Cofferdam device without inner support based on soft soil foundation and construction method of cofferdam device

Abstract

The invention relates to an inner-support-free cofferdam device based on a soft soil foundation and a construction method of the inner-support-free cofferdam device. The cofferdam splicing units are connected in an inserted mode to define a cofferdam module, cement mixing pile groups are constructed on the inner sides and the outer sides of the cofferdam splicing units correspondingly to form a first protection structure and a second protection structure correspondingly, the cofferdam module is maintained, the foundation bearing capacity and the anti-surge capacity are improved, and the inserting and driving depth of the cofferdam splicing units and the design elevation of a foundation pit are reduced. And the soil body in the cofferdam module is excavated, and at least two layers of concrete ring beams are arranged in the cofferdam module, so that the requirement of the cofferdam module without an inner support is met, the influence of cross construction is reduced, and the convenience of excavation operation and the construction efficiency of a bearing platform are improved. And compared with a profile steel enclosing purlin, only concrete materials are used, and the using amount of turnover materials such as profile steel is saved. According to the cofferdam device without the inner support, through the arrangement of the first protection structure, the second protection structure and the concrete ring beam, the use of steel materials is reduced, the structural safety is high, and the construction process is simplified.

Description

Technical Field

[0001] The present application relates to the technical field of cofferdams, and in particular to a cofferdam device without internal support based on a soft soil foundation and a construction method thereof. Background Art

[0002] In the process of bridge construction, it is often necessary to build bridge piers in areas with complex geological conditions such as riverbanks and riverbanks. These areas are often rich in groundwater, with thick soft soil layers with high water content and large thixotropic flow, which brings challenges to bridge foundation construction.

[0003] In order to build bridge pier caps in these areas, it is usually necessary to construct deep and large foundation pit cofferdams during construction. Traditional construction methods mainly rely on steel sheet piles or steel pipe piles, and set up multi-layer steel purlins and steel pipe pile top support structures inside the cofferdam to support the stability of the cofferdam. However, this structural design requires a large amount of steel, which on the one hand leads to a significant increase in material costs, and on the other hand, the internal support structure of the steel purlin is easily deformed due to force during construction, resulting in reduced safety and may also cause safety accidents; on the other hand, the multi-layer internal support structure leads to limited construction space in the foundation pit, affecting the work efficiency of the foundation pit excavation, and the subsequent layered construction of the cap requires multiple conversion constructions according to the form of the cofferdam internal support, which prolongs the construction period. Summary of the invention

[0004] Based on this, it is necessary to provide a non-inner-supported cofferdam device based on soft soil foundation and its construction method in view of the problems of high material cost, low structural safety and low construction efficiency of traditional foundation pit cofferdams when facing complex geological conditions and water environments.

[0005] A non-inner-supported cofferdam device based on a soft soil foundation, the non-inner-supported cofferdam device comprises a cofferdam module, a concrete ring beam, a first protective structure and a second protective structure, the cofferdam module comprises a plurality of cofferdam splicing units, the plurality of cofferdam splicing units are plugged in sequentially, and the plurality of cofferdam splicing units are connected end to end and gathered together to form a circular foundation pit in the cofferdam module; the number of the concrete ring beams is at least two, and each of the concrete ring beams is arranged on the inner wall of the cofferdam module at intervals along the depth direction of the cofferdam module; the first protective structure is arranged on the inner side of the cofferdam module, and the first protective structure is composed of a cement mixing pile group; the second protective structure is arranged on the outer peripheral side of the cofferdam module, and the second protective structure is composed of a cement mixing pile group.

[0006] In one embodiment, the unsupported cofferdam device also includes an anchoring assembly, and an anchoring hole is provided at the position where the concrete ring beam is arranged on the cofferdam module, and the axial direction of the anchoring hole is in an oblique downward direction from the cofferdam module to the outer soil body; one end of the anchoring assembly passes through the anchoring hole and is anchored in the soil body outside the cofferdam module, and the other end is fixed on the concrete ring beam.

[0007] In one embodiment, the concrete ring beam includes a steel cage and a ring beam concrete body, the steel cage is an annular steel cage, the steel cage is fixed on the inner wall of the cofferdam module having the anchor hole, and the ring beam concrete body is cast on the steel cage; an outer wall of the ring beam concrete body is formed as a fixed wall, and the plane where the fixed wall is located is perpendicular to the axis of the anchor hole; the anchor assembly includes an anchor head and an anchor rod, one end of the anchor rod passes through the anchor hole and is anchored in the soil outside the cofferdam module, and the other end passes through the steel cage, and the anchor head is installed on the other end of the anchor rod and fixed to the fixed wall of the ring beam concrete body.

[0008] In one of the embodiments, at least two anchor holes are provided at the position of each of the concrete ring beams, and the anchor holes are spaced apart around the axis of the cofferdam module. The number of the anchor assemblies is consistent with the number of the anchor holes, and one anchor assembly is correspondingly provided in each of the anchor holes, and the anchor assemblies on two adjacent concrete ring beams are staggered.

[0009] In one embodiment, the number of the cofferdam modules is two, the two cofferdam modules are arranged at intervals along the direction away from the water area, the two cofferdam modules are connected by a connecting module, and the axial direction of the anchor hole does not extend in the direction toward the water area; at least five anchor assemblies are arranged on the cofferdam module away from the water area, and the extension direction of each anchor assembly on the cofferdam module is away from the connecting module or parallel to the position of the connecting module; at least four anchor assemblies are arranged on the cofferdam module close to the water area, and the extension direction of each anchor assembly on the cofferdam module is toward the connecting module or parallel to the position of the connecting module.

[0010] In one embodiment, the first protective structure includes a first protective unit, which includes a plurality of first cement mixing piles. The first cement mixing piles are arranged on the inner side of the cofferdam splicing unit and are adjacent to the cofferdam splicing unit. Each of the first cement mixing piles is engaged with two first cement mixing piles adjacent to the left and right.

[0011] In one embodiment, the first protection structure also includes a second protection unit and a plurality of third protection units, the second protection unit is located on the inner side of the first protection unit, the second protection unit includes a plurality of second cement mixing piles, and the second cement mixing piles are arranged at intervals; the third protection unit is arranged between the first protection unit and the second protection unit, and the third protection units are arranged at intervals around the axis of the cofferdam module, the third protection unit includes a plurality of third cement mixing piles, and the third cement mixing piles of each third protection unit are interlocked with each other.

[0012] In one embodiment, the cement mixing piles of the cement mixing pile group forming the first protective structure include a reinforcement section and an excavation section, the reinforcement section is connected to the excavation section, and the reinforcement section is located below the excavation section, the connection between the reinforcement section and the excavation section is located above the design depth of the foundation pit, and the strength of the reinforcement section is greater than the strength of the excavation section, and the cement mixing pile group of the first protective structure can be excavated to the bottom wall of the foundation pit.

[0013] In one embodiment, the second protective structure includes a plurality of mixing positioning piles and a plurality of interlocking piles, and every two of the mixing positioning piles are interlocked with each other through an interlocking pile to form a protective wall. The protective walls are arranged at intervals around the outer periphery of the cofferdam module, and at least two layers are arranged. The intervals between the protective walls form a circuitous channel from the outside to the cofferdam module.

[0014] In one of the embodiments, a cushion layer is cast on the bottom wall of the foundation pit, and the thickness of the cushion layer is 0.2m-0.5m.

[0015] In one embodiment, the cofferdam device without internal support also includes a plurality of first supporting columns and a plurality of second supporting columns. The plurality of first supporting columns are arranged at intervals around the axis of the cofferdam module and are all located between two adjacent concrete ring beams, and the opposite ends of each of the first supporting columns are respectively abutted against the two adjacent concrete ring beams; the plurality of second supporting columns are arranged at intervals around the axis of the cofferdam module and are all located between the bottom wall of the foundation pit and the concrete ring beam at the lowest layer, and the opposite ends of each of the second supporting columns are respectively abutted against the bottom wall of the foundation pit and the concrete ring beam at the lowest layer.

[0016] In the above-mentioned non-inner-supported cofferdam device based on soft soil foundation, each cofferdam splicing unit is plugged into each other to form a cofferdam module, and cement mixing pile groups are constructed on the inner and outer sides of the cofferdam splicing unit to form a first protective structure and a second protective structure respectively. On the one hand, it can maintain the cofferdam module and improve the anti-deformation ability of the cofferdam module. On the other hand, it can reinforce the soil on both sides of the cofferdam module to improve the bearing capacity and surge resistance of the foundation. Therefore, the insertion depth of the cofferdam splicing unit can be appropriately reduced, and the design elevation of the foundation pit can also be appropriately reduced to improve construction efficiency. Then, the soil in the cofferdam module is excavated and removed, and at least two layers of concrete ring beams are set in the cofferdam module. The concrete ring beams are supported and reinforced from the inner side of the cofferdam module to improve the stability of the cofferdam module structure. The setting of the concrete ring beam eliminates the need for an internal support structure in the cofferdam module. On the one hand, it can reduce the impact of cross-construction, increase the convenience of excavation operations, effectively reduce the excavation period of the foundation pit, seal the bottom as soon as possible, and improve the safety of the foundation pit construction; on the other hand, it can optimize the layered construction process of the pedestal and reduce the process conversion time; there are no obstacles in the cofferdam, which has little impact on the pedestal construction, effectively improving the efficiency of the pedestal construction. Moreover, the concrete ring beam has high redundancy and easy control of precision. Compared with the steel purlin, it fully utilizes the structural force characteristics of the circular concrete ring beam; the concrete ring beam only uses concrete materials, which greatly saves the amount of circulating materials such as steel. The above-mentioned cofferdam device without internal support replaces the steel purlin with a concrete ring beam, reduces the use of steel, simplifies the construction process, and improves the stability and safety of the structure through the first protective structure, the second protective structure and the concrete ring beam.

[0017] A construction method for a cofferdam device without internal support, wherein the construction method is used to form the cofferdam device without internal support as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application.

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] In addition, the drawings are not drawn to a 1:1 scale, and the relative sizes of various elements are drawn only as examples in the drawings and are not necessarily drawn according to the true scale.

[0021] Figure 1 It is a structural schematic diagram of a cofferdam device without internal support in an embodiment applied in a soft soil foundation area.

[0022] Figure 2 for Figure 1 A partial top view of a cofferdam device without internal support is shown.

[0023] Figure 3 for Figure 1 The cofferdam device without internal support shown omits a partial top view of the first protective structure and the second protective structure.

[0024] Figure 4 for Figure 3 The cross-sectional view of the cofferdam device without internal support along the AA line is shown.

[0025] Figure 5 for Figure 3 The cross-sectional view of the cofferdam device without internal support along the BB line is shown.

[0026] Figure 6 for Figure 5 Enlarged view of point C in the middle.

[0027] Description of reference numerals: A cofferdam device without internal support 10; a cofferdam module 100; a cofferdam splicing unit 110; a foundation pit 120; an anchor hole 130; a concrete ring beam 200; a fixed wall 210; a first protective structure 300; a first protective unit 310; a first cement mixing pile 312; a second protective unit 320; a second cement mixing pile 322; a third protective unit 330; a third cement mixing pile 332; a second protective structure 400; a protective wall 402; a mixing positioning pile 410; a snap pile 420; an anchor assembly 500; an anchor head 510; an anchor rod 520; a connection module 600; and a cap 20. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] See also Figures 1 to 3The non-inner-supported cofferdam device 10 based on a soft soil foundation in one embodiment of the present application can also be understood as a non-inner-supported cofferdam device 10 used in waterfront areas. Specifically, the cofferdam device 10 without internal support includes a cofferdam module 100, a concrete ring beam 200, a first protective structure 300 and a second protective structure 400. The cofferdam module 100 includes a plurality of cofferdam splicing units 110, which are plugged in sequentially, and the plurality of cofferdam splicing units 110 are connected end to end and gathered together to form a circular foundation pit 120 in the cofferdam module 100; the number of concrete ring beams 200 is at least two, and each concrete ring beam 200 is arranged on the inner wall of the cofferdam module 100 at intervals along the depth direction of the cofferdam module 100; the first protective structure 300 is arranged on the inner side of the cofferdam module 100, and the first protective structure 300 is composed of a cement mixing pile group; the second protective structure 400 is arranged on the outer peripheral side of the cofferdam module 100, and the second protective structure 400 is composed of a cement mixing pile group.

[0030] During construction, the first section of the cofferdam splicing unit 110 is inserted and driven into the preset construction area; when the first section of the cofferdam splicing unit 110 is inserted and driven into place, the next section of the cofferdam splicing unit 110 is continuously inserted and driven until all the cofferdam splicing units 110 are surrounded to form a cofferdam module 100. A cement mixing pile group is constructed inside the inserted cofferdam splicing unit 110 to form a first protective structure 300. A cement mixing pile group is constructed outside the inserted cofferdam splicing unit 110 to form a second protective structure 400. Cement mixing pile groups are constructed on the inner and outer sides of the cofferdam splicing unit 110 to form a first protective structure 300 and a second protective structure 400. On the one hand, this can protect the cofferdam module 100 and improve the deformation resistance of the cofferdam module 100. On the other hand, this can reinforce the soil on both sides of the cofferdam module 100 to improve the bearing capacity and surge resistance of the foundation. As a result, the insertion depth of the cofferdam splicing unit 110 can be appropriately reduced, and the design elevation of the foundation pit 120 can also be appropriately reduced, thereby improving construction efficiency.

[0031] Then, the soil in the cofferdam module 100 is excavated to the design elevation of a layer of concrete ring beam 200; the concrete ring beam 200 is cast at the design elevation of the layer of concrete ring beam 200 inside the cofferdam module 100; when the concrete ring beam 200 of this layer reaches the design strength, the soil in the cofferdam module 100 is continued to be excavated to the design elevation of the next layer of concrete ring beam 200; the casting is repeated until all concrete ring beams 200 are cast; the soil in the cofferdam module 100 is continued to be excavated to the bottom of the foundation pit 120. The concrete ring beam 200 is supported and reinforced from the inside of the cofferdam module 100 to improve the stability of the cofferdam module 100 structure. The setting of the concrete ring beam 200 makes it unnecessary to set up an internal support structure in the cofferdam module 100. On the one hand, it can reduce the impact of cross-construction, increase the convenience of excavation operations, effectively reduce the excavation period of the foundation pit 120, seal the bottom as soon as possible, and improve the construction safety of the foundation pit 120; on the other hand, it can optimize the layered construction process of the cap 20 and reduce the process conversion time; there are no obstacles in the cofferdam, which has little impact on the construction of the cap 20, and effectively improves the construction efficiency of the cap 20. Moreover, the construction redundancy of the concrete ring beam 200 is high and the precision is easy to control. Compared with the steel purlin, it fully utilizes the structural force characteristics of the circular concrete ring beam 200; the concrete ring beam 200 only uses concrete materials, which greatly saves the amount of circulating materials such as steel. The above-mentioned cofferdam device 10 without internal support replaces the steel purlin with the concrete ring beam 200, reduces the use of steel, simplifies the construction process, and improves the stability and safety of the structure through the first protective structure 300, the second protective structure 400 and the concrete ring beam 200.

[0032] In this embodiment, the cofferdam splicing unit 110 is a steel pipe pile, which has good structural stability when driven and is easy to plug in. In other embodiments, the cofferdam splicing unit 110 may also be a steel sheet pile.

[0033] In one embodiment, the first protective structure 300 includes a first protective unit 310, and the first protective unit 310 includes a plurality of first cement mixing piles 312. The first cement mixing piles 312 are arranged inside the cofferdam splicing unit 110 and are adjacent to the cofferdam splicing unit 110, and each first cement mixing pile 312 is engaged with two first cement mixing piles 312 adjacent to the left and right. By constructing the first cement mixing piles 312 at a position adjacent to the cofferdam splicing unit 110, the first cement mixing piles 312 can be directly supported on the cofferdam splicing unit 110, and at the same time, since the first cement mixing piles 312 are engaged together to form the first protective unit 310, the first protective unit 310 can be evenly and stably supported on the inside of the cofferdam module 100, ensuring the uniformity of force at each position. In other embodiments, the first cement mixing piles 312 may not be engaged or may be partially engaged together.

[0034] Specifically, the first protective structure 300 also includes a second protective unit 320, which is located inside the first protective unit 310. The second protective unit 320 includes a plurality of second cement mixing piles 322, and each second cement mixing pile 322 is arranged at intervals. The first protective structure 300 also includes a plurality of third protective units 330, which are arranged between the first protective unit 310 and the second protective unit 320, and each third protective unit 330 is arranged at intervals around the axis of the cofferdam module 100. The third protective unit 330 includes a plurality of third cement mixing piles 332, and each third cement mixing pile 332 of each third protective unit 330 is engaged with each other. The second cement mixing piles 322 can reinforce the foundation of the entire construction area of ​​the cap 20, and ensure the reliability of the subsequent support of the cap 20; and the uniform arrangement of each second cement mixing pile 322 can improve the uniformity of the support. The first protection unit 310 and the second protection unit 320 are connected via a third protection unit 330 formed by a third cement mixing pile 332 , and the third protection units 330 are arranged at intervals to avoid constructing too many cement mixing piles while reinforcing the soil inside the cofferdam module 100 .

[0035] During construction, after inserting a section or part of the cofferdam splicing unit 110, the first cement mixing pile 312 of the first protection unit 310 and the second cement mixing pile 322 of the second protection unit 320 can be constructed first. After the first cement mixing pile 312 and the second cement mixing pile 322 are solidified, the third cement mixing pile 332 of the third protection unit 330 can be constructed, thereby improving construction efficiency while ensuring the effect of reinforcing the soil.

[0036] In one embodiment, the cement mixing piles of the cement mixing pile group forming the first protective structure 300 include a reinforcement section and an excavation section, the reinforcement section is connected to the excavation section, and the reinforcement section is located below the excavation section. The connection between the reinforcement section and the excavation section is located above the design depth of the foundation pit 120, and the strength of the reinforcement section is greater than the strength of the excavation section. The cement mixing pile group of the first protective structure 300 can be excavated to the bottom wall of the foundation pit 120. The cement mixing pile group forming the first protective structure 300 is located inside the cofferdam module 100. In the subsequent construction, the inside of the cofferdam module 100 needs to be excavated to form the foundation pit 120, so as to facilitate the pouring of the cap 20. Then, the part of the cement mixing pile forming the first protective structure 300 located on the foundation pit 120 and the part located below the foundation pit 120 are formed by different slurries, so that the strength of the reinforcement section is greater than the strength of the excavation section, so that the excavation section can be easily removed in the subsequent construction, reducing the difficulty of excavation and ensuring the construction efficiency.

[0037] For example, the cement specific gravity of the mud forming the reinforcement section is greater than the cement specific gravity of the cement forming the excavation section, thereby improving the strength of the reinforcement section. In other embodiments, other substances that improve the solidification strength may also be added to the mud forming the reinforcement section.

[0038] In one embodiment, the second protective structure 400 includes a plurality of mixing and positioning piles 410 and a plurality of interlocking piles 420. Every two mixing and positioning piles 410 are interlocked by an interlocking pile 420 to form a protective wall 402. Each protective wall 402 is arranged at intervals around the outer periphery of the cofferdam module 100, and at least two layers are arranged. The intervals between each protective wall 402 form a detour channel from the outside to the cofferdam module 100. The second protective structure 400 can improve the foundation strength outside the cofferdam module 100 and reduce the lateral pressure of the soil on the cofferdam module 100. And because the protective walls 402 are arranged at intervals and staggered, a detour channel can be formed. While strengthening, the influence of external soil creep or deformation on the cofferdam module 100 is reduced, and the protective wall 402 is prevented from being completely enclosed outside the cofferdam module 100, and the pressure of soil creep or deformation is prevented from being fully applied to the second protective structure 400, which affects the reliability of the second protective structure 400. In this embodiment, both the mixing and positioning piles 410 and the engaging piles 420 are cement mixing piles.

[0039] See also Figures 3 to 6 In one embodiment, the cofferdam device without internal support 10 also includes an anchoring assembly 500, and an anchoring hole 130 is opened at the position where the cofferdam module 100 is provided with a concrete ring beam 200, and the axial direction of the anchoring hole 130 is in an oblique downward direction from the cofferdam module 100 to the outer soil; one end of the anchoring assembly 500 passes through the anchoring hole 130 and is anchored in the soil outside the cofferdam module 100, and the other end is fixed on the concrete ring beam 200.

[0040] In the waterfront area, the foundation pit cofferdam is built and the foundation pedestal 20 is poured. The soft soil layer is thick. If the water level in the water area drops rapidly, the pore water pressure inside the slope of the water area cannot be dissipated in time, and the pressure difference will cause seepage in the construction area toward the water area. If the water level in the water area rises suddenly, the water rate in the construction area will increase and the thixotropic flow will increase. The cofferdam device 10 without internal support needs to be constructed in such an area. Therefore, it is particularly important to ensure the stability of the construction environment and the reliability of the structure of the cofferdam device 10 without internal support after construction.

[0041] like Figure 1As shown, when the water level in the water area rises or falls, the infiltration line in the slope will also rise or fall accordingly, and the cofferdam module 100 is built on a soft soil foundation or a muddy foundation. The subsequent construction base will exert gravity on the soft soil. The soft soil at the base of the cofferdam is prone to slip under the gravity of the structure, which may cause the cofferdam module 100 to become unstable. Therefore, by drilling the anchor hole 130 directly in the inner side of the cofferdam module 100 in the outward direction and forming the anchor assembly 500 in the anchor hole 130, the horizontal deformation of the soft soil layer or the muddy soil layer caused by the change of the water level can be resisted. At the same time, the anchor assembly 500 is fixed by the concrete ring beam 200 inside the cofferdam module 100. The concrete ring beam 200 fixes the anchor assembly 500 while supporting the structural stability of the cofferdam module 100. In turn, the tension of the anchor assembly 500 can be used to firmly press the concrete ring beam 200 against the inner wall of the cofferdam module 100.

[0042] In this embodiment, anchoring grout is poured into the anchor hole 130 to form the anchor assembly 500. Specifically, high-pressure splitting grouting can be used to further improve the anchoring effect of the anchor assembly 500. For example, secondary grouting can be used to perform grouting.

[0043] In one embodiment, an outer wall of the concrete ring beam 200 is formed as a fixed wall 210, and the plane where the fixed wall 210 is located is perpendicular to the axis of the anchor hole 130. The anchor assembly 500 includes an anchor head 510 and an anchor rod 520. One end of the anchor rod 520 passes through the anchor hole 130 and is anchored in the soil outside the cofferdam module 100, and the other end passes through the concrete ring beam 200. The anchor head 510 is installed on the other end of the anchor rod 520 and fixed on the fixed wall 210 of the concrete ring beam 200. By forming the fixed wall 210 on the concrete ring beam 200, the uniformity of the pressure applied by the anchor head 510 on the fixed wall 210 when the anchor rod 520 is fixed on the concrete ring beam 200 can be ensured, thereby avoiding excessive stress on the local part of the concrete ring beam 200 and affecting its structural stability.

[0044] Specifically, the concrete ring beam 200 includes a steel cage and a ring beam concrete body. The steel cage is an annular steel cage, which is fixed on the inner wall of the cofferdam module 100 with an anchor hole 130, and the ring beam concrete body is cast on the steel cage. An outer wall of the ring beam concrete body is formed as a fixed wall 210. The other end of the anchor rod 520 passes through the steel cage, and the anchor head 510 is installed on the other end of the anchor rod 520 and fixed on the fixed wall 210 of the ring beam concrete body. The anchor hole 130 can be opened first and the anchor rod 520 can be anchored in the anchor hole 130, and then the steel cage is set so that the other end of the anchor rod 520 passes through the steel cage. Then, concrete is cast to form the concrete ring beam 200, and the other end of the anchor rod 520 passes through the fixed wall 210, so that the anchor rod 520 can be tightened and fixed on the fixed wall 210 through the anchor head 510.

[0045] In one embodiment, at least two anchor holes 130 are provided at the position of each concrete ring beam 200, and each anchor hole 130 is arranged at intervals around the axis of the cofferdam module 100. The number of anchor assemblies 500 is consistent with the number of anchor holes 130, and an anchor assembly 500 is correspondingly arranged in each anchor hole 130, and the anchor assemblies 500 on two adjacent concrete ring beams 200 are staggered. By providing at least two layers of concrete ring beams 200, the fixing reliability of the cofferdam module 100 can be improved, and the anchor assembly 500 is provided at the position of each layer of concrete ring beams 200, which can ensure that the cofferdam module 100 is anchored at different positions at different depths, improve the reliability of anchoring, and the staggered arrangement of the anchor assemblies 500 on different layers can achieve anchoring at different positions of the circumference of the cofferdam module 100.

[0046] In one embodiment, there are two cofferdam modules 100, and the two cofferdam modules 100 are arranged at intervals in the direction away from the water area. The two cofferdam modules 100 are connected by a connecting module 600, and the axis direction of the anchor hole 130 does not extend in the direction toward the water area. At least five anchor assemblies 500 are arranged on the cofferdam module 100 away from the water area, and the extension direction of each anchor assembly 500 on the cofferdam module 100 is opposite to the connecting module 600 or parallel to the position of the connecting module 600. At least four anchor assemblies 500 are arranged on the cofferdam module 100 close to the water area, and the extension direction of each anchor assembly 500 on the cofferdam module 100 is toward the connecting module 600 or parallel to the position of the connecting module 600. When the water level in the water area changes, the soil at the construction location creeps or changes direction mainly to deform or collapse toward the water area. Therefore, by setting the extension direction of the anchor assembly 500 to be parallel to or opposite to the water area, the cofferdam module 100's ability to resist deformation can be improved.

[0047] For example, in this embodiment, the number of the concrete ring beams 200 is three layers. In other embodiments, the number of the concrete ring beams 200 can also be two layers.

[0048] In one embodiment, the cofferdam device 10 without internal support further includes a plurality of first support columns and a plurality of second support columns. The plurality of first support columns are arranged at intervals around the axis of the cofferdam module 100 and are all located between two adjacent concrete ring beams 200. The opposite ends of each first support column are respectively abutted against two adjacent concrete ring beams 200. The plurality of second support columns are arranged at intervals around the axis of the cofferdam module 100 and are all located between the bottom wall of the foundation pit 120 and the concrete ring beam 200 at the lowest layer. The opposite ends of each second support column are respectively abutted against the bottom wall of the foundation pit 120 and the concrete ring beam 200 at the lowest layer. By providing the first support columns and the plurality of second support columns, the concrete ring beam 200 can be supported vertically downward, thereby ensuring the reliability of the concrete ring beam 200 being arranged in the cofferdam module 100.

[0049] In this embodiment, a cushion layer is cast on the bottom wall of the foundation pit 120, and the thickness of the cushion layer is 0.2m-0.5m. The present application forms a first protective structure 300 and a second protective structure 400 by constructing cement mixing pile groups on both the inner and outer sides of the cofferdam splicing unit 110, thereby strengthening the protection of the cofferdam splicing unit 110 and reinforcing the soil on both the inner and outer sides of the cofferdam module 100, so that the insertion depth of the cofferdam splicing unit 110 can be appropriately reduced, and the design elevation of the foundation pit 120 can also be appropriately reduced. By setting the anchor assembly 500, the stability effect of the cofferdam module 100 in the soil is improved, and the ability of the cofferdam module 100 to resist horizontal surge and deformation is increased. The concrete ring beam 200 is set on the inner side of the cofferdam module 100 to realize the cofferdam module 100 without internal support, reserve sufficient construction space, reduce cross-influence, and increase the convenience of excavation operations. In summary, the thickness of the cushion layer poured on the bottom wall of the foundation pit 120 can be reduced to 0.2m-0.5m. The thickness of the traditional cushion layer generally requires more than 3m. Compared with the traditional solution, the excavation depth of the foundation pit 120 can be reduced by about 3m, and the insertion depth of the cofferdam splicing unit 110 can be reduced by at least 3m, which can reduce the amount of cofferdam splicing units 110 by at least 3m, thereby improving construction efficiency and saving steel usage. In the present application, the cofferdam module 100 can be a permanent cofferdam, and the cofferdam module 100 can be used to protect the internal cap 20 structure, thereby improving the service life of the cap 20 and the reliability during use.

[0050] See also Figures 1 to 3 In one embodiment, a construction method of a cofferdam device without internal support 10 can form a cofferdam device without internal support 10 in any of the above embodiments, and the construction method includes: Step S1: inserting the first section of the cofferdam splicing unit 110 in a preset construction area; Step S2: After the first section of the cofferdam splicing unit 110 is inserted and driven into place, the next section of the cofferdam splicing unit 110 is continuously inserted and driven until all the cofferdam splicing units 110 are gathered together to form a cofferdam module 100; Step S3: constructing a cement mixing pile group inside the inserted cofferdam splicing unit 110 to form a first protective structure 300; Step S4: constructing a cement mixing pile group outside the inserted cofferdam splicing unit 110 to form a second protective structure 400; Step S5: excavating the soil in the cofferdam module 100 to the designed elevation of a layer of concrete ring beam 200; Step S6: pouring the layer of concrete ring beam 200 at the designed elevation of the layer of concrete ring beam 200 inside the cofferdam module 100 .

[0051] Specifically, the step S6 includes: Step S61: at the designed elevation, drilling an anchor hole 130 from the inner side of the cofferdam module 100 in a direction away from the water area; installing an anchor rod 520 in the anchor hole 130; Step S61: fixing the steel cage of the concrete ring beam 200 on the inner wall of the cofferdam module 100, and installing the ring beam template on the outer side of the steel cage so that the anchor rod 520 passes through the steel cage; Step S63: pouring anchor slurry into the anchor hole 130; Step S64: Casting the concrete ring beam 200 in the ring beam template so that the concrete ring beam 200 covers the slurry in the anchor hole 130; Step S65: When the concrete ring beam 200 reaches the designed strength, the anchor rods 520 are tensioned and the anchor rods 520 are sealed on the concrete ring beam 200 through the anchor heads 510 .

[0052] Step S7: When the concrete ring beam 200 of this layer reaches the designed strength, continue to excavate the soil in the cofferdam module 100 to the designed elevation of the next layer of concrete ring beam 200; Step S8: Repeat the steps of pouring the current layer of concrete ring beams 200 and continuing to excavate to the design elevation of the next layer of concrete ring beams 200 until the pouring of all concrete ring beams 200 is completed.

[0053] Step S9: Continue to excavate the soil in the cofferdam module 100 to the designed elevation of the foundation pit 120 .

[0054] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0055] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0056] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0057] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0058] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0059] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A non-inner-supported cofferdam device based on soft soil foundation, characterized in that: The cofferdam device without internal support comprises: A cofferdam module, wherein the cofferdam module comprises a plurality of cofferdam splicing units, the plurality of cofferdam splicing units are plugged in sequentially, and the plurality of cofferdam splicing units are connected end to end and gathered together, so that a circular foundation pit is formed in the cofferdam module; Concrete ring beams, the number of which is at least two, each of which is arranged on the inner wall of the cofferdam module at intervals along the depth direction of the cofferdam module; A first protective structure, which is arranged inside the cofferdam module and is composed of a cement mixing pile group; and The second protective structure is arranged on the outer peripheral side of the cofferdam module, and the second protective structure is composed of a cement mixing pile group.

2. The cofferdam device without inner support according to claim 1, characterized in that: The unsupported cofferdam device also includes an anchoring assembly. An anchoring hole is provided at the position where the concrete ring beam is arranged on the cofferdam module. The axial direction of the anchoring hole is in an oblique downward direction from the cofferdam module to the outer soil body. One end of the anchoring assembly passes through the anchoring hole and is anchored in the soil body outside the cofferdam module, and the other end is fixed on the concrete ring beam.

3. The cofferdam device without inner support according to claim 2, characterized in that: The concrete ring beam includes a steel cage and a ring beam concrete body, the steel cage is an annular steel cage, the steel cage is fixed on the inner wall of the cofferdam module with the anchor hole, and the ring beam concrete body is cast on the steel cage; an outer wall of the ring beam concrete body is formed as a fixed wall, and the plane where the fixed wall is located is perpendicular to the axis of the anchor hole; the anchor assembly includes an anchor head and an anchor rod, one end of the anchor rod passes through the anchor hole and is anchored in the soil outside the cofferdam module, and the other end passes through the steel cage, and the anchor head is installed on the other end of the anchor rod and fixed to the fixed wall of the ring beam concrete body.

4. The cofferdam device without inner support according to claim 3, characterized in that: At least two anchor holes are provided at the position of each of the concrete ring beams, and the anchor holes are spaced apart around the axis of the cofferdam module. The number of the anchor components is consistent with the number of the anchor holes. An anchor component is correspondingly provided in each of the anchor holes, and the anchor components on two adjacent concrete ring beams are staggered.

5. The cofferdam device without inner support according to claim 4, characterized in that: There are two cofferdam modules, which are spaced apart in a direction away from the water area, connected by a connecting module, and the axial direction of the anchor hole does not extend in a direction toward the water area; at least five anchor assemblies are arranged on the cofferdam module away from the water area, and an extension direction of each anchor assembly on the cofferdam module is away from the connecting module or is parallel to a position of the connecting module; at least four anchor assemblies are arranged on the cofferdam module close to the water area, and an extension direction of each anchor assembly on the cofferdam module is toward the connecting module or is parallel to a position of the connecting module.

6. The cofferdam device without inner support according to any one of claims 1 to 5, characterized in that: The first protective structure includes a first protective unit, which includes a plurality of first cement mixing piles. The first cement mixing piles are arranged on the inner side of the cofferdam splicing unit and are adjacent to the cofferdam splicing unit. Each of the first cement mixing piles is engaged with two adjacent first cement mixing piles on the left and right.

7. The cofferdam device without inner support according to claim 6, characterized in that: The first protection structure also includes a second protection unit and multiple third protection units, the second protection unit is located on the inner side of the first protection unit, the second protection unit includes multiple second cement mixing piles, and each of the second cement mixing piles is arranged at intervals; the third protection unit is arranged between the first protection unit and the second protection unit, and each of the third protection units is arranged at intervals around the axis of the cofferdam module, the third protection unit includes multiple third cement mixing piles, and each of the third cement mixing piles of each of the third protection units is interlocked with each other.

8. The cofferdam device without inner support according to claim 6, characterized in that: The cement mixing piles of the cement mixing pile group forming the first protective structure include a reinforcement section and an excavation section. The reinforcement section is connected to the excavation section and is located below the excavation section. The connection between the reinforcement section and the excavation section is located above the designed depth of the foundation pit, and the strength of the reinforcement section is greater than the strength of the excavation section. The cement mixing pile group of the first protective structure can be excavated to the bottom wall of the foundation pit.

9. The cofferdam device without inner support according to any one of claims 1 to 5, characterized in that: The second protective structure includes a plurality of mixing and positioning piles and a plurality of bite piles, and each two of the mixing and positioning piles are bitten by a bite pile to form a protective wall, and each of the protective walls is arranged at intervals around the outer periphery of the cofferdam module, and at least two layers are arranged, and the intervals between each of the protective walls form a circuitous channel from the outside to the cofferdam module; and / or A cushion layer is cast on the bottom wall of the foundation pit, and the thickness of the cushion layer is 0.2m-0.5m; and / or The unsupported cofferdam device also includes a plurality of first supporting columns and a plurality of second supporting columns. The plurality of first supporting columns are spaced apart around the axis of the cofferdam module and are all located between two adjacent concrete ring beams, and the opposite ends of each of the first supporting columns are respectively abutted against two adjacent concrete ring beams; the plurality of second supporting columns are spaced apart around the axis of the cofferdam module and are all located between the bottom wall of the foundation pit and the concrete ring beam at the lowest layer, and the opposite ends of each of the second supporting columns are respectively abutted against the bottom wall of the foundation pit and the concrete ring beam at the lowest layer.

10. A construction method for a cofferdam device without internal support, characterized in that: The construction method is used to form a cofferdam device without internal support as described in any one of claims 1-9.

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