Multi-modulus Geotextile for Cavity Subsidence Detection
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Solution Overview
Problem
Existing geosynthetics in civil engineering lack a dual-stage deformation behavior to effectively alert for and limit subsidence or collapse in soils with cavities or faults, and to optimize load transfer on rigid inclusions, requiring a material that can deform significantly initially while maintaining high resistance and stability.
Innovation Solution
A geosynthetic with multiple elongation zones, featuring a low modulus for initial deformation detection and a high modulus for subsequent load resistance, allowing significant deformation during cavity or fault formation while ensuring structural stability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If geosynthetics use high tensile modulus fibers to oppose ground movement forces, then reinforcement strength is improved, but the ability to detect early subsidence or collapse through visible deformation is lost
Solution Approach 1:
The geosynthetic is segmented into two distinct fiber populations: high-modulus fibers for immediate reinforcement and low-modulus fibers for detectable deformation. This segmentation allows each fiber type to fulfill its specific function without compromising the other, resolving the contradiction between strength and detectability.
Solution Approach 2:
The invention changes the modulus parameter of the geosynthetic by incorporating fibers with different deformation moduli. The low-modulus fibers enable visible deformation at low stress levels for detection, while high-modulus fibers provide strength at higher stress levels, thus resolving the contradiction through parameter differentiation.
2Stability of the object's composition
If geosynthetics are designed with minimum allowable deflection to guarantee maximum surface settlement control, then structural stability is improved, but the required tensile force and material cost increase
Solution Approach 1:
The geosynthetic segments the deformation response into two stages: initial detectable deformation handled by low-modulus fibers, and final stability control handled by high-modulus fibers. This segmentation allows the structure to tolerate larger total deflections while maintaining stability, reducing material requirements.
Solution Approach 2:
The low-modulus fibers act as a preliminary cushion that absorbs initial deformations and provides early warning through visible movement. This beforehand cushioning prevents sudden failures and allows for planned interventions, reducing the need for excessive reinforcement material.
3Speed
If geosynthetics use fibers with higher deformation modulus for immediate reaction, then reinforcement response speed is improved, but the ability to accommodate large deformations from cavities or faults is reduced
Solution Approach 1:
The geosynthetic segments the response timeline: high-modulus fibers provide immediate reaction to ground movement, while low-modulus fibers gradually engage to accommodate large deformations from cavities or faults. This temporal and functional segmentation resolves the contradiction between speed and adaptability.
Solution Approach 2:
The invention creates a dynamic response system where the effective modulus of the geosynthetic changes over time and deformation level. Initially, high-modulus fibers dominate for rapid response; as deformation increases, low-modulus fibers progressively engage to accommodate large movements, providing adaptive behavior.
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
Enables early detection of subsidence or collapse, reduces material costs by allowing greater deflection, and provides high resistance against large cavity formations, enhancing structural safety and load transfer efficiency.
Implementation Method 1
it exhibits a very low modulus (i.e., the slope of the curve representing tensile stress on the y-axis as a function of elongation on the x-axis) at the initial elongation level, allowing for rapid initial deformation resulting from collapse or local subsidence, or from rigid inclusions such as piles. Subsequently, at higher elongations, a higher modulus enables the development of significantly greater reinforcement properties
Data Source
Figure 1~2B
Figure 3A~3B
Figure 4A~4B
AI summary
The invention relates to a geosynthetic for soil reinforcement which has, in a representation of the variation of the modulus of the geosynthetic with the deformation in the x-axis and the applied tension in the y-axis, at least two separate elongation areas under tension in at least one direction, respectively: a first major elongation area for deformation of the geosynthetic comprised between 0 % and a limit comprised between 0.5 % and 6 % in at least one direction for tensions of 0 and 10 to 400 kN/m corresponding to this limit deformation; and a second elongation area, beyond said first elongation area, characterised by a maximum deformation of 2 % to 20 % in at least one direction for tensions of 100 to 3000 kN/m at least, corresponding to said maximum deformation. The difference in the elongation areas is due to the nature of the threads that make up the geosynthetic and/or the structure of said geosynthetic.