W-shaped semi-closed composite cofferdam construction method for inclined double-amplitude bearing platform in river shoal area

Abstract

A construction method of a W-shaped semi-closed composite cofferdam of an inclined double-amplitude bearing platform in a river shoal area comprises steel sheet piles, steel pipe anchor piles, steel enclosing purlins, tension-compression profile steel, inner side angle braces and outer side angle braces, the steel sheet piles are sequentially connected to form a W shape at a river bank line, the steel pipe anchor piles are constructed on the inner sides of the steel sheet piles in the river shoal area, the steel enclosing purlins are welded to the steel sheet piles, and the tension-compression profile steel is welded to the outer side angle braces. The tension-compression profile steel is welded between the steel pipe anchor piles and the steel purlins, the inner side angle braces are welded between the steel purlins at two included angles on the inner sides of the W-shaped steel sheet piles, and the outer side angle braces are welded between the steel purlins at one included angle on the outer sides of the W-shaped steel sheet piles, so that the W-shaped semi-closed cofferdam is formed. A W-shaped semi-closed composite cofferdam system is adopted, the cofferdam system is provided with a tension-compression profile steel and steel support composite stress system, a dynamic balance structure is formed in internal and external pressure changes, the lateral stress of a soil body can be balanced, water pressure impact can be effectively resisted, and a closed-loop stress mode with the outer portion being rigid and the inner portion being flexible is formed under the synergistic effect of the tension-compression profile steel and steel support composite stress system and the dynamic balance structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge foundation construction, and particularly relates to a W-shaped semi-closed composite cofferdam construction method for inclined double-width pile caps in a river beach area. BACKGROUND

[0002] With the continuous optimization and expansion of urban layout, urban bridges, as an important link connecting different regions, are increasingly appearing in river-crossing projects. In the construction process of river-crossing bridges, the design and construction of water-bearing pile caps are crucial. The pile cap is not only the foundation of the upper structure of the bridge, but its stability directly affects the safety and durability of the entire bridge. Cofferdams play a crucial role in the construction of water-bearing pile caps. The design of cofferdams needs to consider the safety factors of construction and its impact on the surrounding water area to ensure that it can effectively isolate the water area to meet the construction needs and create a relatively dry construction environment, and at the same time, it will not cause negative impact on the water ecology.

[0003] For the construction of pile caps located in the river beach area, it is particularly necessary to balance the construction operation requirements and environmental protection requirements. The traditional construction method usually sets up a steel sheet pile cofferdam to block water on the river beach, and then backfills the interior to form a construction operation surface. However, in this process, the function of the cofferdam will undergo a fundamental transformation from a water-blocking structure to a soil-blocking structure. At the same time, the complex geological conditions of the construction area, the dynamic change of the backfill soil pressure, and the significant tidal water level fluctuation pose severe challenges to the safety and stability of the cofferdam structure. Conventional rectangular or circular cofferdam structures often cannot effectively adapt to such complex stress system transformation and alternating load action, which can easily lead to structural deformation or even instability, not only threatening construction safety, affecting project progress and cost, but also possibly causing disturbance to the surrounding water ecological environment. Therefore, it is urgent to develop a cofferdam structure form that can effectively cope with the complex construction conditions of the river beach backfill area, especially can adapt to the transformation of water-blocking and soil-blocking functions, and resist the influence of tides. SUMMARY

[0004] The present application aims to solve the safe, efficient and environmentally friendly construction problems of double-width pile caps in the river beach area, and provides a W-shaped semi-closed composite cofferdam construction method for inclined double-width pile caps in a river beach area, which is a new type of W-shaped semi-closed composite cofferdam for double-width pile caps in the river beach backfill area, and is suitable for the construction of double-width pile caps after backfilling near the river shoreline.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] The W-shaped semi-closed composite cofferdam of the inclined double-width pile cap in the river beach area comprises a steel sheet pile, a steel pipe anchor pile, a steel enclosing purlin, a tension-compression steel, an inner side gusset and an outer side gusset, the steel sheet piles are sequentially connected into a W shape at the river bank line, the steel pipe anchor piles are constructed in the steel sheet piles in the river beach area, the steel enclosing purlins are welded on the steel sheet piles, the tension-compression steels are welded between the steel pipe anchor piles and the steel enclosing purlins, the inner side gussets are welded between the steel enclosing purlins of the two included angles on the inner side of the W-shaped steel sheet piles, the outer side gussets are welded between the steel enclosing purlins of one included angle on the outer side of the W-shaped steel sheet piles, and a W-shaped semi-closed cofferdam is formed.

[0007] The steel sheet pile is opened at the lowest water level during driving.

[0008] The area between the river bank side area of the river bank line and the inner side of the cofferdam is a backfill area.

[0009] The steel enclosing purlin is welded at the average water level of the steel sheet pile.

[0010] The spacing of the steel pipe anchor piles is 4-6 m.

[0011] The tension-compression steel adopts a combined structure of an H-shaped steel and a channel steel, the flange of the H-shaped steel is welded with the steel enclosing purlin, and the web of the channel steel is connected with the steel pipe anchor pile through high-strength bolts.

[0012] A construction method of a W-shaped semi-closed composite cofferdam of an inclined double-width pile cap in a river beach area, comprising the following steps:

[0013] S1, clean the backfill area and throw the stone, drive the steel sheet pile and the steel pipe anchor pile on the river bank side, open the steel sheet pile at the lowest water level, and keep the water level inside and outside the cofferdam consistent after the cofferdam is closed;

[0014] S2, weld the steel enclosing purlin on the steel sheet pile at the lowest water level to ensure the overall stress of the steel sheet pile;

[0015] S3, weld the tension-compression steel between the steel pipe anchor pile and the steel enclosing purlin to form a tension-compression system at the lowest water level;

[0016] S4, weld the steel pipe inner support on the steel enclosing purlin to form the inner side gusset and the outer side gusset at the same time, and complete the sealing of the cofferdam at the lowest water level after the construction is completed;

[0017] S5, backfill the river bank side area, gradually backfill the original riverbed sand soil inside the cofferdam, pump water while backfilling to ensure that the steel sheet pile does not deform greatly, at this time, the tension-compression steel and the inner side gusset mainly resist compression, and the outer side gusset mainly resists tension;

[0018] S6, when the inner side soil pressure approaches the lowest water pressure on the outer side, continue to backfill, at this time, the tension-compression steel and the inner side gusset mainly resist tension, and the outer side gusset mainly resists compression, until the backfilling is completed to the design elevation, after the construction of the backfilling area is completed, the steel sheet pile maintains overall balance through the tension-compression system and the gusset system, and then the construction of the double-width pile cap is carried out.

[0019] The beneficial effects of the present application are: the present application adopts a W-shaped semi-closed composite cofferdam system, and realizes the double promotion of engineering efficiency and ecological benefits through three-dimensional force structure optimization. The cofferdam system is configured with a steel bracing composite force system, which forms a dynamic balance structure in the change of internal and external pressure, can balance the lateral stress of the soil body, and can effectively resist water pressure impact, and under the synergistic action of the two, forms a closed loop force mode of "external rigidity and internal flexibility". Through engineering verification, the method can reduce the self-weight of the cofferdam structure and reduce the earthwork excavation amount, realizes the significant benefits of shortening the construction period and reducing the comprehensive cost under the premise of ensuring the safety of the structure, and creates an innovative engineering practice scheme for bridge foundation construction under complex hydrological conditions. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of the present application;

[0021] Figure 2 is a structural schematic diagram of the present application before backfilling in the backfilling area;

[0022] Figure 3 is a structural schematic diagram of the present application after backfilling;

[0023] In the figure: 1-steel sheet pile; 2-steel pipe anchor pile; 3-steel enclosing purlin; 4-tension-compression steel; 5-inside corner brace; 6-outside corner brace; 7-backfilling area; 8-river bank line; 9-double-width pile cap;

[0024] The present application will be described in detail below with reference to the embodiments of the present application and the accompanying drawings. DETAILED DESCRIPTION

[0025] The present application will be further described below in combination with the accompanying drawings and embodiments:

[0026] A W-shaped semi-closed composite cofferdam of a river beach area inclined double-width pile cap comprises a steel sheet pile 1, a steel pipe anchor pile 2, a steel enclosing purlin 3, a tension-compression steel 4, an inside corner brace 5 and an outside corner brace 6, the steel sheet pile 1 is sequentially connected into a W shape at a river bank line 8, the steel pipe anchor pile 2 is constructed inside the steel sheet pile 1 in the river beach area, the steel enclosing purlin 3 is welded on the steel sheet pile 1, the tension-compression steel 4 is welded between the steel pipe anchor pile 2 and the steel enclosing purlin 3, the inside corner brace 5 is welded between the steel enclosing purlins 3 of the two included angles inside the W-shaped steel sheet pile 1, the outside corner brace 6 is welded between the steel enclosing purlins 3 of one included angle outside the W-shaped steel sheet pile 1, and a W-shaped semi-closed cofferdam is formed.

[0027] The steel sheet pile 1 is opened at the lowest water level when being driven.

[0028] The area between the river bank side area of the river bank line 8 and the inside of the cofferdam is a backfilling area 7.

[0029] The steel enclosing purlin 3 is welded at the average water level of the steel sheet pile 1.

[0030] The steel pipe anchor pile 2 has a spacing of 4-6 m.

[0031] The pull-pressure type steel 4 adopts a combined structure of H-shaped steel and channel steel, the flange of the H-shaped steel is welded with the steel enclosing purlin 3, and the web of the channel steel is connected with the steel pipe anchor pile 2 through high-strength bolts.

[0032] A construction method of a new W-shaped semi-closed composite cofferdam of an inclined double-width pile cap in a river beach backfill area, the steps of which are:

[0033] S1, clean the riprap of the backfill area, drive the steel sheet pile 1 and the steel pipe anchor pile 2 on the river bank side, open at the lowest water level of the steel sheet pile 1, and keep the water level inside and outside the cofferdam consistent after the cofferdam is closed;

[0034] S2, weld the steel enclosing purlin 3 on the steel sheet pile 1 at low water level to ensure the overall stress of the steel sheet pile 1;

[0035] S3, weld the pull-pressure type steel 4 on the steel pipe anchor pile 2 and the steel enclosing purlin 3 at low water level to form a pull-pressure system;

[0036] S4, weld the steel pipe inner support on the steel enclosing purlin 3 at low water level to form the inner side angle brace 5 and the outer side angle brace 6 at the same time, and complete the sealing of the cofferdam at low water level after the construction is completed;

[0037] S5, backfill the river bank side area, gradually backfill the original riverbed sand soil inside the cofferdam, pump water while backfilling to ensure that the steel sheet pile 1 does not deform greatly, at this time the pull-pressure type steel 4 and the inner side angle brace 5 are mainly compression-resistant, and the outer side angle brace 6 is mainly tension-resistant;

[0038] S6, when the inner side soil pressure approaches the outer side lowest water pressure, continue to backfill, at this time the pull-pressure type steel 4 and the inner side angle brace 5 are mainly tension-resistant, and the outer side angle brace 6 is mainly compression-resistant, until backfilling to the design elevation, after the backfilling area is completed, the steel sheet pile 1 maintains overall balance through the pull-pressure system and the angle brace system, and then the construction of the double-width pile cap 9 is carried out.

[0039] The W-shaped semi-closed composite cofferdam system developed for the special working condition of the inclined double-width pile cap realizes the organic unity of flexible deformation and rigid support in the interaction of tidal water pressure and soil pressure through the innovative integration of the steel sheet pile 1 retaining wall, the steel pipe anchor pile 2 consolidation, the steel enclosing purlin 3 force transmission, and the pull-pressure type steel 4 and the two-way angle brace collaborative support, and builds a stress balance system with self-adaptive function. The engineering measurement shows that the three-dimensional space structure reduces the amount of steel compared with the traditional scheme, improves the construction efficiency, successfully overcomes the foundation construction difficulties of the inclined double-width pile cap on the river bank side under the tidal rise and fall, and forms a green construction technology system that can be replicated and popularized.

[0040] In the description of the invention, it needs to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the invention.

[0041] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0042] In the invention, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or communicate with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication or interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the invention can be understood according to the specific circumstances.

[0043] The invention has been described above in conjunction with the drawings, and it is obvious that the specific implementation of the invention is not limited by the above manner, as long as various improvements are made by adopting the method concept and technical solutions of the invention, or directly applied to other occasions without improvement, all within the protection scope of the invention.

Claims

1. A W-shaped semi-closed composite cofferdam of a beveled double-width pile cap in a beach area, characterized by, The utility model relates to a steel sheet pile cofferdam structure, including steel sheet pile (1), steel pipe anchor pile (2), steel enclosing purlin (3), tension and compression type steel (4), inboard gusset (5) and outboard gusset (6), steel sheet pile (1) is connected into W type at river bank line (8) in proper order, constructs steel pipe anchor pile (2) in the inboard of steel sheet pile (1) in beach area, steel enclosing purlin (3) is welded on steel sheet pile (1), tension and compression type steel (4) is welded between steel pipe anchor pile (2) and steel enclosing purlin (3), welds inboard gusset (5) between the steel enclosing purlin (3) of two included angles in the inboard of W type steel sheet pile (1), welds outboard gusset (6) between the steel enclosing purlin (3) of one included angle on the outboard of W type steel sheet pile (1), forms a W type semi-closed cofferdam.

2. A W-type semi-closed composite cofferdam of the inclined double-width pile raft in the beach area according to claim 1, characterized in that, The steel sheet pile (1) is opened at the lowest water level when being driven.

3. A W-type semi-closed composite cofferdam of beveled double-width pile caps in a beach area according to claim 2, characterized in that, The area between the river bank side area of the river bank line (8) and the inside of the cofferdam is a backfill area (7).

4. A W-type semi-closed composite cofferdam of beveled double-width pile caps in a beach area according to claim 3, characterized in that, The steel enclosing purlin (3) is welded at the average water level of the steel sheet pile (1).

5. A W-type semi-closed composite cofferdam of beveled double-width pile caps in a beach area according to claim 4, characterized in that, The spacing of the steel pipe anchor pile (2) is 4-6 m.

6. A W-type semi-closed composite cofferdam of beveled double-width pile caps in a beach area according to claim 5, characterized in that, The tension and compression type steel (4) adopts a combined structure of H-shaped steel and channel steel, the flange of the H-shaped steel is welded with the steel enclosing purlin (3), and the web of the channel steel is connected with the steel pipe anchor pile (2) through high-strength bolts.

7. The construction method of a W-shaped semi-closed composite cofferdam of a beach area inclined double-width pile cap according to claim 6, characterized in that, The steps are as follows: S1, clean the backfill area and throw the stones, drive the steel sheet pile (1) and the steel pipe anchor pile (2) on the river bank side, open at the lowest water level of the steel sheet pile (1), and keep the water level inside and outside the cofferdam consistent after the cofferdam is closed; S2, weld the steel enclosing purlin (3) on the steel sheet pile (1) at the low water level to ensure the overall stress of the steel sheet pile (1); S3, weld the tension and compression type steel (4) between the steel pipe anchor pile (2) and the steel enclosing purlin (3) at the low water level to form a tension and compression system; S4, weld the steel pipe inner support on the steel enclosing purlin (3) at the low water level to form the inboard gusset (5) and the outboard gusset (6), and complete the sealing of the cofferdam at the low water level after the construction is completed; S5, backfill the river bank side area, gradually backfill the original riverbed sand soil inside the cofferdam, pump water while backfilling to ensure that the steel sheet pile (1) does not deform greatly, at this time, the tension and compression type steel (4) and the inboard gusset (5) are mainly compression-resistant, and the outboard gusset (6) is mainly tension-resistant; S6, when the internal soil pressure approaches the external lowest water pressure, continue to backfill, at this time, the tension and compression type steel (4) and the inboard gusset (5) are mainly tension-resistant, and the outboard gusset (6) is mainly compression-resistant, until backfilling to the design elevation, after the backfilling area is completed, the steel sheet pile (1) maintains overall balance through the tension and compression system and the gusset system, and then the construction of the double-width pile cap (9) is carried out.

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