Large-diameter offshore rock-socketed pile foundation pit excavation method

Abstract

The invention discloses a large-diameter offshore rock-socketed pile foundation pit excavation method. The method comprises the following processes of putting a guide well protection barrel in, mechanically drilling and digging a guide well, drilling and lowering a casing pipe to protect a hole, charging in the casing pipe and blasting, lowering a rock-socketed pile steel protection barrel, sucking silt, pulling out the guide well protection barrel and the drilling casing pipe, and grabbing slag. The method adopts the combination of mechanical excavation of the guide well and blasting and expanding excavation; main blast holes are strengthened and broken by high specific consumption, and the impact of a shock wave and blasting vibration is controlled by adopting an electronic detonating technology; profile blasting adopts smooth blasting; and the depth of the guide well is 0.1-0.15 times the depth of a pile well, and the well completion design depth is guaranteed. Main blast hole continuous charging and profile hole interval charging are adopted; and blast holes on the inner ring and the outer ring are detonated in sections, a main blast hole inner ring is detonated before a main blast hole outer ring, and the bottom section of the inner ring is simultaneously detonated. The method can effectively solve the problem that an offshore rock-socketed pile foundation with the diameter of 8-10m or more is excavated by using a 2-4m diameter petroleum drilling machine and a common geological drilling machine, 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 108842807A "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 pullout resistance of rock-socketed piles , but the operation is complex and requires the cooperation of the main crane and the auxiliary crane, the construction period is long and the cost is high

[0005] The patent number is CN106088140A "A Construction Technology of Rock-socketed Single Pile Foundation for Offshore Fans on Rock Seabed", which 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 bedrock strength, which depends on the drilling rig. The construction period is long, limited by machinery, and the cost higher

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