CN114059444B

CN114059444B - A bridge abutment structure and its construction method for a cross-sea bridge

Info

Publication number: CN114059444B
Application number: CN202111635609.2A
Authority: CN
Inventors: 杨帆; 袁慧芳; 王培晓; 李琳; 张伟; 郭俊伟; 孙祥
Original assignee: Shanghai Municipal Engineering Design Insitute Group Co Ltd
Current assignee: Shanghai Municipal Engineering Design Insitute Group Co Ltd
Priority date: 2021-12-29
Filing date: 2021-12-29
Publication date: 2026-02-13
Anticipated expiration: 2041-12-29
Also published as: CN114059444A

Abstract

This invention discloses a bridge abutment structure and its construction method for a cross-sea bridge. The abutment is located on the water surface outside the seawall. A ring of precast concrete sheet piles is installed in front of and on both sides of the abutment, forming a closed anti-scour structure. The backfill behind the abutment uses lightweight foamed soil and boulders, and a filter structure is installed. The abutment of this invention is located on the water surface outside the seawall, directly bearing the scour of ocean waves. The abutment has anti-scour and anti-erosion functions, solving the problem of unsuitable abutment placement on the seaward side through comprehensive measures. Simultaneously, the abutment is suitable for complex sites with high fill and soft foundations.

Description

Bridge abutment structure of cross-sea bridge and construction method thereof

Technical Field

The invention relates to the technical field of cross-sea bridges, in particular to a novel bridge abutment structure of a cross-sea bridge and a construction method thereof.

Background

Along with the development of economy and society, a large number of cross-sea bridges have been built in China. Conventional cross-sea bridges span seawalls, and the land where the bridge abutment is disposed within the seawall is not very different from the bridge abutment of conventional bridges. However, in the coastal city road network, coastal roads are built along the coastal levees, the cross-sea bridge needs to level the coastal roads, and the bridge abutment can only be arranged outside the coastal levees and needs to bear the effects of ocean wave force and scouring.

On the one hand, the abutment is positioned on the open sea side and faces the soil body scouring problem, huge ocean currents can empty the filling soil in front of the abutment, and the filling soil behind the abutment is eroded, so that the land is emptied, the pavement collapses and the abutment is unstable, and serious accidents and casualties can be caused. On the other hand, the strong wave suction force and the weak soil foundation in the coastal area lead the settlement control of the bridge abutment to face serious challenges. Wave suction and post-abutment earth pressure are mutually overlapped, and weak lower lying layers are commonly existing in coastal areas, so that the wave suction and post-abutment earth pressure are very adverse factors for the design of abutment friction piles.

Disclosure of Invention

The invention aims to solve the defect that a conventional bridge abutment is only arranged in a sea wall, and provides a bridge abutment structure of a cross-sea bridge. The bridge abutment is positioned on the water surface outside the seawall and directly bears the scouring and wave suction force of ocean waves, has the functions of scour prevention and hollowing prevention, and solves the problem that the bridge abutment is not suitable to be arranged on the sea side through comprehensive measures. Meanwhile, the abutment is suitable for complex sites with high filling and soft foundations.

In order to achieve the purpose, the technical scheme of the invention is that the bridge abutment structure of the cross-sea bridge is characterized in that the bridge abutment is positioned on the water surface outside a seawall, a circle of precast concrete slab piles are arranged in front of and on two sides of the bridge abutment, the slab piles are connected to form a closed scour prevention structure, and filling soil behind the bridge abutment adopts light foam soil and block stones and is provided with a reverse filtering structure.

Further, fine stone concrete is poured into double concave grooves between the end parts of adjacent precast concrete slabs, and the space between the slab piles and the retaining wall of the adjacent engineering is sealed by high-pressure jet grouting piles.

The precast concrete slab pile and the bridge abutment are filled by the broken stone and concrete post-cast layer, the construction is performed firstly, then soil is filled, then the post-cast layer is constructed, the condition that the slab pile bears the soil pressure after the construction is avoided, the stone blocks are filled in front of the slab pile, and the front of the slab pile is prevented from being hollowed out.

The sheet pile is higher than the ground line by about 4 meters during construction, so that the cofferdam is constructed. And knocking out sheet piles higher than the ground after the abutment construction is finished. One pile is multipurpose, and the engineering cost and the construction period are saved.

The bridge abutment is characterized in that the light foam soil is adopted on the water level line after filling the soil to reduce the soil pressure, the stone block is adopted below the water level line, two stones, a mixed inverted filter layer and filter layer geotechnical cloth are sequentially arranged below the stone block, a complete inverted filter structure can be formed, soil loss can be prevented, the internal friction angle of the filled soil can be increased, the soil pressure can be reduced, and the water drain hole and the sand gravel filter bag are arranged on the water level line.

In order to meet the durability requirement, the bridge abutment adopts various measures such as high-performance marine concrete, a concrete surface coating, a rust inhibitor, an enlarged reinforcing steel bar protection layer and the like.

The construction method of the bridge abutment structure of the cross-sea bridge is characterized by comprising the following steps of:

A. Leveling a field and constructing a dry field;

B. Constructing prefabricated sheet piles, pouring fine stone concrete into double grooves between the sheet piles at the end parts, and sealing the sheet piles and retaining walls of adjacent projects by using high-pressure jet grouting piles;

C. constructing a bored pile and a bridge abutment;

D. constructing a reverse filtering structure behind the bridge abutment, refilling the stone blocks to the elevation of the water level line, and then constructing an upper structure;

E. filling light foam soil behind the abutment;

F. Knocking out sheet piles higher than the ground, bending reinforcing steel bars, and filling broken stone and concrete post-pouring layers between the bridge abutment and the sheet piles.

The invention has the obvious technical characteristics that the technical characteristics are formed by the scheme, firstly, the airtight structure formed by the precast concrete slab piles can effectively prevent scouring, secondly, the sheet piles and the bridge abutment are mutually independent, after the soil filling after the abutment is completed, the gap between the sheet piles and the bridge abutment is filled with concrete, thirdly, the soil filling above the water level line behind the bridge abutment adopts light foam concrete, and the soil filling below the water level line adopts block stones, so that the soil pressure behind the abutment can be greatly reduced, and the integral sedimentation of the bridge abutment is reduced. Fourth, the rear stone blocks of the bridge abutment and the inverted filter layer form an inverted filter structure together, so that land soil loss is prevented. Fifthly, the bridge abutment adopts a whole set of anti-corrosion measures, thereby ensuring the requirement of durability.

Drawings

FIG. 1 is an overall schematic of the present invention;

FIG. 2 is an elevational schematic view of an anti-scour construction of the present invention;

FIG. 3 is a schematic plan view of an anti-scour construction of the present invention;

FIG. 4 is a schematic view of sheet piles;

in the figure, a precast concrete pile 1, a pier body 2, a bearing platform 3, an upper beam 4, a water discharge hole 5, a cast-in-place pile 6, a sand gravel filter bag 7, a seawall sideline 8, light foam soil 9, a pavement structure 10, 10-100 kg of stone blocks 11, 12, 13, a mixed inverted filter layer, 14, filter geotextiles 15, surface layer reinforcing steel bars 16, 200-400 kg of stone blocks 17, crushed stone 18, a C40 concrete post-cast layer 19, fine stone concrete 20, a positioning sheet pile 21, a corner sheet pile 22, a standard sheet pile 23 and a high-pressure rotary spray pile 24 are adopted.

Detailed Description

The precast concrete slab pile 1 is arranged in front of the bridge abutment, the precast concrete slab pile and the bridge abutment are filled by broken stone 18 and a C40 concrete post-pouring layer, and the precast concrete slab pile and the bridge abutment are mutually independent, so that the slab pile 1 is prevented from bearing the post-abutment soil pressure. 200-400 kg of stone blocks 17 are filled in front of the sheet piles, preventing the sheet pile from being emptied.

The abutment rear filling adopts the light foam soil 9 on the water level line to reduce the soil pressure, adopts 10~100kg block stone 11 under the water level line, sets gradually two stones 12 below the block stone, mixes the inverted filter 13 and filtering layer geotechnical cloth 14, both can form complete inverted filter structure, prevents soil body loss, also can increase the internal friction angle of filling and reduce the soil pressure. A water drain hole 5 and a sand gravel filter bag 7 are arranged on the water line.

The specific implementation method comprises the following steps:

1) Leveling a field and constructing a dry field. Filling earth to the designed pavement height, and reversely excavating the abutment construction surface after pre-pressing.

2) And (5) constructing the prefabricated sheet piles. The sheet pile is not allowed to be out of tenoned during the construction. Fine stone concrete is poured into the double grooves between the end sheet piles. And sealing the space between the sheet pile and the retaining wall of the adjacent engineering by using high-pressure jet grouting piles. The airtight space is required to be formed in front of the abutment to prevent soil leakage under the abutment. The sheet pile is higher than the ground line by about 4 meters during construction, so that the cofferdam is constructed. The distance between the prefabricated sheet piles and the bridge abutment is 1000-1500 mm.

3) And (5) constructing the bored pile and the bridge abutment. Bridge abutment concrete placement must take measures to avoid cracking due to excessive internal surface temperature differences caused by hydration heat. The casting should be carried out in the day when the air temperature is low, the cement consumption is reduced, the thickness of the casting layer is reduced by adopting low-hydration cement, and a cooling pipe (horizontal

The spacing and the layer distance are generally 80 cm-100 cm), and the hydration heat temperature of the concrete is strictly controlled by water cooling and other methods. And after casting, measuring the surface and internal temperature of the concrete, and controlling the temperature difference within the range required by the specification.

The superstructure can be erected after the abutment concrete strength reaches 100% of the design strength for not less than 14 days.

4) And constructing a reverse filtering structure after the abutment, refilling the stone blocks to the elevation of the water level line, and then constructing an upper structure.

5) And filling light foam soil behind the abutment. The light foam soil adopts D1000 grade, and the anti-floating performance of the filling soil is improved. Before pouring construction of foam lightweight soil roadbed, the substrate should not have obvious ponding and sundries, and the substrate compactness index

More than or equal to 85 percent. The casting thickness of the foam light soil single layer is controlled according to 0.3 m-1.0 m, the casting construction time of a single casting area casting layer is not longer than the initial setting time of cement paste, and the casting interval time of two adjacent upper and lower casting layers is not smaller than 8 hours. The single casting layer is preferably cast once, and is cast twice at most if necessary, and the interval time between the two casting is controlled to be 6-24 hours. The foamed light soil at the road bed should be covered with plastic film or non-woven geotextile for moisture maintaining after casting, and the maintaining time should not be less than 7 days after casting to the designed elevation.

6) Knocking out sheet piles higher than the ground, and bending reinforcing steel bars. And concrete with the height of 800mm is filled between the bridge abutment and the sheet pile.

The cross-sea bridge faces serious seawater corrosion problems, and the durability requirements of the bridge abutment are as follows:

1) Thickness of protective layer

In a concrete structure in a marine environment, the thickness of the concrete protective layer should be larger than that of a common concrete protective layer due to the existence of chloride salt. The minimum protective layer thickness of the engineering is determined by referring to similar engineering except for meeting the minimum protective layer thickness determined in bridge design specifications, wherein the minimum protective layer thickness of the pier column and the bridge abutment main rib is 70mm, the protective layer of the bearing platform bottom main rib is 160mm, the minimum protective layer thickness of the rest main ribs is 70mm, and the minimum protective layer thickness of the bored pile main rib is 85mm.

2) High-performance marine concrete

The high performance marine concrete differs from ordinary concrete in that the specific properties required for the concrete under specific conditions, such as high modulus of elasticity, low permeability, and resistance to certain types of damage, are enhanced by the incorporation of one or more admixtures of fly ash, blast furnace slag, silica fume.

From the index point of view, the high-performance concrete has stricter regulation requirements on the aspects of maximum particle size, highest water cement ratio and the like of aggregate compared with the common concrete.

3) A concrete surface coating system. The outer surface of the abutment is coated with an anti-corrosion coating and impregnated with silane.

4) The concrete is doped with a rust inhibitor.

The invention will be further described with reference to a specific example.

A bridge is newly built between two artificial islands in a certain city, the bridge head is positioned at a crossroad of a level crossing, and the bridge abutment can only be arranged on the overseas side. The basic bearing layer is powdery clay, and the soil body performance is poor. The abutment is filled with 12 meters of soil, and is a high-filling abutment with poor foundation conditions. When engineering design is carried out, a circle of precast concrete is arranged in front of and at two sides of the bridge abutment

The soil filling after the abutment adopts light foam concrete and stone blocks with small internal friction angle, thus better solving the soil pressure problems of scour prevention and high filling.

Claims

1. A construction method for the abutment structure of a cross-sea bridge, characterized in that the abutment is located on the water surface outside the seawall; a ring of precast concrete sheet piles is set in front of and on both sides of the abutment, and the sheet piles are connected to form a closed anti-scour structure; the backfill behind the abutment uses lightweight foamed soil and boulders, and an inverted filter structure is set; the space between the precast concrete sheet piles and the abutment is filled with crushed stone and a post-cast concrete layer; the sheet piles are 4 meters above the ground line during construction, serving as a construction cofferdam; after the abutment construction is completed, the sheet piles above the ground are removed, and the reinforcing bars are bent up; the sheet piles and the abutment are independent of each other; after the backfill behind the abutment is completed, the gap between the sheet piles and the abutment is filled with concrete; the abutment uses high-performance marine concrete, a concrete surface coating, a rust inhibitor, and an increased reinforcing bar protective layer to meet durability requirements.

The construction method includes the following steps:

A. Level the site and construct on dry ground;

B. Construct precast sheet piles, and fill the double grooves between the ends of adjacent precast concrete sheet piles with fine stone concrete. Seal the sheet piles with high-pressure jet grouting piles between them and the retaining wall of the adjacent project.

C. Construction of bored piles and bridge abutments;

D. Construct the inverted filter structure behind the bridge abutment, then fill it with rubble to the water level, and then construct the superstructure.

E. Fill the abutment with lightweight foamed soil;

F. Remove the sheet piles that protrude above the ground, bend the reinforcing bars, and fill the space between the abutment and the sheet piles with gravel and a post-cast layer of concrete.

2. The construction method of the abutment structure of the cross-sea bridge according to claim 1, characterized in that the backfill behind the abutment uses lightweight foamed soil above the water level to reduce soil pressure, and boulders below the water level. Below the boulders, two boulders, a mixed inverted filter layer, and a filter geotextile are sequentially arranged to form a complete inverted filter structure, which can prevent soil loss and increase the internal friction angle of the backfill and reduce soil pressure; the abutment is provided with drainage holes and gravel filter bags above the water level.