Double-wall steel cofferdam suitable for large water head difference of large-gradient riverbed

Abstract

The utility model discloses a double-wall steel cofferdam suitable for a large water head difference of a large-gradient riverbed, a foundation pit is excavated on the riverbed, a ring groove is arranged on the bottom surface of the foundation pit, the double-wall steel cofferdam comprises a steel cofferdam body, the steel cofferdam body is of an annular structure, and a blade foot is arranged at the bottom of the steel cofferdam body; the bottom surface of the blade foot is a plane, an orifice is formed in the side wall of the blade foot, and the blade foot is fixed in the annular groove through a concrete layer; the boot leg is fixedly arranged at the lower end of the steel cofferdam body in a sleeving mode, and the outer side of the boot leg abuts against the inner wall of a foundation pit; and the multiple sets of horizontal supports are arranged in the steel cofferdam body at intervals in the height direction. The utility model can effectively solve the problem that the pouring quality is poor due to the influence of large flow velocity and large water head difference on the concrete pouring of the blade foot of the slotting type double-wall steel cofferdam under the easily disturbed geology.

Description

Technical Field

[0001] The utility model relates to the field of cofferdam construction. More specifically, the utility model relates to a double-wall steel cofferdam applicable to a large-slope riverbed and a large water head difference. Background Art

[0002] The bridge foundation forms in China are rich and diverse. For underwater foundations, it is usually necessary to first construct a cofferdam, pump out the water to form a dry construction environment, and then construct the foundation. For shallow water areas, sheet pile cofferdams are mostly used, including I-shaped sheet piles, Larsen sheet piles, etc. For medium water depths, lock-joint steel pipe piles are generally used. For deep water areas where the water head difference exceeds 20m and deep-buried foundation construction is carried out, a double-wall steel cofferdam structure is mostly used. When the base geological conditions are relatively soft, such as clay or sand layers, cutting edges are mostly provided at the bottom of the double-wall steel cofferdam to facilitate the sinking of the cofferdam. For bare rock or strongly weathered geology, it is difficult to directly penetrate the soil. Usually, a notch is reserved according to the method of a caisson, and it is aligned and sunk, and then the cutting edge concrete is poured. At this time, the penetration depth of the cofferdam will not be very large, and the pouring quality of the cutting edge concrete is crucial for the safety and stability of the cofferdam structure. However, for large slopes and fast-flowing water areas, the strength of strongly weathered sandy granite drops sharply when encountering water or being disturbed. There are problems such as easy hole collapse at the reserved notch and poor pouring quality of the cutting edge concrete. If slope excavation is adopted, the underwater operation workload is large and the economic benefit is relatively large. At present, there is a lack of a cutting edge structure and construction method with a reliable boundary. Therefore, it is urgent to propose a cutting edge structure and construction method for a double-wall steel cofferdam applicable to a large-slope riverbed and a large water head difference to solve this problem. Summary of the Utility Model

[0003] An object of the utility model is to solve at least the above problems and provide at least the advantages described later.

[0004] To achieve these objects and other advantages according to the utility model, there is provided a double-wall steel cofferdam applicable to a large-slope riverbed and a large water head difference. A foundation pit is excavated on the riverbed, and an annular groove is opened on the bottom surface of the foundation pit, including:

[0005] A steel cofferdam body, which is of an annular structure, and a cutting edge is provided at the bottom of the steel cofferdam body; the bottom surface of the cutting edge is flat, and an orifice is opened on the side wall, and the cutting edge is fixed in the annular groove through a concrete layer;

[0006] A boot cylinder, which is fixedly sleeved on the lower end of the steel cofferdam body, and the outer side of the boot cylinder abuts against the inner wall of the foundation pit;

[0007] Multiple groups of horizontal braces, and multiple groups of the horizontal braces are arranged at intervals in the height direction inside the steel cofferdam body.

[0008] Preferably, a baffle is further included, which is horizontally arranged on the inner wall of the steel cofferdam body; when the steel cofferdam body is lowered into the annular groove, the bottom surface of the baffle just abuts against the top surface of the annular groove.

[0009] Preferably, the steel cofferdam body includes an inner wall plate and an outer wall plate, which are arranged at intervals, and a connecting truss is arranged between the two.

[0010] Preferably, multiple groups of ring ribs are symmetrically arranged on the opposite sides of the inner wall plate and the outer wall plate, and the ring ribs are evenly distributed at the lower part of the steel cofferdam body.

[0011] Preferably, the boot includes a wall plate, which is arranged at intervals outside the steel cofferdam body, and a plurality of transverse connections are arranged at intervals in the height direction between the wall plate and the steel cofferdam body.

[0012] Preferably, the top of the wall plate is flush with the riverbed line outside the foundation pit.

[0013] The utility model has at least the following beneficial effects:

[0014] The double-wall steel cofferdam applicable to a large-slope riverbed and a large water head difference provided by the utility model, due to adopting grooving positioning and sinking, sets the bottom surface of the cutting edge to be a flat section, and a boot is arranged at the lower part of the steel cofferdam body to bear the active earth pressure of the lateral riverbed. After the steel cofferdam body is positioned and lowered, the cutting edge concrete is poured. By arranging orifices at the cutting edge position, the compactness during the concrete pouring stage is ensured to improve the stability and strength of the cutting edge; it can effectively solve the problem that the cutting edge concrete pouring of the grooving double-wall steel cofferdam is affected by large flow velocity and large water head difference and the pouring quality is poor under easily disturbed geology.

[0015] Other advantages, objectives and features of the utility model will be partly reflected by the following description, and partly will be understood by those skilled in the art through the research and practice of the utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic side structure view of the double-wall steel cofferdam applicable to a large-slope riverbed and a large water head difference described in the utility model;

[0017] Figure 2 It is a schematic structure view of the annular groove described in the utility model;

[0018] Figure 3 It is a schematic structure view of the boot described in the utility model; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The following further detailed description of the utility model is made with reference to the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0020] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation schemes are all conventional methods, and the reagents and materials, unless otherwise specified, can all be obtained from commercial channels; in the description of the present utility model, the terms "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. 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 utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present utility model.

[0021] As Figures 1 to 3 shown, the present utility model provides a double-wall steel cofferdam applicable to large-slope riverbeds with large water head differences. A foundation pit is excavated on the riverbed, and a ring groove 7 is opened on the bottom surface of the foundation pit. The double-wall steel cofferdam applicable to large-slope riverbeds with large water head differences includes:

[0022] A steel cofferdam body 1, which is of a circular structure, and a cutting edge 3 is provided at the bottom of the steel cofferdam body 1; the bottom surface of the cutting edge 3 is flat, and an orifice 9 is opened on the side wall, and the cutting edge 3 is fixed in the ring groove 7 through a concrete layer 4;

[0023] A boot cylinder 2, which is fixedly sleeved at the lower end of the steel cofferdam body 1, and the outer side of the boot cylinder 2 abuts against the inner wall of the foundation pit;

[0024] Multiple groups of horizontal braces 6, and multiple groups of the horizontal braces 6 are arranged at intervals in the height direction inside the steel cofferdam body 1.

[0025] In this technical solution, the boot cylinder 2 and the steel cofferdam body 1 are pre-installed during the processing. First, use a grab to excavate and preliminarily level the riverbed, and excavate the ring groove 2 at the designated position. During the excavation process, simply slope the riverbed line 5; then hoist the steel cofferdam body 1 into the ring groove 2. Then pour the concrete layer 4 underwater, and the concrete fills the entire cutting edge 3 through the orifice 9 to form the concrete layer 4. As Figure 1 shown, the concrete layer is fully filled in the cutting edge 3, the ring groove 2, and the boot cylinder 2 corresponding to the cutting edge 3. Then pump water while constructing the horizontal braces 6, pump water to the bottom surface of the cofferdam. After all the horizontal braces 6 are installed, construct the bearing platform and pier body inside the cofferdam.

[0026] In another technical solution, the double-wall steel cofferdam applicable to large-slope river beds with large water head differences further includes a baffle 8, which is horizontally arranged on the inner wall of the steel cofferdam body 1; when the steel cofferdam body 1 is lowered into the annular groove 2, the bottom surface of the baffle 8 just abuts against the top surface of the annular groove 1. As Figure 3 shown, when the steel cofferdam body 1 is hoisted and lowered into the annular groove 2, the baffle 8 just falls onto the river bed surface inside the cofferdam, that is, the top surface of the annular groove 2.

[0027] In another technical solution, the steel cofferdam body 1 includes an inner wall plate 12 and an outer wall plate 11, the inner wall plate 12 and the outer wall plate 11 are arranged at intervals, and a connecting truss 13 is arranged between the two.

[0028] Furthermore, multiple groups of ring ribs 14 are symmetrically arranged on the opposite sides of the inner wall plate 12 and the outer wall plate 11, and the ring ribs 14 are evenly distributed at the lower part of the steel cofferdam body 1. The strength of the lower part of the steel cofferdam body 1 is strengthened by multiple groups of the ring ribs 14 to cope with the earth pressure of the lateral river bed.

[0029] In another technical solution, the boot cylinder 2 includes a wall plate 21, the wall plate 21 is arranged at intervals outside the steel cofferdam body 1, and multiple transverse connections 22 are arranged at intervals between the wall plate 21 and the steel cofferdam body 1 in the height direction.

[0030] Furthermore, as Figure 1 shown, the top of the wall plate 21 is flush with the river bed line 5 outside the foundation pit. The boot cylinder 2 is used to bear the active earth pressure of the lateral river bed to cope with the problems of large slopes and fast-flowing water areas, and the strength of strongly weathered sandy granite decreases sharply when it meets water or is disturbed.

[0031] Although the implementation schemes of the present invention have been disclosed as above, it is not limited to only the applications listed in the description and implementation modes. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details and the illustrations shown and described here.

Claims

1. A double-walled steel cofferdam suitable for a riverbed with a large slope and a large head difference, wherein a foundation pit is excavated on the riverbed, and an annular groove is provided on the bottom surface of the foundation pit, characterized in that: include: The steel cofferdam body is an annular structure, and a blade foot is arranged at the bottom of the steel cofferdam body; the bottom surface of the blade foot is flat, and a hole is opened on the side wall, and the blade foot is fixed in the annular groove through a concrete layer; A boot, which is fixedly sleeved on the lower end of the steel cofferdam body, and the outer side of the boot abuts against the inner wall of the foundation pit; A plurality of groups of horizontal supports are arranged inside the steel cofferdam body at intervals along the height direction.

2. The double-walled steel cofferdam suitable for large-slope riverbeds with large water head differences as claimed in claim 1, characterized in that: It also includes a baffle plate, which is horizontally arranged on the inner wall of the steel cofferdam body; when the steel cofferdam body is lowered into the annular groove, the bottom surface of the baffle plate just abuts against the top surface of the annular groove.

3. The double-walled steel cofferdam suitable for large-slope riverbeds with large water head differences as claimed in claim 1, characterized in that: The steel cofferdam body comprises an inner wall plate and an outer wall plate, the inner wall plate and the outer wall plate are arranged at an interval, and a connecting truss is arranged between the two.

4. The double-walled steel cofferdam suitable for a riverbed with a large slope and a large water head difference as claimed in claim 3, characterized in that: A plurality of groups of annular ribs are symmetrically arranged on one side opposite to the inner wall plate and the outer wall plate, and the annular ribs are evenly distributed on the lower part of the steel cofferdam body.

5. The double-walled steel cofferdam suitable for a riverbed with a large slope and a large water head difference as claimed in claim 1, characterized in that: The boot comprises a wall plate, and the wall plate is arranged at intervals outside the steel cofferdam body, and a plurality of transverse connections are arranged at intervals between the wall plate and the steel cofferdam body along the height direction.

6. The double-walled steel cofferdam suitable for a riverbed with a large slope and a large water head difference as claimed in claim 4, characterized in that: The top of the wall panel is flush with the riverbed line outside the foundation pit.

Images