I encounter this device from youtube.
The engineer drops a weight on the device to measure something. After they doing some earthmoving.
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https://en.wikipedia.org/wiki/Seismic_source – DKNguyen Jan 07 '22 at 14:58
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1Rather obviously, they are calibrating a Thumper before they set it up to attract a Sandworm – Carl Witthoft Jan 07 '22 at 17:46
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This looks like Light weight deflectometer used to determine the deflection capacity of the subgrade under the dynamic load. It is suitable for monitoring and testing the construction quality of railway, highway, airport, urban traffic, port, wharf and industrial and civil buildings under dynamic loads, especially in narrow areas, such as bridge (culvert) transition section and shoulder detection, existing line subgrade, etc.
The instrument can simulate the impact effect of high-speed train on subgrade, which can better reflect the actual stress of subgrade soil. It can quickly measure the dynamic deformation modulus Evd value.
figure: source zealchontesting
NMech
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This is a variation of Standard Penetration Test , falling deflectometer.
It is one of the most common methods in soil strength testing systems. This method is credited to Mohr and Terzaghi.
There are different rods and hammers and different ways of performing the test.
Some tests measure penetration ofter one the drop of mass.
Some tests measure how many drops, N, are needed to reach a certain depth of penetration.
The basic idea is the mass, m has dropped a height of H, to reach a speed of v.
$$v=\sqrt{2gH}$$
The kinetic energy of this mass moving with a speed of v is equal to the average force, F soil resists multiplied by the penetration depth, D.
$$\frac{1}{2}mv^2=F_{averge}D$$ This test after calibration can read the compaction of the soils.
kamran
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It is a lightweight falling weight deflectometer.
The falling weight deflectometer is used to measure the vertical deflection of the load plate response of a surface to an impulse load. the deflections is either correlated to pavement surface or used to determine characteristics of the materials used for the pavement foundation. It can quickly & precisely obtain the dynamic deformation modulus (Evd value) of soil and other construction materials.
The deflectometer is comprised of a loading mechanism, a loading plate, an electronic settlement measuring device.
r13
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