Offshore Monopile Grouting for Rock Foundation Stability
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Solution Overview
Problem
Conventional large-diameter monopile construction technologies face challenges in rock foundation areas, particularly in regions like Fujian and Guangdong, where self-stabilization and hydraulic pile driving are not feasible, leading to poor pile stability, long construction periods, high costs, and structural safety risks.
Innovation Solution
A non-driven-in large-diameter monopile foundation structure is developed, involving drilling a hole in the rock foundation, implanting a large-diameter monopile with underwater bottom-sealing concrete, and using a grouting system with horizontal and vertical pipes to fill the gap between the pile and the hole, ensuring stability and bearing capacity through grouting from bottom to top.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional large-diameter monopile construction technology is used in rock foundation areas, then the pile can be installed using standard methods, but the pile stability is poor and construction period is long
Solution Approach 1:
The patent applies preliminary action by pre-drilling holes in the rock foundation before monopile installation. The drilling holes are prepared in advance with specific dimensions and spacing, allowing the monopiles to be installed directly into the pre-prepared holes rather than requiring complex in-situ stabilization measures during construction. This significantly reduces construction period while ensuring pile stability.
Solution Approach 2:
The patent uses grouting material as an intermediary substance to fill the gaps between the monopile outer wall and the drilling hole wall. This grouting material acts as a mediator that bonds the monopile to the surrounding rock foundation, enhancing pile stability and load transfer efficiency without requiring additional mechanical stabilization structures.
2Reliability
If auxiliary measures are used to self-stabilize the monopile body, then stability can be achieved, but construction cost increases and structural safety risk increases
Solution Approach 1:
The patent extracts and removes the need for complex auxiliary stabilization measures by using a simplified approach: pre-drilled holes in the rock foundation combined with grouting. Instead of adding multiple auxiliary systems (such as additional anchoring structures, complex foundation treatments, or extensive reinforcement), the solution takes out the unnecessary complexity and relies on the fundamental combination of mechanical insertion into pre-drilled holes and chemical bonding through grouting.
Solution Approach 2:
The patent applies parameter changes by optimizing the dimensions, spacing, and depth of the pre-drilled holes, as well as the properties of the grouting material (such as viscosity, setting time, and strength). By carefully controlling these parameters, the system achieves reliable monopile stabilization without requiring complex auxiliary measures, thus reducing device complexity while maintaining high reliability.
3Ease of manufacture
If hydraulic pile hammer is used to drive the monopile, then installation can be achieved, but the pile cannot be driven in due to rock foundation conditions
Solution Approach 1:
The patent replaces the mechanical pile driving system (hydraulic pile hammer) with a drilling-based installation method. Instead of attempting to force the monopile into the rock foundation using high-energy impact from a hydraulic pile hammer, the system substitutes this mechanical approach with a drilling process that creates holes in the rock, into which the monopiles are then inserted and grouted. This substitution makes installation feasible in hard rock conditions where conventional pile driving would fail.
Solution Approach 2:
The patent applies inversion by reversing the conventional installation sequence. Instead of trying to drive the monopile into the rock from the surface using impact forces, the approach is inverted: holes are first created in the rock foundation, and then the monopiles are inserted into these pre-formed holes. This inverted sequence transforms an impossible mechanical driving operation into a feasible insertion and grouting process.
4Productivity
If conventional monopile construction is used, then standard construction procedures can be followed, but construction cost is high
Solution Approach 1:
The patent applies segmentation by dividing the construction process into distinct, manageable stages: (1) drilling holes in the rock foundation, (2) installing monopiles into the drilled holes, and (3) grouting the gaps between monopiles and hole walls. Each stage can be performed by specialized equipment and crews independently, improving construction efficiency and productivity while keeping the overall technology complexity manageable through clear process segmentation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method simplifies construction, enhances stability, reduces construction noise, and increases efficiency by leveraging the horizontal bearing capacity of the monopile, while eliminating the need for high-energy hydraulic pile hammers, thus improving overall foundation stability and reducing costs.
Implementation Method 1
a gap between the outer wall of the large-diameter single pile and the hole wall of the drilling hole is filled with a grouting material that is grouted in a grouting system preloaded inside the large-diameter monopile
Implementation Method 2
the bottom of the large-diameter monopile is sealed by underwater bottom-sealing concrete
Data Source
AI summary
The present invention relates to an offshore non-driven-in large-diameter monopile foundation structure and a construction method. An object of the invention is to provide an offshore non-driven-in large-diameter monopile foundation structure with simple structure, convenient construction and clear mechanic behavior, and a construction method. The technical solution adopted by the invention is as follows: an offshore non-driven-in large-diameter monopile foundation structure suitable for rock foundations is characterized in that a drilling hole is drilled in a rock foundation, a large-diameter monopile is implanted into the drilling hole, the bottom of the large-diameter monopile is sealed by underwater bottom-sealing concrete, and the gap between the outer wall of the large-diameter monopile and the hole wall of the drilling hole is filled with a grouting material goofed by a grouting system that is preset inside the large-diameter monopile. The invention is applied to offshore wind power and other industries.