Shear pressure cylinder

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A shear pressure cylinder is a mobile shear device for investigating the shear strength of soils and loose materials at the point of sampling. The cohesion and the friction angle of the material samples are determined with the shear pressure cylinder .

Such studies of soil samples are also carried out in laboratories with a frame shear device or triaxial device . However, these have the disadvantage that the sample to be measured first has to be transported to the laboratory. The history of the sample can be changed by transport influences ( vibration ). A sample modified in this way is no longer representative.

With the shear pressure cylinder according to Wagner, on-site and laboratory tests are possible. Comparative measurements with a frame shear device have shown this.

Working method

The shear pressure cylinder consists of the 4 main assemblies: base plate with clamping elements, cutter cylinder with soil sample , pneumatic system and rotating wing body with torque wrench .

The determination of the soil pressure-dependent shear strength takes place in this shear device in a cutter cylinder, which is filled with the soil sample and mounted on the base plate. The soil pressure is generated with the help of a pneumatic system that compresses the soil sample using a compression piston with the desired normal stress . After the selected compression duration, the soil sample in the cutter cylinder is sheared off with the rotary vane probe with the normal tension set and the shear tension that occurs is measured. The parameters friction angle and cohesion c for the maximum shear strength and residual shear strength are calculated from the shear stresses at different ground pressures.

The shear pressure cylinder is designed for an artificial ground pressure of 10N / cm2 to 70N / cm2 or 70t / m2. The maximum recordable shear stresses are 80N / cm2 or 80t / m2. With this large measuring range, all stress states that occur in practice can be simulated and the soil mechanical strength examined.

With the investigation of undisturbed and disturbed soil samples of the clay, silt and sand fraction, this system covers a wide range of applications. Both the soil pressure-dependent shear strength and the storage density are determined in one operation. Artificial compression of the sample in the cutter ( Proctor density ) can also determine the influence of the storage density on the shear strength on site.

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