NKYS-500 Portable Rock Direct Shear Machine

Technical Specifications

Test Methods

Rock Deformation Test (including compressive strength test)

· Sample: Φ50 mm or 50×50 mm square prism; height 100–112 mm.

· Install the sample between two bearing plates; align axes and gently apply force.

· Use a dial indicator mounted on the compression fixture to measure axial deformation.

· Use vertical jack for loading.

· The test ends when the specimen cracks or reaches failure.

Point Load Strength Test

· Sample: small-sized irregular sample with approximately parallel surfaces (40–60 mm in size).

· Install sample on the point load fixture; adjust upper cone tip using handle to ensure both ends contact the sample surface.

· Apply vertical load via hand pump until sample breaks.

· Record peak load value.

· The point load strength is calculated as:

· Is = P / De²

· Where:

· Is – point load strength (MPa),

· P – failure load (N),

· De – equivalent diameter of the rock specimen (mm), calculated as:

· De = √(4A/π)

· (A – minimum cross-sectional area of sample, mm²)

Direct Shear Test for Intact Rock

· Sample: Ø50, 56, 71.5, 90 mm cylinder or 50×50 mm square prism.

· Split the sample into two and place in the direct shear box.

· Apply vertical load with vertical jack to simulate normal stress.

· Then apply horizontal load with horizontal jack to shear the sample.

· Record shear force corresponding to failure.

Direct Shear Test on Structural Planes and Weak Rock

· Sample: irregular rock block with natural structural plane or artificial joint surface.

· Place in large direct shear box.

· Apply vertical force first, then shear horizontally until failure.

· Record peak shear load.

Tensile Strength Test

· Sample: Ø50–56 mm; height: 50–56 mm.

· Place sample flat between semi-circular jaws of the splitting fixture.

· Apply vertical load until sample splits.

· Calculate tensile strength using:

· σt = 2P / (πDL)

· Where:

· σt – tensile strength (MPa),

· P – failure load (N),

· D – diameter (mm),

· L – height (mm)

Soil Direct Shear Test

· Sample: Ø90 mm core sample or undisturbed soil trimmed to fit the fixture.

· Install in the direct shear box; place porous plates and load plate.

· Apply vertical force for normal stress.

· Apply horizontal shear load.

· Use two dial indicators to measure horizontal displacement and vertical deformation.

· Record shear force at failure.

Direct Shear Test on Gravelly Soil

· Sample: natural or remolded gravelly soil (gravel ≤ 2.0 cm).

· Install into large shear box (160×140×160 mm; V = 35 cm³).

· Same procedure as 4.6, but for coarser soils.

· Suitable for field conditions with high gravel content.

Configuration List