Air-Boosted Vacuum Preloading for Soft Ground Reinforcement
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Solution Overview
Problem
Existing soft ground reinforcement methods, such as the combination of bagged grouting gravel piles and vacuum preloading, face issues with clogging areas that reduce treatment effectiveness and are limited to shallow applications, complicating construction and affecting radial consolidation and drainage efficiency.
Innovation Solution
A method combining granular material piles with air-boosted vacuum preloading, where alternating vacuum and pressurization are used in the early stage and negative pressure grouting in the later stage, eliminating the need for geotextile bags and reducing the number of vertical drainage channels, thus avoiding clogging and improving radial permeability and grouting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bagged grouting gravel piles and vacuum preloading are combined, then soft ground reinforcement is achieved, but clogging areas form around geotextile bags reducing treatment effectiveness
Solution Approach 1:
The invention removes the geotextile bag component from the system entirely, extracting the harmful element that causes clogging. Instead of using geotextile bags to contain gravel, the patent employs hollow steel pipes filled with gravel directly, eliminating the interface between geotextile and soil that generates clogging areas during vacuum preloading.
Solution Approach 2:
The invention replaces the geotextile bag with a more durable steel pipe structure that can withstand vacuum pressures without deforming or clogging. The steel pipe serves as both the structural element and the vacuum transmission path, eliminating the need for disposable geotextile materials that are prone to clogging.
2Reliability
If multiple vertical drainage channels are installed, then drainage function is provided, but construction process becomes complicated and radial permeability coefficient decreases
Solution Approach 1:
The invention merges the drainage channel function and the vacuum transmission path into a single integrated structure. The hollow steel pipe serves dual purposes: as the structural element containing gravel and as the vacuum transmission channel, eliminating the need for separate geotextile bags and independent drainage channels.
Solution Approach 2:
The hollow steel pipe structure performs multiple functions simultaneously: it provides structural support, transmits vacuum pressure, contains gravel for reinforcement, and serves as a drainage channel. This multi-functional design simplifies the overall system compared to separate components for each function.
3Strength
If geotextile bags are used for granular material piles, then pile structure is formed, but radial permeability coefficient around vertical drainage channels is reduced
Solution Approach 1:
The invention extracts and removes the geotextile bag from the system, eliminating the source of radial permeability reduction. The steel pipe structure provides pile strength without creating the clogging and smear zones that geotextile bags generate in the surrounding soil.
Solution Approach 2:
The invention uses a composite structure of steel pipe and gravel that provides both structural strength and maintains soil permeability. The steel pipe acts as a rigid confining structure while the gravel inside provides drainage and reinforcement, without the need for geotextile materials that reduce radial permeability.
4Reliability
If vacuum preloading is applied to ultra-soft clay, then consolidation is promoted, but clay particles gather in geotextile bags forming clogging areas
Solution Approach 1:
The invention removes the geotextile bag that attracts and traps clay particles during vacuum preloading. The steel pipe structure does not create the same suction effect at its surface that causes clay particles to gather and clog, allowing continuous and effective vacuum consolidation throughout the treatment period.
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 enhances the depth and scope of soft ground reinforcement, simplifies construction, reduces costs, and improves treatment efficiency, making it suitable for deep ultra-soft and structural soft grounds with minimal impact on radial permeability.
Implementation Method 1
The vacuum preloading method uses a vacuum pumping system and uses a prefabricated vertical drain as a vacuum transmission path to improve soil strength by promoting drainage and consolidation of the soil
Implementation Method 2
a method for reinforcing soft ground by post-grouting combined with air-boosted vacuum preloading
Implementation Method 3
finally, the bagged gravel piles are grouted through pre-embedded grouting pipes to form a rigid pile composite ground
Data Source
AI summary
A method for reinforcing soft ground by post-grouting combined with pressurized vacuum preloading is proposed, by pre-burying prefabricated vertical drains and air-boosted pipes in granular material piles, and the air-boosted pipes are used as grouting pipes to reduce the number of times of piling, which not only improves the construction efficiency, but also reduces the structural disturbance of the soil and the influence of smear effect, thus reducing the impact on the radial permeability and the radial consolidation coefficients. The method does not use geotextile bags for granular materials, which can avoid the problem of forming a localized clogging area around the geotextile bags, and the method not only improves the efficiency of vacuum transfer in a pre-consolidation stage, but also improves the grouting effect in the later stage, effectively enhances the strength of soft soil and makes granular material piles and the surrounding soil form composite ground.