IK Pile Load Test Equipment High Strain Pile Testing Machine

High Strain Pile Testing Equipment

Principles Of High Strain Testing:

The basic principle of high strain testing is to apply an impact force to the axial hysteresis of the pile top to generate sufficient penetration of the pile, and measure the response of pile particle stress and acceleration resulting from it. Through wave theory analysis, the detection method of vertical compressive bearing capacity and pile integrity of a single pile is determined.

The pile tip is impinged with a heavy hammer to generate enough relative displacement between the pile and soil, so as to fully stimulate the soil resistance around the pile and the supporting force of the pile end. From the direction of pile movement, there are downward movement and upward movement. It is customary to regard pile compression (whether internal force, stress or strain) as positive, and regard pile strain as negative; Think of downward motion (whether displacement, velocity, or acceleration) as positive and upward motion as negative. Due to the complex transmission and reflection of stress waves along the pile, it is necessary to divide the stress waves moving in the pile into ascending wave and descending wave. Because the downward wave travels in the same direction as the specified positive motion, the positive force (pressure) under the downward wave will produce positive motion, and the negative force (tension) will produce negative motion. The upward pressure wave (whose force sign is positive) causes the pile to move negatively, while the upward pull wave (whose force sign is negative) causes the pile to move positively.

Due to the downward propagation of the pressure wave generated by the hammer, a pressure wave will be generated at the side friction resistance of the pile or the sudden increase of the pile section. When the pressure returns to the top of the pile, the force at the top of the pile will increase and the speed will decrease. At the same time, the downward pressure wave will produce a tension echo where the pile section suddenly decreases or there is negative friction. When the tension wave returns to the top of the pile, the force value at the top of the pile decreases and the velocity increases. This basic concept can be used to judge the various conditions of pile according to the relationship between the measured force wave curve and velocity curve.

Technical Specification

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