Polyurethane Foam Injection for Deep Soil Liquefaction Mitigation
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Solution Overview
Problem
Existing methods for preventing liquefaction in loose soil are costly, time-consuming, or ineffective, particularly when the loose soil is deep or the water table is high, and existing equipment for resin injection is prone to malfunction and provides insufficient feedback.
Innovation Solution
A method and system using a plurality of injectors with a proximal and distal portion, where the distal portion is perforated, to inject a two-part polyurethane liquid into the loose soil stratum, forming a tacky foam that cures to a solid foam matrix, stabilizing the soil and displacing water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If loose soil is removed and replaced with compact soil material, then liquefaction resistance is improved, but cost and time consumption increase significantly
Solution Approach 1:
The invention changes the physical and chemical parameters of the loose soil in place by injecting expanding resin that reacts with water to form solid foam, transforming the soil's liquefaction resistance without removal or replacement. This resolves the contradiction by achieving reliable liquefaction resistance avoidance of costly and time-consuming excavation and replacement operations
Solution Approach 2:
The invention replaces mechanical compaction methods (such as heavy weight dropping or vibrational compaction) with a chemical expansion process. The resin expands in situ to densify and stabilize the soil, eliminating the need for heavy mechanical equipment and repeated compaction passes, thereby reducing both time and cost while maintaining effectiveness even at greater depths
2Reliability
If surface compaction methods are used to densify loose material, then liquefaction resistance is improved, but effectiveness decreases when loose soil depth exceeds compaction zone
Solution Approach 1:
The invention transitions from surface-level compaction (two-dimensional surface operation) to deep subsurface treatment by injecting resin through holes drilled to the exact depth of the loose soil stratum. The resin expands throughout the entire depth of the loose soil layer, ensuring complete stabilization regardless of depth, thereby resolving the limitation of surface compaction methods
Solution Approach 2:
The invention performs preliminary drilling of holes to the precise depth of the loose soil before injection. This preliminary action ensures that the resin is delivered exactly where needed and expands to treat the entire loose soil stratum, guaranteeing effective penetration and stabilization throughout the full depth rather than relying on surface compaction that cannot reach deep layers
3Reliability
If pilings are driven through loose soil to compact surrounding soil, then some liquefaction resistance is improved, but lateral support is lost during liquefaction events
Solution Approach 1:
The invention merges the functions of compaction and lateral support into a single integrated system. The expanding resin simultaneously densifies the loose soil and binds soil particles together to form a unified stabilized mass. This merged approach provides both liquefaction resistance and lateral support through the same mechanism, eliminating the contradiction present in piling methods where the two functions are separate and conflicting
Solution Approach 2:
The invention creates a composite material system by combining the resin with the soil particles. The resin-soil composite forms a unified structure where the resin binds particles together, providing both density improvement and lateral strength. This composite approach resolves the contradiction by making the stabilized soil itself provide lateral support rather than relying on separate piling elements that lose support during liquefaction
4Reliability
If French drains are installed to escape water pressure, then some pore pressure relief is achieved, but adequate escape paths are not provided during rapid pressure buildup
Solution Approach 1:
The invention converts the harmful effect of water pressure buildup into a beneficial process by utilizing the water itself as a reactant. The injected resin reacts with the pore water to expand and form solid foam, transforming the pressurized water from a hazard into the mechanism for stabilization. This resolves the contradiction by eliminating the need for separate drainage paths while effectively managing the water pressure through chemical reaction
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
The method effectively reduces liquefaction potential by forming a solid foam matrix within the soil, providing stable support and preventing soil movement during seismic events, with improved efficiency and feedback compared to existing techniques.
Implementation Method 1
injecting a predetermined amount of a two-part polyurethane liquid into the stratum... while the two-part polyurethane liquid reacts forming a tacky foam, the tacky foam displacing water and binding to the soil within the stratum, and slowly curing to form a solid foam matrix
Implementation Method 2
the two-part polyurethane liquid reacts forming a tacky foam, the tacky foam displacing water... Increase in volume as liquid polymer expands and cures to a solid foam matrix
Data Source
AI summary
A method for the reduction of liquefaction potential within soil of a stratum located a distance deep below a foundation of a structure through the injection of a two-part polyurethane liquid forming a polymer foam.