Electro hydraulic rock direct shear tester

HTZJ-1BElectro hydraulic rock direct shear tester

1、 Product Introduction:

The rock direct shear strength test adopts the flat push method, which is suitable for direct shear tests of rock blocks, structural planes, and contact surfaces between concrete and rock. Adopting a new type of electric hydraulic oil pump for pressurization, with fast rise rate and reduced labor force, according to national industry standards（Developed in accordance with the provisions of SLT264-2020 "Rock Testing Code for Water Resources and Hydropower Engineering" and JTG E41-2005 "Rock Testing Code for Highway Engineering".

2、 Technical parameters and indicators:

1. Cylinder stroke:200mmDiameter of oil cylinder piston:125Millimeter

*High output power：50T(Vertical jack) (Horizontal jack)

2. Oil pump flow rate:0.9LPressure range:1-60MPA

3. Trial mold size:F150×150 F50×100

4. Range of dial gauge:0-10mmquantity4a

5. Magnetic meter base:4a

3、 The preparation of test specimens shall comply with the following regulations:

1. During the process of taking, transporting, and preparing the test piece, measures should be taken to prevent disturbance and water loss.

2. The diameter or side length of rock direct shear specimens should not be less than50mmThe height of the specimen should be greater than the diameter or side length.

3. According to the needs, the specimen can be in a natural water containing state or a saturated state.

4. Each group of specimens in the same moisture state should not be less than5One.

4、 The experimental installation shall comply with the following regulations:

1. Place the specimen in the shear box of the direct shear tester, and fill the gap between the specimen and the inner wall of the shear box with filler, so that the specimen and the shear box become a whole. The shear direction of the specimen installation should be consistent with the stress direction of the engineering rock mass, and the predetermined shear plane should be located in the middle of the shear joint.

2. The action of normal load and shear load should pass through the geometric center of the predetermined shear plane. Both normal and tangential displacement gauges should not be less than2Support should be symmetrically arranged.

3. The width of the reserved shear joint should be equal to the length of the specimen in the shear direction5%Or the thickness of the filling material for the structural surface.

5、 The application of normal load shall comply with the following regulations:

1. The maximum value of normal load * should be the engineering pressure1.2Twice. For specimens containing weak fillers in structural planes, the maximum normal load should be limited to not extruding the fillers.

2. The normal load applied to each specimen should be applied in equal steps, and the number of steps should not be less than5Grade.

3. For specimens that do not require consolidation, the normal load can be applied in one go and the normal displacement can be immediately measured,5minAfter reading once, the shear load can be applied.

4. For specimens that require consolidation, within one hour after the normal load is applied, every15minRead once, then every30minRead once. When the normal displacement per hour does not exceed0.05mmAt this time, shear load can be applied.

5. The normal load should remain constant throughout the experimental process.

6、 The application of shear load shall comply with the following regulations:

1. According to the estimated maximum shear load10-12After each level of load is applied, immediately measure the shear displacement and normal displacement,5minAfter reading once, the next level of shear load can be applied. When the shear displacement increases significantly, the level difference can be appropriately reduced. The shear load applied before the peak should not be less than10Grade.

2. After shear failure, the shear load and normal load are respectively reduced to zero. After resetting the test piece, adjust the gauge according to this article1Conduct friction tests under the same normal load.

7、 The shear failure standard shall comply with one of the following provisions:

1. The increment of shear displacement significantly increases, and under shear stressႠShear displacementｕThere is a significant abrupt change on the S-relationship curve.

2. The total shear displacement reaches the edge length of the specimen10%.

8、 The description of the shear surface after shear failure should include the following:

1. Shear surface damage, scratch distribution, direction, and length.

2. Shear surface undulation and variation curve along the shear direction.

3. When there is filling material in the structural plane, the precise position of the shear plane, the composition, properties, thickness, and water content of the filling material should be described. Take representative samples as needed to determine the physical properties and clay mineral composition of the filling material.

9、 The organization of experimental results should comply with the following regulations:

1. Normal stress and shear stress should follow the formula（5.5.10-1) and Equation (5.5.10-2) calculation:

a= （5.5.10-1）

Ⴀ = （5.5.10-2）

Where: a-Normal stress,MPa；

Ⴀ-Shear stress,MPa；

P-Normal load,N；

Q-Shear load,N；

A-Shear area,mm².

2. Draw shear stress ႠShear displacementｕS and shear stress ႠCompared to normal displacementｕThe relationship curve of n determines the shear stress values of characteristic points in each shear stage.

3. Based on the shear stress and normal stress values of characteristic points in each cutting stage, plot the points onto a coordinate graph and use the least squares method or graphical fitting to fit the shear stress Ⴀandnormal stress aRelationship curve and determine the corresponding shear strength parameters.

HTZJ-1BElectro hydraulic rock direct shear tester