Perimeter Pile Anchor Foundation for Weak Soil Stability
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Solution Overview
Problem
Conventional pile anchor foundations face challenges in constructing deep concrete foundations in weak soils and cohesionless sands, as these soils tend to cave or slough when excavated vertically, limiting their effectiveness.
Innovation Solution
A perimeter pile anchor foundation is created by drilling individual piles in a large circular pattern with overlapping piles, forming a continuous arch that resists soil caving through compression and friction, using a combination of concrete, steel plates, and post-tensioned bolts to stabilize the soil and allow for safe excavation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional pile anchor foundations are used with spaced piles, then the foundation structure is simple to construct, but the soil caves or sloughs when excavating vertically in weak soils
Solution Approach 1:
The foundation is divided into multiple discrete pile anchors arranged in a circular pattern rather than a single continuous structure. Each pile acts as an independent segment that collectively forms a stable perimeter, allowing simple construction of individual piles while achieving overall soil stabilization through their combined arch effect.
Solution Approach 2:
The piles are arranged in a circular pattern rather than a straight line, creating a curved arch structure. This curvature allows the piles to effectively resist lateral soil pressures and prevent caving during vertical excavation, transforming the structural geometry to better suit the soil stabilization function while maintaining construction simplicity.
2Ease of manufacture
If piles are spaced apart in conventional foundations, then construction is easier, but the foundation cannot resist soil caving in weak soils
Solution Approach 1:
Multiple discrete pile anchors are combined to form a unified circular arch structure. The individual piles work together through compression and friction to create a collective resistance against soil caving, merging their individual strengths to achieve soil stabilization capability that none could provide alone while maintaining the construction ease of individual pile installation.
Solution Approach 2:
The circular pattern of pile anchors is pre-configured before excavation begins, creating a stable perimeter structure in advance. This preliminary arrangement of piles in a specific geometric pattern establishes the structural framework needed to resist soil pressures during subsequent vertical excavation operations.
3Reliability
If a continuous arch form is created with overlapping piles, then soil caving is resisted through compression, but the foundation structure becomes more complex
Solution Approach 1:
The continuous arch is segmented into discrete pile anchors that are individually constructed and then positioned to form the circular pattern. This segmentation allows each pile to be built using simple, standardized construction methods while the overall circular arrangement creates the continuous arch effect needed for soil stabilization, reducing individual component complexity while maintaining system reliability.
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 solution enables the construction of deep concrete foundations in weak soils and cohesionless sands without soil sloughing, providing a stable base for large structures by forming a compressive arch that resists excavation pressures.
Implementation Method 1
adjacent piles overlap and form an arch with compression between the piles to resist soil caving in weak soils
Implementation Method 2
compression and friction, using a combination of concrete, steel plates, and post-tensioned bolts to stabilize the soil
Data Source
AI summary
A perimeter pile anchor foundation is built by forming a plurality of individual perimeter pile anchors in a large generally circular pattern to form a perimeter wall. The individual pile anchors are contiguous, each pile overlapping the adjacent piles on either side. The overlapping pile anchors form an arch such that compression and friction between the pile anchors resist soil caving and sloughing pressure when soil inside the perimeter wall is excavated, enabling the perimeter pile foundation to be effectively constructed in weak saturated soils and/or cohesionless sands that will not allow conventional concrete foundation excavations. A concrete foundation ring is formed inside the pile perimeter wall to support a tall and/or heavy tower or other structure subject to high upset forces.