CN114703762A

CN114703762A - Foundation construction method of steel-concrete composite beam

Info

Publication number: CN114703762A
Application number: CN202210533782.XA
Authority: CN
Inventors: 杨定军; 杜传鹏; 卢伟; 任海滨; 黄靓; 虞伟; 胥春林; 曾斌
Original assignee: Sichuan Road and Bridge (Group) Co Ltd
Current assignee: Sichuan Road and Bridge (Group) Co Ltd
Priority date: 2022-05-16
Filing date: 2022-05-16
Publication date: 2022-07-05

Abstract

The invention provides a foundation construction method of a steel-concrete composite beam, and relates to the technical field of bridge engineering. The supporting pile arranged in the invention is better than a vertical pile in the aspect of horizontal bearing capacity, has stronger ultimate bearing capacity, has larger horizontal rigidity as a foundation form with strong adaptability, and can better resist impact load, share water and soil pressure and the like; according to the invention, the distributing beams are distributed on the top surface of the cofferdam bottom plate, then the bottom sealing concrete is poured, so that the cofferdam bottom plate, the distributing beams and the bottom sealing concrete are superposed to form an integral stressed structure, and the thickness of the bottom sealing is optimized; in the invention, a plurality of groups of rock anchors are used as a main anti-floating stress system of the cofferdam in the water pumping stage, so that the problems that the self weight of a single-wall cofferdam and a thin back cover is small, the uplift bearing capacity of an inclined supporting pile does not participate in anti-floating calculation and the like are solved.

Description

Foundation construction method of steel-concrete composite beam

Technical Field

The invention relates to the technical field of bridge engineering, in particular to a foundation construction method of a steel-concrete composite beam.

Background

The bridge deep water foundation is a foundation type which is often encountered when a large-span bridge is built on rivers, lakes and oceans. The conventional foundations of this type adopt a steel box cofferdam, a steel hanging box cofferdam, a steel sheet pile cofferdam, a locking notch steel pipe pile cofferdam, a composite cofferdam, a concrete cofferdam and the like as water retaining structures for foundation construction to reach the 'dry construction' condition. The steel boxed cofferdam and the steel hanging box cofferdam are mostly double-arm steel cofferdams, the steel sheet pile cofferdam is suitable for the environment with shallow water depth, a deep covering layer needs to be inserted into the locking steel pipe pile cofferdam, the composite cofferdam is suitable for the bank side abrupt slope environment, and the concrete cofferdam needs to be poured in layers and times and has a self-weight. For a sea area with deep water depth and frequent water level change in a tidal period, the pier foundation obtained by the conventional construction method cannot be well adapted to the sea area conditions.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a foundation construction method of a steel-concrete composite girder for solving the problems of the background art.

In order to achieve the above and other related objects, the present invention provides a foundation construction method of a steel-concrete composite beam, including:

the method comprises the following steps of (1) mounting and constructing a supporting pile, mounting and constructing a cofferdam and constructing a bearing platform;

the mounting construction steps of the supporting pile comprise: inserting and fixing a plurality of supporting piles at the bottom of a seabed by a non-vertical inclined angle to form an inclined pile combined structure, wherein the bottom end of each supporting pile in the inclined pile combined structure deviates to the outer side; installing a first pile bracket and a connecting piece at the position of each supporting pile close to the top end to form a supporting system of the cofferdam;

the cofferdam installation and construction steps comprise: after the cofferdam is manufactured in a factory, determining the position and the size of a mounting hole of a cofferdam bottom plate according to the pile foundation arrangement condition of the support piles arranged on site; after the cofferdam is transported to a construction site, the cofferdam is hoisted to the position of the inclined pile combined structure through a floating crane, the supporting piles are ensured to be matched with the mounting holes of the cofferdam bottom plate, and then the supporting system is connected with the cofferdam bottom plate in an underwater welding manner, so that the installation of the cofferdam is completed;

the construction steps of the bearing platform comprise: firstly, performing primary concrete pouring inside the cofferdam, and forming a bottom sealing concrete layer on the inner surface of a cofferdam bottom plate; the distributing beams are distributed on the top surface of the cofferdam bottom plate, and the cofferdam bottom plate, the distributing beams and the bottom sealing concrete layer are overlapped to form an integral stressed structure; after the bottom sealing concrete layer is formed, pumping out water in the cofferdam, and fixing the cofferdam through a tension rock anchor while pumping out the water in the cofferdam; and after pumping and tensioning, performing secondary concrete pouring on the back cover concrete layer to form a bearing platform.

Optionally, a second pile bracket is installed at a position of the supporting pile close to the top end, the second pile bracket is higher than the first pile bracket in position, and a temporary construction platform is arranged on the second pile bracket. The temporary construction platform is mainly used as an underwater welding operation platform and a support pile reinforced concrete pouring construction platform.

Optionally, the pouring of reinforced concrete of the support piles is completed, after the welding of the first pile bracket and the connecting piece is completed, the temporary construction platform is dismantled, then the underwater redundant support piles are cut off by using underwater hydraulic automatic circular cutting equipment, and the highest points of the support piles are kept on the same horizontal plane, so that the cofferdam is prevented from generating spatial interference with the support piles when being integrally placed on the inclined pile combined structure.

Optionally, the floating crane is positioned to accurately hoist the installation position by retracting and releasing the anchor chain through the winch, and meanwhile, in the hoisting process, timely correction is performed according to the sea water level change so as to ensure the accurate installation of the cofferdam;

and arranging an observation point at the top of the cofferdam, carrying out coordinate tracking observation on the cofferdam through a measuring robot in the installation process of the cofferdam, calculating the center deviation of the cofferdam, and carrying out position deviation correction on the floating crane according to the center deviation.

Optionally, after the cofferdam is placed and installed on the inclined pile combined structure, whether gaps exist between the bottom plate of the cofferdam and each supporting pile is checked, if gaps exist, the gaps are filled and installed by utilizing a sealing steel plate underwater, so that each supporting point can be effectively contacted, and after the cofferdam completely transfers load, the supporting points are welded.

Optionally, after the strength of the bottom-sealed concrete layer meets the requirement, a hydraulic jack is arranged on an anchor beam at the top of the cofferdam for stretching the rock anchors, the rock anchors are stretched and the water pumping is divided into a plurality of stages for operation, a certain amount of water is extracted in each stage, and meanwhile, the synchronous rock anchors are correspondingly stretched, so that the buoyancy generated by the cofferdam after the water in the cofferdam is extracted in each stage is balanced with the stretching force generated by the rock anchors, and the displacement and the deformation of the cofferdam are monitored in the whole process of water pumping until the water in the cofferdam is finally extracted.

Optionally, after pumping water, cleaning the surface of the chiseled bottom-sealed concrete layer to enable the chiseled bottom-sealed concrete layer to meet the flatness requirement, installing the template of the bearing platform on the surface of the bottom-sealed concrete layer, installing and laying the reinforcing steel bars, and finally pouring concrete to form the bearing platform.

Optionally, the bottom sealing concrete is poured by adopting a mode of pumping truck conveying concrete and single guide pipe quick pouring, the guide pipe is quickly transferred to a subsequent pouring point by utilizing the cooperation of a truck crane in the pouring process, the pouring direction is sequentially moved from one end to the other end of the transverse bridge, the slump is strictly controlled for ensuring the pouring quality of the concrete, and the high-efficiency slow-setting admixture is doped to ensure that the fluidity of the concrete meets the requirement, and the cofferdam displacement and deformation are monitored in the whole process of pouring.

Optionally, in the construction of the supporting pile, a barge is used as an operation platform, and the supporting pile is inserted into bedrock of the seabed through a hydraulic impact hammer;

in the construction process, a sufficient safety distance is ensured to be reserved between the supporting pile and the barge, and the collision between the barge and the supporting pile during the rising tide and the falling tide is prevented.

Optionally, during the construction process of inserting the support pile into the seabed, pins are installed at the pile heads of all the support piles contacting with the rock, and the hole sites of the pins are implemented in advance by a hydraulic drilling machine.

As described above, the foundation construction method of the steel-concrete composite beam of the present invention has at least the following beneficial effects:

compared with the traditional vertical pile inserting method, the supporting pile provided by the invention has better horizontal bearing capacity than a vertical pile, has stronger ultimate bearing capacity, is used as a foundation form with strong adaptability, has higher horizontal rigidity, can better resist impact load, share water and soil pressure and the like, and better adapts to the background environment of foundation with deeper water depth, frequent water level change in the tidal period, larger water surface flow rate, large impact load and deep covering layer;

according to the cofferdam, after holes of pile positions are reserved in the cofferdam bottom plate, the rest parts are processed in a factory to form a whole and transported to the site to be integrally installed by using a floating crane so as to reduce the links of site operation, the traditional cofferdam is spliced section by section on the site and is not integrally formed at one time, most of the traditional cofferdam needs to be sunk into a covering layer bearing layer, and the cofferdam is directly installed on the supporting piles to be connected into a whole to serve as a subsequent bearing platform construction waterproof structure, so that the stress is clear;

the top parts of the supporting piles are distributed on the periphery of the bottom plane of the bearing platform, the maximum horizontal distance between the piles is larger, and the conventional mode of bearing water pressure only by using bottom sealing concrete causes the thickness of the bottom sealing to be larger;

according to the cofferdam construction method, multiple groups of rock anchors are used as a main anti-floating stress system of the cofferdam in the water pumping stage, so that the problems that the self weight of a single-wall cofferdam and a thin back cover is small, the uplift bearing capacity of an inclined supporting pile does not participate in anti-floating calculation and the like are solved, the water pumping process and the tensioning process of the rock anchors are synchronously carried out, the buoyancy generated by the cofferdam in the water pumping process and the tensioning force generated by the rock anchors can be kept synchronously balanced, and the overall anti-floating process of the cofferdam in the construction process can be more stable.

Drawings

Figure 1 shows a schematic view of the arrangement of a cofferdam according to the invention mounted on a underpinning pile;

FIG. 2 is a schematic view of the arrangement of the support piles in the present invention;

FIG. 3 is a schematic view of the structure of the cofferdam of the present invention;

FIG. 4 is a schematic view showing the connection of the support pile and the cap in the present invention;

fig. 5 shows a top view of the connection of the support pile and the cap according to the invention.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

Please refer to fig. 1 to 5. It should be understood that the structures, ratios, sizes, and the like shown in the drawings are only used for matching the disclosure of the present disclosure, and are not used for limiting the conditions of the present disclosure, so that the present disclosure is not limited to the technical essence, and any modifications of the structures, changes of the ratios, or adjustments of the sizes, can still fall within the scope of the present disclosure without affecting the function and the achievable purpose of the present disclosure. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.

The following examples are for illustrative purposes only. The various embodiments may be combined, and are not limited to what is presented in the following single embodiment.

Referring to fig. 1 to 5, the present invention provides a foundation construction method for a steel-concrete composite beam, including a step of installing and constructing a support pile 1-1, a step of installing and constructing a cofferdam, and a step of constructing a bearing platform 01; the installation and construction steps of the support pile 1-1 comprise: a plurality of supporting piles 1-1 are inserted and fixed at the bottom of a seabed at a non-vertical inclined angle to form an inclined pile combined structure, and the bottom end of each supporting pile 1-1 in the inclined pile combined structure is deviated outwards; installing a first pile bracket 1-3 and a connecting piece 1-2 at the position of each supporting pile 1-1 far away from the top end to form a supporting system of the cofferdam; the cofferdam installation and construction steps comprise: after the cofferdam is manufactured in a factory, determining the position and the size of a mounting hole of a cofferdam bottom plate according to the pile foundation arrangement condition of the supporting piles 1-1 arranged on site; after the cofferdam is transported to a construction site, the cofferdam is hoisted to the position of the inclined pile combined structure through a floating crane, so that each supporting pile 1-1 is matched with a mounting hole of a cofferdam bottom plate, and meanwhile, a support system is welded with the cofferdam bottom plate to complete the mounting of the cofferdam; the construction steps of the bearing platform 01 comprise: firstly, performing primary concrete pouring inside the cofferdam, and forming a bottom-sealed concrete layer 2-7 on the inner surface of a cofferdam bottom plate; after the bottom sealing concrete layer 2-7 is formed, water in the cofferdam is pumped out, and the cofferdam is tensioned and fixed through the rock anchors 2-6 while the water in the cofferdam is pumped out; and after water pumping and tensioning are finished, performing secondary concrete pouring on the back cover concrete layers 2-7 to form a bearing platform 01. Referring to fig. 4 and 5, after the subsequent construction is completed, each of the underpinning piles 1-1 is used to support a bearing platform 01 of a pier and an upper structure thereof together. The bottom ends of all supporting piles 1-1 in the inclined pile combined structure are deviated inwards to form an inclined arrangement mode that the top ends of all supporting piles 1-1 are contacted densely and the bottom ends are dispersed densely at the top and are sparse at the bottom, wherein the supporting piles 1-1 are end supporting pile structures, the outer parts of the supporting piles are steel pipe structures, and reinforced concrete is poured in the supporting piles. The connecting pieces 1-2 arranged between the supporting piles 1-1 can be of a parallel connection structure, wherein the first pile bracket 1-3 and the connecting pieces 1-2 can be made of section steel materials, the first pile bracket 1-3 can be fixedly arranged on the supporting piles 1-1 in a welding mode, and the whole welding process is completed underwater. Compared with the traditional vertical pile inserting method, the supporting pile 1-1 arranged in the invention is better than a vertical pile in the aspect of horizontal bearing capacity, has stronger ultimate bearing capacity, is used as a foundation form with strong adaptability, has higher horizontal rigidity, can better resist impact load, share water and soil pressure and the like, and better adapts to the background environment of a foundation with deeper water depth, frequent water level change in the tidal period, larger water surface flow rate, large impact load and deep covering layer; according to the invention, after holes of pile positions are reserved on a cofferdam bottom plate, the rest parts are processed in a factory to form a whole and transported to the site to be integrally hoisted by using a floating crane so as to reduce the links of site operation, the traditional common cofferdam is spliced section by section on the site and is not integrally formed once, most of the traditional cofferdam needs to be sunk into a supporting layer of a river bed, and the cofferdam is directly arranged on a supporting pile 1-1 to be connected into a whole to serve as a construction water-blocking structure of a subsequent bearing platform 01, so that the stress is more stable; as the change range of the full tide level is large during construction, the steel pipe of the supporting pile 1-1 can not be prevented from being filled with seawater. Therefore, the air lift reverse circulation slag removal process can be adopted to drain the seawater remained in the steel pipe of the supporting pile 1-1, and the steel pipe of the supporting pile 1-1 is ensured to be in a water-free state before the concrete is poured. Before pumping water, the steel pipe of the supporting pile 1-1 is weighted by a concrete block on a temporary construction platform, so that the supporting pile 1-1 is prevented from floating upwards in the pumping process. And after the water pumping is finished, a camera is used for shooting in the hole to ensure that no water exists in the hole, and after the water pumping of the supporting pile 1-1 steel pipe is finished, a steel reinforcement cage is placed downwards and concrete is poured. According to the cofferdam construction method, multiple groups of rock anchors 2-6 are adopted as a main anti-floating stress system of the cofferdam in the water pumping stage, so that the problems that the self weight of a single-wall cofferdam and a thin back cover is small, the uplift bearing capacity of an inclined supporting pile 1-1 does not participate in anti-floating calculation and the like are solved, the water pumping process and the tensioning process of the rock anchors 2-6 are synchronously carried out, the buoyancy generated by the cofferdam in the water pumping process and the tensioning force generated by the rock anchors 2-6 can be synchronously balanced, and the overall anti-floating process of the cofferdam in the construction can be more stable.

In the embodiment, referring to fig. 1-3, the cofferdam includes four side plates 2-1 and a bottom plate 2-2, the four side plates 2-1 and the bottom plate 2-2 enclose a cofferdam body with an opening, and the inside of the cofferdam body can be used for pouring construction of a bearing platform 01; the supporting assembly comprises a plurality of inner supports 2-3 and surrounding purlins 2-4, the inner supports 2-3 are arranged between the side plates 2-1, the surrounding purlins 2-4 are installed on the inner walls of the side plates 2-1, and the surrounding purlins 2-4 are used for connecting and supporting the inner supports 2-3; the anchor beam 2-5 is arranged at the top of the side plate 2-1, a rock anchor 2-6 is arranged on the anchor beam 2-5, one end of the rock anchor 2-6 is fixed on the anchor beam 2-5, the other end of the rock anchor 2-6 can be fixed at the bottom of the seabed, and the rock anchor 2-6 is drilled by a hydraulic drilling machine and then poured with mortar and anchored with steel strands in the mortar for a certain length. And the inner supports 2-3 and the enclosing purlins 2-4 in the support assemblies are arranged inside the cofferdam body and can be used for ensuring the structural rigidity, strength and stability of the whole cofferdam.

In this embodiment, referring to fig. 1 and 2, a second pile bracket 1-4 is installed at a position of a supporting pile 1-1 near the top end, the second pile bracket 1-4 is higher than the first pile bracket 1-3, and a temporary construction platform is arranged on the second pile bracket 1-4; in the invention, a temporary construction platform is arranged on a supporting pile 1-1 and mainly used as a welding operation platform of an underwater cofferdam supporting system and a reinforced concrete pouring construction operation platform of the supporting pile. The top positions of the supporting piles 1-1 are distributed on the periphery of the bottom plane of the bearing platform 01, the maximum horizontal distance between the piles is larger, and the conventional mode of bearing water pressure only by using bottom sealing concrete causes the thickness of the bottom sealing to be larger, so that the invention forms an integral stress structure by distributing the distribution beams on the top surface of the cofferdam bottom plate and then pouring the bottom sealing concrete, so that the cofferdam bottom plate, the distribution beams and the bottom sealing concrete layer 2-7 are superposed, and the thickness of the bottom sealing is optimized.

In the embodiment, redundant supporting piles 1-1 in water are cut off by using underwater hydraulic automatic circular cutting equipment, and the highest point position of each supporting pile 1-1 is kept on the same horizontal plane, so that the cofferdam is ensured not to generate spatial interference when being integrally placed on an inclined pile combined structure. And the redundant supporting piles 1-1 are cut off, so that the subsequent cofferdam installation and construction can be more conveniently carried out. The highest point position of each supporting pile 1-1 is kept on the same horizontal plane, so that the bottom plate of the cofferdam and the supporting pile 1-1 are better matched in the process of lowering the cofferdam.

In the embodiment, the floating crane can accurately position the installation position by winding and unwinding the anchor chain through the winch, and can correct the sea water level in time according to the sea water level change in the hoisting process so as to ensure the accurate installation of the cofferdam; before the cofferdam is installed, in order to quickly and accurately locate the corresponding installation position of the cofferdam on the supporting pile 1-1, the supporting pile 1-1 is lifted and forwards laid with the floating ball, and the position of the steel cofferdam is roughly located through the floating ball, so that the installation positions of the cofferdam and the supporting pile 1-1 can be quickly located, the construction efficiency can be improved, the position can be timely corrected according to the change of environmental factors in the hoisting process, and the installation accuracy can be ensured. And arranging an observation point at the top of the cofferdam, carrying out coordinate tracking observation on the cofferdam through a measuring robot in the installation process of the cofferdam, calculating the center deviation of the cofferdam, and carrying out position deviation correction on the floating crane according to the center deviation.

In the embodiment, after the cofferdam is placed and installed on the inclined pile combined structure, whether a gap exists between the bottom plate of the cofferdam and each supporting pile 1-1 is checked, if the gap exists, the gap is filled and installed by using a sealing steel plate under water, so that each supporting point can be effectively contacted, and after the cofferdam completely transfers load, the supporting points are welded. In the whole process, underwater operation construction operation can be carried out through divers, and gaps among the supporting pads are filled by using sealing steel plates with different thicknesses, so that all supporting points can be effectively contacted.

In the embodiment, after the strength of the bottom-sealed concrete layers 2-7 meets the requirement, hydraulic jacks are distributed on anchor beams at the top of the cofferdam for stretching the rock anchors 2-6, the stretching of the rock anchors 2-6 and the water pumping are divided into a plurality of stages for operation, and the rock anchors 2-6 are correspondingly and synchronously stretched while a certain amount of water is pumped in each stage, so that the buoyancy generated by the cofferdam after the water in the cofferdam is pumped in each stage is balanced with the tension generated by the rock anchors 2-6 until the water in the cofferdam is pumped out finally. Because the water pumping speed is relatively slow, if the rock anchor pieces 2-6 are directly tensioned to the designed tension, the water pumping speed cannot be kept up with the designed tension, the buoyancy generated by the cofferdam after water in the cofferdam is pumped is not balanced with the tension generated by the rock anchor pieces 2-6, so that the cofferdam fractures the first pile bracket 1-3 or the tension is too large, so that the first pile bracket 1-3 and the connecting piece 1-2 generate large deformation, and the construction safety is influenced. Optionally, the operation can be performed in two stages, first the first section is tensioned by hydraulic jacks to reach 60% of the design tension of the rock anchors 2-6, corresponding to 60% of the water in the cofferdam, and the second stage is tensioned by the remaining 40% of the rock anchors 2-6, and then corresponding to 40% of the water in the cofferdam is pumped out.

In this embodiment, after the pumping is completed, the surfaces of the back cover concrete layers 2 to 7 are cleaned, the template of the bearing platform 01 is installed on the surfaces of the back cover concrete layers 2 to 7, the reinforcing steel bars are installed and arranged, and finally, concrete is poured to form the bearing platform 01. Before pouring bottom sealing concrete, cleaning attachments on the supporting piles 1-1, installing a cover plate in the hole gap of the bottom plate, fixedly welding the cover plate and the bottom plate, and sealing the tiny gap by adopting foam and cotton wool. The method is characterized in that a pump truck is adopted to convey concrete and a single guide pipe to be quickly poured to carry out concrete pouring in the process of bottom sealing concrete pouring construction, the guide pipe is quickly transferred to a subsequent pouring point by utilizing the cooperation of a truck crane in the pouring process, the pouring direction is sequentially moved to the other end from one end of a transverse bridge, the slump is strictly controlled for ensuring the pouring quality of the concrete, and a high-efficiency slow-setting admixture is doped to ensure that the fluidity of the concrete meets the requirement.

In the embodiment, a construction platform of the supporting pile 1-1 is operated by a barge, and the supporting pile 1-1 is inserted into bedrock of a seabed by a hydraulic impact hammer; during construction, a sufficient safety distance is ensured between the supporting pile 1-1 and the barge, and collision between the barge and the supporting pile 1-1 during rising, falling and tide is prevented. A65 x 17m barge is adopted as a construction platform of the supporting pile 1-1, a pair of splayed anchors are respectively arranged at the head and the tail of the barge for fixation, a 280t crawler crane is placed on the barge, a hydraulic ram is adopted for tamping the supporting pile 1-1, and a steel pipe is inserted into bedrock through the hydraulic ram. In the construction process of inserting the supporting pile 1-1 into the seabed, pins are arranged at the pile head positions of all the supporting piles 1-1 which are contacted with rocks, hole positions of the pins are constructed in advance by a hydraulic drilling machine, and the special design of the pile head of the supporting pile 1-1 can effectively avoid the bottom end deformation of the supporting pile 1-1 in the inserting and driving process and improve the rigidity of the pile end.

In conclusion, in the foundation construction method of the steel-concrete composite beam, the supporting pile 1-1 arranged in the invention is better than a vertical pile in the aspect of horizontal bearing capacity, the ultimate bearing capacity is stronger, the supporting pile has larger horizontal rigidity as a foundation form with strong adaptability, and can better resist impact load, share water and soil pressure and the like, the invention distributes the distribution beams on the top surface of the cofferdam bottom plate and then pours bottom sealing concrete, so that the cofferdam bottom plate, the distribution beams and the bottom sealing concrete are superposed to form an integral stress structure, thereby optimizing the thickness of the bottom sealing, and meanwhile, a plurality of groups of rock anchors 2-6 are adopted as a main anti-floating stress system of the cofferdam in the water pumping stage, thereby solving the problems that the self weight of the cofferdam and the thin bottom sealing is smaller, the anti-pulling bearing capacity of the inclined supporting pile 1-1 does not participate in anti-floating calculation and the like, meanwhile, the process of pumping water and the tensioning process of the rock anchor pieces 2-6 are synchronously carried out, so that the buoyancy generated by the cofferdam in the process of pumping water and the tensioning force generated by the rock anchor pieces 2-6 are synchronously balanced, and the overall anti-floating stress of the cofferdam in the construction process is reasonable. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A foundation construction method of a steel-concrete composite beam is characterized by comprising the following steps:

the method comprises the following steps of (1) mounting and constructing a supporting pile, mounting and constructing a cofferdam and constructing a foundation;

the mounting construction steps of the support pile comprise: inserting and fixing a plurality of supporting piles at the bottom of a seabed by a non-vertical inclined angle to form an inclined pile combined structure, wherein the bottom end of each supporting pile in the inclined pile combined structure is deviated outwards; installing a first pile bracket and a connecting piece at the position of each supporting pile far away from the top end to form a supporting system of the cofferdam;

the cofferdam installation and construction steps comprise: after the cofferdam is manufactured in a factory, determining the position and the size of a mounting hole of a cofferdam bottom plate according to the pile foundation arrangement condition of the support piles arranged on site; after the cofferdam is transported to a construction site, the cofferdam is hoisted to the position of the inclined pile combined structure through a floating crane, the matching of each supporting pile and the mounting hole of the cofferdam bottom plate is ensured, and then the underwater welding connection of the supporting system and the cofferdam bottom plate is carried out, so that the mounting of the cofferdam is completed;

the construction steps of the bearing platform comprise: firstly, performing primary concrete pouring inside the cofferdam, and forming a bottom sealing concrete layer on the inner surface of a cofferdam bottom plate; distributing beams are distributed on the top surface of the cofferdam bottom plate, so that the cofferdam bottom plate, the distributing beams and the bottom sealing concrete layer are overlapped to form an integral stressed structure; after the bottom sealing concrete layer is formed, pumping out water in the cofferdam, and fixing the cofferdam through a tension rock anchor while pumping out the water in the cofferdam; and after pumping and tensioning, performing secondary concrete pouring on the back cover concrete layer to form a bearing platform.

2. The foundation construction method of the steel-concrete composite beam according to claim 1, characterized in that:

installing a second pile bracket at a position, close to the top end, of the supporting pile, wherein the second pile bracket is higher than the first pile bracket, and arranging a temporary construction platform on the second pile bracket; the temporary construction platform can be used as an underwater welding operation platform and a support pile reinforced concrete pouring construction platform.

3. The foundation construction method of the steel-concrete composite beam according to claim 2, characterized in that:

after the reinforced concrete pouring of the support piles is completed and the welding of the first pile corbels and the connecting pieces is completed, the temporary construction platform is dismantled, then the underwater redundant support piles are cut off by using underwater hydraulic automatic circular cutting equipment, and the highest points of the support piles are kept on the same horizontal plane, so that the cofferdam can not generate spatial interference with the support piles when integrally placed on the inclined pile combined structure.

4. The foundation construction method of the steel-concrete composite beam according to claim 1, characterized in that:

the floating crane positioning is realized by winding and unwinding an anchor chain through a winch to accurately hoist the installation position, and meanwhile, in the hoisting process, the timely correction is carried out according to the sea water level change so as to ensure the accurate installation of the cofferdam;

5. The foundation construction method of the steel-concrete composite beam according to claim 1, characterized in that:

after the cofferdam is placed and installed on the inclined pile combined structure, whether gaps exist between the bottom plate of the cofferdam and each supporting pile is checked, if gaps exist, the gaps are filled and installed underwater by utilizing a sealing steel plate, so that each supporting point can be effectively contacted, and after the cofferdam completely transfers load, the supporting points are welded.

6. The foundation construction method of the steel-concrete composite beam according to claim 1, characterized in that:

after the strength of the bottom-sealed concrete layer meets the requirement, hydraulic jacks are arranged on anchor beams at the top of the cofferdam and used for stretching rock anchors, the rock anchors are stretched and pumped into water to be divided into a plurality of stages for operation, a certain amount of water is extracted in each stage, meanwhile, the rock anchors are synchronously stretched, so that the buoyancy generated by the cofferdam after the water in the cofferdam is extracted in each stage is balanced with the tension generated by the rock anchors, and the displacement and the deformation of the cofferdam are monitored in the whole process of pumping water until the water in the cofferdam is finally extracted.

7. The foundation construction method of the steel-concrete composite beam according to claim 1, characterized in that:

and after pumping water, cleaning the surface of the chiseled bottom-sealed concrete layer to enable the chiseled bottom-sealed concrete layer to meet the flatness requirement, installing the template of the bearing platform in the steel cofferdam, installing and laying reinforcing steel bars, and finally pouring concrete to form the bearing platform.

8. The foundation construction method of the steel-concrete composite beam according to claim 1, characterized in that:

the method is characterized in that the bottom sealing concrete is poured by adopting a pump truck conveying and single-guide-pipe rapid pouring mode, a truck crane is matched with a rapid transfer guide pipe to a subsequent pouring point in the pouring process, the pouring direction is sequentially moved to the other end from one end of a transverse bridge, the slump is strictly controlled for ensuring the pouring quality of the concrete, and high-efficiency slow-setting type additives are doped, so that the flowability of the concrete is ensured to meet the requirement, and the cofferdam displacement and deformation are monitored in the whole process of pouring.

9. The foundation construction method of the steel-concrete composite beam according to claim 1, characterized in that:

in the construction of the supporting pile, a barge is used as an operation platform, and the supporting pile is inserted into bedrock of the seabed through a hydraulic impact hammer;

10. A foundation construction method of a steel-concrete composite beam according to claim 9, characterized in that:

in the construction process of inserting the supporting piles into the seabed, pins are arranged at the pile heads of all the supporting piles contacted with rocks, and hole positions of the pins are constructed in advance by a hydraulic drilling machine.