Shielded Tamper Prevents Sidewall Collapse in Aggregate Columns

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Solution Overview

Problem

In soft or unstable soil environments, existing aggregate column construction techniques often result in sidewall collapse during tamping, leading to inefficiencies and the need for additional soil removal or cavity re-opening, especially when thicker lifts of aggregate are attempted.

Innovation Solution

A tamper device with a shielded tamper head and shaft, where the tamper head has a flat, blunt bottom face and a tapered surface extending circumferentially, and a shield that extends upwardly to prevent sidewall collapse, allowing for thicker aggregate lifts and more efficient construction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional tamper heads are used in soft soil environments, then the tamping process can be performed, but sidewall collapse occurs during tamping

Engineering Contradiction:

Improvesidewall stabilityVSAvoidsidewall collapse

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A shield is introduced as an intermediary component between the tamper head and the soil sidewalls. The shield extends upwardly from the tamper head to provide temporary support to the sidewalls during the tamping process, preventing collapse while allowing the tamping operation to proceed effectively.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The shield provides beforehand support to the sidewalls before collapse can occur. By extending upwardly from the tamper head, the shield creates a protective barrier that prevents the sidewalls from collapsing during the application of lateral pressure from the tamping operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Productivity

If thicker lifts of aggregate are used, then construction efficiency is improved, but sidewall failure becomes more likely

Engineering Contradiction:

Improveconstruction efficiencyVSAvoidsidewall stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The shield acts as a mediator that enables the use of thicker aggregate lifts by providing sidewall support during tamping. This allows construction efficiency to improve through thicker lifts while the shield prevents the sidewall failure that would normally occur with thicker material placements.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The shield provides beforehand support that allows thicker aggregate lifts to be used without causing sidewall failure. The shield is in place before tamping begins, cushioning the sidewalls against the increased lateral pressure that results from compacting thicker lifts of aggregate material.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Manufacturing precision

If lateral pressure is applied to compact aggregate, then compaction effectiveness is improved, but sidewall rotation and collapse occur

Engineering Contradiction:

Improveaggregate compaction qualityVSAvoidsoil rotation and collapse

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The shield serves as an intermediary that receives and distributes the lateral pressure applied during tamping. Instead of the pressure directly causing sidewall rotation and collapse, the shield mediates the force application, maintaining aggregate compaction quality while preventing harmful soil movement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The shield provides beforehand cushioning to the sidewalls during the application of lateral pressure. This prevents the soil rotation and collapse that would normally occur when lateral pressure is applied to compact aggregate, while still allowing effective compaction to take place.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 shielded tamper device effectively prevents sidewall collapse and allows for thicker aggregate lifts, enhancing the efficiency of aggregate column construction by maintaining lateral earth pressure and reducing the need for frequent soil removal, thus improving the construction process in soft ground conditions.

Implementation Method 1

maintaining lateral earth pressure

Methodology Applied

Scientific EffectLateral earth pressure: Pressure Increase

Implementation Method 2

tamping the aggregate lift with a specially designed beveled tamper head

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

the beveled sides force the aggregate into the sidewalls of the hole thereby increasing the lateral stresses in the surrounding ground

Methodology Applied

Scientific EffectLateral stress: Pressure Increase

Data Source

PatentEP2313562B1Shielded tamper and method of use for making aggregate columns

Publication Date: 2012.06.27 GEOPIER FOUNDATION COMPANY INC

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AI summary

A tamper device includes a shaft for driving a tamper head. A tamper head is attached to the end of the shaft for tamping a lift of aggregate in a cavity formed in a ground surface. A shield extends upwardly a predetermined height from the tamper head an amount sufficient to prevent sidewalls of the cavity from failing and collapsing. Methods of constructing aggregate columns with thicker lifts are also disclosed.