A sinking well foundation of a superimposed sunk continuous wall and a construction method thereof

Abstract

The application relates to a caisson foundation of a superimposed embedded continuous wall, which comprises a caisson provided with a well wall, a continuous wall located below the well wall and connected with the well wall, and the bottom of the continuous wall is located below a local scour line; the continuous wall is a double-thin-wall cylinder structure, which comprises an outer wall plate, an inner wall plate and a plurality of partition plates located between the outer wall plate and the inner wall plate and connecting the two. The application superimposes the continuous wall below the existing caisson, on one hand, the bottom of the continuous wall is located below the local scour line, the bearing ground soil under the caisson bottom plate is isolated from the water flow, so that the soil cannot be scoured and eroded, the construction difficulty is reduced, and the risk of sand overturning and sudden sinking accidents during earth taking is reduced; on the other hand, the well wall and the continuous wall jointly provide stable support for the soil outside the well wall, completely isolate the soil from the earth taking construction in the well, and solve the problem of the sand overturning and sudden sinking accidents during the sinking construction of the conventional caisson.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge engineering, in particular to a sinking well foundation of a superimposed sinking type continuous wall and a construction method thereof. BACKGROUND

[0002] The sinking well foundation is a structure in the form of a shaft, which is sunk to a designed elevation after soil is excavated from the well and the gravity of the sinking well foundation itself overcomes the frictional resistance of the well wall, and then a bottom plate is formed by sealing the bottom with concrete, so that the sinking well foundation becomes the foundation of a bridge pier or other structure, and has the advantages of large rigidity, strong resistance to horizontal load, high vertical bearing capacity, etc.

[0003] In the related art, the sinking well foundation needs to be cut and sunk in the well hole, and the sinking well posture needs to be controlled while cutting and sinking. Affected by factors such as uneven destruction of the soil column of the well wall, interference of the cutting and sinking construction in the well, and the like, the soil outside the well wall is prone to locally sanding and flowing into the well, the sinking well loses support locally, and cannot maintain balance, and thus the sinking well may suddenly sink, the sinking well posture may be tilted, and even the sinking well may be locally damaged, which has high safety risks, low construction efficiency, and large control difficulty.

[0004] In addition, when designing a conventional sinking well foundation, in addition to meeting the bearing capacity requirement, the sinking well bottom plate also needs to be placed below the local scouring line to prevent the bridge from being damaged due to long-term erosion of the foundation soil by water flow. Influenced by this, although the bearing capacity of some soil layers already meets the bearing requirement, the sinking well bottom plate cannot be used as a bearing layer because the embedding depth is above the local scouring line, and thus the embedding depth of the sinking well bottom plate needs to be increased, which further increases the risk of sanding and sudden sinking during soil cutting. SUMMARY

[0005] Embodiments of the present application provide a sinking well foundation of a superimposed sinking type continuous wall and a design method thereof, to solve the technical problems of the related art that the sinking well foundation is prone to sanding and sudden sinking during sinking, and the depth and difficulty of soil cutting of the sinking well are increased due to the water flow scouring factor.

[0006] A first aspect of embodiments of the present application provides a sinking well foundation of a superimposed sinking type continuous wall, which includes a sinking well provided with a well wall, and a continuous wall located below the well wall and connected with the well wall, and the bottom of the continuous wall is located below the local scouring line.

[0007] The continuous wall is a double-thin-walled cylindrical structure, which includes an outer wall plate, an inner wall plate, and a plurality of partition plates located between the outer wall plate and the inner wall plate and connecting the two.

[0008] In some embodiments, the well wall comprises a well wall outer shell, a well wall inner shell, a well wall blade foot, and a water jet pipe, the well wall outer shell, the well wall inner shell, and the well wall blade foot collectively define a receiving space, the water jet pipe is arranged in the receiving space and penetrates through the well wall blade foot and extends into the continuous wall, and the inner wall plate is provided with a plurality of mud discharge holes and / or mud discharge grooves.

[0009] In some embodiments, the mud discharge holes and / or the mud discharge grooves are uniformly distributed on the inner wall plate.

[0010] In some embodiments, the mud discharge holes and / or the mud discharge grooves are circular or polygonal.

[0011] In some embodiments, the bottom of the inner wall plate is a flat surface or is provided with a plurality of circular arc surfaces recessed from the bottom to the top.

[0012] In some embodiments, the caisson is provided with a partition wall connected with the well wall in the well wall, the partition wall is provided with a partition wall blade foot, and in the vertical direction, the bottom of the partition wall blade foot is between the top and the bottom of the continuous wall.

[0013] In some embodiments, the bottom of the caisson is above the local scour line.

[0014] The second aspect of the embodiments of the present application provides a construction method of a caisson foundation of a composite caisson embedded continuous wall, comprising the following steps:

[0015] The continuous wall and the caisson are moved to the pier site, and the bottom of the caisson is connected with the top of the continuous wall;

[0016] The concrete is poured in the well wall of the caisson, so that the continuous wall and the caisson are sequentially embedded into the foundation;

[0017] The soil is removed from the caisson by undrained excavation until the bottom of the caisson reaches the design elevation, and the bottom of the continuous wall is below the local scour line;

[0018] The concrete is poured at the bottom and the top of the caisson respectively, the bottom plate and the top cover of the caisson are constructed, and the caisson foundation of the composite caisson embedded continuous wall is formed.

[0019] In some embodiments, the well wall is provided with a water jet pipe extending into the continuous wall, and the inner wall plate of the continuous wall is provided with a plurality of mud discharge holes and / or mud discharge grooves penetrating therethrough;

[0020] When the soil is taken out in the caisson, the sludge discharge holes and / or sludge discharge grooves on the inner wall plate of the continuous wall expose the sludge surface, water is sprayed into the continuous wall through the water jet pipe, and the sludge water formed is taken into the caisson through the sludge discharge holes and / or sludge discharge grooves together with the soil in the caisson.

[0021] In some embodiments, the caisson and / or the continuous wall are segmented and prefabricated.

[0022] The technical scheme provided in the application has the beneficial effects including:

[0023] The continuous wall is superimposed below the existing caisson, on the one hand, the bottom of the continuous wall is located below the local scouring line, which isolates the bearing foundation soil below the caisson bottom plate from the water flow, so that it will not be eroded by the water flow, and fundamentally solves the problem of increased caisson soil taking depth caused by water flow scouring, reduces the construction difficulty and the risk of sand overturning and sudden sinking accidents during soil taking; on the other hand, the continuous wall is located below the caisson and connected with the well wall, the well wall and the continuous wall jointly provide stable support for the soil outside the well wall, which is completely isolated from the water jet, soil breaking, mud suction and other well interior soil taking construction, fundamentally solving the problem of sand overturning and sudden sinking accidents during the sinking construction of the conventional caisson, realizing fast and safe construction and saving cost. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical scheme in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0025] Figure 1 It is a schematic diagram of the overall structure of the caisson foundation superimposed with the continuous wall in the embodiment of the application.

[0026] Figure 2 It is an internal sectional view of the caisson foundation superimposed with the continuous wall in the embodiment of the application.

[0027] Figure 3 It is a structural schematic diagram of the well wall in the embodiment of the application.

[0028] Figure 4 It is an external side view of the continuous wall in the embodiment of the application.

[0029] Figure 5 It is an internal side view of the continuous wall in the embodiment of the application.

[0030] Figure 6 It is a sectional view of the continuous wall in the embodiment of the application.

[0031] REFERENCE NUMERALS:

[0032] 1, caisson; 11, shaft wall; 111, shaft wall outer shell; 112, shaft wall inner shell; 113, shaft wall blade foot; 114, water jet pipe; 12, partition wall; 121, partition wall blade foot; 13, bottom plate; 14, top cover; 2, continuous wall; 21, outer wall plate; 22, inner wall plate; 221, sludge discharge hole; 23, partition plate. DETAILED DESCRIPTION

[0033] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying 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 of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0034] Referring to Figure 1 , Figure 2 illustrated, wherein, Figure 1 is a whole structure schematic diagram of a caisson foundation of a composite sinking continuous wall in the embodiments of the present application. Figure 2 is an internal section view of the caisson foundation of the composite sinking continuous wall in the embodiments of the present application.

[0035] The first aspect of the embodiments of the present application provides a caisson foundation of a composite sinking continuous wall, which comprises a caisson 1 provided with a shaft wall 11, and a continuous wall 2 located below the shaft wall 11 and connected with the shaft wall 11, and the bottom of the continuous wall 2 is located below a local scour line.

[0036] The continuous wall 2 is a double-thin-wall cylinder structure, which comprises an outer wall plate 21, an inner wall plate 22, and a plurality of partition plates 23 located between the outer wall plate 21 and the inner wall plate 22 and connecting the two, and the top of the outer wall plate 21 and the top of the inner wall plate 22 are respectively connected with the bottom of the shaft wall 11.

[0037] The embodiments of the present application superimpose the continuous wall below the existing caisson. On the one hand, the local scour refers to the scouring around the bridge pier due to the change of water flow structure caused by the water blocking of the bridge pier. Under the action of water flow scouring, the bottom of the continuous wall is located below the local scour line, which isolates the bearing foundation soil under the caisson bottom plate from the water flow, so that it will not be scoured and eroded, and fundamentally solves the problem of increased caisson soil depth caused by water flow scouring, reduces the construction difficulty and the risk of sand overturning and sudden sinking accidents during soil taking; on the other hand, the continuous wall is located below the caisson and connected with the shaft wall, and the shaft wall and the continuous wall jointly provide stable support for the soil outside the shaft wall, completely isolating it from the water jet, soil breaking, mud suction and other in-well soil taking construction, fundamentally solving the problem of sand overturning and sudden sinking accidents during the sinking construction of the conventional caisson, and realizing fast and safe construction and cost saving.

[0038] The caisson 1 is specifically a steel shell caisson, and the steel shell is filled with concrete.

[0039] As shown in the drawings, Figure 2 The caisson 1 includes a shaft wall 11, a partition wall 12, a bottom plate 13 and a top cover 14. The shaft wall 11 bears water and soil pressure. The partition wall 12 is located inside the shaft wall 11 and connected thereto, and divides the internal space of the shaft wall 11 into several shaft holes as earth removal passages. The partition wall 12 increases the rigidity of the caisson 1, improves the stress condition of the shaft wall 11, balances earth removal, and facilitates deviation correction. The bottom plate 13 and the top cover 14 are both casted by concrete. The bottom plate 13 is located at the bottom of the caisson 1 and connected to the bottom of the shaft wall 11 and the partition wall 12 respectively. The top cover 14 is located at the top of the caisson 1 and connected to the top of the shaft wall 11 and the partition wall 12 respectively.

[0040] As shown in the drawings, Figure 3 Figure 3 The structure of the shaft wall in the embodiments of the present application is shown.

[0041] In some embodiments, the shaft wall 11 includes a shaft wall outer shell 111, a shaft wall inner shell 112, a shaft wall blade foot 113 and a water jet pipe 114. The shaft wall outer shell 111, the shaft wall inner shell 112 and the shaft wall blade foot 113 together enclose a receiving space, and the water jet pipe 114 is arranged in the receiving space and penetrates through the shaft wall blade foot 113 and extends into the continuous wall 2.

[0042] Specifically, the shaft wall 11 is a steel shell concrete structure. The shaft wall outer shell 111 and the shaft wall inner shell 112 are both steel shells, and the receiving space enclosed by the shaft wall outer shell 111, the shaft wall inner shell 112 and the shaft wall blade foot 113 is filled with concrete. The bottom of the shaft wall outer shell 111 is connected to the top of the outer wall plate 21 of the continuous wall 2, and the bottom of the shaft wall inner shell 112 is connected to the top of the inner wall plate 22 of the continuous wall 2, so as to connect the shaft wall 11 and the continuous wall 2 into one body.

[0043] The shaft wall blade foot 113 is connected to the bottom of the shaft wall outer shell 111 and the shaft wall inner shell 112 respectively, and the upper part thereof is inclined to the inner side of the caisson 1. The water jet pipe 114 penetrates through the concrete and penetrates through the through hole formed on the shaft wall blade foot 113 and extends into the top of the continuous wall 2.

[0044] As shown in the drawings, Figure 2 In some embodiments, the bottom of the partition wall 12 is provided with a partition wall blade foot 121. In the vertical direction, the height of the bottom of the partition wall blade foot 121 is lower than the height of the bottom of the shaft wall blade foot 113. Further, the bottom of the partition wall blade foot 121 is between the top and the bottom of the continuous wall 2, that is, the position of the bottom of the partition wall blade foot 121 is higher than the position of the bottom of the continuous wall 2 and lower than the position of the top of the continuous wall 2.

[0045] ​In some embodiments, the bottom of the caisson 1 is located above the local flush line.

[0046] When the bearing capacity of the foundation meets the requirements, the bottom of the caisson 1, that is, the bottom plate 13 can be placed above the local scour line, which can appropriately reduce the soil excavation depth of the caisson 1, reduce the amount of soil excavation, and reasonably reduce the project cost and construction difficulty.

[0047] In some embodiments, the continuous wall 2 is a steel structure, and the outer wall panels 21, inner wall panels 22 and partition panels 23 are all steel plates. The continuous wall 2 is a bottomless and coverless grid structure surrounded by the outer wall panels 21, inner wall panels 22 and partition panels 23.

[0048] like Figure 4 As shown, Figure 4 1. The outer side view of the continuous wall in the embodiment of the present invention. In some embodiments, the outer wall plate 21 is not provided with holes or grooves, providing sufficient support for the soil outside the well wall 11.

[0049] like Figure 5 As shown, Figure 5 This is a side view of the interior of a continuous wall according to an embodiment of the present invention. In some embodiments, the inner wall panel 22 is provided with a plurality of mud drainage holes 211 and / or mud drainage grooves therethrough to facilitate the drainage of muddy water. Mud drainage holes and mud drainage grooves may be provided in combination, or alternatively, depending on actual working conditions.

[0050] In some embodiments, the mud discharge holes 211 and / or mud discharge grooves are evenly distributed on the inner wall plate 22. The even distribution leads to a more uniform mud discharge effect.

[0051] In some embodiments, the mud discharge hole 211 and / or the mud discharge groove are circular or polygonal. The shape and size of the mud discharge hole and the mud discharge groove are not limited and can be set according to actual working conditions.

[0052] In some embodiments, the bottom of the inner wall plate 22 is a flat surface, or is provided with a plurality of arc surfaces that are concave from the bottom to the top. When the bottom of the inner wall plate 22 is an arc surface, the sinking resistance can be reduced.

[0053] like Figure 6 As shown, Figure 6 2 is a cross-sectional view of a continuous wall in an embodiment of the present invention.

[0054] In some embodiments, the cross section of the continuous wall 2 is I-shaped at the diaphragm 23 , and the local bending stiffness is greater.

[0055] A second aspect of the present application provides a method for constructing a caisson foundation of a superimposed sunken continuous wall, comprising the following steps:

[0056] Step 1: Move the continuous wall 2 and the caisson 1 to the pier position, and connect the bottom of the caisson 1 with the top of the continuous wall 2;

[0057] Step two, pouring concrete in the shaft wall 11 of the caisson 1, so that the continuous wall 2, caisson 1 in turn sink into the foundation;

[0058] Step three, using undrained excavation method from the caisson 1 to take soil until the bottom of the caisson 1 reaches the design elevation, the bottom of the continuous wall 2 is below the local scour line;

[0059] Step four, pouring concrete at the bottom and top of the caisson 1 respectively, completing the construction of the bottom plate 13 and the top cover 14 of the caisson to form the caisson foundation of the superimposed sinking continuous wall.

[0060] In step one, the continuous wall 2 and the caisson 1 are both prefabricated, as they are large structural components, the caisson 1 and the continuous wall 2 can be prefabricated in segments, such as being divided into several segments in the height direction and several blocks in the plane direction during prefabrication, and then transported to the site to be connected into a whole on site, facilitating transportation and installation.

[0061] When connecting the caisson 1 and the continuous wall 2, the first step is the process of assisted floating and self-sinking, as the continuous wall 2 cannot float by itself, it needs to rely on the floating box to make its top surface exposed to the water. The first segment of the caisson 1 has a shaft wall blade foot 113, which is moved to the pier position and installed above the continuous wall 2 and connected thereto; then the subsequent caisson segments are gradually connected in height, and as part of the caisson segments are installed, the floating box can be gradually released, allowing the installed part to gradually sink until the floating box is completely released.

[0062] In step two, concrete is poured in the shaft wall 11 of the caisson 1 to increase the weight, which is for the process of weight-increasing sinking, so that the continuous wall 2 sinks into the foundation first; then the caisson segments are continuously connected in height and concrete is continuously poured, the caisson 1 also sinks into the foundation, keeping the top of the constructed part above the water surface by a certain distance.

[0063] In step three, when the weight-increasing sinking is slow, or the height of the constructed part is not convenient for construction, for the process of normal soil excavation sinking, the soil is taken out underwater in the caisson 1, until the soil surface in the caisson reaches the height of the partition wall blade foot 121.

[0064] When taking out the soil, the support resistance generated by the hard soil column formed at the end face of the shaft wall 11 and the partition wall blade foot 121 is the end resistance, and the soil resistance received by the side surface of the shaft wall 11 and the partition wall 12, including friction and cohesion, is the side resistance. The soil is taken out in an undrained excavation manner, and the air suction dredger can be used for preliminary soil taking, and the suction pipe thereof is a suspended flexible equipment.

[0065] When the soil is shallow, the air suction dredger can eliminate part of the side resistance and part of the end resistance in the caisson 1, and the constructed part continues to sink under the action of its own weight.

[0066] When the suction dredging of soil in the caisson 1 is continued, and the soil surface in the caisson is lower than the height of the blade foot 121 of the partition wall 12 and higher than the bottom of the continuous wall 2, the resistance of the partition wall 12 and the resistance of the inner side of the shaft wall are removed, and the caisson 1 continues to sink.

[0067] Since the blade foot 113 of the shaft wall is below the soil extraction blind area, there is usually a hard soil column supporting it, and if it is not removed, it will generate a large end resistance. At this time, the soil extraction process is over, and the height of the free surface on both sides of the soil column can be increased by the super suction soil extraction technology, so that the soil column is more easily removed.

[0068] Since the position of the blade foot 113 of the shaft wall is higher than the position of the blade foot 121 of the partition wall, when the blade foot 121 of the partition wall is separated from the soil surface, the soil discharge hole 221 on the inner wall plate 22 below the blade foot 113 of the shaft wall is exposed to the soil surface, which provides the condition for removing the soil column. At this time, water is sprayed into the top cavity of the continuous wall 2 through the water jet pipe 114 to break the soil column supporting the shaft wall 11. After the soil column is broken, the mud water formed by the soil column is discharged into the caisson 1 through the soil discharge hole 221, and is discharged from the caisson 1 together with the suction dredging of soil. The end resistance of the shaft wall 11 is removed, and the caisson 1 continues to sink.

[0069] During the super suction soil extraction in the caisson 1 and the water jet breaking of the shaft wall 11, the continuous wall 2 always stably supports the soil on the outside of the shaft wall 11 to avoid disturbance from the soil extraction and water jet construction, so that the soil is prevented from being unstable and sanding, and the problem of sanding and sudden sinking accidents during the sinking construction of the caisson is completely solved, and the rapid sinking construction of the caisson foundation structure can be realized.

[0070] When the bottom of the caisson 1 approaches the design elevation, the water jet and super suction soil extraction are stopped for the stop suction and leveling process, so that the blade foot 121 of the partition wall, which is separated from the soil surface, re-contacts and inserts into the soil surface, and the caisson 1 slowly sinks, and the blade foot 121 of the partition wall is immersed in the soil surface. At the same time, the soil surface in the caisson 1 is leveled, and the soil attached to the shaft wall 11 and the partition wall 12 is cleaned. When the elevation of the blade foot 121 of the partition wall has reached the design height and cannot insert into the soil surface to separate the bottom plate 13 into compartments, graded gravel can be thrown and filled into the well hole of the caisson 1 and leveled, so that the blade foot 121 of the partition wall is lower than the surface of the graded gravel.

[0071] In step four, the construction method of the bottom plate 13 and the top cover 14 is a prior art, which is not described here.

[0072] In the description of the present application, it needs to be explained that the terms "upper", "lower" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise expressly specified and limited, the terms "mounting", "connection", "connection", "floating box", "mud", "soil", "soil column" should be understood broadly, for example, "connection" can be fixed connection, or detachable connection, or integral connection; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0073] It should be noted that in the present application, relational terms such as "first" and "second" and the like are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the sentence "including a..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0074] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications of these embodiments will be apparent 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 will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A caisson foundation for a diaphragm wall, characterised in that, It comprises a caisson (1) provided with a shaft wall (11), and a continuous wall (2) located below the shaft wall (11) and connected with the shaft wall (11), the bottom of the continuous wall (2) is below the local scour line; The continuous wall (2) is a double-thin-wall cylinder structure, comprising an outer wall plate (21), an inner wall plate (22), and a plurality of partitions (23) located between the outer wall plate (21) and the inner wall plate (22) and connecting the two; The shaft wall (11) comprises a shaft wall outer shell (111), a shaft wall inner shell (112), a shaft wall blade foot (113), and a water jet pipe (114), the shaft wall outer shell (111), the shaft wall inner shell (112), and the shaft wall blade foot (113) together enclose a receiving space, the water jet pipe (114) is provided in the receiving space and penetrates the shaft wall blade foot (113) and extends into the double-thin-wall continuous wall (2), the inner wall plate (22) is provided with a plurality of mud discharge holes (221) and / or mud discharge grooves penetrating therethrough; The caisson (1) is provided with a partition wall (12) connected with the shaft wall (11) in the shaft wall (11), the partition wall (12) is provided with a partition wall blade foot (121), and in the vertical direction, the bottom of the partition wall blade foot (121) is between the top and bottom of the continuous wall (2).

2. A caisson foundation for a diaphragm wall according to claim 1, wherein The mud discharge holes (221) and / or the mud discharge grooves are uniformly distributed on the inner wall plate (22).

3. A caisson foundation for a diaphragm wall according to claim 1, wherein The mud discharge holes (221) and / or the mud discharge grooves are circular or polygonal.

4. A caisson foundation for a diaphragm wall according to claim 1, wherein The bottom of the inner wall plate (22) is a flat surface or is provided with a plurality of circular arc surfaces recessed from the bottom to the top.

5. A caisson foundation for a diaphragm wall according to claim 1, wherein The bottom of the caisson (1) is above the local scour line.

6. A method of constructing a caisson foundation for a diaphragm wall according to any one of claims 1 to 5, wherein It comprises the following steps: The continuous wall (2) and the caisson (1) are moved to the pier position, and the bottom of the caisson (1) is connected with the top of the continuous wall (2); The shaft wall (11) of the caisson (1) is poured with concrete, so that the continuous wall (2) and the caisson (1) are successively sunk into the foundation; The soil is taken out from the caisson (1) by undrained excavation until the bottom of the caisson (1) reaches the design elevation, and the bottom of the continuous wall (2) is below the local scour line; The bottom and top of the caisson (1) are respectively poured with concrete, the bottom plate and top cover of the caisson (1) are completed, and the caisson foundation of the superimposed sinking continuous wall is formed; The shaft wall (11) is provided with a water jet pipe (114) extending into the continuous wall (2), and the inner wall plate (22) of the continuous wall (2) is provided with a plurality of mud discharge holes (221) and / or mud discharge grooves penetrating therethrough; When soil is taken out of the caisson (1), the position of the wall blade foot (113) is higher than the position of the partition wall blade foot (121), when the partition wall blade foot (121) is separated from the mud surface, the mud discharge hole (221) and / or the mud discharge groove on the inner wall plate (22) of the continuous wall (2) are exposed to the mud surface, water is sprayed into the continuous wall (2) through the water spraying pipe (114), the mud water formed is taken into the caisson (1) through the mud discharge hole (221) and / or the mud discharge groove, and is taken out together with the soil in the caisson (1).

7. A method of constructing a caisson foundation for a diaphragm wall according to claim 6, wherein The caisson (1) and / or the continuous wall (2) are precast in sections.

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