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Spiral High-Pressure Jet Wing-Expanded Base Rigid Composite Pile: Technical Advantages and Construction Process

Introduction to Spiral High-Pressure Jet Wing-Expanded Base Rigid Composite Pile

The Spiral High-Pressure Jet Wing-Expanded Base Rigid Composite Pile represents an innovative foundation technology that combines the advantages of flexible granular piles and rigid high-strength concrete piles. This composite construction method significantly expands the application range of single-pile techniques while creating complementary reinforcement and cooperative load-bearing capabilities.

This advanced pile technology comprehensively addresses the limitations of single-pile methods, improving pile quality, strength, and stiffness while simultaneously reducing construction difficulty and costs. The composite pile demonstrates remarkable load-bearing capacity while dramatically improving the weak state of inter-pile soil and enhancing soil participation in load-bearing. The technology achieves synergistic effects where the combined performance exceeds the sum of individual components (1+1>2, sometimes even reaching 5 times the effectiveness).

Key Applications

  • Serves as vertical reinforcement in composite foundations

  • Functions as a single rigid pile (resisting shear, uplift, and compression)

  • Applicable for foundation pit support and anti-seepage wall engineering

  • Offers broad application prospects in various construction scenarios

Technical Terminology

The Spiral High-Pressure Jet Wing-Expanded Base Rigid Composite Pile utilizes high-pressure rotary jet grouting or spray mixing grouting to form reinforced bodies, filling and expanding various concrete piles at the pile tip. This includes:

  • Wing-expanded base precast concrete rigid composite piles

  • Wing-expanded base, cast-in-place reinforced concrete rigid composite piles

As a patented innovation, this technology aligns with national energy conservation and emission reduction policies, ensuring safety, applicability, economic efficiency, and environmental protection during construction.

Construction Technology Overview

Developed independently by Central City Construction Co., Ltd., this advanced pile foundation technology has demonstrated exceptional load-bearing capacity in engineering applications and pile foundation tests.

Project Case Study: Agricultural Investment International Center

  • Pile type: PHC-AB-400-11 with 5m expanded composite section

  • Testing conducted 14 days post-construction

  • Single pile vertical compressive static load test results:

    • Bearing capacity: 4840KN

    • Settlement: 24.43mm

    • Ultimate bearing capacity: 8-10 times that of conventional bored piles with equivalent length

    • Q-S curve shows “gradual transition” pattern without obvious inflection points, indicating the elastic working state

Technical Characteristics

1. Geological Adaptability

  • Wide applicability across various soil conditions

  • Improves soil characteristics through strength enhancement

  • Increases soil bearing capacity with minimal environmental impact

2. Construction Process

  • Combining the advantages of multiple pile types

  • Utilizes ultra-hard fine aggregate concrete at the base to increase end resistance

  • Enhances soil shear and compression resistance through the rotary jet process

  • Employs precast pipe piles to compact the surrounding improved soil and base concrete

3. Quality Assurance

  • A combination of ultra-hard fine aggregate concrete and precast pipe piles ensures pile integrity

  • Soil mixing further enhances pile shear resistance

4. Economic Benefits

  • Achieves equivalent compressive performance to conventional bored piles

  • Reduces pile length by 1/2

  • Saves total cost by 15%-30%

5. Energy Conservation and Emission Reduction

  • Unaffected by dust control periods that restrict commercial concrete use

  • Eliminates issues with mud transportation that delay other pile methods

  • Maintains construction schedule reliability

Fundamental Theory

1. Core Principles

The technology employs high-pressure rotary jet grouting or spray mixing grouting to reach the pile bottom elevation. A transfer pump then fills the base with ultra-hard concrete to create wing-expanded sections approximately 2m deep, followed by pressing precast pipe piles to design elevation. The core innovation involves deep soil reinforcement and increased effective bearing area through wing-expanded bases to enhance end bearing capacity.

Compared to other foundation treatment solutions, this method offers significant advantages in cost and construction efficiency. It also outperforms natural foundations by transferring structural loads to deeper soil layers with higher bearing capacity and lower compressibility, effectively controlling building deformation and uneven settlement.

2. Composite Pile Composition

Consisting of cement slurry, ultra-hard concrete, and precast pipe piles, this technology significantly improves soil density and compression modulus. Benefits include:

  • High bearing capacity

  • Excellent stability

  • Consistent quality assurance

  • Cost efficiency

  • Enhanced side friction resistance (also applicable to uplift piles)

3. Suitable Geological Conditions

Applicable to various soil conditions, including:

  • Silty clay

  • Silt

  • Clay

  • Fine sand

  • Medium-coarse sand

  • Highly weathered rock

  • Muddy soil

4. Construction Scope

Widely applicable in industrial, civil, and municipal engineering projects. Core piles can use precast pipe piles (400mm, 500mm, or 600mm diameter) with single pile capacity up to 7200KN. Ongoing technological improvements promise significant municipal construction cost savings.

Application Scope

  1. Industrial and civil buildings

  2. Municipal engineering, road subgrades, and bridge foundation reinforcement

  3. Large and medium-sized water conservancy project foundation reinforcement

Construction Process

(1) Process Flow:

  1. Positioning and layout

  2. Elevation measurement

  3. Soil reinforcement with spiral high-pressure jet mixing pile machine

  4. Wing-expanded base section completion with ultra-hard fine aggregate concrete

  5. Cement grout spraying to the pile top

  6. Pile pressing

  7. Completion and equipment relocation

(2) Construction Control:

  1. Spiral high-pressure jet mixing pile machine uses short spiral drill bits for grout-spraying spiral drilling. After reaching design depth, pump concrete while lifting the drill rod approximately 2m, then begin grout spraying while lifting to the design pile top.

  2. Wing-expanded section grouting pressure: 25MPa

    • Water-cement ratio: 0.5

    • High-pressure jet head configuration: 2 lateral nozzles, 1 vertical nozzle (separate pipeline)

Project Overview: Agricultural Investment International Center

Pile Foundation Specifications:

  • Main building area: Compression piles with characteristic compressive capacity ≥3400KN

  • Annex and garage area: Uplift piles with 5m wing-expanded composite section

    • Characteristic uplift capacity ≥950KN

    • Characteristic compressive capacity ≥2000KN

  • Construction requirements:

    • The empty pile length should not exceed 3m or be less than 1.5m

Stratigraphic Structure:

Based on drilling, cone penetration, and standard penetration tests combined with laboratory soil tests, the geological layers from top to bottom include:

  1. Silt: Yellow-brown, wet, slightly dense, low dry strength and toughness, rapid shake reaction

  2. Silty Clay: Brown-yellow, plastic, medium dry strength and toughness

  3. Silt: Brown-yellow, wet, slightly to medium dense, low dry strength and toughness

  4. Silty Clay: Yellow-brown, plastic, medium dry strength and toughness

  5. Silty Clay: Yellow-brown to gray-brown, plastic, medium dry strength and toughness

  6. Silt: Gray-brown, wet, medium dense, low dry strength and toughness

  7. Mucky Silty Clay: Gray-brown to gray-black, fluid-plastic, medium dry strength and toughness

  8. Silt: Gray-brown, wet, dense, low dry strength and toughness

  9. Silty Sand: Gray-brown, saturated, dense, well-graded

  10. Fine Sand: Brown-yellow, saturated, dense, well-graded

Construction Technology for Rigid Composite Piles

I Pre-construction Preparation

  1. Site leveling and elevation measurement

    • Measure construction surface elevation (approximately 12m)

    • Calculate the empty pile length based on pthe ile top elevation

    • Mark special areas (elevator pits, sumps) separately

  2. Layout and verification

    • Verify all pile center coordinates on drawings

    • Number piles systematically for easy identification

    • Conduct on-site verification within tolerance limits

II. Pile Machine Positioning

  • Ensure machine stability and verticality

  • Adjust using a level or a plumb bob

  • Vertical deviation ≤1%

III. Drilling Operation

  1. Depth control

    • Mark depth references on the pile frame

    • Verify depth before operation

    • Monitor for abnormal conditions (rod jumping, frame shaking)

    • Ensure the minimum design depth is achieved

  2. Grout spraying and mixing

    • Activate the grout pump at the design depth

    • Maintain preset speed and air pressure during lifting

    • Ensure continuous operation

    • For interruptions, resume with ≥50cm overlap

    • Monitor grout volume and pressure continuously

IV. Ultra-Hard Concrete Placement

  • Follow mixing with conduit placement

  • Install an effective water stop at the conduit

  • Maintain 0.3m-0.5m between the conduit bottom and the hole bottom

  • Place approximately 2m of concrete (≥1.3m³ volume)

  • Record placement details meticulously

V. Static Pressure Pile Driving

  • After concrete placement, press the precast pipe pile to the design depth

  • Ensure 0.3 m- 1.0 m penetration into ultra-hard concrete

  • Limit pressing depth to 8m maximum

  • Maintain pressing force within 1.1 times the allowable pile pressure capacity

This comprehensive construction process ensures the high performance and reliability of Spiral High-Pressure Jet Wing-Expanded Base Rigid Composite Piles in diverse engineering applications.

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