Foundation System for Collapsible Soils Using Stone Columns
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Solution Overview
Problem
Developing a cost-effective foundation system for collapsible soils that can absorb tensile and lateral loads is challenging due to the significant loss of in-situ dry strength when soils become wetted, requiring a design that can stabilize and distribute loads effectively across unstable soil deposits.
Innovation Solution
A foundation system comprising a below-ground rigid raft foundation with granular cushions, piles, and stone columns, where the stone columns are encapsulated with a non-woven geofabric and stabilized with a cementing agent, providing a stable load distribution and absorption of tensile and lateral loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deep foundations are used to transmit loads to bearing strata below collapsible soil, then load transmission is improved, but the design process becomes tedious and costly
Solution Approach 1:
The foundation system is divided into multiple functional segments: a rigid raft foundation for load distribution, granular cushions for stress relief, stone columns for soil stabilization, and piles for deep load transmission. Each segment performs a specific function, allowing the system to achieve reliable load transmission through simplified, modular components rather than complex monolithic designs.
Solution Approach 2:
The invention employs composite ground improvement by combining stone columns with cementing agents to create stabilized soil columns. This composite approach enhances the承载 capacity of collapsible soils while simplifying the overall foundation design, as the stabilized soil itself becomes part of the load-bearing system rather than requiring entirely separate structural elements.
2Ease of manufacture
If traditional foundation systems are used on collapsible soils, then initial construction is simpler, but the soils lose strength when wetted leading to foundation failure
Solution Approach 1:
The stone columns are installed and stabilized with cementing agents before the structure is loaded and before potential wetting events occur. This preliminary stabilization transforms the weak collapsible soil into stronger, more stable columns that can withstand future wetting and loading conditions, preventing strength loss rather than addressing it after the fact.
Solution Approach 2:
The cementing agent modifies the physical and chemical parameters of the soil within the stone columns, changing its engineering properties. The treatment alters the soil's collapsibility characteristics and strength parameters, transforming it from a weak, moisture-sensitive material into a stable, load-bearing element that maintains strength under varying moisture conditions.
3Ease of manufacture
If shallow foundations are used on collapsible soils, then construction cost is reduced, but the foundations cannot adequately support structures on weak soils
Solution Approach 1:
The solution transitions from a purely horizontal shallow foundation approach to a combined shallow-deep system by adding vertical stone columns that extend into the soil profile. This dimensional addition allows the foundation to utilize both shallow raft action for load distribution and deep columnar elements for reinforcement, achieving enhanced support capability while maintaining cost-effectiveness through relatively simple column installation.
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 system effectively stabilizes collapsible soils, enhances load distribution, and reduces the cost of geotechnical works by improving the carrying capacity and rate of soil consolidation, while predicting load carrying capacity through an analytical model.
Implementation Method 1
A plurality of below-ground stone columns are encapsulated with a non-woven geofabric
Implementation Method 2
The below-ground stone columns have a cementing agent for stabilization
Implementation Method 3
A plurality of granular cushions formed below the below-ground rigid raft foundation and the granular cushions are configured for uniform load distribution
Data Source
AI summary
The foundation system includes a below ground rigid raft foundation to bear a load for an above ground structure, and granular cushions and piles formed below the raft foundation. The granular cushions are configured for uniform load distribution of the raft foundation and the piles are configured to bear a load of the above ground structure and the raft foundation. The foundation system further includes stone columns encapsulated with a non-woven geofabric and configured to stabilize the raft foundation. The raft foundation is disposed adjacent and above the stone columns, the granular cushions are present between neighboring stone columns, and the granular cushions are present between the stone columns and the piles. The stone columns have a cementing agent for stabilization.