Construction method of offshore deep-water boulder layer pile foundation construction structure

Abstract

The application provides a construction method of a deep-water boulder layer pile foundation construction structure on the sea, and comprises the following steps: floating guide system assembly and positioning; support unit construction; system conversion; pile end rock-embedding; bearing unit construction; and support pile consolidation. Through the action of the floating box and the guide frame, accurate positioning of the support pile group in complex sea conditions is realized, and the method of inserting piles and connecting simultaneously is adopted, so that a flat link frame is installed immediately after two support piles are completed, four support piles of adjacent guide frames quickly form a stable frame structure similar to a "dining table structure", the overall rigidity is ensured, and the support piles can be more conveniently embedded into the boulder layer and the rock layer for effective consolidation in a punching and sinking manner, the influence of platform shaking on accurate positioning of the steel casing is avoided, and the safety hidden danger of support pile body buckling when a heavy drilling machine drills a bridge pile foundation on the platform is avoided, the stability of subsequent pile foundation construction is ensured, and the quality is ensured.

Description

Technical Field

[0001] This invention relates to the field of marine pile foundation construction technology, and in particular to a construction method for a deep-water pebble layer pile foundation structure. Background Technology

[0002] With the continuous development of large-scale marine infrastructure construction such as cross-sea bridges and offshore wind power, deep-water pile foundation construction technology is facing increasingly complex engineering geological and environmental conditions.

[0003] In offshore pile foundation construction with thick overburden, pile driving vessels or floating crane vessels are usually used to directly drive steel casings. A single steel casing can stand stably and the accuracy can be controlled. However, in the case of thin overburden above pebble or rock layers, the "jacket method" is often used to provide a working platform for the casing to stand stably. However, the "jacket method" has high requirements for the size of the assembly site, the draft of the wharf, and the lifting capacity of the floating crane. This leads to a significant increase in construction costs and greater risks in offshore hoisting operations when constructing in deep water areas, and the overall construction period is also extended accordingly. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a construction method for deep-water pebble layer pile foundation structures, which solves the problems of high cost, long construction period, and high hoisting risk in existing pile foundation construction technologies.

[0005] According to an embodiment of the present invention, a construction method for a deep-water pebble layer pile foundation structure includes the following steps: S1: Assemble and position the floating guidance system, fix the winch and multiple guide frames on the pontoon, and use the winch to retract and extend the anchor chain to accurately position the pontoon; S2: Support unit construction, each support pile is hoisted and lowered into the guide holes at both ends of each guide frame to form two support pile groups, and then the support piles are driven in sequence. When each pair of support piles is completed, a flat connecting frame is installed between them so that the four support piles of the adjacent guide frames form a stable frame structure. S3: System conversion. During the slack tide period, the floating box is removed and prefabricated platform panels are installed on the established stable frame structure to complete the conversion from a floating platform to a fixed working platform. S4: Rock embedding at the pile tip, drilling and pile driving operations are carried out on the precast platform panel; S5: Construction of load-bearing unit; S6: Support pile consolidation involves drilling and cleaning the support pile hole, lowering the reinforcing cage, and pouring fine aggregate concrete to consolidate the support pile with the bedrock.

[0006] Compared with the prior art, the present invention has the following beneficial effects: In this method, firstly, the precise positioning of the support pile group in complex sea conditions is achieved through the action of the pontoon and guide frame. Simultaneously, the method of simultaneous pile insertion and connection is adopted, with a horizontal connecting frame installed immediately after each two support piles are completed. This allows the four support piles of adjacent guide frames to quickly form a stable frame structure similar to a "bench structure," ensuring overall rigidity. Furthermore, the use of perforation and sinking methods allows the support piles to more easily penetrate and effectively consolidate into the pebble and rock layers, avoiding the impact of platform sway on the precise positioning of the steel casing and the safety hazard of pile buckling that can occur when heavy drilling rigs drill bridge foundations on the platform. This ensures the stability and quality of subsequent pile foundation construction. Secondly, the constructed support unit forms a spatial frame system through multiple support piles and horizontal connecting frames. The horizontal connecting frames effectively distribute the forces on the support piles to the entire support unit and even the entire structure, thereby greatly improving the platform's resistance to overturning and deformation. At the same time, the entire construction structure is composed of modular components of the load-bearing unit and support unit, effectively reducing the complexity, construction period, and cost of offshore construction. Attached Figure Description

[0007] Figure 1 These are the front and top views of the construction structure in an embodiment of the present invention.

[0008] Figure 2 These are side views and enlarged partial views of the construction structure in an embodiment of the present invention.

[0009] Figure 3 This is a schematic diagram of the structure in an embodiment of the present invention, showing how the supporting piles are connected by a horizontal connecting frame.

[0010] Figure 4 These are front and top views of the assembly steps of the floating guidance system in an embodiment of the present invention.

[0011] Figure 5 These are the front and top views of the support unit construction steps in an embodiment of the present invention.

[0012] Figure 6 These are side and front views of the system conversion step in an embodiment of the present invention.

[0013] Figure 7 This is a schematic diagram of the rock embedding step at the pile end in an embodiment of the present invention.

[0014] Figure 8 This is a structural schematic diagram of the construction steps of the bearing unit in an embodiment of the present invention.

[0015] Figure 9 These are side and front views of the support pile consolidation step in an embodiment of the present invention.

[0016] Figure 10This is a schematic diagram of the steel casing installation in an embodiment of the present invention.

[0017] Figure 11 This is a schematic diagram of the structure during the construction of bored piles in an embodiment of the present invention.

[0018] In the above attached figures: 1. Support piles; 2. Flat frame; 3. Patterned steel plate; 301. Pile top crossbeam; 302. Bailey bridge beam; 303. Distribution beam; 4. Reinforcing cage; 5. Prefabricated platform panels; 6. Floating box; 601. Winch; 602. Anchor chain; 7. Guide frame; 701. Guide hole. Detailed Implementation

[0019] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] like Figures 4 to 11 As shown in the figure, this invention proposes a construction method for a deep-water pebble layer pile foundation structure, which includes the following steps: S1: Assemble and position the floating guidance system, fix the winch 601 and multiple guide frames 7 on the floating box 6, and use the winch 601 to wind up and unwind the anchor chain 602 to accurately position the floating box 6; S2: Construction of the support unit: Each support pile 1 is hoisted and lowered into the guide holes 701 at both ends of each guide frame 7 to form two support pile groups. Then, the support piles 1 are driven in sequence. When two support piles 1 are completed, a horizontal connecting frame 2 is installed between them so that the four support piles 1 of adjacent guide frames 7 form a stable frame structure. After the stable frame structure is formed, the connection between the guide frame 7 and the floating box 6 is promptly released, and S1 and S2 are repeated to complete the construction of the support unit on the other side. S3: System conversion. During the slack tide period, the floating box 6 is removed, and the prefabricated platform panel 5 is installed on the established stable frame structure to complete the conversion from a floating platform to a fixed working platform. S4: Rock embedding at the pile end, drilling and pile driving operations are carried out on the precast platform panel 5; when drilling, an impact drill is used to drill holes at each pile position one by one to penetrate the pebble layer and enter the designed depth below the rock surface, and release the constraints of each horizontal connecting frame 2 of the target support pile 1; when driving the pile, a floating crane is used to drive the target support pile 1 to the designed depth below the rock surface; after each support pile 1 is driven, the horizontal connecting frame 2 is installed again on the adjacent support pile 1. S5: Construction of load-bearing unit; S6: Consolidation of support pile 1: Drilling, cleaning, lowering the steel cage 4, and pouring fine stone concrete into the pile hole of support pile 1 to consolidate support pile 1 with the bedrock.

[0021] like Figure 1 and Figure 2 As shown, the completed deep-water pebble layer pile foundation construction structure includes a bearing unit and two support units located at both ends of the bearing unit. The bearing unit includes a patterned steel plate 3, a distribution beam 303, multiple Bailey beams 302 and multiple pile top crossbeams 301 arranged from top to bottom. The multiple Bailey beams 302 are spaced apart at the bottom of the distribution beam 303 and the multiple pile top crossbeams 301 are spaced apart at the bottom of the Bailey beams 302. The support unit includes at least two parallel support pile groups, each support pile group including multiple support piles 1 that are intermittently embedded in the pebble layer, and each support pile 1 is connected by a horizontal connecting frame 2; the pile top beam 301 is erected on the top of each support pile 1 in the support pile group.

[0022] In the construction structure completed according to this plan, the support unit forms a spatial frame system through multiple support piles 1 and horizontal connecting frames 2. The force on the support piles 1 can be effectively distributed to the entire support unit and even the entire structure through the horizontal connecting frames 2, thereby greatly improving the platform's anti-overturning and anti-deformation capabilities.

[0023] Secondly, the two support units are installed on both sides of the bearing unit, which not only ensures the stability of the bearing unit but also reduces the number of support piles 1 used, thus reducing costs. Moreover, when every four support piles 1 are connected by the horizontal connecting frame 2, the four support piles 1 form a highly stable "bench structure" that can resist the forces brought by waves and tides. At the same time, the entire construction structure is composed of modular components of the bearing unit and support unit. When assembling the entire construction structure, the support piles 1, checkered steel plates 3, distribution beams 303, multiple Bailey beams 302, and multiple pile top crossbeams 301 can be prefabricated and assembled separately, reducing the weight of offshore hoisting and the requirements for hoisting equipment, thereby indirectly reducing the complexity, construction period, and cost of offshore construction.

[0024] Furthermore, the support pile group of the support unit is a vertical row of support piles 1 arranged in a column. To ensure the stability of the support unit, the support pile group forming the support unit needs to form a rectangular structure. Therefore, the support pile group constituting the support unit can be two, three, or more parallel piles. Preferably, such as... Figure 3 As shown, there are two support pile groups. While ensuring stability, the spacing between the two support pile groups is controlled so that the spacing between the two support pile groups is the same as the spacing between the two support piles 1 in the same support pile group. This makes each support pile 1 of the two support pile groups form a square structure, which constitutes a stable frame structure.

[0025] Specifically, in S2, when installing the horizontal connecting frame 2, the horizontal connecting frame 2 is connected between two adjacent support piles 1 in the two support pile groups. When connecting the horizontal connecting frame 2, it can be sequentially connected between each support pile 1 in the support pile group, so as to... Figure 3 For example, support piles 1#, 2#, 3#, 4#, and 5# constitute a support pile group. The horizontal connecting frame 2 can sequentially connect support piles 1# and 2#, 2# and 3#, 3# and 4#, and 4# and 5#. After the connection is completed, the horizontal connecting frame 2 connects the two support piles 1#, 2#, 3#, 4#, and 5# of the two support pile groups. This allows the two support piles 1# and 2#, 2# and 3#, 4# and 5# to form a "bench structure". After each support pile 1 is driven into the pebble layer, the stability of the entire support unit can be guaranteed, thereby ensuring the stability of the bearing unit.

[0026] Specifically, for ease of connection, when installing the flat frame 2, the flat frame 2 and the corresponding support pile 1 are fixedly connected by bolts to achieve quick installation and quick disassembly in the later stage. It is also convenient for prefabrication and separate transportation. During transportation, barges and hoisting equipment can be used. It is lightweight and has low transportation requirements.

[0027] Specifically, in S1, all assembly work is completed on shore under suitable conditions, avoiding high-risk high-altitude operations and precision assembly at sea, thus improving safety, accuracy, and efficiency. Meanwhile, as... Figure 4 As shown, the pontoon 6, guide frame 7, and winch 601 are integrated into a floating guidance system, which not only facilitates overall transportation but also enables precise positioning of the support pile assembly in complex sea conditions. Utilizing the maneuverability of the pontoon 6 and the fine-tuning capability of the winch 601 for the anchor chain 602, the influence of wind, waves, and currents in deep-sea areas can be overcome, achieving extremely high-precision positioning of the pontoon 6 and guide frame 7. Specifically, the planar deviation of the precisely positioned pontoon 6 and guide frame 7 is <10cm. The guide hole 701 on the precisely positioned guide frame 7 provides reliable verticality and planar position assurance for the subsequent driving of the support pile 1, ensuring the regular shape of the "bench structure".

[0028] In the construction of the support unit of S2, such as Figure 5As shown, the guide frame 7 is a truss structure with a hollow structure. Two limiting plates can be installed at the ends of the guide frame 7 based on the dimensions of the support pile 1 to form guide holes 701. The dimensions of the guide holes 701 correspond to the dimensions of the support pile 1. When the position of the guide frame 7 is fixed, the guide holes 701 can guide and limit the lowering position of the support pile 1, ensuring that the support pile 1 will not move or deflect during driving. During driving, to avoid deformation of the support pile 1 due to strong impact, the support pile 1 is initially driven, ensuring initial stability while maintaining shallow penetration into the pebble layer. Since a single support pile 1 has no lateral constraint in the pebble layer, the guide holes 701 are used to guide and limit the lowering position of the support pile 1 after each pair of support piles are driven. The method of installing horizontal connecting frames 2 quickly transforms a single support pile 1 into a stable frame structure. At the same time, when the four support piles 1 are connected, a stable frame structure of bench structure is formed, which obtains great rigidity and stability and can independently resist horizontal loads. The support unit can be used as a set. When one type is used, the support unit is located directly below the bearing unit. Preferably, two sets of support units are used and set in parallel. After the support piles 1 of the support unit on one side are driven and connected, the construction of the support unit on the other side is carried out. The construction of the support structure on both sides of the bearing unit is initially completed, so that the two ends of the bearing unit form a symmetrical support structure, ensuring that the platform is subjected to uniform force, avoiding eccentric loads, and ensuring the stability and safety of the overall structure.

[0029] Meanwhile, because the pontoon 6 will continuously sway due to the waves, and the driven support pile 1 is still in the guide hole 701 of the guide frame 7, in S2, after the stable frame structure is formed, the connection between the guide frame 7 and the pontoon 6 is promptly released. Furthermore, to facilitate system conversion, the pontoon 6 and the guide frame 7 are also removed. Figure 6 As shown, the prefabricated platform panel 5, which has been transported to the site, is installed between the two support pile groups, so that the surface of the prefabricated platform panel 5 forms a stable fixed platform, which provides ideal conditions for subsequent precision operations such as drilling and pile driving, and facilitates the entry of large drilling rigs and other equipment.

[0030] In S4, this involves the secondary lowering of support pile 1. Due to insufficient penetration depth of support pile 1, stability in deep-sea areas cannot be guaranteed. Therefore, the prefabricated platform panel 5 is installed in segments, such as... Figure 3As shown, multiple prefabricated platform panels 5 are respectively installed on the horizontal connecting frame 2 between two No. 1 support piles 1 and two No. 2 support piles 1, on the horizontal connecting frame 2 between two No. 2 support piles 1 and two No. 3 support piles 1, on the horizontal connecting frame 2 between two No. 3 support piles 1 and two No. 4 support piles 1, and on two No. 4 support piles 1 and two No. 5 support piles 1. During pile driving, an inside-out approach is adopted, that is, taking the two No. 3 support piles 1 as the target support piles 1, disconnecting the connection between the horizontal connecting frame 2 and the No. 3 support piles 1, and simultaneously disconnecting the horizontal connecting frame 2 between the two No. 3 support piles 1. A percussion drill is used to drill holes at the position of the No. 3 support piles 1 corresponding to the pebble layer. Figure 7 As shown, the layer below the pebble layer is rock. To ensure that the support pile 1 completely penetrates the pebble layer, the drilling depth should be at least 0.5m deep, penetrating the pebble layer and entering the rock layer. After the two No. 3 support piles are embedded in the rock, the impact drill will be installed on the horizontal connecting frame 2 between the two No. 1 support piles 1 and the two No. 2 support piles 1, or on the two No. 4 support piles 1 and the two No. 5 support piles 1, in preparation for construction on No. 2 support piles 1 or No. 4 support piles 1. Before construction, the horizontal connecting frame 2 connected to No. 2 support piles 1 or No. 4 support piles 1 needs to be disconnected. Meanwhile, the horizontal connecting frame 2 is connected to the 3# support pile 1 after construction is completed. When the 2# support pile 1 or the 4# support pile 1 is completed, it is quickly connected to the corresponding horizontal connecting frame 2 to reconstruct a stable "bench structure". Since the 2# support pile 1, the 3# support pile 1 and the 4# support pile 1 have all been embedded in the rock, and the precast platform panel 5 cannot be constructed on the side of the 1# support pile 1 and the 5# support pile 1, that is, the 1# support pile 1 and the 5# support pile 1 do not undergo rock embedding construction. At the same time, all the horizontal connecting frames 2 are controlled at the same horizontal height.

[0031] After the target support pile 1 is embedded in the rock, in order to ensure stability, the final driving depth of the target support pile 1 is to penetrate the pebble layer and enter the rock layer by no less than 0.5m.

[0032] In S5, such as Figure 8 As shown, when constructing the bearing unit, the pile head of the support pile 1 is cut off according to the design elevation, and a pile top beam 301 is installed on the pile top of each support pile 1 in the two support units. Then, Bailey beam 302, distribution beam 303 and patterned steel plate 3 are installed on the pile top beam 301 to form the bearing unit.

[0033] Since the support piles 1 at both ends do not undergo rock-socketing construction (i.e., support piles 1# and 5# do not undergo rock-socketing construction), in order to construct the bearing unit, all support piles 1 are cut according to the design elevation to ensure that the tops of all support piles 1 are on the same plane and meet the elevation requirements. During the construction of the bearing unit, an onshore assembly method can be used. After assembling the pile top beam 301, Bailey beam 302, distribution beam 303, and checkered steel plate 3, they can be directly hoisted / transported between the two completed support units for direct installation. Alternatively, they can be installed in stages to reduce the weight of the hoisting, but this requires increasing the number of hoisting operations. By placing the pile top beam 301 on the support piles 1 of the same set of support piles and gradually installing the Bailey beam 302, distribution beam 303, and checkered steel plate 3, the bearing unit is formed. The checkered steel plate 3 can be installed in sections, and the entire bearing panel is formed by splicing the sections together.

[0034] Even though support pile 1 penetrates the entire pebble layer, due to the instability of the pebble layer and the environment of deep-sea areas, in order to further enhance the stability of support pile 1, in S6, such as Figure 9 As shown, the bottom of the support pile 1 is further fixed and connected. A geological drilling rig is used to drill a hole at the bottom of the support pile 1 and clean the hole. The steel cage 4 is lowered into the rock layer. The rock layer, pebble layer and support pile 1 are connected by pouring fine stone concrete, so that the support pile 1 is integrated with the rock layer, which improves its compressive, tensile and shear resistance, ensures the stability of the bearing unit and improves the quality of subsequent pile foundation construction.

[0035] Specifically, in S6, the number of drill holes shall not be less than four to ensure the quality of the pouring. If the number of drill holes is four, they shall be evenly arranged around the perimeter. At the same time, the number of reinforcing cages 4 shall correspond to the number of drill holes. The diameter of the drill holes shall be controlled between 15cm and 25cm, preferably 20cm. The size of the reinforcing cages 4 shall be 1cm to 3cm smaller than the diameter of the drill holes.

[0036] After all the support piles 1 were consolidated, the construction of the structure was completed. Subsequently, the steel casing construction was carried out, such as... Figure 10 As shown, the rectangular frame between the two support units represents the steel casing. Construction of the steel casing should be completed quickly when the tide flow velocity is zero. Simultaneously, when inserting the steel casing, a vibratory pile driver should be used immediately for vibratory driving, requiring strong driving and vibration to ensure that each casing penetrates the overburden layer and embeds into the pebble layer. After driving, it is connected to the support pile 1 via the horizontal connecting frame 2 for fixed connection. Figure 11 As shown, the drilling, cage lowering, and concrete pouring of the bored piles are finally completed on the bearing unit.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A construction method of a marine deep-water boulder layer pile foundation construction structure, characterized by, Includes the following steps: S1: Assemble and position the floating guidance system, fix the winch (601) and multiple guide frames (7) on the floating box (6), and use the winch (601) to wind up and unwind the anchor chain (602) to accurately position the floating box (6); S2: The support unit is constructed by hoisting and lowering each support pile (1) into the guide holes (701) at both ends of each guide frame (7) to form two support pile groups. Then, the support piles (1) are driven in sequence, and a flat connecting frame (2) is installed between the two when each pair of support piles (1) is completed, so that the four support piles (1) of the adjacent guide frames (7) form a stable frame structure. S3: System conversion, during the slack tide period, the floating box (6) is removed and the prefabricated platform panel (5) is installed on the established stable frame structure to complete the conversion from a floating platform to a fixed working platform; S4: Rock embedding at the pile end, drilling and pile driving operations are carried out on the precast platform panel (5); S5: Construction of load-bearing unit; S6: Consolidation of support pile (1): Drilling, cleaning, lowering the steel cage (4) into the pile hole of support pile (1) and pouring fine stone concrete to consolidate support pile (1) into bedrock. In S4, when drilling is carried out, an impact drill is used to drill holes at each pile location one by one to penetrate the pebble layer and reach the designed depth below the rock surface. The constraints of each horizontal connecting frame (2) of the target support pile (1) are released. When driving the pile, a floating crane is used to drive the target support pile (1) to the designed depth below the rock surface. After each support pile (1) is driven, the horizontal connecting frame (2) is installed again on the adjacent support pile (1).

2. A method of constructing a pile foundation structure for offshore deep water shingle layer according to claim 1, wherein In S2, when installing the flat frame (2), the flat frame (2) is connected between two adjacent support piles (1) in the two support pile groups.

3. The construction method for a deep-water pebble layer pile foundation structure according to claim 2, characterized in that, The horizontal connecting frame (2) is fixedly connected to the corresponding support pile (1) by bolts.

4. The construction method for a deep-water pebble layer pile foundation structure according to claim 1, characterized in that, In S5, when constructing the bearing unit, the pile head of the support pile (1) is cut off according to the design elevation, and a pile top beam (301) is installed on the pile top of each support pile (1) of the two support units. Then, Bailey beam (302), distribution beam (303) and patterned steel plate (3) are installed on the pile top beam (301) to form the bearing unit.

5. The construction method for a deep-water pebble layer pile foundation structure according to claim 1, characterized in that, In S1, the plane deviation of the precisely positioned pontoon (6) and guide frame (7) is <10cm.

6. The construction method for a deep-water pebble layer pile foundation structure according to claim 1, characterized in that, In S2, after a stable frame structure is formed, the connection between the guide frame (7) and the pontoon (6) is promptly released, and S1 and S2 are repeated to complete the construction of the other side support unit.

7. The construction method for a deep-water pebble layer pile foundation structure according to claim 1, characterized in that, The drilling depth is to penetrate the pebble layer and enter the rock layer by no less than 0.5m.

8. The construction method for a deep-water pebble layer pile foundation structure according to claim 1, characterized in that, The target support pile (1) has a final driving depth of at least 0.5m, which penetrates the pebble layer and enters the rock layer.

9. The construction method for a deep-water pebble layer pile foundation structure according to claim 1, characterized in that, In S6, the number of holes must be no less than four.

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