Large Direct Shear Simple Shear Apparatus

Large Direct Shear / Simple Shear Apparatus – Series Overview

Description

This series consists of large direct shear / simple shear apparatuses designed for shear testing of coarse‑grained soils, rockfill, geosynthetics, soil‑structure interfaces, and other large‑size specimens. The equipment uses a detachable gantry reaction frame and offers various force ranges and specimen size options. Main models include:

First group (Large Direct Shear / Simple Shear Apparatus)

• BTU-DDS-100: 100 T (1200 kN) class, max. specimen L.750×B.750×H.400 mm
• BTU-DDS-40FM: 40 T (400 kN) class, specimen Ø500×H.300 mm or 300×300×300 mm
• BTU-DDS-35FM: 20 T (200 kN) class, specimen 300×300×300 mm or 200×200×200 mm

Second group (Fully Automatic Large Direct Shear Apparatus)

• BTU-DDS-35F: 20 T (200 kN) class, specimen 300/150/200/100 mm
• BTU-DDS-45F: 40 T (400 kN) class, specimen 500 mm (square or round)

Common features:

• Capable of standard consolidation, standard shear, fast shear, reciprocating shear, cyclic shear, rheological direct shear, simple shear, etc.
• Equipped with multi‑channel data acquisition unit and Windows acquisition/processing software.
• Horizontal shear speed steplessly adjustable (0.00001–10 mm/min).
• Optional upgrades: interface shear, simple shear, temperature control, etc.

Test Standards (International)

• ASTM D3080(Direct shear test)
• ASTM D5321(Geosynthetic‑soil interface direct shear)
• ASTM D6243(Geosynthetic‑soil interface shear strength)
• ASTM D3080‑04(Large‑scale direct shear for coarse‑grained soils)
• ASTM D6528(Simple shear test)
• ISO 17892‑10(Direct shear test)
• BS 1377‑7(Direct shear test)
• EN 1997‑2(Eurocode 7 – Part 2)

The series meets the requirements of these standards for large specimens, coarse‑grained soils, interface shear, and simple shear tests.

Specification

Based on the two screenshots, parameters for each model are summarised as follows (some data combined from both images):

> Note: The BTU-DDS-35FM frame capacity is written as 1200 kN but vertical loading is only 200 kN – likely a typo; actual frame capacity should match the loading capability.

Detail

• Detachable gantry reaction frame– Easy to transport and install on‑site; suitable for large specimens and high loads.
• Multiple specimen sizes– From 100 mm up to 750 mm side length/diameter, covering coarse soils and rockfill that cannot be tested in conventional triaxial cells.
• Shear box lifting system– Electric hoist for the largest model (100T), manual hoist or chain block for medium models, facilitating handling of heavy shear boxes.
• High‑accuracy load cells– Accuracy ±0.1% FS ensures precise measurements at high tonnages.
• Wide stepless speed range– 0.00001–10 mm/min, capable of simulating creep to rapid shearing.
• Simple shear capability– Some models support simple shear tests using stacking‑ring shear boxes.
• Rich software modules– Include standard consolidation, standard shear, reciprocating shear, fast shear, cyclic shear, rheology, simple shear, etc.; users can combine as needed.
• Upgrade flexibility– Software upgrades (coupling modules) and hardware options (interface shear, temperature control) available.

Application

• Coarse‑grained soils and rockfill– Determine shear strength parameters for high dams, subgrades, mine waste dumps, and other large‑scale engineering fills.
• Soil‑structure interfaces– Study friction characteristics of pile‑soil, retaining wall‑soil, pipe‑soil, etc. (requires optional interface shear module).
• Geosynthetics– Interface shear strength between geotextiles, geomembranes, geogrids and soil.
• Simple shear tests– Simulate simple shear stress states for studying soil anisotropy or cyclic response.
• Reciprocating and cyclic shear– Evaluate strength degradation and residual strength under repeated loading (e.g., earthquakes, waves).
• Rheological behaviour– Creep under sustained load.
• High‑tonnage testing– Up to 1200 kN vertical force, suitable for high‑strength rock interfaces or large boulders.

Advantages

• High capacity and large size– Up to 1200 kN force and specimen 750×750×400 mm, allowing direct testing of field‑graded fills and avoiding scale effects.
• Modular frame– Detachable construction for easy transport and installation, suitable for limited lab space or on‑site use.
• High measurement accuracy– Load cells ±0.1% FS, displacement resolution down to 0.001 mm (1 μm).
• Multi‑function testing– One machine can perform direct shear, simple shear, reciprocating shear, cyclic shear, rheology, etc.
• Wide speed range– From extremely slow creep to fast shear, meeting various standards.
• Automated acquisition and processing– Windows software automatically collects data, displays real‑time curves, and calculates strength parameters.
• Expandability– Optional interface shear, temperature control, coupling modules for future research needs.
• Robust and safe– Strong reaction frame with overload protection.

What To Choose

Select the appropriate model based on testing requirements:

> Note: “FM” in DDS-40FM/35FM likely stands for “Direct shear + Simple shear”. DDS-35F/45F may support only direct shear (no simple shear). Confirm software module availability when selecting.

Process Flow

Example:Large rockfill direct shear test (BTU-DDS-100, specimen 750×750×400 mm, constant normal stress)

• Specimen preparation
  • Prepare rockfill material according to field gradation, control water content, compact in layers to target density.
  • Specimen size 750×750×400 mm; total mass can be several tonnes.
• Shear box installation
  • Use electric hoist to place the lower shear box onto the frame base.
  • Place the specimen into the lower box, level the surface.
  • Position the upper shear box and attach the vertical loading plate.
• Install sensors
  • Install vertical load cell (1200 kN) and horizontal load cell (1200 kN).
  • Install vertical displacement sensors (multiple, e.g., one at each corner) and horizontal displacement sensor.
  • Connect the data logger to the computer.
• Apply normal stress
  • Apply target normal stress (e.g., 500 kPa, total force ≈ 0.5 MPa × 0.5625 m² = 281 kN) via the vertical loading system.
  • Start the software and record vertical deformation (consolidation) until stable.
• Set shear parameters
  • Select “standard shear module”.
  • Set shear rate (e.g., 1 mm/min).
  • Set shear displacement limit (e.g., 50 mm or 6‑10% of specimen side length).
  • For reciprocating shear, set number of cycles and displacement amplitude.
• Start shearing
  • Start the horizontal loading system to push the upper (or lower) shear box.
  • Software records horizontal shear force, horizontal displacement, vertical displacement, and time in real time.
  • Plot shear stress‑displacement curve.
• Stop condition
  • Automatically stops when preset displacement is reached or after a clear peak shear stress drop.
• Disassembly and cleaning
  • Unload normal force, retract horizontal piston.
  • Lift the upper shear box, remove specimen, clean the shear box.
• Data processing
  • Software calculates peak shear stress.
  • For tests at different normal stresses, plot Mohr‑Coulomb envelope to obtain c and φ.
  • If reciprocating shear was performed, obtain residual strength.
  • Generate test report.

> **For simple shear tests** : Use a stacking‑ring shear box, maintain constant volume (undrained) or constant height (drained) during shearing, and select the “simple shear module” in the software.

Summary:This series of large direct shear / simple shear apparatus covers force ratings from 20 T to 100 T and specimen sizes from 100 mm to 750 mm. It can perform direct shear, simple shear, reciprocating shear, cyclic shear, rheology, and other tests. It is suitable for large‑scale testing of coarse soils, rockfill, soil‑structure interfaces, and geosynthetics. Selection should be based on maximum specimen size, required force, need for simple shear capability, and future upgrade requirements. The BTU-DDS-100 is the top‑level configuration for large‑scale engineering research; DDS-35F/45F are cost‑effective fully automatic direct shear systems; the FM series additionally provide simple shear capability.

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