Construction method of high pile foundation for high-speed deep-water bare rock geology in mountainous area

Abstract

The invention discloses a method for constructing a high-pile foundation in bare rock geology in mountainous areas with high speed and deep water. In a riverbed bare area with deep water and relatively hard rock or a non-bank slope river channel area such as a large-diameter pebble covering layer, a steel casing is inserted to assist in impact drilling to form pile holes, thereby ensuring the stability of the pile foundation in a deep water and bare rock environment, so that the pile foundation can be smoothly and safely bored to lift the foundation to above the water level, while avoiding the high construction measures and safety fees caused by underwater construction tie beams, greatly reducing the construction difficulty, improving construction safety, having the characteristics of safety, economy and environmental protection, and having obvious economic, progress and social benefits, and having good promotion and application value.

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction, and in particular to a method for constructing a high-pile foundation in deep-water bare rock geology at a mountainous area. Background Art

[0002] Our company has recently constructed a highway bridge project, in which there is a node project for the construction of a bridge. The location of the bridge is as follows: The bridge is located in a mountainous area. For a long time, the traffic on both sides of the river has been isolated by the Liuchi River, and there is no bridge for passage. The residents of the two towns need to detour or take a boat for daily travel, which is extremely inconvenient; According to the hydrological data provided by the local authorities, the maximum water depth at the underwater pier bridge location exceeds 30 meters. Affected by the water storage and power generation of the downstream hydropower station, the water level cannot be lowered. At the same time, combined with the comprehensive load under construction and operation status, the design is verified, and the underwater pile foundation must ensure a rock penetration depth of more than 20m. Combined with the survey data of the underwater geological conditions conducted by the design and survey unit, the riverbed has a large vertical drop, dense gullies, and the bottom of the riverbed is basically a rock accumulation layer 2 or a large rock belt layer 3, that is, there is no soft geology such as soil layer on the surface of the bottom of the riverbed, and the bottom layer is extremely uneven, with a large height difference, which belongs to the typical deep-water bare rock geological conditions; it is preliminarily determined that it is difficult for the deep-water pile foundation to take root and it is difficult to construct the tie beam underwater.

[0003] According to the above description, the design of this project mainly has the following technical difficulties:

[0004] First, the rooting problem of the pile foundation of the underwater pier bridge; because it is a typical deep-water bare rock geological condition, the design unit plans to adopt a multi-pile foundation mode (no less than 4), and the underwater pile foundation must be firmly connected to the bottom of the riverbed to avoid disturbance caused by the river or geological reasons; there are basically two methods for the construction of underwater pile foundations: 1. If the bottom of the water is basically a soft geological layer such as soil, the steel casing is first pre-pressed at the designated position to shape it, and then a drilling rig or other mechanism is used to drill along the direction of the steel casing to form the pile hole 4 of the underwater pile foundation, and the steel casing is used as a permanent device to form an underwater pile foundation through steel bars + grouting; 2. If the bottom of the water is basically a hard geological layer such as rock and the bottom of the water needs to be basically flat, the rock is first crushed at the designated position by an impact drill to form a preliminary hole, and then the steel casing is pre-pressed at the crushed position; then the impact drill is used to further crush and penetrate, and the corresponding steel casing is pre-pressed again, and this is repeated. Finally, all the steel casings are installed in the pile hole 4 of the underwater pile foundation and also form an underwater pile foundation as a permanent structure. The above two methods have a common problem: the cast underwater pile foundation (the underwater pile foundation in this project is more than 20 meters) is surrounded by a layer of steel casing, and the structural material of the steel casing itself is completely independent of the waterbed geological material and does not interfere with it. At the same time, the concrete cast later cannot produce any physical or chemical reaction with the waterbed geology during the solidification process. At the same time, due to the existence of the steel casing, the underwater pile foundation is completely independent of the waterbed (that is, the underwater pile foundation is directly inserted into the waterbed). In the early stage, since the steel casing has to be inserted into the pile hole 4 of the underwater pile foundation, there is a gap between the steel casing and the waterbed foundation, which may cause the underwater pile foundation to be deflected by water flow or geological changes in the later stage.

[0005] Second, due to the existence of multiple underwater pile foundations (no less than 4), if the tie beam is used to connect the multiple underwater pile foundations underwater, high construction measures and safety fees will be incurred (if the current common underwater steel cofferdam construction is used, the technical difficulty is also very high in the high drop and extremely flowing water environment); the pedestal mode is adopted for construction, and the pedestal is raised above the water surface for construction (but in order to ensure the stability of the bridge, the pedestal cannot be higher than 1 meter above the existing water surface, that is, the position of the pedestal in the total height of the bridge should not be too high). For this pedestal construction mode, the biggest difficulty is the installation of the pedestal formwork and the subsequent removal of the formwork, especially the installation and removal of the pedestal bottom formwork. Since the bottom of the pedestal is too low from the water surface (it is impossible for personnel and construction equipment to be installed or removed directly at the bottom of the pedestal), it will cause The difficulty of completion is very high; because the pedestal area of ​​this project is large (about 100 square meters), the amount of concrete required is large, and the bottom shape is complex (the middle part must have holes of the same number and size as the underwater pile foundation). If the existing commonly used steel formwork structure is adopted, the difficulty of production, installation and disassembly is extremely high; if the bottom formwork adopts the construction method of main beam + cross beam + square timber + bamboo plywood, there will be the problem of how to dismantle the bottom formwork later (due to this construction mode, there must be a fixed support underneath it, and the main beam + cross beam + square timber + bamboo plywood are constructed on the support in turn, and finally the pedestal concrete is cast in place. Due to the deformation of the concrete's own weight, the main beam + cross beam + square timber + bamboo plywood will be stuck between the fixed support and the lower surface of the poured pedestal concrete, and the main beam + cross beam + square timber + bamboo plywood cannot be dismantled). Summary of the invention

[0006] The purpose of the present invention is to provide a method for constructing high-pile foundations for high-speed deep-water bare rock geology in mountainous areas. The method is suitable for hydrogeological environments where the water level is deep, the hard bedrock of the riverbed is exposed, or there is a covering layer of large-diameter pebbles when constructing high-pile foundations in mountainous areas. The method can raise the high-pile foundations to the water surface, thereby solving the problem that the steel hanging box and tie beam must be constructed underwater to build a bridge. The method is also suitable for situations where the stability of underwater pile construction is difficult to ensure under the action of gravity load, etc., to overcome the shortcomings of the prior art.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for constructing a high-pile cap in high-speed deep-water bare rock geology in mountainous areas, comprising the following steps:

[0008] Step 1: Pile foundation in water; the underwater pile foundation is formed by underwater drilling and pouring piles, and the underwater part is formed by steel casing and poured into piles;

[0009] Step 2: Construction of the foundation;

[0010] 1) The base formwork of the pedestal is fixed and supported; support structures are set on both sides of each standard-diameter steel casing exposed on the horizontal surface, and all support structures are located at the same height;

[0011] 2) Installation of the pedestal bottom formwork: The main crossbeam of the pedestal bottom formwork is set up between the corresponding supporting structures, and the longitudinal and transverse beams perpendicular to the main crossbeams are laid at equal intervals on the main crossbeams, and then the square wood and bamboo plywood are laid on the longitudinal and transverse beams in sequence to form the pedestal bottom formwork; a demoulding gasket is set between the main crossbeam and the supporting structure;

[0012] The demoulding gasket comprises a base of a cavity structure, the base is fixed on a corresponding supporting structure, a gasket block is arranged above the base, the upper part of the gasket block is consistent with the cavity structure of the base and they are clearance matched with each other, and the lower part of the gasket block is a conical plug structure; the cavity of the base is filled with fine sand with good fluidity, a plurality of threaded holes for facilitating the outflow of fine sand are evenly arranged at the lower end of the base, and corresponding threaded rod-type plugs are arranged at the threaded holes; the upper part of the gasket block is embedded in the cavity of the base and a gap H is formed between the end of the plug structure and the bottom side of the cavity structure of the base, and a main beam slot is arranged on the upper surface of the gasket block; all bases are filled with an equal amount of fine sand, and the gasket blocks are embedded in the corresponding bases and then pressed flat, and then the corresponding main beams are inserted into the corresponding main beam slots, and then the other parts of the base bottom mold are installed to form the base bottom mold structure;

[0013] 3) Processing and installation of steel bars for the cap; the steel bars of the pier columns on the upper part of the bridge pier and the steel bars of the pile columns in the underwater pile foundation are tied together with the steel bars of the cap; they are fixed together with the steel bars of the cap by spot welding. In order to ensure the position of the steel bars of the pier columns and prevent the displacement of the embedded steel bars of the pier columns, channel steel brackets are welded around the cap to support and stabilize the steel bars of the bridge piers. When embedding the steel bars of the bridge piers, they must be checked with the longitudinal and transverse axes of the bridge piers, and sufficient anchoring length must be ensured;

[0014] Step 3: Install the side formwork of the pedestal. The side formwork of the pedestal adopts a standardized steel formwork. The internal and external support reinforcement system of the side formwork adopts channel steel for longitudinal reinforcement. The sides are connected with fasteners. The front, rear and side side formworks are reinforced with tension bolts. Combined channel steel is used for transverse reinforcement and channel steel is used for longitudinal reinforcement. Before installation, the inner surface of the formwork should be evenly coated with a release agent to ensure the verticality of the formwork and control the centerline position and elevation.

[0015] Step 4: Transportation and pouring of the cap concrete; cooling water pipes are set up to cool the interior of the cap concrete, and heat storage or water storage measures are taken for the exterior of the concrete; when water is passed through the interior of the concrete to cool it down, the temperature difference between the inlet and outlet water should not exceed 10°C, and the temperature difference between the water temperature and the internal concrete should not be greater than 20°C, and the cooling rate should not be greater than 2°C / d; when the cooling water discharged from the cooling water pipe is used to store water on the top surface of the concrete for thermal insulation, the difference between the curing water temperature and the concrete surface temperature should not be greater than 15°C;

[0016] Step 5: Remove the formwork of the side support of the pedestal and maintain the pedestal concrete; Use geotextile to cover and store water for maintenance, use the raised part of the formwork, and slowly flow water into the concrete surface after the initial setting. At the same time, monitor the internal temperature of the concrete. The side support formwork of the pedestal can be removed only when the difference between the internal temperature and the surface temperature is no more than 25°C;

[0017] Step 6: Dismantle the bottom formwork of the pedestal; after the casting of the pedestal is completed, the bottom formwork of the pedestal needs to be recycled to ensure the reuse of materials; first, unscrew the threaded rod plug on the base of the demoulding gasket at the same time, so that the fine sand in the base gradually flows out through the threaded hole and is recycled. Due to the outflow of fine sand, the gasket block will gradually move down along the axis of the base cavity. Due to the conical plug structure, under the action of the deadweight of the bottom formwork of the pedestal, the conical plug structure will push the fine sand in the base downward and outward uniformly, thereby pushing the fine sand to gradually flow out through the threaded hole, and the corresponding gasket block will also move down until the plug structure of the gasket block reaches the bottom side and stops, and the moving distance is H; the bottom formwork of the pedestal will also move down by a distance of H, and then the parts on the bottom formwork of the pedestal will be pulled out and recycled from top to bottom by a pulling method;

[0018] Step seven: Construction of bridge piers and columns.

[0019] As a further solution of the present invention: the support structure is a bracket structure symmetrically arranged on both sides of the corresponding steel casing, or a support beam structure passing through the central axis of the corresponding steel casing.

[0020] As a further solution of the present invention: the cavity of the base is a cylindrical structure or a square cavity structure, and the plug structure is a conical structure or a multi-faceted conical structure.

[0021] As a further solution of the present invention: a flexible retaining ring is embedded in the upper part of the cavity of the base, and the flexible retaining ring is transitionally matched with the upper tail of the gasket block to prevent fine sand from overflowing from the base.

[0022] As a further solution of the present invention: the method for forming piles in the water is: firstly, a large-diameter steel casing is placed at a corresponding position on the bottom of the riverbed, and then a drilling rig is used to construct the pile holes of the water pile foundation under the guidance of the large-diameter steel casing. After the construction is completed, a standard-diameter steel casing is buckled and inserted into the upper end of the large-diameter steel casing, and adjacent standard-diameter steel casings are fixedly connected, and the last standard-diameter steel casing is made to extend out of the water, and then the reinforcement construction and concrete pouring construction of the water pile foundation are carried out in sequence.

[0023] As a further solution of the present invention: the method for placing the large-aperture steel casing is: if the upper layer of the riverbed bottom is a rock accumulation layer and the lower layer is a large rock belt layer, the large-aperture steel casing is first inserted into the upper rock accumulation layer by pre-pressing to form a preliminary guide groove for the drilling rig, and then the drilling rig constructs the pile hole of the underwater pile foundation.

[0024] As a further solution of the present invention: the method for placing the large-diameter steel casing is: if the bottom of the riverbed is a large rock layer as a whole, first install a large-size impact drill bit at the end of the drilling rig to break the rock at the bottom of the riverbed and form a shallow groove drill hole of a certain depth, and then install the large-diameter steel casing in the drill hole by pre-pressing; replace the normal-size impact drill bit, and then use the drilling rig to construct the pile hole of the underwater pile foundation, so that the shallow groove drill hole and the pile hole of the underwater pile foundation form a pile hole structure with an annular clamp.

[0025] As a further solution of the present invention: the surface area of ​​the large-aperture steel casing covered by the riverbed bottom is not less than 1 / 4 of the entire surface area of ​​the large-aperture steel casing.

[0026] As a further solution of the present invention: an annular card is arranged in the upper connecting end of the large-diameter steel casing, the net size surrounded by the annular card is smaller than the outer size of the standard-diameter steel casing, and the net size of the large-diameter steel casing is larger than the outer size of the standard-diameter steel casing, so that the standard-diameter steel casing can be gap-matched with the large-diameter steel casing and clamped on the annular card;

[0027] A sealing strip is arranged above the large-diameter steel casing, and the sealing strip and the connecting end of the standard-diameter steel casing are transitionally matched to achieve sealing between the standard-diameter steel casing and the large-diameter steel casing.

[0028] As a further solution of the present invention: the inner surface of the pile hole of the underwater pile foundation is made of high-roughness rock material, and the large-diameter steel casing, the standard-diameter steel casing in the water and the standard-diameter steel casing extending out of the water constitute a steel cofferdam structure of the pile hole of the underwater pile foundation.

[0029] As a further solution of the present invention: the underwater pile foundation structure includes a deep section located in the pile hole of the underwater pile foundation, the deep section completely fills the pile hole corresponding to the underwater pile foundation and is in full contact with the high-roughness rock material in the pile hole, the upper part of the deep section is a transition section wrapped by a large-diameter steel casing, and the transition section is partially embedded in the bottom of the riverbed; the upper part of the transition section is a main section wrapped by a standard-diameter steel casing, and the upper end of the main section extends out of the water.

[0030] As a further solution of the present invention: the size of the transition section is larger than that of the deep-entry section and the main section, and the transition section as a whole is a convex column structure, or a convex column structure of a lower annular embedded body.

[0031] The design principle of the present invention, the technical differences and effects compared with the prior art:

[0032] 1. In order to avoid the cost and safety risks of installing tie beams in deep and flowing rivers in mountainous areas, the present invention adopts a capping construction method, and the capping can only raise the water surface of the river to a certain height.

[0033] 2. Since the base bottom formwork of the present invention has a large area and a complex structure, the base bottom formwork is assembled by longitudinal beams + transverse beams + square wood + bamboo plywood, and a supporting mechanism of the base magic wand is arranged on the corresponding pile foundation, so that the base bottom formwork can be quickly installed and disassembled, and the bearing capacity and installation progress are better than the installation progress of the existing steel formwork (if the steel formwork is used to make the base bottom formwork, the processing complexity and installation degree are too high, and the bearing capacity is weak).

[0034] 3. In order to facilitate the demoulding of the pedestal bottom mold, a demoulding gasket is provided between the supporting mechanism and the pedestal bottom mold. The fine sand with good fluidity in the demoulding gasket can be used to adjust the distance between the supporting mechanism and the pedestal bottom mold, so as to provide a demolition space for the later demolition of various parts of the pedestal bottom mold. Compared with the prior art, this structural design does not require any electrical components and wire circuits to be implemented. Since the height difference between the pedestal bottom mold and the water surface is very small, if circuits or electrical components are set on the lower surface of the pedestal bottom mold, the safety risk will increase.

[0035] 4. The pile foundation construction of the present invention is particularly suitable for typical deep-water bare rock geological conditions (the river bottom is basically hard geology such as rock layers, the river bottom surface is uneven and has a large drop, the river is deep and the flow rate is fast, the river drop is cross-bottom, etc.).

[0036] 5. The surface of the pile hole of the underwater pile foundation in the present invention is made of a rock layer with high roughness and is completely exposed, and the large-diameter steel casing and other standard-diameter steel casings form a steel cofferdam structure of the pile hole of the lower pile foundation, so that when concrete is poured for the underwater pile foundation in the later stage, the concrete entering the pile hole can be fully contacted and mixed with the rock layer with high roughness, which greatly improves the compactness and connection strength.

[0037] 6. The underwater pile foundation structure obtained by the present invention comprises a deep section located in the pile hole of the underwater pile foundation, the deep section completely fills the pile hole corresponding to the underwater pile foundation and is in full contact with the high-roughness rock material in the pile hole, the upper part of the deep section is a transition section wrapped by a large-diameter steel casing, and the transition section is partially embedded in the bottom of the riverbed; the upper part of the transition section is a main section wrapped by a standard-diameter steel casing, and the upper end of the main section extends out of the water surface. That is, the deep section of the underwater pile foundation is fully in contact with the underwater geology (without interruption, and the concrete can completely fill the gaps in the underwater geology), and will not be disturbed by the water flow. The large-sized transition section in the middle can be partially embedded in the water bottom, so that the underwater pile foundation located at the bottom of the water is completely connected with the water bottom to form a whole, and the transition section can become an independent support of the main section (at this time, the size of the transition section is larger than that of the main section, so that the transition section forms a new foundation. The transition section is a convex column structure, or a convex column structure of a lower annular embedded body, so that the stability and firmness of the underwater pile foundation located at the bottom of the water are better).

[0038] Aiming at special geographical and geological environments, the present invention, on the basis of existing construction technology, creatively solves the problem of weak stability and firmness of underwater pile foundation construction, and also solves the problem of needing to install tie beams in water, while providing a relatively objective solution for the rapid installation and disassembly of the pedestal formwork. The present invention overcomes the difficulties of hard riverbed rock strata, large vertical drop, difficulty in underwater pile foundation construction, difficulty in effectively fixing the base, great environmental pressure, and difficulty in ensuring stability under load, and accumulates valuable technical experience for pedestal construction in deep-water bare rock geology under similar hydrogeological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Figure 1 The riverbed geology in the present invention is double-layer geology, which is the installation position of the large-aperture steel casing;

[0041] Figure 1.1 This is the connection relationship diagram of large-diameter steel casing and standard-diameter steel casing when the riverbed geology is double-layer geology;

[0042] Figure 1.2 This is a schematic diagram of the underwater pile foundation after cast-in-place when the riverbed geology is double-layer geology;

[0043] Figure 1.3 It is a schematic diagram of the concrete structure of the underwater pile foundation when the riverbed geology is double-layer geology;

[0044] Figure 1.4 for Figure 1.2 Middle A is a partial enlarged schematic diagram;

[0045] Figure 1.5 for Figure 1.1 Partial enlarged diagram of B in the middle

[0046] Figure 2 The installation position of the large-diameter steel casing is the single-layer geology of the riverbed;

[0047] Figure 2.1 This is the connection relationship diagram between the large-diameter steel casing and the standard-diameter steel casing when the riverbed geology is single-layer geology;

[0048] Figure 2.2 This is a schematic diagram of the underwater pile foundation after cast-in-place when the riverbed geology is single-layer geology;

[0049] Figure 2.3 Schematic diagram of the concrete structure of the underwater pile foundation when the riverbed geology is single-layer geology

[0050] Figure 3 It is a schematic diagram of the overlapping installation position of the main cross beam and the longitudinal and transverse beams in the cap in the present invention;

[0051] Figure 4 It is a schematic diagram of the installation of the base mold of the cap in the present invention;

[0052] Figure 5 It is a schematic structural diagram of the demoulding gasket in the present invention;

[0053] Figure 5.1 It is a schematic diagram of the structure of the gasket plug in the present invention.

[0054] The serial numbers in the figure are: 1. water flow; 2. rock accumulation layer; 3. large rock belt layer; 4. pile hole; 5. large-diameter steel casing; 5.1. ring card; 5.2. sealing strip; 6. standard-diameter steel casing; 7. underwater pile foundation; 7.1. deep section; 7.2. transition section; 7.3. main section; 7.4. annular embedded body; 8. demoulding gasket; 8.1. base; 8.2. gasket block; 8.3. plug structure; 8.4. fine sand; 8.5. threaded hole; 8.6. threaded rod plug; 8.7. beam slot; 8.8. flexible retaining ring; 10. main beam; 11. longitudinal and transverse beams; 12. square wood; 13. bamboo plywood; 14. corbel. DETAILED DESCRIPTION

[0055] The embodiments of the present invention will be described in detail below in conjunction with examples and drawings thereof, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0056] Referring to the figure, this embodiment is applied to the Dejiang (Hexing) to Yuqing Expressway in Guizhou Province. The implementation of this project is a beneficial supplement and improvement to the expressway network in the northern Guizhou region. It is a fast channel connecting Dejiang, the western part of Sinan County, the eastern part of Fenggang, Shiqian Benzhuang Heba, Yuqing and other places to the Anjiang Expressway. After completion, it will connect the north-south expressways along the river to Rongjiang in the Guizhou Expressway Network, and form a complete transportation network with the surrounding national and provincial roads, county and township roads, and village roads.

[0057] In this project, a Liuchi River Bridge is required to be built. The site of the Liuchi River Bridge is located about 40m downstream of the Baijiawan Bridge on the main line of Deyu Expressway. The upper structure of the new bridge adopts prestressed concrete (post-tensioned) T-beams (3x40m), which are simply supported first and then structurally continuous. The total length of the bridge is 132.04m, and the center pile number is K0+125; the lower structure abutment adopts U-abutment, the bridge pier adopts a single rectangular column pier, and the pier adopts pile foundation. There are 4 pile foundations under each pier, and the abutment is a rounded rectangle with high piles above water, with 2 pieces.

[0058] According to the hydrological data provided by the local authorities, the maximum water depth at the two underwater pier bridges in the water exceeds 30 meters. Affected by the water storage and power generation of the downstream hydropower station, the water level cannot be lowered. At the same time, combined with the comprehensive load under construction and operation status, the underwater pile foundation must ensure a rock penetration depth of more than 20 meters. Combined with the survey data of the underwater geological conditions conducted by the design and survey unit, it is revealed that the riverbed has a large vertical drop, dense gullies, large blocks of gray rocks are exposed, the bottom layer is extremely uneven, and the height difference is large, which belongs to the typical deep-water bare rock geological conditions. It is preliminarily determined that it is difficult for deep-water pile foundations to take root and it is difficult to construct tie beams underwater. After repeated discussions and demonstrations with the designer and the owner, it was proposed to raise the elevation of the pedestal to a position above the water surface line to avoid the construction of tie beams underwater, reduce safety risks and reduce the construction costs of underwater steel hanging boxes. At the same time, in order to avoid the difficulty of construction in the rainy season and minimize construction costs and construction risks, the pedestal construction must be completed during the dry season. Faced with realistic challenges, the project department rose to the challenge, actively planned, and repeatedly conducted scheme comparison and discussion with the Deyu Expressway Project Company and the design and survey units. It established research projects to address problems such as exposed riverbed rock, large vertical drop, difficulty in underwater pile foundation construction, difficulty in underwater drilling operations, and difficulty in ensuring stability under load.

[0059] The construction process is as follows:

[0060] Step 1: Pile foundation in water; the underwater pile foundation 7 is formed by underwater bored piles, and the underwater part is formed by steel casing and poured into piles;

[0061] Specifically, a large-diameter steel casing 5 is first placed at a corresponding position on the bottom of the riverbed, and then a drilling rig is used to construct the pile hole 4 of the underwater pile foundation under the guidance of the large-diameter steel casing 5. After the construction is completed, a standard-diameter steel casing 6 is buckled and inserted into the upper end of the large-diameter steel casing 5, and adjacent standard-diameter steel casings 6 are fixedly connected, and the last standard-diameter steel casing 6 is made to extend out of the water, and then the reinforcement construction and concrete pouring construction of the underwater pile foundation are carried out in turn.

[0062] The above construction should be further distinguished from the geological conditions of the riverbed. If the riverbed bottom is composed of a rock accumulation layer 2 on the upper layer and a large rock belt layer 3 on the lower layer, firstly, a large-diameter steel casing 5 is inserted into the upper rock accumulation layer 2 by preloading to form a preliminary guide groove for the drilling rig, and then the drilling rig constructs the pile hole 4 of the underwater pile foundation (see Figure 1-Figure 1.2 and Figure 1.4 If the bottom of the riverbed is a large rock layer 3, first install a large-size impact drill bit at the end of the drilling rig to break the rock at the bottom of the riverbed and form a shallow groove drill hole of a certain depth, and then install a large-diameter steel casing 5 in the drill hole by pre-pressing; replace the normal-size impact drill bit, and then use the drilling rig to construct the pile hole 4 of the underwater pile foundation, so that the shallow groove drill hole and the pile hole 4 of the underwater pile foundation form a pile hole structure with an annular card platform (see Figure 2-Figure 2.2 In this project, about 1 / 3 of the underwater pile foundation is composed of a large rock belt layer 3, and the rest is composed of a rock accumulation layer 2 on the upper layer and a large rock belt layer 3 on the lower layer). The surface area of ​​the large-aperture steel casing 5 covered by the riverbed bottom is not less than 1 / 4 of the entire surface area of ​​the large-aperture steel casing 5.

[0063] See Figure 1.5 A ring card 5.1 is arranged in the upper connecting end of the large-aperture steel casing 5, and the net size surrounded by the ring card 5.1 is smaller than the outer size of the standard-aperture steel casing 6, and the net size of the large-aperture steel casing 5 is larger than the outer size of the standard-aperture steel casing 6, so that the standard-aperture steel casing 6 can be gap-matched with the large-aperture steel casing 5 and stuck on the ring card 5.1; a sealing strip 5.2 is arranged above the large-aperture steel casing 5, and the connecting end of the sealing strip 5.2 and the standard-aperture steel casing 6 is a transition fit, so as to achieve the sealing between the standard-aperture steel casing 6 and the large-aperture steel casing 5; the inner surface of the pile hole 4 of the underwater pile foundation is a rock material with high roughness, and the large-aperture steel casing 5, the standard-aperture steel casing 6 in the water and the standard-aperture steel casing 6 extending out of the water constitute the steel cofferdam structure of the pile hole 4 of the underwater pile foundation.

[0064] A submerged pile foundation structure obtained by the above process (see Figure 1.3 and Figure 2.3 ), the underwater pile foundation 7 structure includes a deep section 7.1 located in the pile hole 4 of the underwater pile foundation, the deep section 7.1 completely fills the pile hole 4 of the corresponding underwater pile foundation and is in full contact with the high-roughness rock material in the pile hole 4 (see Figure 1.4 ), the upper part of the deep section 7.1 is a transition section 7.2 wrapped by a large-diameter steel casing 5, and the transition section 7.2 is partially embedded in the bottom of the riverbed; the upper part of the transition section 7.2 is a main section 7.3 wrapped by a standard-diameter steel casing 6, and the upper end of the main section 7.3 protrudes out of the water surface. The size of the transition section 7.2 is larger than that of the deep section 7.1 and the main section 7.3. The transition section 7.2 is a convex column structure as a whole, or a convex column structure of a lower annular embedded body 7.4.

[0065] Step 2: Construction of the foundation;

[0066] 1. The base mold is fixedly supported and installed; support structures are set on both sides of each standard-diameter steel casing 6 exposed on the horizontal surface, and all support structures are located at the same height; the support structure is a corbel 14 structure symmetrically set on both sides of the corresponding steel casing, or a support beam structure that runs through the central axis of the corresponding steel casing (this embodiment is made of corbel 14). The corbel assembly materials are first processed and formed by the steel processing plant according to the design drawings. After the corbel steel plate processing is accepted, it is transported to the site for welding with the steel casing. During welding, it is arranged symmetrically along the axis of the casing. The elevation is controlled according to the design elevation. The corbel and the casing are welded by full welding, and the weld width and height meet the requirements of the specifications. The elevation of the top surface of the corbel shall not be higher than the design elevation.

[0067] 2. Installation of the base mold; see Figure 3 and Figure 4 , a main crossbeam 10 of the foundation base formwork is set up between the corresponding supporting structures, longitudinal and transverse beams 11 perpendicular to the main crossbeam 10 are laid at equal intervals on the main crossbeam 10, and then square wood 12 and bamboo plywood 13 are laid on the longitudinal and transverse beams 11 in sequence to form a foundation base formwork;

[0068] Specifically, after the welding construction is completed, demoulding pads are installed on the corbels of the steel casing, and then double-jointed I40a I-beam crossbeams are set up on the demoulding pads as the platform support skeleton, and the crossbeams are perpendicular to the direction of the bridge; 9 full-length double-jointed I20a I-beam longitudinal beams are laid on top, and each side is welded in parallel. To ensure the relative stability of the longitudinal and transverse beams, two 50*50*16mm steel plates are welded at the contact point between the main longitudinal beam and the cross beam as limiters. At the same time, 10*10cm square timbers are fully laid on the top of the distribution beam I-beams with a spacing of 20cm, and 15mm bamboo plywood is fully laid on the square timber as the construction platform plane and the base bottom formwork.

[0069] After the installation of the bottom formwork of the pedestal is completed, in order to ensure the safety of personnel working, it is necessary to set up safety protection fences around the platform. The fence is built with φ48mm steel pipes and fasteners. The height of the vertical poles is 1.2m, the distance between the vertical poles is not more than 2m, and there are two layers of upper and lower horizontal bars. The upper horizontal bar is 1.2m away from the platform surface, and the lower horizontal bar is 0.6m away from the platform surface. The roots of the vertical poles are welded to the transverse distribution beams, and an 18cm high skirting board is set at the bottom.

[0070] See Figure 5 and Figure 5.1A demoulding gasket 8 is arranged between the main crossbeam 10 and the supporting structure; the demoulding gasket 8 comprises a base 8.1 of a cavity structure, the cavity of the base 8.1 is a cylindrical structure or a square cavity structure, the plug structure 8.3 is a conical or multi-faceted conical structure, the base 8.1 is fixed on the corresponding supporting structure, a gasket block 8.2 is arranged above the base 8.1, the upper part of the gasket block 8.2 is consistent with the cavity structure of the base 8.1 and they are clearance-matched with each other, and the lower part of the gasket block 8.2 is a conical plug structure 8.3; the cavity of the base 8.1 is filled with fine sand 8.4 with good fluidity, a plurality of threaded holes 8.5 for facilitating the outflow of the fine sand 8.4 are evenly arranged at the lower end of the base 8.1, and a threaded hole 8.5 is arranged at the threaded hole 8.5 There is a corresponding threaded rod plug 8.6; the upper part of the gasket block 8.2 is embedded in the cavity of the base 8.1 and the end of the plug structure 8.3 forms a gap H with the bottom side of the cavity structure of the base 8.1, and a main beam slot 8.7 is provided on the upper surface of the gasket block 8.2, and a flexible retaining ring 8.8 is embedded in the upper part of the cavity of the base 8.1. The flexible retaining ring 8.8 and the upper tail of the gasket block 8.2 are transitionally matched to prevent fine sand 8.4 from overflowing from the base 8.1; all bases 8.1 are filled with an equal amount of fine sand 8.4 and the gasket block 8.2 is embedded in the corresponding base 8.1 and then pressed flat, and then the corresponding main beam 10 is inserted into the corresponding main beam slot 8.7, and then the other parts of the base bottom mold are installed to form the base bottom mold structure;

[0071] The demoulding pad is 200mm high and is made of Q238B steel plate. When welding the node box, the weld must be fully penetrated and the weld height must not be less than 8mm.

[0072] 3. Processing and installation of steel bars for the cap; the steel bars for the pier columns on the upper part of the pier and the steel bars for the pile columns in the underwater pile foundation are tied together with the steel bars for the cap; they are fixed together with the steel bars for the cap by spot welding. To ensure the position of the steel bars for the pier columns and prevent the displacement of the pre-embedded steel bars for the pier columns, channel steel brackets are welded around the cap to support and stabilize the steel bars for the piers. When pre-embedded steel bars for the piers, they must be checked with the longitudinal and transverse axes of the piers, and sufficient anchoring length must be ensured;

[0073] Step 3: Install the side formwork of the pedestal support; the pedestal formwork adopts a standardized steel formwork. The formwork must have sufficient strength, rigidity and stability, the joints must be tight and leak-proof, and it must be able to withstand various loads that may be generated during the construction process. The formwork size is customized according to the pedestal size requirements.

[0074] Before installing the template, polish it clean and fully apply the release agent. The release agent should be a special release agent, and waste oil should not be used as a substitute. Ensure that the flatness of a single template is less than 1mm, the flatness should be less than 2mm when checked with a 3m ruler, and the misalignment between templates should be controlled below 1mm.

[0075] The formwork is supported on a solid base and is temporarily supported by brackets. Tie rods are set at the top and bottom of the formwork for support.

[0076] The internal and external support reinforcement system of the side formwork should take into account the order of concrete pouring and the influence of vibration load on the side formwork. Therefore, the formwork is reinforced horizontally and vertically with channel steel, and the formwork is connected with fasteners. The front, rear and side formworks are reinforced with M20 tension bolts. Four groups of combined channel steels are arranged with a spacing of 75cm for horizontal reinforcement, and 55cm for vertical reinforcement with channel steels. Before installation, the inner surface of the formwork should be evenly coated with release agent. During installation, strictly follow the design drawings to ensure the verticality of the formwork, control the centerline position and elevation, and make its accuracy meet the requirements of the design specifications. The template joints should be horizontal and vertical, the plate joints should be clamped with double-sided tape, and the tie rod eyes should be sealed with rubber rings or foam glue to ensure that there is no leakage during concrete pouring.

[0077] After the formwork is installed, its plane position, top elevation, and vertical and horizontal stability should be checked, and the design elevation of the pedestal top should be measured on the inner wall of the formwork to facilitate the control of concrete pouring. After the inspection is qualified, it can be reported to the supervising engineer for inspection and approval before pouring concrete.

[0078] Step 4: Transportation and pouring of cap concrete;

[0079] 1. Concrete mix ratio and temperature control measures

[0080] In order to reduce the hydration heat of large-volume concrete and avoid the early concentrated release of hydration heat and the generation of shrinkage cracks, the following measures will be taken during the construction of the cap concrete:

[0081] (1) Mix design: Reduce the amount of cement appropriately and add a certain proportion of ground fly ash and high-efficiency water reducer to increase the workability and early strength of concrete and reduce the hydration heat of concrete.

[0082] (2) Concrete raw materials must be inspected upon arrival to ensure they are qualified.

[0083] (3) The slump of concrete is controlled at 160-200mm (it can be adjusted according to the actual pumping effect during construction).

[0084] (4) Before construction, temperature control design and temperature control monitoring design should be carried out according to factors such as raw materials, mix ratio, environmental conditions, construction plan and construction technology, and the temperature inside and on the surface of the concrete should be monitored and controlled according to the design requirements after pouring. When temperature control is performed on large-volume concrete, the maximum internal temperature should not exceed 75°C, the temperature difference between the inside and the surface should not exceed 25°C, and the temperature difference between the concrete surface and the atmosphere should not exceed 20°C.

[0085] (5) The temperature control of large-volume concrete should be carried out in accordance with the principle of "cooling the interior and protecting the exterior". Cooling the interior of the concrete should be carried out by setting up cooling water pipes to circulate water, and covering the exterior of the concrete to store heat or store water for insulation. When cooling the interior of the concrete with water, the temperature difference between the inlet and outlet water should be less than or equal to 10°C, and the temperature difference between the water temperature and the internal concrete should not be greater than 20°C, and the cooling rate should not be greater than 2°C / d; when using the cooling water discharged from the cooling water pipe to store water on the top surface of the concrete for thermal insulation, the difference between the curing water temperature and the concrete surface temperature should not be greater than 15°C.

[0086] Step 5: Dismantle the side formwork of the cap and maintain the cap concrete;

[0087] Use geotextile to cover water storage and curing. Use the raised part of the formwork to slowly pour water after the initial setting of the concrete surface. It is strictly forbidden to force it in. The water storage curing time is determined according to the actual strength growth and hydration heat release. When the temperature of cooling water and top surface curing water is close to the air temperature, stop water storage and curing. At the same time, when pouring concrete, the internal temperature of the concrete should be monitored by pre-embedded temperature monitoring chips. The formwork can be removed only when the difference between the internal temperature and the surface temperature is no more than 25°C.

[0088] The maintenance work must not be affected or interrupted when removing the formwork, and the newly exposed concrete surface should be moisturized and maintained in time.

[0089] It is strictly forbidden to cause damage to the concrete when removing the formwork, and do not pry it hard to avoid large pieces of collapse and injuring people; the removed formwork is strictly forbidden to pile up on the platform, and should be lifted and stacked neatly outside the factory in a timely manner.

[0090] Step 6: Dismantle the bottom formwork of the pedestal; after the pedestal is cast, in order to ensure the reuse of materials, the bottom formwork of the pedestal needs to be recycled; first, unscrew the threaded rod plug 8.6 on the base 8.1 in the demoulding gasket 8 at the same time, so that the fine sand 8.4 in the base 8.1 gradually flows out through the threaded hole 8.5 and is recovered, and the gasket block 8.2 will gradually move down along the axis of the cavity of the base 8.1 due to the outflow of fine sand 8.4, and due to the shape of the conical plug structure 8.3, under the action of the deadweight of the bottom formwork of the pedestal, the conical plug structure 8.3 will push the fine sand 8.4 in the base 8.1 downward and outward uniformly, thereby pushing the fine sand 8.4 to gradually flow out through the threaded hole 8.5, and the corresponding gasket block 8.2 will also move down until the plug structure 8.3 of the gasket block 8.2 reaches the bottom side and stops, and the moving distance is H; the bottom formwork of the pedestal will also move down H distance accordingly, and then the parts on the bottom formwork of the pedestal are pulled out and recycled from top to bottom by a pulling method;

[0091] Step seven: Construction of bridge piers and columns.

[0092] Compared with the traditional construction experience, this embodiment requires the construction of underwater tie beams in deep water to meet the overall stability requirements of the two columns of the bridge. To construct underwater tie beams, steel hanging boxes must be used to assist in construction. This will incur very high construction safety measures and coordination fees, and coordination with upstream and downstream hydropower stations is also required, and the safety and environmental protection pressure is also relatively high. However, the high-pile foundation construction method only requires four piles to be lifted above the water surface to construct the foundation, successfully avoiding the safety risks of underwater construction operations, and there is no need to construct steel hanging boxes in the water. The construction is relatively simple and the cost is relatively low, which has accumulated technical experience for deep-water foundation construction under similar hydrogeological conditions.

[0093] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-speed deep-water bare rock geological high-pile foundation construction method in mountainous areas, characterized in that The following steps are involved: Step 1: forming piles in water; the pile foundation (7) is formed by underwater bored piles, and the underwater part is formed by steel casing and cast-in-place piles; Step 2: Capping construction; 1) The base mold is fixedly supported and installed; support structures are set on both sides of each standard-aperture steel casing (6) exposed on the horizontal surface, and all support structures are located at the same height; 2) Installation of the foundation bottom formwork; a main crossbeam (10) of the foundation bottom formwork is set up between the supporting structures at corresponding positions, longitudinal and transverse beams (11) perpendicular to the main crossbeam (10) are laid at equal intervals on the main crossbeam (10), and then square wood (12) and bamboo plywood (13) are laid on the longitudinal and transverse beams (11) in sequence to form the foundation bottom formwork; a demoulding gasket (8) is arranged between the main crossbeam (10) and the supporting structure; The demoulding gasket (8) comprises a base (8.1) with a cavity structure, the base (8.1) being fixed on a corresponding supporting structure, a gasket block (8.2) being arranged above the base (8.1), the upper portion of the gasket block (8.2) being consistent with the cavity structure of the base (8.1) and being clearance-matched with each other, and a conical plug structure (8.3) being arranged at the lower portion of the gasket block (8.2); the cavity of the base (8.1) being filled with fine sand (8.4) with good fluidity, a plurality of threaded holes (8.5) being evenly arranged at the lower end of the base (8.1) for facilitating the outflow of the fine sand (8.4), and a plurality of threaded holes (8.5) being arranged at the threaded holes (8.5) for facilitating the outflow of the fine sand (8.4) A corresponding threaded rod plug (8.6) is provided; the upper portion of the gasket block (8.2) is embedded in the cavity of the base (8.1) and a gap H is formed between the end of the plug structure (8.3) and the bottom side of the cavity structure of the base (8.1); a main beam slot (8.7) is provided on the upper surface of the gasket block (8.2); all bases (8.1) are filled with an equal amount of fine sand (8.4) and the gasket block (8.2) is embedded in the corresponding base (8.1) and then pressed flat, and then the corresponding main beam (10) is inserted into the corresponding main beam slot (8.7), and then the other parts of the base bottom mold are installed to form the base bottom mold structure; 3) Processing and installation of steel bars for the cap; the steel bars of the pier columns on the upper part of the bridge pier and the steel bars of the pile columns in the underwater pile foundation are tied together with the steel bars of the cap; they are fixed together with the steel bars of the cap by spot welding. In order to ensure the position of the steel bars of the pier columns and prevent the displacement of the embedded steel bars of the pier columns, channel steel brackets are welded around the cap to support and stabilize the steel bars of the bridge piers. When embedding the steel bars of the bridge piers, they must be checked with the longitudinal and transverse axes of the bridge piers, and sufficient anchoring length must be ensured; Step 3: Install the side formwork of the pedestal. The side formwork of the pedestal adopts a standardized steel formwork. The internal and external support reinforcement system of the side formwork adopts channel steel for longitudinal reinforcement. The sides are connected with fasteners. The front, rear and side side formworks are reinforced with tension bolts. Combined channel steel is used for transverse reinforcement and channel steel is used for longitudinal reinforcement. Before installation, the inner surface of the formwork should be evenly coated with a release agent to ensure the verticality of the formwork and control the centerline position and elevation. Step 4: Transportation and pouring of the cap concrete; cooling water pipes are set up to cool the interior of the cap concrete, and heat storage or water storage measures are taken for the exterior of the concrete; when water is passed through the interior of the concrete to cool it down, the temperature difference between the inlet and outlet water shall not exceed 10°C, and the temperature difference between the water temperature and the internal concrete shall not exceed 20°C, and the cooling rate shall not exceed 2°C / d; when the cooling water discharged from the cooling water pipe is used to store water on the top surface of the concrete for heat preservation and curing, the difference between the curing water temperature and the concrete surface temperature shall not exceed 15°C; Step 5: Remove the formwork of the side support of the pedestal and maintain the pedestal concrete; Use geotextile to cover and store water for maintenance, use the raised part of the formwork, and slowly flow water into the concrete surface after the initial setting. At the same time, monitor the internal temperature of the concrete. The side support formwork of the pedestal can be removed only when the difference between the internal temperature and the surface temperature is no more than 25°C; Step 6: Dismantle the bottom formwork of the pedestal. After the pedestal is cast, the bottom formwork of the pedestal needs to be recycled to ensure the reuse of materials. First, unscrew the threaded rod plug (8.6) on the base (8.1) in the demoulding gasket (8) at the same time, so that the fine sand (8.4) in the base (8.1) gradually flows out through the threaded hole (8.5) and is recycled. The gasket block (8.2) will gradually move down along the axis of the cavity of the base (8.1) due to the outflow of the fine sand (8.4). Due to the shape of the conical plug structure (8.3), the gasket block (8.2) will gradually move down along the axis of the cavity of the base (8.1). Under the action of the deadweight of the platform bottom mold, the conical plug structure (8.3) will push the fine sand (8.4) in the base (8.1) downward and outward uniformly, thereby pushing the fine sand (8.4) to gradually flow out through the threaded hole (8.5), and the corresponding gasket block (8.2) will also move downward until the plug structure (8.3) of the gasket block (8.2) reaches the bottom side and stops, and the moving distance is H; and the platform bottom mold will also move downward by the distance H, and then the parts on the platform bottom mold are pulled out and recovered from top to bottom by a pulling method; Step seven: Construction of bridge piers and columns.

2. The method for constructing high-pile caps in high-speed deep-water bare rock geology in mountainous areas according to claim 1 is characterized by: The support structure is a bracket (14) structure symmetrically arranged on both sides of the corresponding steel casing, or a support beam structure penetrating the central axis of the corresponding steel casing.

3. The method for constructing high-pile caps in high-speed deep-water bare rock geology in mountainous areas according to claim 1 is characterized by: The cavity of the base (8.1) is a cylindrical structure or a square cavity structure, and the plug structure (8.3) is a conical structure or a multi-faceted conical structure.

4. The method for constructing high-pile caps in high-speed deep-water bare rock geology in mountainous areas according to claim 1 is characterized by: A flexible retaining ring (8.8) is embedded in the upper part of the cavity of the base (8.1), and the flexible retaining ring (8.8) is transitionally matched with the upper tail of the gasket block (8.2) to prevent fine sand (8.4) from overflowing from the base (8.1).

5. The method for constructing high-pile caps in high-speed deep-water bare rock geology in mountainous areas according to claim 1 is characterized in that The method for forming a pile foundation in water comprises: firstly placing a large-diameter steel casing (5) at a corresponding position on the bottom of a riverbed, then using a drilling machine to guide the large-diameter steel casing (5) to construct a pile hole (4) of the pile foundation in water, and after the construction is completed, a standard-diameter steel casing (6) is inserted into the upper end of the large-diameter steel casing (5), adjacent standard-diameter steel casings (6) are fixedly connected, and the last standard-diameter steel casing (6) is extended out of the water surface, and then the reinforcement construction and concrete pouring construction of the pile foundation in water are carried out in sequence.

6. The method for constructing high-pile caps in high-speed deep-water bare rock geology in mountainous areas according to claim 5 is characterized in that The method for placing the large-aperture steel casing (5) is as follows: if the upper layer of the riverbed bottom is a rock accumulation layer (2) and the lower layer is a large rock belt layer (3), firstly, the large-aperture steel casing (5) is inserted into the upper rock accumulation layer (2) by pre-pressing to form a preliminary guide groove of the drilling rig, and then the drilling rig constructs the pile hole (4) of the underwater pile foundation.

7. The method for constructing high-pile caps in high-speed deep-water bare rock geology in mountainous areas according to claim 5 is characterized in that The method for placing the large-diameter steel casing (5) is as follows: if the bottom of the riverbed is a large rock layer (3), firstly, a large-size impact drill bit is installed at the end of the drilling rig to break the rock at the bottom of the riverbed and form a shallow groove drill hole of a certain depth, and then the large-diameter steel casing (5) is installed in the drill hole by pre-pressing; the impact drill bit of normal size is replaced, and then the drilling rig constructs the pile hole (4) of the underwater pile foundation, so that the shallow groove drill hole and the pile hole (4) of the underwater pile foundation form a pile hole structure with an annular clamping platform.

8. The method for constructing high-pile caps in high-speed deep-water bare rock geology in mountainous areas according to claim 6 or 7, characterized in that: The surface area of ​​the large-aperture steel casing (5) covered by the riverbed bottom is not less than 1 / 4 of the entire surface area of ​​the large-aperture steel casing (5).

9. The method for constructing high-pile caps in high-speed deep-water bare rock geology in mountainous areas according to claim 5 is characterized by: An annular card (5.1) is arranged in the upper connecting end of the large-diameter steel casing (5), the net size of the annular card (5.1) is smaller than the outer size of the standard-diameter steel casing (6), and the net size of the large-diameter steel casing (5) is larger than the outer size of the standard-diameter steel casing (6), so that the standard-diameter steel casing (6) can be gap-matched with the large-diameter steel casing (5) and clamped on the annular card (5.1); A sealing strip (5.2) is arranged above the large-diameter steel casing (5), and the connection end of the sealing strip (5.2) and the standard-diameter steel casing (6) is transitionally matched to achieve sealing between the standard-diameter steel casing (6) and the large-diameter steel casing (5); The inner surface of the pile hole (4) of the underwater pile foundation is made of a rock material with a high roughness. The large-diameter steel casing (5), the standard-diameter steel casing (6) in the water, and the standard-diameter steel casing (6) extending out of the water form a steel cofferdam structure of the pile hole (4) of the underwater pile foundation.

10. An underwater pile foundation structure formed by the construction method according to claim 9, characterized in that: The underwater pile foundation (7) structure comprises a deep section (7.1) located in a pile hole (4) of the underwater pile foundation, the deep section (7.1) completely fills the pile hole (4) of the corresponding underwater pile foundation and is in full contact with the high-roughness rock material in the pile hole (4), the upper part of the deep section (7.1) is a transition section (7.2) wrapped by a large-diameter steel casing (5), and the transition section (7.2) is partially embedded in the bottom of the riverbed; the upper part of the transition section (7.2) is a main section (7.3) wrapped by a standard-diameter steel casing (6), and the upper end of the main section (7.3) protrudes out of the water surface; The size of the transition section (7.2) is larger than the size of the deep-entry section (7.1) and the main section (7.3); the transition section (7.2) is a convex column structure as a whole, or a convex column structure of the lower annular embedded body (7.4).

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