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The Development and Multi-Purpose Applications of Diaphragm Walls in Modern Construction

1. Evolution of Diaphragm Wall Technology

The diaphragm wall technique traces its origins to 1938 when Italy conducted pioneering experiments, later implementing a 40-meter-deep cutoff wall in the Santan Malin Dam project. Key milestones include:

  • 1958: China’s first pile-type diaphragm walls were constructed at Qingdao Zizikou Reservoir and Beijing Miyun Reservoir

  • 1973: France’s Soletanche company developed the first hydraulic trench cutter

  • 1974: Shanghai initiated diaphragm wall trials using conventional grab systems

  • 1976: Guangdong Province first applied diaphragm walls for building foundation support

  • 1996: China introduced BC30 hydraulic trench cutters for the Three Gorges Project

  • 2004: Shanghai Metro Line 4 rehabilitation project implemented 1.2 m-thick, 65 m-deep walls

  • Current: Japanese projects achieve depths of 140m, with global applications in high-rise basements, metro stations, and dams

Typical Applications:

  • 3-level basements: 14m deep walls (dual-function as permanent walls)

  • 4-level basements: 17m deep walls

  • Metro stations: 23m deep walls (serving as anti-floating structures)

2. Multi-Functional Diaphragm Wall Systems

2.1 Construction Process & Equipment

  • Grab-type trenching machines

  • Impact-type cutter heads

  • Hydraulic milling machines

2.2 Technical Advantages

  • High structural rigidity and strength for superior lateral displacement control

  • Advanced joint designs ensure waterproof reliability

  • Low-vibration, quiet operation minimizes neighborhood impact

  • Adaptable to complex geological conditions

  • Space-efficient solution with rapid construction cycles

  • Compatible with top-down construction methods

2.3 Dual-Function as Permanent Basement Walls

Key considerations when using diaphragm walls as permanent structural elements:

  • Wall thickness: Typically >600mm (exceeding conventional basement walls)

  • Reinforcement: Designed for higher lateral earth pressures

  • Deformation control: Must limit cracking to <0.2mm for waterproofing

  • Structural integration:

    • Embedded connectors for slab/wall junctions

    • Reinforcement cages form concealed columns

    • Rough surfaces remedied with 200-300mm interior lining walls

Waterproofing Strategies:

  • Preventive measures:

    • Extended I-beam flange connections

    • External swellable waterstops

    • Jet grouting at joints

    • Waterstop plates at the base slabs

  • Drainage systems:

    • Cavity drainage membranes

    • Sub-floor collection channels

2.4 Combined Foundation/Anti-Float Systems

  • Functions as wide, shallow piles with significant skin friction

  • Deep embedment provides anti-flotation stability

  • Localized deepening addresses capacity deficiencies

  • Requires stricter construction tolerances than temporary walls

3. Case Studies

Project 1: Guangzhou Hospital Complex

  • Scope: 21.1 m-deep excavation for the 19-story hospital with 4 underground levels

  • Challenges: Adjacent to major roads and existing structures in a sensitive urban area

  • Solution:

    • 800mm thick diaphragm wall (serving as structure/waterproofing/piles)

    • Single strut + two-tier anchors

    • 200mm interior lining wall

  • Performance:

    • Maximum deflection: 27.2mm (within limits)

    • 6m embedment in weathered rock met all requirements

  • Cost Savings: ¥2.502 million

Project 2: Zhujiang New CBD Development

  • Scope: 18.3 m-deep excavation near Metro Line 5

  • Solution:

    • Diaphragm wall with 300mm lining + three-tier struts

  • Performance:

    • Maximum deflection: 21.6mm

    • 5-6m rock embedment

  • Cost Savings: ¥1.648 million

4. Economic Benefits

Comparative analyses demonstrate:

  • Case 1: 14% reduction in project costs

  • Case 2: 11% savings through integrated design
    Additional advantages include:

  • Reduced construction duration

  • Increased usable basement space

  • Simplified construction sequencing

5. Conclusions

Diaphragm walls offer transformative potential beyond conventional deep excavation support when engineered for multi-functionality. Successful implementation requires:

  1. Comprehensive verification of both temporary and permanent performance criteria

  2. Specialized waterproofing detailing at construction joints

  3. Precision construction quality control

  4. Integrated structural connection design

This approach proves economically viable even in favorable ground conditions, delivering compounded benefits in urban development projects where space, time, and environmental factors are critical constraints.

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