Prestressed Precast LNG Dike Blocks for Rapid Construction
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Solution Overview
Problem
Existing methods for constructing LNG tanks using precast blocks are inefficient due to the need for extensive concrete pouring and placement, which interferes with internal facility construction and increases construction time and costs, and may result in air gaps and increased costs due to complex formwork requirements.
Innovation Solution
A method involving precast blocks with integrated joints and plates that allow for minimal concrete use in masonry joints, avoiding air gaps and simplifying construction by using tension members to introduce prestress without sheath pipes in joints, and utilizing plates as formworks to reduce interference with internal facility work.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If precast blocks are used for dike construction with traditional coupling joints requiring concrete pouring, then the dike structure can be assembled, but the construction period increases and interferes with internal facility construction
Solution Approach 1:
The patent removes the traditional coupling joint structure that required concrete pouring and formwork. Instead, it uses a simplified joint design where the upper precast block directly rests on the lower precast block with minimal grouting only at the bearing surface, eliminating the time-consuming concrete pouring and formwork removal processes while maintaining structural integrity.
Solution Approach 2:
The patent incorporates prestressing cables and anchorage devices into the precast blocks during manufacturing. The prestress is applied after block assembly, allowing the blocks to be quickly positioned and stacked without waiting for concrete curing. This preliminary preparation of structural elements enables rapid assembly and reduces construction period.
2Reliability
If complex formwork is used for coupling joints between precast blocks, then the joints can be properly formed, but construction costs increase and air gaps may occur
Solution Approach 1:
The patent eliminates the need for complex formwork by using a simplified joint design where minimal grout is applied directly to the bearing surface of the lower block. The joint reliability is achieved through the prestressing force and precise block fabrication tolerances rather than formwork confinement, removing the source of air gaps and formwork complexity.
Solution Approach 2:
The precast blocks are designed with self-aligning and self-leveling features that ensure proper joint formation without external formwork. The blocks automatically position themselves correctly through gravity and geometric constraints, with only minimal grout needed to fill imperfections, eliminating the need for complex formwork systems.
3Reliability
If extensive concrete pouring is required for masonry joints, then the joints can be properly sealed, but construction time increases and internal facility work is interfered with
Solution Approach 1:
The patent applies grout only partially - specifically at the bearing surface of the lower block where contact occurs - rather than pouring extensive concrete throughout the joint. This minimal grouting is sufficient to seal the joint and transfer loads, while avoiding the time-consuming extensive concrete pouring that interferes with internal facility construction.
Solution Approach 2:
The patent segments the joint sealing function into two parts: the primary load transfer and sealing is achieved through the precise fit and prestressing of the blocks themselves, while minimal grout is used only for filling small gaps and ensuring full contact. This segmentation eliminates the need for extensive concrete pouring while maintaining joint sealing quality.
4Strength
If traditional coupling joints with fixing elements are used, then the precast blocks can be connected, but the construction process becomes complex and time-consuming
Solution Approach 1:
The patent removes the complex fixing elements and coupling joint structures from the design. Instead, it relies on the weight of upper blocks, prestressing cables, and friction between block surfaces to provide the necessary connection strength. This extraction of unnecessary components simplifies the joint structure while maintaining adequate block connection strength.
Solution Approach 2:
The precast blocks are designed to connect to each other through their own weight and geometry, with prestressing cables providing additional anchorage. The blocks self-align and self-connect without requiring external fixing elements or complex coupling mechanisms, reducing joint structure complexity while maintaining connection strength through gravity and friction.
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 approach reduces construction time, ensures reliable load-bearing and liquid-tightness, and lowers costs by minimizing concrete usage and simplifying the construction process while maintaining structural integrity and preventing air gaps.
Implementation Method 1
prestress is applied to the dike 20 by tension members (not shown) disposed in the vertical direction and the circumferential direction of the dike 20
Implementation Method 2
Prestress is introduced to the dike by tension members in the circumferential direction of the dike and tension members in the vertical direction of the dike
Data Source
AI summary
In an LNG tank, a dike is formed by arranging precast blocks in the circumferential direction and layering the precast blocks in the vertical direction. Each of the precast blocks has loop joints on the top, bottom, left, and right side faces, and concrete is deposited between each two precast blocks adjacent in the circumferential direction and the vertical direction, whereby masonry joints are formed in the vertical direction and the circumferential direction. Prestress is imparted to the dike by PC steel members. The PC steel members are provided in the circumferential direction and the vertical direction of the dike, and are arranged so as to avoid the masonry joints in the circumferential direction and the vertical direction. Therefore, it is possible to construct the dike in a short time, and it is possible to provide a tank or the like that can reduce the construction period.