Excavation method of large-diameter offshore rock-socketed pile foundation pit

Abstract

The invention discloses a method for excavating a foundation pit of a large-diameter offshore rock-socketed pile. The procedure is as follows: putting in the casing of the guide well, mechanically drilling the guide well, drilling and lowering the casing to protect the hole, charging and blasting the casing, and lowering the casing. Rock-socketed pile steel casing, absorbing silt, pulling out the pilot well casing and drilling casing, and grabbing slag. The invention adopts the combination of mechanical excavation guide shaft and blasting expansion excavation; the main blasting hole adopts high unit consumption to strengthen the crushing, and adopts electronic detonation technology to control the impact of shock wave and blasting vibration; contour blasting adopts smooth blasting; the super depth of the guide shaft is 0.1-0.15 Double the depth of the pile well to ensure the design depth of the completed well. The main blast hole is continuously charged, and the contour hole is charged at intervals; the inner and outer ring blast holes are detonated in sections, the inner ring of the main blast hole is detonated before the outer ring of the main blast hole, and the bottom section of the inner ring is detonated simultaneously. The invention can effectively solve the problem of using 2-4m diameter oil drilling rigs and ordinary geological drilling rigs to complete the excavation of offshore rock-socketed pile foundations with a diameter of 8-10m or more, and has the advantages of high speed, low cost and the like.

Description

technical field [0001] The invention belongs to the technical field of foundation pit excavation for offshore wind power foundations, in particular to a method for excavating a large-diameter offshore rock-socketed pile foundation pit. Background technique [0002] In recent years, with the increasing consumption of resources and the reduction of non-renewable energy sources, the development and utilization of clean energy have received more and more attention. Offshore wind power occupies an important proportion in the development and utilization of clean energy due to its rich resources, high power generation efficiency, and suitability for large-scale development. [0003] Offshore wind power often needs to face harsh conditions including typhoon, surf, etc., and because the bedrock on the seabed is often covered with overburden, the geological conditions of the bedrock are complex, which adds a lot of difficulties to the pile foundation construction of wind turbines. At...

AI Technical Summary

Problems solved by technology

At present, large-diameter rock-socketed pile foundation pits are excavated by large-diameter drilling rigs at one time, but with the increase of wind power installed capacity, the size of rock-socketed pile foundation pits is increasing day by day. The supply of drilling rigs is in short supply, which seriously affects the construction progress; and due to the lithology of the deep complex stratum in the overburden layer, the piling process of steel pipe piles is easy to cause the outer and inner mouth of the bottom pipe wall, which affects the subsequent construction steps such as mechanical expansion. long cycle

However, when constructing in a complex offshore environment, the construction is greatly affected by the weather, and the effective construction period is very short. It is necessary to adopt an economical and efficient foundation pit excavation method to meet the needs of offshore wind turbine construction.

[0004] There are many new ideas in the existing rock-socketed pile foundation excavation methods, but it is difficult to reduce costs and speed up the construction progress while effectively meeting the structural design and construction requirements

Patent No. CN 108842807 A "Construction Technology for Implanted Rock-socketed Single Pile for Offshore Wind Power Foundation" uses platform-assisted positioning and steel casings for rock-socketed construction, which can effectively improve the horizontal resistance and pull-out resistance of rock-socketed piles capacity, but the operation is complex and requires the cooperation of the main crane and the auxiliary crane for construction, the construction period is long and the cost is high

[0005] Patent No. CN106088140 A "A Construction Technology of Rock-socketed Single Pile Foundation for Offshore Fans on Rock Seabed" proposes a construction technology of "drilling-drilling-drilling". Carry out drilling and excavation to the design elevation, and finally use the hydraulic impact hammer to sink the pile to the design elevation. This method uses the drilling rig to excavate or reduce the strength of the bedrock, which depends on the drilling rig. The construction period is long and is limited by machinery. higher cost

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