural construction of the outer wall, inner wall, partition wall group and connecting partition wall of the caisson; S2: In the initial stage of sinking, the soil at the bottom of the outer well wall cutting edge and the partition wall cutting edge is retained to form a multi-step support; multiple devices simultaneously extract soil and mud inside the caisson hole for sinking, and the mud extraction and sinking are carried out according to the principles of first inside and then outside, first high and then low, layered symmetry, and synchronous uniformity; in the later stage of sinking, the soil at the bottom of the partition wall cutting edge is extracted, transitioning to a situation where only the bottom of the outer well wall cutting edge has a support step.

[0011] S3: Excavate the soil at the bottom of each cutting edge to form a pot-shaped structure until the caisson sinks to the design elevation. At this point, the height of the cutting edge of the partition wall from the soil surface meets the second preset value, and the height of the cutting edge of the inner well wall from the soil surface meets the first preset value.

[0012] In some embodiments, the principle of taking soil from the inside out includes: First, remove the soil below the cutting edge and on the inner side of the inner well wall, then remove the soil between the outer and inner well walls; The principle of selecting soil from higher to lower elevations includes: First, remove the soil from the relatively high-lying areas, and then gradually remove the soil from the lower-lying areas.

[0013] Thirdly, a method for sealing the bottom of a large caisson is provided, including the following steps: S1: After the caisson is lowered to the design elevation and the foundation is cleared, a guide pipe is placed along the wall of the filling hole, and crushed stone of a predetermined height is filled into the guide pipe to cover the bottom of the cutting edge of the partition wall. S2: Based on the partition walls, the caisson is divided into a core area and an edge area, wherein: The core area is a central rectangular area surrounded by partition walls and the outer wall of the middle section of the caisson; The edge region is a fan-shaped area between the partition wall and the outer walls at both ends of the caisson; S3: First, pour the core area sealing concrete. After the core area concrete reaches its initial setting strength, pour the edge area sealing concrete.

[0014] In some embodiments, the core area is poured using a diagonal sequential construction method, specifically including: S31: Dividing the core area into four quadrants, and pouring the first diagonal quadrant first; S32: After the concrete in the first diagonal quadrant has initially set, pouring the second diagonal quadrant; The edge area is poured using a symmetrical construction method, specifically including: S33: After the core area has initially set as a whole, pouring the edge area in symmetrical blocks along the circumference of the caisson.

[0015] This application provides a large caisson and its soil extraction and bottom sealing construction method. Since the bottom of the inner caisson wall is higher than the outer caisson wall by a first preset value, and the bottom of the partition wall group is higher than the outer caisson wall by a second preset value, and the first preset value is greater than the second preset value, when the caisson sinks, after the outer caisson wall sinks, the partition wall group provides primary support to the caisson. The significant height difference between the inner and outer caisson walls allows the soil extraction equipment ample vertical space to reach the blind zone at the bottom of the cutting edge. This overcomes the limitations of traditional caissons in terms of soil extraction depth at the inner and outer cutting edges and the difficulty of soil extraction in blind zones. By using excavators for synchronous partitioned excavation, the single excavation depth is increased compared to conventional caissons, thereby achieving efficient and free soil extraction, rapid excavation, reduced waiting time, improved soil extraction efficiency, and expanded working space. Since the connecting partition wall cutting edge is an inclined plane sloping downwards from the inner caisson wall cutting edge to the outer caisson wall cutting edge or the partition wall cutting edge, forming a triangular support structure, it can provide secondary support for the caisson, improving the structural support strength and providing a support foundation for the large height difference between the inner and outer cutting edges. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the planar structure of a large caisson provided in an embodiment of this application; Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure of the middle AA section; Figure 3 for Figure 1 Schematic diagram of the cross-sectional structure of the middle BB section; Figure 4A schematic diagram of soil extraction for a large caisson provided in this application embodiment. Figure I ; Figure 5 A schematic diagram of soil extraction for a large caisson provided in this application embodiment. Figure II ; Figure 6 This is a schematic diagram of the sealing partition of a large caisson provided in an embodiment of this application.

[0018] In the diagram: 1. Outer well wall; 11. Outer well wall cutting edge; 2. Inner well wall; 21. Inner well wall cutting edge; 3. Partition wall group; 31. Partition wall; 32. Partition wall cutting edge; 4. Connecting partition wall; 41. Connecting partition wall cutting edge; 5. Sealing concrete. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] This application provides a large caisson that can solve the problems in related technologies where the height difference between the tread surfaces of the outer wall cutting edge and the inner partition wall cutting edge of a traditional caisson is small, resulting in low construction efficiency; while when the height difference is large, the structure is unable to bear the load and the quality of the bottom sealing pouring is poor.

[0021] The construction of large caissons has always faced numerous challenges: ① The caisson has a wide support area, and the soil properties and bearing capacity vary in different areas during the sinking process, making it difficult to control and adjust the spatial posture of the caisson; ② The caisson has a large excavation area, but the number of operating machines is limited, and some equipment often needs to be stopped to coordinate the overall progress, ultimately resulting in a long construction period; ③ The outer wall of a large caisson is longer, and the possibility of the foundation soil shearing and sliding into the well hole during the soil extraction and sinking process is greater than that of a small caisson; ④ The critical state of sinking of a large caisson is difficult to detect in real time. At the same time, due to limitations in machinery and equipment and construction organization, soil extraction and sinking often require over-excavation to a great depth to break through the critical state. In this case, there is a risk of sudden sinking, sand overturning, and tilting.

[0022] like Figures 1 to 2 As shown, this application provides a large caisson, comprising: The outer well wall 1 has an outer well wall cutting edge 11 on its bottom end face. The outer well wall cutting edge 11 serves as the reference point for the sinking of the caisson, and the bottom elevation is set to the design value (±0.00m). The inner well wall 2 is located inside the outer well wall 1 and is coaxially arranged with the outer well wall 1 to form a double-layer cylindrical structure. Its bottom end face is provided with an inner well wall cutting edge 21. The bottom elevation of the inner well wall cutting edge 21 is higher than the design value by a first preset value, which is 2-8m. The partition wall group 3 includes multiple partition walls 31 arranged perpendicularly to each other, which divide the space inside the outer well wall 1 and the inner well wall 2 into multiple areas. The bottom end face of the partition wall is provided with partition wall cutting feet 32. The bottom elevation of the outer well wall cutting feet 11 is the design value. The bottom elevation of the partition wall cutting feet 32 ​​is higher than the design value by a second preset value. The second preset value is 0.5m-1.0m. The connecting partition wall 4 is used to connect the outer well wall 1 and the inner well wall 2, and the inner well wall 2 and the partition wall 31. Its bottom end face is provided with a connecting partition wall cutting foot 41. The bottom of the connecting partition wall 4 is an inclined surface that slopes downward from the inner well wall cutting foot 21 to the outer well wall cutting foot 11 or the partition wall cutting foot 32.

[0023] In this embodiment, as Figure 1 , Figure 2 As shown, the caisson has a planar dimension of 120m (length) * 58m (width). Based on the location and function of the walls, four types of walls are designed: outer wall 1, inner wall 2, partition wall group 3, and connecting wall 4, each with corresponding cutting edges. The bottom elevation of the outer wall cutting edge 11 is the design value (±0.00m). The bottom elevation of the partition wall cutting edge 32 is 0.5m higher than the design value, located at +0.50m elevation, i.e., h1 in the diagram is 0.5m. The inner wall cutting edge 21 is raised 5m according to calculations, located at +5.00m elevation, i.e., h2 in the diagram is 5m. When the connecting wall 4 connects the outer wall 1 and the inner wall 2, its bottom slopes from the inner wall cutting edge 21 to the outer wall cutting edge 11; when the connecting wall 4 connects the inner wall 2 and the partition wall 31, its bottom slopes from the inner wall cutting edge 21 to the partition wall cutting edge 32.

[0024] The outer well wall cutting edge 11 is the first part to contact the soil layer. After engaging with the soil layer in advance, the elevation of the partition wall cutting edge 32 is only 0.5m higher than the design value, with a minimal height difference between it and the outer well wall cutting edge 11. This allows for rapid follow-up to the sinking progress of the outer well wall cutting edge 11 during the initial sinking of the caisson. The large space within the outer well wall 1 is divided into multiple independent working areas. The influence of differences in soil properties in each area on the overall posture is effectively isolated, and soil removal operations can be carried out simultaneously in each area without frequent equipment shutdowns, thus improving the efficiency of mechanical operations. Each independent working area is supported by the partition wall cutting edge, preventing local collapse caused by overload of soil in a single area, further balancing the overall stress on the caisson, and reducing the probability of tilting.

[0025] Because the inner well wall cutting edge 21 is 5m higher than the outer well wall cutting edge 11, the large height difference provides ample vertical space for the soil removal equipment, allowing it to reach the blind zone at the bottom of the cutting edge. This overcomes the limitations of the traditional caisson's inner and outer cutting edge soil removal depth and the difficulty of soil removal in the blind zone. By using excavators for zoned and synchronous excavation, the single excavation depth is increased compared to conventional caissons, thereby achieving efficient and free soil removal, rapid excavation, reduced waiting time, improved soil removal efficiency, and expanded operating space.

[0026] During caisson sinking, the connecting wall cutting edge 41 needs to withstand complex loads such as the reaction force of the soil and the compressive force of the caisson's own weight. The inclined cutting edge can convert the vertical load into "vertical + horizontal components" and evenly transfer them to the outer caisson wall or partition wall (both of which are already stable load-bearing structures) through the inclined surface. This avoids cracking and deformation of the cutting edge due to local stress concentration, extends the service life of the caisson structure, and reduces repair costs during construction. At the same time, during the sinking process, the inclined cutting edge can gradually cut into the soil like an "inclined wedge." Compared with a vertical cutting edge, it can reduce the contact area and frictional resistance with the soil, which reduces the power required for caisson sinking, such as reducing the amount of counterweight or excavation. It can also avoid local jamming caused by uneven resistance and improve sinking efficiency.

[0027] Furthermore, the bottom end face of the inner well wall cutting edge 21 is a tread surface.

[0028] The bottom end face of the inner well wall cutting foot 21 is a tread surface. In the early stage of caisson caisson preparation, the tread surface of the inner well wall cutting foot 21 can fit with the top surface of the unexcavated soil below to form temporary support, effectively preventing the inner well wall 2 from sinking prematurely due to its own weight.

[0029] Furthermore, the bottom sides of the partition wall blade 32 are sloped.

[0030] It can optimize the soil action pattern during caisson sinking and reduce the contact resistance between the partition wall cutting edge 32 and the soil. Compared with the traditional right angle or vertical side, the slope can gradually cut into the soil through the inclined surface, disperse the lateral squeezing force of the soil on the cutting edge, avoid the cutting edge getting stuck locally due to excessive friction between the side and the soil, and reduce the power cost required for the overall sinking of the caisson, making the sinking process smoother.

[0031] Furthermore, the bottom of the outer well wall cutting edge 11 is sloped on the side near the inner well wall, which can reduce the resistance of the inner soil to the cutting edge when the caisson sinks. When the outer well wall sinks first, the slope can guide the inner soil to slide towards the inner side of the well wall, avoiding the accumulation of soil at the bottom of the cutting edge to form excessive resistance, making it easier for the outer well wall to sink smoothly according to the design elevation.

[0032] A method for soil extraction and construction of a large caisson includes the following steps: S1: Complete the structural construction of the outer well wall, inner well wall, partition wall group and connecting partition wall of the caisson.

[0033] After the caisson is prefabricated, it is positioned using temporary hoisting or traction equipment to ensure that the outer well wall cutting edge 11 and the partition wall cutting edge 32 are fully embedded in the bottom soil, forming an initial support system. At this time, the inner well wall cutting edge 21 and the connecting partition wall cutting edge 41 are suspended in the air to avoid premature contact with the soil layer and increase resistance.

[0034] S2: Multiple devices simultaneously extract soil and mud inside the caisson borehole for sinking. The mud extraction and sinking are carried out according to the principles of inside to outside, high to low, layered symmetry, and synchronous uniformity. In the early stage of sinking, the soil at the bottom of the outer well wall cutting edge and the cutting edge of the partition wall is retained to form a multi-step support. In the later stage of sinking, the soil at the bottom of the cutting edge of the partition wall is extracted, transitioning to a situation where only the bottom of the outer well wall cutting edge has a support step.

[0035] Furthermore, the principle of removing soil from the inside first and then from the outside includes: first excavating the soil below the cutting edge of the inner well wall and the soil on the inner side, and then excavating the soil between the outer well wall and the inner well wall.

[0036] Furthermore, the principle of removing soil from higher to lower areas includes: first excavating the soil in the relatively higher areas, and then gradually excavating the soil in the lower areas to keep the soil surface in the wellbore uniform.

[0037] By delaying the excavation of the outer ring wellbore compared to the inner ring wellbore, and retaining the outer ring soil layer as temporary support, the load on the caisson is evenly distributed, avoiding uneven settlement caused by insufficient local soil bearing capacity and reducing the risk of tilting. The delayed excavation of the inner ring wellbore cutting edge 21 with its large elevation difference and the outer ring wellbore ensures that the outer ring wellbore cutting edge 11 remains embedded in the soil, maintaining soil stability. The outer ring soil layer also acts as an isolation zone, forming a soil barrier that effectively prevents soil shear failure and prevents outer soil from sliding into the well. By excavating the outer ring wellbore layer by layer in a step-like, symmetrical manner with small advances, the sinking resistance changes in a stepped manner, is cyclically controllable, and ensures balanced resistance during the sinking process. Real-time judgment of the caisson's condition based on resistance changes facilitates accurate adjustment of the caisson's sinking posture.

[0038] like Figure 4 and Figure 5 As shown, by using multi-step support for the initial caisson, the suspended span is reduced, and the caisson's flexural cracking is controlled while ensuring effective sinking. Combined with the gradual transition to at least step support in the later stage, the depth of the cutting edge is controlled, thereby preventing sand boiling and sudden sinking of the caisson.

[0039] S3: Excavate the soil at the bottom of each cutting edge to form a pot-shaped structure until the caisson sinks to the design elevation. At this point, the height of the cutting edge of the partition wall from the soil surface meets the second preset value, and the height of the cutting edge of the inner well wall from the soil surface meets the first preset value.

[0040] Soil is removed in a stepped manner, initially forming support on the outer well wall and partition walls. Soil is removed sequentially from the inside to the outside according to the sinking requirements. As the caisson sinks under its own weight, a repetitive process is formed, which realizes the controllable and continuous reduction of sinking resistance - small sinking after the critical state is broken - significant increase in sinking resistance - controllable and continuous reduction of sinking resistance. This process enables the controllable sinking of large caissons.

[0041] A method for sealing the bottom of a large caisson includes the following steps: S1: After the caisson is lowered to the design elevation and the foundation is cleared, a guide pipe is placed along the wall of the filling hole, and crushed stone of a preset height is filled into the guide pipe to cover the bottom of the partition wall cutting edge.

[0042] According to the design requirements, determine the height of the crushed stone filling, calculate the filling volume per hole, carry out layered filling operations, and after filling, use a vibrator to insert into the guide pipe to vibrate and ensure that the crushed stone is compacted and avoids the formation of holes.

[0043] S2: Based on the partition walls, the caisson is divided into a core area and an edge area, wherein: The core area is a central rectangular area surrounded by partition walls and the outer wall of the middle section of the caisson; The edge area is a fan-shaped area between the partition wall and the outer walls of the two ends of the caisson.

[0044] like Figure 6 As shown, the core region is a central rectangular region composed of BCFG, and the edge region is a fan-shaped region composed of ADEH.

[0045] S3: First, pour the core area sealing concrete. After the core area concrete reaches its initial setting strength, pour the edge area sealing concrete.

[0046] The core area is poured using a diagonal sequential construction method, specifically including: S31: Dividing the core area into four quadrants, and pouring the first diagonal quadrant first; S32: After the concrete in the first diagonal quadrant has initially set, pouring the second diagonal quadrant; The edge area is poured using a symmetrical construction method, specifically including: S33: After the core area has initially set as a whole, pouring the edge area in symmetrical blocks along the circumference of the caisson.

[0047] Specifically, as an example, such as Figure 3 and Figure 6 As shown, the root zone partition wall will be poured in 8 sections after the caisson is lowered into place and the bottom is sealed. First, 0.5m of gravel will be poured and leveled, and then each section will be poured in the order of "BG→CF→AH→DF".

[0048] The applicant discovered that simply increasing the height difference between the inner and outer cutting edges, without setting up partition wall group 3, and using a vertical method for connecting the partition wall cutting edge 41, not only would the structure be difficult to support, but during the bottom sealing process, when filling with crushed stone to plug leaks and pouring bottom sealing concrete through the outer ring holes, a mixed zone of crushed stone and concrete would be formed. This mixed zone has low load-bearing capacity and cannot effectively play its supporting role, affecting the overall stability and load-bearing capacity of the bottom sealing structure, which is detrimental to the subsequent normal use of the caisson. After some of the cement in the concrete mixes with the crushed stone, it is difficult to remove it together with the crushed stone later, which may cause material waste and also bring difficulties to possible subsequent construction adjustments or cleaning. This application sets a small height difference between the partition wall cutting edge 32 and the outer well wall cutting edge 11, which can reduce the generation of the mixed zone of crushed stone and concrete during the bottom sealing process when filling with crushed stone to plug leaks and pouring bottom sealing concrete through the outer ring holes, avoiding the situation where the low load-bearing capacity of the mixed zone affects the overall stability and load-bearing capacity of the bottom sealing structure, and ensuring the subsequent normal use of the caisson. Based on the actual underwater concrete supply, the caisson bottom sealing zones should be rationally arranged to control costs while ensuring the quality of the caisson bottom sealing.

[0049] In this embodiment, the caisson is large in size. Among the soil layers through which the caisson sinks, the silty clay and clay layers are 26.5m thick, accounting for 55.7%, making sinking difficult and the sinking posture difficult to control. Using the caisson structure of this application can reduce the difficulty of soil removal in blind areas, increase soil removal efficiency, and shorten the construction period without affecting the bottom sealing.

[0050] In summary, this application provides a large caisson. Because the bottom of the inner caisson wall is higher than the outer caisson wall by a first preset value, and the bottom of the partition wall group is higher than the outer caisson wall by a second preset value, and the first preset value is greater than the second preset value, when the caisson sinks, after the outer caisson wall sinks, the partition wall group provides primary support to the caisson. The significant height difference between the inner and outer caisson walls provides ample vertical space for the soil removal equipment, allowing it to reach the blind zone at the bottom of the cutting edge. This overcomes the limitations of traditional caissons in terms of soil removal depth at the inner and outer cutting edges and the difficulty of soil removal in blind zones. By using excavators for synchronous partitioned excavation, the single excavation depth is increased compared to conventional caissons, thereby achieving efficient and free soil removal, rapid excavation, reduced waiting time, improved soil removal efficiency, and expanded working space. Since the bottom of the connecting partition wall is an inclined surface sloping downwards from the inner caisson wall cutting edge to the outer caisson wall cutting edge or the partition wall cutting edge, forming a triangular support structure, it provides secondary support for the caisson, enhancing the structural support strength and providing a support foundation for the large height difference between the inner and outer cutting edges.

[0051] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0052] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0053] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A large caisson, characterized in that, It includes: The outer well wall (1) has an outer well wall cutting edge (11) on its bottom end face. The inner well wall (2) is located inside the outer well wall (1), and its bottom end face is provided with an inner well wall cutting foot (21). The bottom elevation of the inner well wall cutting foot (21) is higher than the bottom elevation of the outer well wall cutting foot (11) by a first preset value. The partition wall group (3) includes multiple partition walls (31) arranged perpendicularly to each other, which divide the space inside the outer well wall (1) into multiple areas. The bottom end face of the partition wall is provided with partition wall cutting edge (32), and the bottom elevation of the partition wall cutting edge (32) is higher than the bottom elevation of the outer well wall cutting edge (11) by a second preset value. The first preset value is greater than the second preset value. The connecting partition wall (4) connects the outer well wall (1), the inner well wall (2) and the partition wall (31). Its bottom end face is provided with a connecting partition wall cutting foot (41). The connecting partition wall cutting foot (41) is an inclined surface that slopes downward from the inner well wall cutting foot (21) to the outer well wall cutting foot (11) or the partition wall cutting foot (32).

2. The large caisson as described in claim 1, characterized in that: The first preset value can be determined as 2~8m based on structural calculations.

3. The large caisson as described in claim 1, characterized in that: The second preset value is 0.5-1.0m.

4. The large caisson as described in claim 1, characterized in that: The bottom end face of the inner well wall cutting foot (21) is a tread surface.

5. The large caisson as described in claim 1, characterized in that: The bottom sides of the partition wall blade (32) are sloped.

6. The large caisson as described in claim 1, characterized in that: The bottom of the outer well wall cutting edge (11) is sloped on the side near the inner well wall.

7. A method for excavating soil for constructing a large caisson, characterized in that, The following steps are included: S1: Complete the structural construction of the outer well wall, inner well wall, partition wall group and connecting partition wall of the caisson; S2: Multiple devices simultaneously extract soil and mud inside the caisson borehole for sinking. The mud extraction and sinking are carried out according to the principles of inside to outside, high to low, layered symmetry, and synchronous uniformity. In the early stage of sinking, the soil at the bottom of the outer well wall cutting edge and the cutting edge of the partition wall is retained to form a multi-step support. In the later stage of sinking, the soil at the bottom of the cutting edge of the partition wall is extracted, transitioning to a situation where only the bottom of the outer well wall cutting edge has a support step. S3: Excavate the soil at the bottom of each cutting edge to form a pot-shaped structure until the caisson sinks to the design elevation. At this point, the height of the cutting edge of the partition wall from the soil surface meets the second preset value, and the height of the cutting edge of the inner well wall from the soil surface meets the first preset value.

8. The method for excavating and constructing a large caisson as described in claim 7, characterized in that: The principle of taking soil from the inside out includes: First, remove the soil below the cutting edge and on the inner side of the inner well wall, then remove the soil between the outer and inner well walls; The principle of selecting soil from higher to lower elevations includes: First, remove the soil from the relatively high-lying areas, and then gradually remove the soil from the lower-lying areas.

9. A method for sealing the bottom of a large caisson, characterized in that, Includes the following steps: S1: After the caisson is lowered to the design elevation and the foundation is cleared, a guide pipe is placed along the wall of the filling hole, and crushed stone of a predetermined height is filled into the guide pipe to cover the bottom of the cutting edge of the partition wall. S2: Based on the partition walls, the caisson is divided into a core area and an edge area, wherein: The core area is a central rectangular area surrounded by partition walls and the outer wall of the middle section of the caisson; The edge region is a fan-shaped area between the partition wall and the outer walls at both ends of the caisson; S3: First, pour the core area sealing concrete. After the core area concrete reaches its initial setting strength, pour the edge area sealing concrete.

10. The method for sealing the bottom of a large caisson as described in claim 9, characterized in that: The core area is poured using a diagonal sequential construction method, specifically including: S31: Dividing the core area into four quadrants, and pouring the first diagonal quadrant first; S32: After the concrete in the first diagonal quadrant has initially set, pouring the second diagonal quadrant; The edge area is poured using a symmetrical construction method, specifically including: S33: After the core area has initially set as a whole, pouring the edge area in symmetrical blocks along the circumference of the caisson.

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