Editorial Technical Reference

Diaphragm Wall Grab

This page explains how Diaphragm Wall Grab is classified within Repair and Installation of Machinery and Equipment. Technical values and manufacturer relationships are research references; confirm the current specification and supplier evidence for each order.

Technical Definition & Core Assembly

A specialized excavation tool used for constructing diaphragm walls in geotechnical engineering.

Representative product image. Confirm appearance and specifications with the manufacturer.

Product Specifications

Technical details and manufacturing context for Diaphragm Wall Grab

Definition
A diaphragm wall grab is a heavy-duty excavation device designed specifically for creating deep, vertical trenches in soil and rock formations. It operates by opening and closing its clamshell-like jaws to excavate material, which is then removed to form the trench for diaphragm wall construction. This equipment is essential for creating underground retaining walls, cut-off walls, and foundation elements in civil engineering projects. The grab is typically suspended from a crane or a dedicated rig and is lowered into the excavation site. Its jaws, equipped with hardened cutting teeth, penetrate the ground and capture material. The cycle of opening, closing, lifting, and discharging is repeated to achieve the required trench dimensions. The device is constructed from high-strength steel and wear-resistant alloy steel to withstand harsh conditions. Key parameters include excavation width (600–1500 mm), depth (50–120 m), operating weight (15–45 t), bucket capacity (0.8–3.5 m³), closing force (200–600 kN), operating pressure (25–35 MPa), max pull force (100–300 kN), opening width (2200–4500 mm), cylinder stroke (500–1200 mm), operating temperature (-20 to 50 °C), material grade (Q345B per GB/T 1591), and hydraulic oil flow (150–300 L/min). These values are reference ranges and must be verified for the specific model and application. The grab is used in geotechnical engineering for constructing diaphragm walls, which serve as retaining structures, cut-off walls, and foundation elements. Selection depends on soil conditions, trench dimensions, and crane capacity. Maintenance signals include wear on cutting teeth, hydraulic leaks, and reduced closing force. Failure boundaries include operating outside specified temperature or pressure ranges, which can affect performance. Always consult the legal manufacturer or supplier for model-specific data and compliance.
Working Principle
The diaphragm wall grab operates through a hydraulic or mechanical system that controls the opening and closing of its jaws. When lowered into the excavation site, the jaws open to their maximum width. As the grab descends, the jaws close under controlled force, capturing soil, clay, or soft rock within the bucket. The filled grab is then lifted to the surface where the material is discharged. This cycle repeats to progressively excavate the trench to the required depth and width. The closing force and speed are influenced by hydraulic pressure and oil flow. The grab's performance depends on matching the operating parameters to the site conditions and crane capacity.
Common Materials
High-strength steel, Wear-resistant alloy steel, Hardened cutting teeth
Technical Parameters
ParameterTypical rangeNotes & selection driver
Excavation WidthRequired600–1500 metersMaximum width of trench that can be excavated
Excavation DepthRequired50–120 metersMaximum depth capability for trench excavation
Operating WeightRequired15–45 tonsTotal weight of the grab assembly during operation
Bucket CapacityRequired0.8–3.5 cubic metersVolume of material captured per grab cycle
Closing ForceRequired200–600 kNMaximum force applied when closing the jaws
Operating Pressure25–35 MPaHydraulic system pressure; below 25 MPa reduces closing force.
Max Pull Force100–300 kNVertical pull on the grab; must match crane capacity.
Opening Width2200–4500 mmMaximum opening of the grab jaws.
Cylinder Stroke500–1200 mmDetermines closing speed and force.
Operating Temperature-20–50 °COutside this range, hydraulic fluid viscosity changes.
Material GradeQ345BHigh-strength steel for wear resistance.GB/T 1591
Hydraulic Oil Flow150–300 L/minRequired flow for optimal closing speed.

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM
  • Main Frame Part
    Provides structural support and connection to the crane or excavator
    Material: High-strength structural steel
  • Jaw Assembly
    Excavation component that opens and closes to capture material
    Material: Wear-resistant steel with hardened cutting edges
  • Hydraulic Cylinders
    Provide controlled opening and closing force to the jaws
    Material: Chromium-plated steel with hydraulic seals
  • Cutting Teeth Part
    Penetrate and break up soil and rock during excavation
    Material: Tungsten carbide or hardened alloy steel
  • Guide System
    Ensures vertical alignment and stability during excavation
    Material: Steel rollers and guides
  • Control System
    Manages hydraulic pressure and jaw movement
    Material: Electronic components with hydraulic valves

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Diaphragm Wall Grab.

Industrial Ecosystem & Supply Chain Structure

Complementary Systems
Downstream Applications
Specialized Tooling

Application Fit & Sizing Matrix

Operational Limits
pressure: Up to 350 bar (hydraulic system maximum working pressure)
flow rate: 80-250 L/min (hydraulic oil flow range for optimal grab operation)
temperature: -10°C to 50°C (operational range for hydraulic systems and structural steel)
slurry concentration: Up to 1.35 specific gravity (maximum bentonite slurry density for effective excavation)
Media Compatibility
✓ Soft to medium stiff clays ✓ Sandy soils and gravels ✓ Weathered rock formations
Unsuitable: Solid bedrock or massive boulder layers (requires pre-drilling or rock excavation equipment)
Sizing Data Required
  • Required excavation depth (meters)
  • Panel width/diameter (meters)
  • Soil/rock strength parameters (kPa or MPa)

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause
Hydraulic Seal Degradation
Cause: Contamination of hydraulic fluid with abrasive soil particles or water ingress, leading to seal wear, internal leakage, and loss of gripping pressure.
Structural Fatigue in Grab Jaws
Cause: Cyclic loading from repeated impact with hard or uneven strata, combined with potential material defects or stress concentrations at weld points, leading to crack initiation and propagation.
Maintenance Indicators
  • Audible: Unusual grinding or knocking sounds during jaw closure, indicating misalignment, severe wear, or foreign object entrapment.
  • Visual: Hydraulic fluid leaks at cylinder rod seals or hose connections, or visible deformation/cracking on the grab jaws or structural arms.
Engineering Tips
  • Implement a strict hydraulic fluid cleanliness program with regular sampling and filtration to prevent abrasive contamination and protect sensitive valve blocks and cylinder seals.
  • Establish a preventive inspection schedule using non-destructive testing (e.g., magnetic particle or ultrasonic) on high-stress areas like jaw hinges and welds after a set number of operating cycles or upon encountering exceptionally hard ground conditions.

Indicative industry ranges for design and RFQ preparation. Confirm the exact figures and applicable standard with the manufacturer before specifying.

Compliance & Manufacturing Standards

Applicable Standards
ASTM A36/A36M Standard Specification for Carbon Structural Steel

Quoted from the published standard.

Manufacturing Precision
  • Bore Diameter: +/-0.05mm
  • Parallelism of Gripping Faces: 0.2mm
Quality Inspection
  • Magnetic Particle Inspection (MPI)
  • Dimensional Verification with CMM

Manufacturers of Diaphragm Wall Grab

7 companies list this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.

GBM Industry
Shanghai, CN
Founded 1998
ISO9001
Also makes: Spreader, Remote Control, Conveyor Belt System and 5 more
Listed on the company's own website · profile compiled by CNFX from public sources
THHI
Jiangsu, CN
Founded 1992
Also makes: Spreader, Telescopic Boom, Offshore Crane and 7 more
Listed on the company's own website · profile compiled by CNFX from public sources
Dafang Crane
Henan, CN
Listed on the company's own website · profile compiled by CNFX from public sources
DGCRANE
Henan, CN
Listed on the company's own website · profile compiled by CNFX from public sources
Jiangsu OUCO Heavy Industry and Technology Co.,Ltd.
Jiangsu, CN
Listed on the company's own website · profile compiled by CNFX from public sources
Kinocranes
Henan, CN
Listed on the company's own website · profile compiled by CNFX from public sources
SANY Group
Taiwan, CN
Listed on the company's own website · profile compiled by CNFX from public sources

Manufacturer listings support early research and capability understanding. They are not certification, ranking, or transaction guarantees.

Technical documentation
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Frequently Asked Questions

What is a diaphragm wall grab used for?

It is used to excavate deep, vertical trenches for constructing diaphragm walls, which serve as retaining walls, cut-off walls, or foundation elements in civil engineering projects.

What are the key parameters to consider when selecting a diaphragm wall grab?

Key parameters include excavation width, depth, operating weight, bucket capacity, closing force, operating pressure, max pull force, opening width, cylinder stroke, operating temperature, material grade, and hydraulic oil flow. These must match the project requirements and crane capacity.

How does the grab excavate material?

The grab is lowered with jaws open, then the jaws close under hydraulic or mechanical force to capture soil or rock. The filled grab is lifted and discharged, and the cycle repeats to excavate the trench.

What maintenance signals indicate potential issues?

Signs include excessive wear on cutting teeth, hydraulic fluid leaks, reduced closing force, or unusual noises. Regular inspection and adherence to operating parameters are essential.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification
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