Nearshore abrupt slope deepwater bare rock pile foundation construction method

Abstract

The invention provides a near-shore abrupt slope deepwater bare rock pile foundation construction method, and aims to solve the problems that a bare inclined rock surface pile foundation steel casing is difficult to embed and slurry is easy to leak during drilling and hole forming, a punching and grabbing drill is adopted for guiding a hole, an overflow hole is annularly formed in a bottom opening of the steel casing, after the hole is guided to the designed elevation of the steel casing, the steel casing is put down, and built-in concrete is poured; the concrete flows to the outer side of the pile casing through the overflow holes to wrap the steel pile casing, the pile casing and a rock stratum are tightly embedded, and guarantee is provided for follow-up pile foundation drilling hole-forming slurry circulation construction. The steel casing adopts the mode that the overflow hole is formed in the bottom, the traditional process that the steel casing is pulled up and down to enable concrete to flow out is avoided, the steel casing does not need to be re-positioned, construction is convenient and fast, precision is high, the defects in the background technology are overcome, and the field construction efficiency is improved; the safety and stability of the trestle steel platform in the pile foundation construction process are guaranteed, and the problem of slurry leakage in the drilling process is solved.

Description

Technical Field

[0001] The invention relates to the field of bare rock pile foundation construction, and in particular to a nearshore steep slope deep water bare rock pile foundation construction method. Background Art

[0002] As a structure that crosses obstacles, the construction of the bridge foundation is of vital importance. With the development of the economy, people have higher and higher demands for the perfection of the transportation network, and the hydrogeological conditions corresponding to the bridge foundation construction are becoming more and more complex. For the construction of bare rock pile foundations on steep slopes and deep waters near the shore of the reservoir area, firstly, it is difficult to form the pile foundation construction platform, and secondly, it is difficult to bury the casing for pile foundation construction on the bare inclined rock surface. During the pile foundation construction, grout leakage is prone to occur, which pollutes the environment and affects the quality of pile drilling.

[0003] At present, in order to solve the problem of nearshore steep slope deep water bare rock pile foundation construction, blasting method, cofferdam filling method and island construction method are often used to form a construction platform, and then conventional pile foundation construction technology is used for pile construction. The uncertainty of underwater blasting results using blasting method is large, the accuracy of blasting equivalent is difficult to determine, and the impact on the environment is large. The environmental protection requirements for reservoir construction are high and the feasibility is poor. The cofferdam filling method and island construction method are theoretically feasible, but the actual effect is difficult to guarantee. Due to the inclination of the rock surface, the surrounding closed overall filling and leveling are adopted, which consumes a large amount of materials, has a long construction period, and occupies the water area of ​​the reservoir. It is difficult to restore after construction, which is not conducive to the protection of the environment and water quality. The latest is to use a pier steel platform or a large floating platform as a pile foundation construction platform, and then carry out the construction of the pile foundation on the water. When using a trestle steel platform, it is difficult to drive and root steel pipe piles due to the inclined bare rock surface, and the platform structure is unstable under deep water conditions, posing a high construction risk. When using a floating platform, it is greatly affected by the water level in the reservoir area, and the platform anchoring and the load of the drill rig are affected. The overall stability of the platform is poor, and the accuracy of the pile foundation construction is difficult to guarantee. Summary of the invention

[0004] The main purpose of the present invention is to provide a nearshore steep slope deep water bare rock pile foundation construction method, which solves the shortcomings of the background technology and improves the efficiency of on-site construction, ensures the safety and stability of the trestle steel platform during the pile foundation construction and solves the problem of slurry leakage during the drilling process.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a nearshore steep slope deep water bare rock pile foundation construction method, the method comprising: S1, trestle abutment of construction foundation; S2. Build a steel platform on the shore side of the trestle and construct concrete rock-embedded piles on the shore side of the trestle; S3. After the strength of the concrete rock-embedded piles reaches the design requirements, a standard steel trestle is erected on top of them; S4, build a steel platform on the trestle side and construct concrete rock-embedded piles on the trestle side; S5, guide hole for constructing pile foundation steel casing; S6. Locate the steel casing and lower it, and pour anchoring concrete inside the steel casing; S7. Use a rotary drill to drill into a bored pile foundation.

[0006] In the preferred embodiment, in step S1, when constructing the pier abutment and the expanded foundation piles on the pier shore side, firstly, the foundation pit is excavated by using an excavator to slope, the base is manually cleaned, and after the foundation bearing capacity is tested and qualified, the cushion layer is constructed in sequence, the abutment steel bars are made and installed, the abutment formwork is made and installed, and the abutment concrete is poured; The abutment formwork uses a combination of wooden formwork, and a scaffold is set up as a personnel operating platform. Workers go up and down the working surface using a safety inclined ladder; The abutment concrete is transported to the site by tank trucks, and poured manually with the help of truck cranes and hoppers. After the construction of the pier abutment and expanded foundation piles is completed, the back of the abutment is backfilled with soil to connect to the existing channel.

[0007] In the preferred embodiment, in step S1, the steel trestle and the steel platform are used as the platform for pile foundation construction. In open waters, a pile-driving ship or a large floating platform can be used as the construction platform for pile foundation; The number of concrete rock-embedded piles on the offshore side of the steel platform and steel trestle is determined according to the load that the platform needs to bear.

[0008] In the preferred embodiment, in step S2, the pipe piles of the inclined bare rock surface trestle are concrete rock-embedded piles to increase the stability of the steel trestle and the steel platform; On the shore, a grab drill is used to drill holes. The steel cage is lowered in sections by a truck crane, and the top of the steel cage is located 0.3m below the top surface of the concrete. The steel cage at the top of the pile and the steel pipe pile of the steel trestle are fixed and welded together through positioning frame 1 and positioning frame 2. Positioning frame 1 is located at the bottom of the steel pipe pile, and positioning frame 2 is located at the top of the steel cage. Positioning frame 1 is formed by welding four positioning steel bars and is used to limit the horizontal position of the steel column. Positioning frame 2 is formed by welding four angle steels. The steel pipe pile can stand on it and is used to limit the horizontal position. The steel cage and steel pipe pile are lowered simultaneously, and then the underwater pile foundation concrete is poured using the conduit method.

[0009] In the preferred embodiment, in step S2, the steel cage is lowered in sections, the top section of the steel cage is welded and connected to the steel pipe pile, and then lowered and positioned synchronously; The first positioning frame is a polygon; The number of positioning frames can be increased according to the depth of the steel pipe pile inserted into the steel cage; The positioning frame 1 is welded to the steel cage.

[0010] In the preferred solution, in step S3, after the strength of the concrete rock-embedded piles reaches the design requirements, the steel trestle in the offshore water is constructed using the "fishing method", where a crawler crane lifts a vibrating hammer to drive the steel pipe piles to the designed elevation. After a row of steel pipe piles is sunk into place, the horizontal joints and diagonal braces are installed in time to connect the steel pipe piles into a whole; After that, the crawler crane installed the load-bearing beam, Bailey beam and bridge deck structure in sequence. After each section of the bridge deck structure was laid, a section of guardrail was installed immediately afterwards. After the construction of one span is completed, the crawler crane moves to the front end of the constructed steel trestle and constructs the next span of the steel trestle according to the same process.

[0011] In the preferred solution, in step S4, the steel platform on the offshore side of the steel trestle needs to bear the construction load of the drilling rig, and the stability of the platform needs to be further increased. The built steel trestle is used as a construction platform to construct the concrete rock-embedded piles on the offshore side of the steel trestle; Then the "fishing method" is used to build the steel platform, and the steel platform and the steel trestle are connected with flat joints, so that the steel platform and the steel trestle form a whole and bear the force together.

[0012] In the preferred embodiment, in step S5, the diameter of the steel casing guide hole is determined according to the designed diameter of the bridge pile foundation. The guide hole diameter is 0.5m larger than the designed pile diameter of the bridge pile foundation. The guide hole depth is 3.5m into the rock surface. According to the strength of the rock formation, a percussion drill is used for guide hole construction.

[0013] In the preferred embodiment, in step S6, a plurality of annular overflow holes are provided at the bottom of the steel casing to ensure that the anchoring concrete can flow out of the steel casing and wrap the steel casing, and be embedded with the surrounding rock mass outside the steel casing; The steel casing is lowered in sections by a crawler crane. After the steel casing is lowered to the designed elevation, the top of the steel casing is fixed to the drilling platform. The steel casing is anchored by pouring underwater anchoring concrete in the steel casing using the conduit method. The anchoring concrete is 2m high. In step S7, after the anchoring concrete of the steel casing is solidified and there is no flow of media inside and outside the steel casing, a rotary drilling rig is used to perform hole construction for the pile foundation.

[0014] In the preferred embodiment, in step S6, no overflow hole is provided on the steel casing. When pouring the anchoring concrete, the steel casing is pulled up and down to allow the anchoring concrete to fill the space between the outer wall of the steel casing and the hole wall, so as to ensure that the steel casing is tightly consolidated with the bottom layer to prevent leakage, and then the steel casing is repositioned; When the steel casing is lowered, a double-layer guide frame is set on the steel trestle to ensure the accuracy of the steel casing lowering; After the steel casing is lowered and before the anchoring concrete is poured, sand bags are piled around the riverbed surface of the steel casing to fix the steel casing for the second time; The anchoring concrete of the steel casing adopts underwater self-compacting concrete, and vibrating rods are used to assist in compacting during pouring.

[0015] The present invention provides a nearshore steep slope deep water bare rock pile foundation construction method, which has the following beneficial effects: ① It is difficult for the foundation pipe piles of the pier and steel platform on the inclined bare rock surface to enter the rock. The embedding depth of the piles by vibrating hammer is limited. In addition, the impact grab drill or rotary drill in the water area has no construction platform and the equipment operation radius is limited, so it is impossible to carry out the construction of leading holes and planting piles. Therefore, the pipe pile foundation of the pier and steel platform on the shore side and the pipe pile foundation of the steel platform on the pier side are designed as concrete rock-embedded piles. The equipment can be positioned on the shore and the pier to carry out the construction of the rock-embedded pile foundation. The foundation form of the pier steel platform with a combination of "steel pipe piles + concrete rock-embedded piles" is adopted to ensure the overall stability of the pier steel platform. At the same time, there is no need for large-scale closed filling or island construction, which saves a lot of materials and labor. The steel pier structure is a turnover material, which saves a lot of cost.

[0016] ② At the connection between the steel cage and the steel pipe pile of the rock-embedded pile foundation of the trestle platform, a double-layer positioning frame is used. The steel cage and the positioning frame are welded together, and the positioning frame and the steel pipe pile are welded together. The steel pipe pile and the steel cage are lowered at the same time, which effectively solves the positioning and connection problems of the rock-embedded pile foundation and the steel pipe column, ensures the construction quality of the rock-embedded pile foundation of the trestle steel platform, and ensures the safety of on-site construction.

[0017] ③ In view of the difficulty in burying steel casings in bare inclined rock faces and the problem of easy leakage of slurry during drilling, the study adopts the method of using punching and grabbing drills to guide holes, and an overflow hole is opened in the annular direction at the bottom of the steel casing. After the hole is guided to the design elevation of the steel casing, the steel casing is lowered and the embedded concrete is poured. The concrete flows to the outside of the casing through the overflow hole, wraps the steel casing, and makes the casing and the rock layer tightly embedded, providing guarantee for the subsequent pile foundation drilling and drilling mud circulation construction. The steel casing adopts the method of opening an overflow hole at the bottom, avoiding the traditional process of pulling the steel casing up and down to make the concrete flow out. The steel casing does not need to be re-positioned, and the construction is convenient and high-precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is the construction drawing of the pier abutment and the shore foundation of the present invention; Figure 2 It is a construction schematic diagram of a trestle abutment of the present invention; Figure 3 It is a schematic diagram of the construction of the enlarged foundation pile of the present invention; Figure 4 It is a construction schematic diagram of the existing channel of the present invention; Figure 5 It is a side elevation view of the steel trestle and steel platform of the present invention; Figure 6 It is a top view of the steel trestle and steel platform of the present invention; Figure 7This is a schematic diagram of the lead hole of the pile foundation steel casing of the present invention; Figure 8 Schematic diagram of the overflow hole of the steel casing of the present invention; Fig. 9 It is a schematic cross-sectional view of the steel trestle of the present invention; Fig.10 It is a partial schematic diagram of the steel trestle of the present invention; Fig.11 It is a schematic diagram of the concrete rock-embedded pile steel column connected to the steel cage of the present invention; Fig.12 is a top view of a positioning frame of the present invention; Fig.13 It is a top view of the positioning frame of the present invention.

[0019] In the figure: trestle abutment 1; cushion layer 101; abutment reinforcement 102; abutment formwork 103; abutment concrete 104; expanded foundation pile 2; scaffolding 3; safety inclined ladder 4; existing passage 5; abutment back soil 501; steel trestle 6; steel pipe pile 601; flat joint 602; diagonal brace 603; load-bearing beam 604; Bailey beam 605; bridge deck structure 606; guardrail 607; steel platform 7; concrete rock-embedded pile 8; reinforcement cage 801; positioning frame one 802; positioning reinforcement 803; positioning frame two 804; angle steel 805; anchoring concrete 806; bridge pile foundation 9; steel casing 10; overflow hole 1001; steep slope 11. DETAILED DESCRIPTION

[0020] Example 1 like Figure 1-13 As shown, a method for constructing a nearshore steep slope deep-water bare rock pile foundation comprises: S1, trestle abutment 1 of the construction foundation; S2, build a steel platform 7 on the shore side of the trestle, and construct concrete rock-embedded piles 8 on the shore side of the trestle; S3, after the strength of the concrete rock-embedded piles 8 reaches the design requirements, a standard steel trestle 6 is set up on top of them; S4, build a steel platform 7 on the trestle side, and construct concrete rock-embedded piles 8 on the trestle side; S5, constructing the guide hole of the pile foundation steel casing 10; S6, positioning the steel casing 10 and lowering it, and pouring anchoring concrete inside the steel casing 10; S7. Use a rotary drill to drill into a bored pile foundation.

[0021] In the preferred solution, in step S1, when constructing the pier abutment 1 and the expanded foundation pile 2 on the pier shore side, firstly, the foundation pit is excavated by using an excavator to slope, the base is manually cleaned, and after the foundation bearing capacity is tested and qualified, the cushion layer 101 is constructed, the abutment steel bars 102 are made and installed, the abutment formwork 103 is made and installed, and the abutment concrete 104 is poured; The abutment formwork 103 uses a combined wooden formwork, and a scaffold 3 is set up as a personnel operating platform. Workers go up and down the working surface through a safety inclined ladder 4; The abutment concrete 104 is transported to the site by a tank truck, and poured manually in cooperation with a truck crane and a hopper. After the construction of the trestle abutment 1 and the expanded foundation piles 2 is completed, the abutment back soil 501 is backfilled to connect the existing channel 5.

[0022] In the preferred embodiment, in step S1, the steel trestle 6 and the steel platform 7 are used as platforms for pile foundation construction. In open waters, a pile-driving ship or a large floating platform can be used as a construction platform for pile foundation; The number of concrete rock-embedded piles 8 on the offshore side of the steel platform 7 and the steel trestle 6 is determined according to the load that the platform needs to bear.

[0023] In the preferred embodiment, in step S2, the pipe piles of the inclined bare rock surface trestle are concrete rock-embedded piles 8 to increase the stability of the steel trestle 6 and the steel platform 7; On the shore, a punching and grabbing drill is used for hole construction. The truck crane lowers the steel cage 801 in sections, and the top of the steel cage 801 is located 0.3m below the top surface of the concrete. The pile top steel cage 801 and the steel pipe pile 601 of the steel trestle 6 are fixed and welded together through a positioning frame 1 802 and a positioning frame 2 804. The positioning frame 1 802 is located at the bottom of the steel pipe pile, and the positioning frame 2 804 is located at the top of the steel cage 801. The positioning frame 1 802 is formed by welding four positioning steel bars 803 and is used to limit the horizontal position of the steel column. The positioning frame 2 804 is formed by welding four angle steels 805. The steel pipe pile 601 can stand on it and is used to limit the horizontal position. The steel cage 801 and the steel pipe pile 601 are lowered simultaneously, and then the underwater pile foundation concrete 806 is poured using the conduit method.

[0024] In the preferred embodiment, in step S2, the steel cage 601 is lowered in sections, and the top section steel cage 601 is welded and connected to the steel pipe pile 601, and lowered and positioned synchronously; The positioning frame 1 802 is a polygon; The number of the positioning frame 802 can be increased according to the depth of the steel pipe pile 601 inserted into the steel cage 801; The positioning frame 802 is welded to the steel cage 801.

[0025] In the preferred solution, in step S3, after the strength of the concrete rock-embedded piles 8 reaches the design requirements, the steel trestle 6 in the offshore water is constructed using the "fishing method", and the crawler crane lifts the vibrating hammer to drive the steel pipe piles 601 to the designed elevation. After a row of steel pipe piles 601 is sunk in place, the flat joints 602 and diagonal braces 603 are installed in time to connect the steel pipe piles 601 into a whole; Then the crawler crane sequentially installs the load-bearing cross beam 604, Bailey beam 605 and bridge deck structure 606. After each section of the bridge deck structure 606 is laid, a section of the guardrail 607 is installed immediately thereafter. After the construction of one span is completed, the crawler crane moves to the front end of the constructed steel trestle 6 and constructs the next span of the steel trestle 6 according to the same process.

[0026] In the preferred solution, in step S4, the steel platform 7 on the offshore side of the steel trestle 6 needs to bear the construction load of the drilling rig, and the stability of the platform needs to be further increased. The built steel trestle 6 is used as a construction platform to construct the concrete rock-embedded piles 8 on the offshore side of the steel trestle 6; Then the steel platform 7 is set up by the "fishing method", and the steel platform 7 and the steel trestle 6 are connected by the flat joint 602, so that the steel platform 7 and the steel trestle 6 form a whole and bear the force together.

[0027] In the preferred embodiment, in step S5, the diameter of the steel casing 10 guide hole is determined according to the designed diameter of the bridge pile foundation. The guide hole diameter is 0.5m larger than the designed pile diameter of the bridge pile foundation. The guide hole depth is 3.5m into the rock surface. According to the strength of the rock formation, a percussion drill is used for guide hole construction.

[0028] In the preferred embodiment, in step S6, a plurality of annular overflow holes 1001 are provided at the bottom of the steel casing 10 to ensure that the anchoring concrete 806 can flow out of the steel casing 10 and wrap the steel casing 10, and be embedded with the surrounding rock mass outside the steel casing 10; The steel casing 10 is lowered in sections by a crawler crane. After the steel casing 10 is lowered to the designed elevation, the top of the steel casing 10 is fixed to the drilling platform. The steel casing 10 is anchored by pouring underwater anchoring concrete 806 in the steel casing 10 by a conduit method. The anchoring concrete is 2m high. In step S7, after the anchoring concrete 806 of the steel casing 10 is solidified and there is no flow of the medium inside and outside the steel casing 10, a rotary drilling rig is used to perform hole construction for the pile foundation.

[0029] In the preferred embodiment, in step S6, the overflow hole 1001 is not provided on the steel casing. When the anchoring concrete 806 is poured, the steel casing 10 is pulled up and down to allow the anchoring concrete 806 to fill the space between the outer wall of the steel casing 10 and the hole wall, so as to ensure that the steel casing 10 is tightly consolidated with the bottom layer to prevent leakage, and then the steel casing 10 is repositioned; When the steel casing 10 is lowered, a double-layer guide frame is set on the steel trestle 6 to ensure the accuracy of the lowering of the steel casing 10; After the steel casing 10 is lowered, before the anchoring concrete 806 is poured, sand bags are piled around the riverbed surface of the steel casing 10 to fix the steel casing 10 for the second time; The anchoring concrete 806 of the steel casing 10 is made of underwater self-compacting concrete, and a vibrating rod is used to assist in vibrating and compacting during pouring. Example 2 Further illustrate with reference to Example 1, Figure 1-13 The structure shown, 1. Construction of pier abutment 1 and onshore foundation. During the construction of pier abutment 1 and expanded foundation piles 2, firstly, use an excavator to slope and excavate the foundation pit, manually clean the base, and after the foundation bearing capacity test is qualified, carry out the cushion layer 101, the abutment steel bar 102, the abutment formwork 103 and the abutment concrete 104 construction in sequence.

[0030] The abutment formwork 103 uses a combined wooden formwork, and a scaffolding 3 is set up as a personnel operating platform. Workers go up and down the working surface through a safe inclined ladder 4. Concrete is transported to the site by a tank truck, and a truck crane + 1.5m³ hopper is used in conjunction with manual pouring. After the construction of the trestle abutment 1 and the expanded foundation piles 2 is completed, the abutment back soil 501 is backfilled to connect the existing channel 5.

[0031] 2. Construction of concrete rock-embedded piles 8 on the shore side of the steel platform 7 and the trestle. The foundation pipe piles of the steel trestle 6 and the steel platform 7 on the inclined bare rock surface are difficult to enter the rock. The embedding depth of the piles using a vibratory hammer is limited. In addition, since there is no construction platform in the water area, the operating radius of the equipment is limited, and it is impossible to carry out hole-drawing and pile-planting construction. Therefore, the pipe pile foundation on the shore side of the steel trestle 6 and the steel platform 7 is designed as a concrete rock-embedded pile 8 to increase the stability of the steel trestle 6 and the steel platform 7.

[0032] On the shore, a percussion drill is used for hole construction. The automobile crane lowers the steel cage 801 in sections. The top of the steel cage 801 is located 0.3m below the concrete surface. In order to ensure that the steel pipe pile 601 is located in the middle of the steel cage 801 and does not fall when the steel cage 801 is lowered, the pile top steel cage 801 and the steel pipe pile 601 of the steel trestle 6 are fixed and welded together through a positioning frame 1 802 and a positioning frame 2 804. The positioning frame 1 802 is located at the bottom of the steel pipe pile 601, and the positioning frame 2 804 is located at the top of the steel cage 801. The positioning frame 1 802 is formed by welding four φ25 steel bars, which only limit the horizontal position of the steel column. The positioning frame 2 804 is formed by welding four ∠63×8 angle steels 805, on which the steel pipe pile 601 can stand, while limiting the horizontal position. The steel cage 801 and the steel pipe pile 601 are lowered synchronously, and underwater concrete is poured using the conduit method.

[0033] 3. Construction of standard trestle. After the strength of concrete rock-embedded piles 8 reaches the design requirements, the offshore underwater steel trestle 6 is constructed using the "fishing method". The crawler crane lifts the vibrating hammer and drives the steel pipe piles 601 to the designed elevation. After a row of steel pipe piles 601 is sunk into place, the flat joints 602 and diagonal braces 603 are installed in time to connect the steel pipe piles 601 into a whole. After that, the crawler crane installs the load-bearing crossbeam 604, Bailey beam 605 and bridge deck structure 606 in sequence. After each section of the bridge deck structure 606 is laid, a guardrail 607 is installed immediately. After the construction of one span is completed, the crawler crane moves to the front end of the constructed steel trestle 6 and constructs the next span of the trestle according to the same process.

[0034] 4. Construction of concrete rock-embedded piles 8 of steel platform 7 on the trestle side and erection of steel platform 7. Steel platform 7 needs to bear the construction load of the drilling rig. To further increase the stability of the platform, the built trestle is used as the construction platform to construct the concrete rock-embedded piles 8 of steel platform 7 on the trestle side. The "fishing method" is used to erect steel platform 7, and the flat joint 602 is used to connect the steel platform 7 and the steel trestle 6, so that the steel platform 7 and the trestle form a whole and bear the force together.

[0035] 5. The lead hole of the pile foundation steel casing 10 is determined according to the designed diameter of the bridge pile foundation 9. The lead hole diameter is 0.5m larger than the designed pile diameter of the bridge pile foundation 9. The lead hole depth is 3.5m into the rock surface. According to the strength of the rock layer, the lead hole construction is carried out by using a grab drill.

[0036] 6. The steel casing 10 is lowered and positioned and the anchoring concrete 806 is poured. An annular overflow hole 1001 is set at the bottom of the steel casing 10 to ensure that the anchoring concrete 806 can flow out to wrap the steel casing 10 and be embedded with the surrounding rock mass.

[0037] The steel casing 10 is lowered in sections using a crawler crane. After the steel casing 10 is lowered to the designed elevation, the top of the steel casing 10 is fixed to the drilling platform. The underwater anchoring concrete 806 is poured into the steel casing 10 using the conduit method to anchor the steel casing 10. The anchoring concrete 806 is 2m high.

[0038] 7. The rotary drill is used to drill into the pile foundation for hole construction. After the anchoring concrete 806 of the steel casing 10 is solidified and there is no flow of the medium inside and outside the steel casing 10, the rotary drill is used to perform the hole construction of the pile foundation.

[0039] Preferably, the construction method uses the steel trestle 6 and the steel platform 7 as the platform for pile foundation construction. In open waters, a pile-driving ship or a large floating platform can also be used as the construction platform for pile foundation; Preferably, the number of concrete rock-embedded piles on the shore side of the steel platform 7 and the steel trestle 6 is determined according to the load that the platform needs to bear; Preferably, the concrete rock-embedded pile 8 can be constructed by using a grab drill, or other pile-forming techniques such as an impact drill or a rotary drill; Preferably, the concrete rock-embedded pile 8 steel cage 801 is lowered in sections, and the top section steel cage 801 is welded and connected to the trestle steel pipe pile 601, and lowered and positioned synchronously; Preferably, the material of the first positioning frame in the scheme can be other materials besides the positioning steel bars 803, as long as it can satisfy the requirement of limiting the plane position of the steel pipe pile 601; Preferably, the positioning frame 1 802 and the positioning frame 2 804 in the scheme can be in a quadrilateral or a pentagonal shape; Preferably, the positioning frame 2 in the scheme can be made of other materials besides ∠63×8 angle steel, as long as its function satisfies the requirement of limiting the falling of the steel pipe pile 601 and its position in the horizontal plane; Preferably, the number of the positioning frames 802 in the scheme can be increased according to the depth of the steel pipe pile 601 inserted into the rock-embedded pile foundation steel cage 801; Preferably, the positioning frame 1 802 and the positioning frame 2 804 in the scheme are connected to the steel cage 801 by welding; Preferably, after the rock-embedded pile construction is completed, the subsequent structural construction of the upper part of the steel trestle 6 is carried out after the concrete strength of the pile top reaches the design requirements; Preferably, the pile foundation steel casing 10 can be constructed by using a rotary drill in conjunction with a slag dredger drill bit to form a hole for the pile planting. Preferably, the steel casing 10 is anchored with concrete 806 for pouring, and the overflow hole 1001 may not be provided on the steel casing 10. However, when the anchored concrete 806 is poured, the steel casing 10 must be pumped up and down to allow the concrete to fill the space between the steel casing 10 wall and the hole wall, to ensure that the steel casing 10 is tightly consolidated with the bottom layer to prevent leakage, and the steel casing 10 needs to be positioned twice; Preferably, a double-layer guide frame can be set on the trestle platform when the steel casing 10 is lowered to ensure the accuracy of the lowering of the steel casing 10; Preferably, after the steel casing 10 is lowered, before the anchoring concrete 806 is poured, sand bags may be piled around the riverbed surface of the steel casing 10 to fix the steel casing 10 for a second time; Preferably, the steel casing 10 anchoring concrete 806 may be made of underwater self-compacting concrete, or conventional concrete, which may be compacted with the aid of a vibrating rod during pouring; Preferably, the diameter, depth and other parameter values ​​of the bored piles in the scheme are all recommended values ​​and can be adjusted according to the actual situation on site.

[0040] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for constructing bare rock pile foundations on a nearshore steep slope and deep water, characterized by: The method includes: S1, construction foundation of the trestle abutment (1); S2, building a steel platform (7) on the bank side of the pier, and constructing concrete rock-embedded piles (8) on the bank side of the pier; S3. After the strength of the concrete rock-embedded piles (8) reaches the design requirements, a standard steel trestle (6) is erected on top of the piles; S4, building a steel platform (7) on the trestle side, and constructing concrete rock-embedded piles (8) on the trestle side; S5, a guide hole for constructing a pile foundation steel casing (10); S6, positioning the steel casing (10) and lowering it, and pouring anchoring concrete inside the steel casing (10); S7. Use a rotary drill to drill into a bored pile foundation.

2. A method for constructing a nearshore steep slope deep-water bare rock pile foundation according to claim 1, characterized in that: in step S1, when constructing the pier abutment (1) and the expanded foundation pile (2) on the pier shore side, firstly, an excavator is used to excavate the foundation pit, the base is manually cleaned, and after the foundation bearing capacity is tested and qualified, the cushion layer (101) is constructed, the abutment steel bars (102) are manufactured and installed, the abutment formwork (103) is manufactured and installed, and the abutment concrete (104) is poured; The abutment formwork (103) is a combined wooden formwork, and a scaffold (3) is set up as a personnel operating platform. Workers go up and down the working surface via a safety inclined ladder (4); The abutment concrete (104) is transported to the site by a tank truck, and poured manually in cooperation with a truck crane and a hopper. After the construction of the trestle abutment (1) and the expanded foundation piles (2) is completed, the abutment back soil (501) is backfilled to connect with the existing channel (5).

3. According to claim 1, a method for constructing bare rock pile foundation on a nearshore steep slope and deep water, characterized in that: In step S1, the steel trestle (6) and the steel platform (7) are used as platforms for pile foundation construction. In open waters, a pile-driving ship or a large floating platform can be used as a pile foundation construction platform; The number of concrete rock-embedded piles (8) on the offshore side of the steel platform (7) and the steel trestle (6) is determined according to the load that the platform needs to bear.

4. According to claim 1, a method for constructing bare rock pile foundation on a nearshore steep slope and deep water, characterized in that: In step S2, the pipe piles of the inclined bare rock surface trestle are concrete rock-embedded piles (8) to increase the stability of the steel trestle (6) and the steel platform (7); On the shore, a percussion drill is used to make holes. The steel cage (801) is lowered in sections by a truck crane. The top of the steel cage (801) is located 0.3m below the top surface of the concrete. The pile top reinforcement cage (801) and the steel pipe pile (601) of the steel trestle (6) are fixed and welded together through a positioning frame 1 (802) and a positioning frame 2 (804). The positioning frame 1 (802) is located at the bottom of the steel pipe pile, and the positioning frame 2 (804) is located at the top of the reinforcement cage (801). The positioning frame 1 (802) is formed by welding four positioning steel bars (803) and is used to limit the horizontal position of the steel column. The positioning frame 2 (804) is formed by welding four angle steels (805). The steel pipe pile (601) can stand on it and is used to limit the horizontal position. The reinforcement cage (801) and the steel pipe pile (601) are lowered synchronously, and then the underwater pile foundation concrete (806) is poured by the conduit method.

5. The method for constructing a nearshore steep slope deep-water bare rock pile foundation according to claim 1, characterized in that: step S2 In the embodiment, the steel cage (601) is lowered in sections, the top section of the steel cage (601) is welded together with the steel pipe pile (601), and they are lowered and positioned synchronously; The first positioning frame (802) is a polygon; The number of the first positioning frame (802) can be increased according to the depth of the steel pipe pile (601) inserted into the steel cage (801); The first positioning frame (802) is welded to the steel cage (801).

6. The method for constructing bare rock pile foundation on a nearshore steep slope and deep water according to claim 1 is characterized by: In step S3, after the strength of the concrete rock-embedded piles (8) reaches the design requirements, the steel trestle (6) in the offshore water is constructed using the "fishing method", where a crawler crane lifts a vibrating hammer to drive the steel pipe piles (601) to the designed elevation. After a row of steel pipe piles (601) is sunk into place, the flat joints (602) and diagonal braces (603) are promptly installed to connect the steel pipe piles (601) into a whole; Then the crawler crane sequentially installs the load-bearing cross beam (604), the Bailey beam (605) and the bridge deck structure (606). After each section of the bridge deck structure (606) is laid, a guardrail (607) is installed immediately thereafter. After the construction of one span is completed, the crawler crane moves to the front end of the constructed steel trestle (6) and constructs the next span of the steel trestle (6) according to the same process.

7. The method for constructing bare rock pile foundation on a nearshore steep slope and deep water according to claim 1 is characterized by: In step S4, the steel platform (7) on the offshore side of the steel trestle (6) needs to bear the construction load of the drilling rig, and the stability of the platform needs to be further increased. The constructed steel trestle (6) is used as a construction platform to construct the concrete rock-embedded piles (8) on the offshore side of the steel trestle (6); Then, the steel platform (7) is set up by the "fishing method", and the steel platform (7) and the steel trestle (6) are connected by a flat joint (602), so that the steel platform (7) and the steel trestle (6) form a whole and bear force together.

8. The method for constructing bare rock pile foundation on a nearshore steep slope and deep water according to claim 1 is characterized by: In step S5, the diameter of the steel casing (10) guide hole is determined according to the designed diameter of the bridge pile foundation. The guide hole diameter is 0.5 m larger than the designed pile diameter of the bridge pile foundation. The guide hole depth is 3.5 m into the rock surface. According to the strength of the rock layer, a percussion drill is used for the guide hole construction.

9. The method for constructing bare rock pile foundation on a nearshore steep slope and deep water according to claim 1, characterized in that: In step S6, a plurality of annular overflow holes (1001) are provided at the bottom of the steel casing (10) to ensure that the anchoring concrete (806) can flow out of the steel casing (10) and wrap around the steel casing (10), and be embedded with the surrounding rock mass outside the steel casing (10); The steel casing (10) is lowered in sections by using a crawler crane. After the steel casing (10) is lowered to the designed elevation, the top of the steel casing (10) is fixed to the drilling platform. Underwater anchoring concrete (806) is poured into the steel casing (10) by using a conduit method to anchor the steel casing (10). The height of the anchoring concrete is 2 m. In step S7, after the anchoring concrete (806) of the steel casing (10) is solidified and the medium inside and outside the steel casing (10) stops flowing, a rotary drill is used to perform hole construction for the pile foundation.

10. The method for constructing bare rock pile foundation on a nearshore steep slope and deep water according to claim 1, characterized in that: In step S6, no overflow hole (1001) is provided on the steel casing. When the anchoring concrete (806) is poured, the steel casing (10) is pulled up and down to allow the anchoring concrete (806) to fill the space between the outer wall of the steel casing (10) and the hole wall, thereby ensuring that the steel casing (10) is tightly bonded to the bottom layer to prevent leakage, and then the steel casing (10) is repositioned; When the steel casing (10) is lowered, a double-layer guide frame is arranged on the steel trestle (6) to ensure the accuracy of lowering the steel casing (10); After the steel casing (10) is lowered, before the anchoring concrete (806) is poured, sand bags are piled around the riverbed surface of the steel casing (10) to fix the steel casing (10) for a second time; The anchoring concrete (806) of the steel casing (10) adopts underwater self-compacting concrete, and a vibrating rod is used to assist in compacting the concrete during pouring.

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