Open caisson structure with preset sinking channel and construction method

Abstract

The invention relates to the technical field of open caisson construction, and particularly discloses an open caisson structure with a preset sinking channel and a construction method.The open caisson structure comprises an open caisson solid structure and the sinking channel, the open caisson solid structure is arranged above the sinking channel and comprises a plurality of criss-cross well walls, and an open caisson is divided into a plurality of well bin areas; the well wall is a double-wall type concrete wall body and is a vertically-through middle hollow body formed by an outer well wall body, an inner well wall body and longitudinal and transverse intersection points, the sinking channel is composed of a plurality of sets of channel piles, the channel piles comprise under-wall channel piles, out-wall channel piles and inter-wall channel piles, the inter-wall channel piles correspond to the middle hollow body in position, and the outer well wall body and the inner well wall body are connected through the channel piles. The under-wall channel piles are arranged below the under-wall blade feet, and the out-wall channel piles are arranged on the outer side of the outer well wall and the outer side of the inner well wall respectively. The open caisson can be built in different soil layers, balanced accompanying sinking can be achieved in the building process, and the open caisson can be built by penetrating through a deep and thick clay layer; and a deep foundation reinforcing and bottom sealing scheme is provided, and dry excavation of well bin earthwork can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of caisson construction, and specifically discloses a caisson structure with a preset sinking channel and a construction method. Background Art

[0002] Caisson technology has a long history of application and a wide range of applications. It has formed a mature method in bridge foundations and anchor foundation projects, and is also widely used in the foundations of construction projects or excavation protection projects.

[0003] At present, the caisson construction technology is to take soil from the well hole and sink it by its own weight, supplemented by air curtain, water jet and other sinking assistance measures to ensure smooth sinking. The caisson construction process includes: leveling the site, making the first section of the caisson, removing the mold and pulling out the pads, digging and sinking, raising the caisson, foundation inspection and other treatments, bottom sealing, filling the well hole and capping the top.

[0004] During the sinking process, the caisson may experience the following problems: difficulty in sinking, sudden sinking or sinking too fast, sand turning over, tilting, deviation, etc. The reasons for these problems are: uneven distribution of strata; uneven soil excavation methods and scope, etc.

[0005] During the construction of the caisson, there are still problems such as difficulty in penetrating thick clay layers and the caisson's own weight cannot overcome the resistance of the well wall; the drainage and sinking process can easily cause the surrounding strata to sink, which is detrimental to surrounding buildings.

[0006] Especially when the caisson is large in scale, the upper soft foundation has low bearing capacity. Before the first section of the caisson is made, the foundation within the longitudinal and transverse walls of the caisson needs to be temporarily reinforced. Sand pile reinforcement to form a composite foundation is a common method. After the reinforcement, the bearing capacity of the foundation is improved, which can ensure the stability of the foundation made in the first section of the caisson. However, the increase in the bearing capacity of the foundation makes sinking difficult. Summary of the invention

[0007] To solve the above problems, the present invention provides the following technical solutions: a caisson structure with a preset sinking channel, comprising a caisson physical structure and a sinking channel, wherein the caisson physical structure is placed above the sinking channel, and is characterized in that: the caisson physical structure comprises a plurality of criss-crossed well walls, which divide the caisson into a plurality of well storage areas, and the vertical and horizontal intersections are solid concrete walls; the well walls are double-walled concrete walls, and an intermediate hollow body which passes through from top to bottom is formed by an outer well wall, an inner well wall and the vertical and horizontal intersections, and both the outer well wall and the inner well wall are provided with under-wall cutting feet; the sinking channel is composed of a plurality of groups of channel piles, and the channel piles comprise under-wall channel piles, outside-wall channel piles and between-wall channel piles, and the between-wall channel piles correspond to the position of the intermediate hollow body, the under-wall channel piles are arranged below the under-wall cutting feet, and the outside-wall channel piles are respectively arranged on the outsides of the outer well wall and the inner well wall.

[0008] Preferably, an inner support is further provided in the middle hollow body, and the inner support is a solid concrete structure fixedly connected to the inner well wall and the outer well wall.

[0009] Preferably, the inner supports are arranged at intervals of 2 meters in the horizontal direction and at intervals of 2 meters in the vertical direction.

[0010] Preferably, the outer side of the outer well wall and the inner well wall are further provided with friction reducing parts, and the friction reducing parts are not convex structures, and are arranged horizontally along the outer side of the outer well wall and the inner well wall.

[0011] Preferably, the channel piles are filled with one of the materials selected from the group consisting of medium sand, fine sand, sandy soil, crushed stone, pebbles, etc., or a combination thereof.

[0012] The present invention also discloses a caisson construction method with a preset sinking channel, and the specific steps are as follows: S1: Mark out the caisson construction area and level the site; S2: Determine the plane size of the sinking channel according to the width of the well wall, and mark the scope of the sinking channel on the ground; S3: Drive inter-wall channel piles at the center of the middle hollow body; drive under-wall channel piles at the center axis of the blade foot under the wall; drive outside-wall channel piles outside the outer well wall and the inner well wall edge line; the channel pile driving method includes pipe pulling, reverse insertion, vibration retention, and repeated driving. By controlling the stroke length and time of pipe pulling, reverse insertion, vibration retention and the number of repeated driving, the foundation bearing capacity of different soil layers can be adjusted.

[0013] S4: Dig two meters from the ground to the bottom of the sinking channel to form a trench for the installation of the first section of the caisson steel shell; S5: After the first section of the caisson steel shell is installed, the working surface groove on the outside of the caisson wall is backfilled and compacted; S6: pouring concrete for the first section of the caisson structure; S7: Use a high-pressure water gun in conjunction with an air sludge suction machine in the middle hollow body to gradually lower the wall channel piles and surrounding soil, and the caisson gradually sinks. When the top surface of the first section of the caisson approaches the ground, stop the air sludge suction machine; S8: Carry out the next section of caisson heightening operation; S9: In the middle hollow body, the high-pressure water gun is used in combination with the air sludge suction machine to gradually lower the wall channel piles and the surrounding soil, and the caisson gradually sinks. When the top surface of this section of the caisson approaches the ground, the air sludge suction machine is stopped; S10: Repeat S8 and S9 until the designed sinking depth is reached; S11: The subsequent soil excavation work in the well storage area is completed and the construction is completed.

[0014] Furthermore, the first section of the caisson solid structure adopts a steel shell concrete structure, and the other sections adopt a reinforced concrete structure.

[0015] Furthermore, the step S11 may have two construction methods according to different back cover technologies, specifically: The first one: S111: Deep foundation reinforcement in the well storage area; S112: Dry excavation of earthwork is carried out in the well storage area; dig to the deep foundation and reinforce the top surface; construction is completed.

[0016] Second type: S111: Underwater concrete pouring is performed in the middle hollow body to make the caisson solid structure reach a stable state; S112: Use a high-pressure water gun and an air suction mud machine to extract soil from the well storage area; S113: When the soil taken from the well storage area reaches the elevation of the caisson bottom, the concrete underwater bottom sealing is carried out and the construction is completed.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. Use channel piles that penetrate the entire depth of the caisson to make the soil layer below the caisson wall consistent and homogenous, so that the caisson sinks more evenly and synchronously; channel piles penetrate the deep clay layer, effectively pre-destroy the bearing capacity and cohesion of the clay layer, and promote smoother sinking; use a high-pressure water gun and an air suction mud machine from the middle hollow body to gradually reduce the wall channel piles and surrounding soil, so that the composite foundation bearing capacity of the sinking channel can be adjusted and reduced during the construction process to meet the needs of caisson sinking, and adjust the foundation bearing capacity during the process of caisson heightening and sinking. Achieve balanced accompanying sinking during the construction process, and at the same time, build caissons through deep clay layers.

[0018] 2. The sinking state of the caisson is changed from relying on the method of height connection configuration to adjusting the bearing capacity of the composite foundation of the sinking channel to promote the sinking of the caisson; the height of each section of the caisson can be lowered, and it can sink once after each height connection. There is no need to connect the heights multiple times to achieve the sinking state. The reduction of the height connection avoids high-altitude operations and makes the construction safer; the mixing of sand and gravel channel piles under the action of water can simultaneously destroy the cohesion of the deep clay layer, which is more efficient in soil extraction in the clay layer and avoids the stagnation of the caisson; the bearing capacity of the composite foundation of the sinking channel can be adjusted and unloaded artificially, and the first section can achieve self-sinking, avoiding the use of drainage methods to assist sinking, and avoiding the impact on surrounding buildings, pipelines, etc.; the setting of the outer wall channel piles and friction reducers can reduce the friction resistance of the outer walls of the longitudinal and transverse walls, making the sinking of the caisson smoother. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a top view of the overall structure of the present invention; Figure 2It is a side view of the local structure of the caisson body of the present invention; Figure 3 It is a side view of the caisson body and the channel piles of the present invention; Among them: 1. Well wall; 11. Outer well wall; 12. Inner well wall; 2. Middle hollow body; 3. Inner support; 4. Vertical and horizontal intersections; 5. Channel piles; 51. Channel piles outside the wall; 52. Channel piles under the wall; 53. Channel piles between the walls; 6. Friction reducing parts; 7. Blade feet under the wall. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] A caisson structure with a preset sinking channel comprises a caisson entity structure and a sinking channel, wherein the caisson entity structure is placed above the sinking channel, and is characterized in that: the caisson entity structure comprises a plurality of criss-crossed shaft walls 1, which divide the caisson into a plurality of shaft storage areas, and the vertical and horizontal intersections 4 are solid concrete walls; the shaft wall 1 is a double-walled concrete wall, and an intermediate hollow body 2 which passes through from top to bottom is formed by an outer shaft wall 11, an inner shaft wall 12 and the vertical and horizontal intersections 4, and both the outer shaft wall 11 and the inner shaft wall 12 are provided with under-wall cutting feet 7; the sinking channel is composed of a plurality of groups of channel piles 5, and the channel piles 5 comprise under-wall channel piles 52, outside-wall channel piles 51 and between-wall channel piles 53, and the between-wall channel piles 53 correspond to the positions of the intermediate hollow body 2, the under-wall channel piles 52 are arranged below the under-wall cutting feet 7, and the outside-wall channel piles 51 are respectively arranged on the outsides of the outer shaft wall 11 and the inner shaft wall 12.

[0022] Specifically, an inner support 3 is further provided in the middle hollow body. The inner support 3 is a solid concrete structure and is fixedly connected to the outer well wall 11 and the inner well wall 12 .

[0023] Specifically, the inner supports 3 are arranged at intervals of 2 meters in the horizontal direction and at intervals of 2 meters in the vertical direction.

[0024] Specifically, the outer sides of the outer well wall 11 and the inner well wall 12 are further provided with friction reducing members 6 . The friction reducing members 6 are convex structures and are arranged horizontally along the outer sides of the outer well wall 11 and the inner well wall 12 .

[0025] Specifically, the channel piles are formed by filling with a combination of medium sand, fine sand, sandy soil, crushed stone, pebbles and other materials.

[0026] The present invention also discloses a caisson construction method with a preset sinking channel, and the specific steps are as follows: S1: Mark out the caisson construction area and level the site; S2: Determine the plane size of the sinking channel according to the width of the well wall 1, and mark the scope of the sinking channel on the ground; S3: An inter-wall channel pile 53 is driven at the center of the middle hollow body 2; a wall channel pile 52 is driven at the center axis of the wall blade foot 7; an outer wall channel pile 51 is driven outside the edge of the outer well wall 11 and the inner well wall 12; the channel pile driving method includes the procedures of pulling out the pipe, reverse insertion, retaining vibration, and repeated driving. By controlling the stroke length and time of the pulling out the pipe, reverse insertion, retaining vibration procedures and the number of repeated driving times, the foundation bearing capacity of different soil layers can be adjusted.

[0027] S4: Dig two meters from the ground to the bottom of the sinking channel to form a trench for the installation of the first section of the caisson steel shell; S5: After the first section of the caisson steel shell is installed, the working surface groove on the outside of the caisson wall is backfilled and compacted; S6: pouring concrete for the first section of the caisson structure; S7: A high-pressure water gun is used in conjunction with an air sludge suction machine to gradually lower the wall channel piles 53 and the surrounding soil in the middle hollow body 2, and the caisson gradually sinks. When the top surface of the first section of the caisson approaches the ground, the air sludge suction machine is stopped; S8: Carry out the next section of caisson heightening operation; S9: A high-pressure water gun is used in conjunction with an air sludge suction machine to gradually lower the wall channel piles 53 and the surrounding soil in the middle hollow body 2, and the caisson gradually sinks. When the top surface of the caisson in this section approaches the ground, the air sludge suction machine is stopped; S10: Repeat S8 and S9 until the designed sinking depth is reached; S11: The subsequent soil excavation work in the well storage area is completed and the construction is completed.

[0028] Specifically, the first section of the caisson solid structure adopts a steel shell concrete structure, and the other sections adopt a reinforced concrete structure.

[0029] Specifically, the step S11 is as follows: S111: pouring underwater concrete in the middle hollow body 2 to make the caisson entity structure reach a stable state; S112: Use a high-pressure water gun and an air suction mud machine to extract soil from the well storage area; S113: When the soil taken from the well storage area reaches the elevation of the caisson bottom, the concrete underwater bottom sealing is carried out and the construction is completed.

[0030] The basic principle of the present invention is to set the caisson wall as a through structure, with the inner and outer walls provided with under-wall blades, and with the assistance of channel piles, a sinking channel is formed, so that the wall can sink while retaining the original soil in the well bin area, and finally, after the caisson wall reaches the designed depth and stabilizes, soil is taken from the well bin. This directly subverts the previous drainage caisson construction method.

[0031] The core technical solution for achieving the purpose of the present invention is the design of channel piles, which reserve a sinking channel for the caisson, adjust the bearing capacity of the foundation of each soil layer, directly avoid the risk of sudden sinking that may occur during the sinking process of the previous caisson construction, and also ensure the balance of the caisson.

[0032] The soil excavation work after the caisson of the present invention sinks to the designed depth is relatively flexible. It is possible to first reinforce the deep foundation and then perform dry soil excavation, or to first stabilize the caisson wall and then perform hydraulic soil excavation. This can provide construction personnel with the best solution when encountering different working conditions.

[0033] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A caisson structure with a preset sinking channel, comprising a caisson entity structure and a sinking channel, wherein the caisson entity structure is placed above the sinking channel, and is characterized in that: The caisson entity structure comprises a plurality of crisscrossing well walls (1) which divide the caisson into a plurality of well storage areas, and the vertical and horizontal intersections (4) are solid concrete walls; the well wall (1) is a double-walled concrete wall, and is composed of an outer well wall (11), an inner well wall (12) and the vertical and horizontal intersections (4) to form a middle hollow body (2) that passes through from top to bottom, and the outer well wall (11) and the inner well wall (12) are both provided with under-wall blade feet (7); the sinking channel is composed of a plurality of groups of channel piles (5), and the channel piles (5) comprise under-wall channel piles (52), outside-wall channel piles (51) and between-wall channel piles (53), and the between-wall channel piles (53) correspond in position to the middle hollow body (2), the under-wall channel piles (52) are arranged below the under-wall blade feet (7), and the outside-wall channel piles (51) are respectively arranged on the outside of the outer well wall (11) and the inner well wall (12).

2. The caisson structure with a preset sinking channel according to claim 1, characterized in that: An inner support (3) is also provided in the middle hollow body (2); the inner support (3) is a solid concrete structure and is fixedly connected to the outer well wall (11) and the inner well wall (12).

3. The caisson structure with a preset sinking channel according to claim 2, characterized in that: The inner supports (3) are arranged at intervals of 2 meters in the horizontal direction and at intervals of 2 meters in the vertical direction.

4. The caisson structure with a preset sinking channel according to claim 1, characterized in that: The outer sides of the outer well wall (11) and the inner well wall (12) are also provided with friction reducing parts (6), and the friction reducing parts (6) are convex structures and are arranged horizontally along the outer sides of the outer well wall (11) and the inner well wall (12).

5. The caisson structure with a preset sinking channel according to claim 1, characterized in that: The channel piles (5) are formed by filling with one of medium sand, fine sand, sandy soil, crushed stone, and pebbles, or a combination thereof.

6. A method for constructing a caisson with a preset sinking channel, comprising a caisson structure with a preset sinking channel as claimed in any one of claims 1 to 5, wherein the specific steps of the caisson construction method are as follows: S1: Mark out the caisson construction area and level the site; S2: Determine the plane size of the sinking channel according to the width of the well wall (1), and mark the scope of the sinking channel on the ground; S3: Driving an inter-wall channel pile (53) at the center of the middle hollow body (2); driving an under-wall channel pile (52) at the center axis of the under-wall blade foot (7); driving an outer-wall channel pile (51) outside the edge of the outer well wall (11) and the inner well wall (12); the channel pile driving method includes the procedures of pulling out the pipe, reverse insertion, retaining vibration, and repeated driving, and the bearing capacity of the foundation of different soil layers is adjusted by controlling the stroke length and time of the pulling out the pipe, reverse insertion, retaining vibration and the number of repeated driving; S4: Dig two meters from the ground to the bottom of the sinking channel to form a trench for the installation of the first section of the caisson steel shell; S5: After the first section of the caisson steel shell is installed, the working surface groove on the outside of the caisson wall is backfilled and compacted; S6: pouring concrete for the first section of the caisson structure; S7: using a high-pressure water gun in conjunction with an air sludge suction machine in the middle hollow body (2) to gradually lower the wall channel piles (53) and the surrounding soil, the caisson gradually sinks, and when the top surface of the first section of the caisson approaches the ground, the air sludge suction machine is stopped; S8: Carry out the next section of caisson heightening operation; S9: using a high-pressure water gun in conjunction with an air sludge suction machine in the middle hollow body (2) to gradually lower the wall channel piles (53) and the surrounding soil, the caisson gradually sinks, and when the top surface of the caisson in this section approaches the ground, the air sludge suction machine is stopped; S10: Repeat S8 and S9 until the designed sinking depth is reached; S11: The subsequent soil excavation work in the well storage area is completed and the construction is completed.

7. A method for constructing a caisson with a preset sinking channel according to claim 6, characterized in that: The first section of the caisson solid structure adopts a steel shell concrete structure, and the other sections adopt a reinforced concrete structure.

8. The method for constructing a caisson with a preset sinking channel according to claim 6, characterized in that: The step S11 is specifically as follows: S111: Deep foundation reinforcement in the well storage area; S112: Dry excavation of earthwork is carried out in the well storage area; dig to the deep foundation and reinforce the top surface; construction is completed.

9. The method for constructing a caisson with a preset sinking channel according to claim 6, characterized in that: The step S11 is specifically as follows: S111: pouring underwater concrete in the middle hollow body (2) so that the caisson solid structure reaches a stable state; S112: Use a high-pressure water gun and an air suction mud machine to extract soil from the well storage area; S113: When the soil taken from the well storage area reaches the elevation of the caisson bottom, the concrete underwater bottom sealing is carried out and the construction is completed.

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