EVD Soil Dynamic Plate Load Light Drop weight Tester

I. Use of field (Soil Dynamic Plate Load)

DIN 18134

The dynamic plate load test employing the Light drop-weight tester is used in earthwork and road construction to determine the soil bearing capacity and the compaction or consolidation of soils and non-cohesive subbases, as well as for soil improvement applications.

II. Technical Specification

EVD Light Drop-weight tester Dynamic Plate Load Test Apparatus deflectometer tester

Principle

The momentary impact load generated by the drop hammer falling freely on the damping device from a certain height is transmitted to the bearing plate with a diameter of 300mm through the damping device and the force transmission system. The dynamic stress generated under the bearing plate (ie the test surface) makes the load The plate sinks s—that is, the amplitude of the vibration of the bearing plate, which is collected and recorded by the sinking tester. The larger the subsidence value s, the smaller the bearing capacity of the measured point; otherwise, the larger.

EVD Soil Dynamic Plate Load Light Drop weight Testerbadopts a drop hammer of a certain quality, which falls freely from a certain height, through the damping device and the bearing plate, it produces an instantaneous impact on the roadbed and causes the roadbed to sink. That is, a drop weight of a certain mass is used to freely fall from a certain height to simulate the impact of the dynamic load on the subgrade when the train is running. Under the same impact energy condition, test the vertical deformation value of the subgrade to calculate the dynamics of the subgrade. Deformation modulus Evd index. Theoretically speaking, the denser the subgrade compaction, the smaller the settlement value, the higher the dynamic deformation modulus Evd value of the subgrade; on the contrary, the lower the Evd value of the subgrade
Calculation formula

The dynamic deformation modulus Evd is the soil deformation modulus measured by a flat test with a certain magnitude and time load applied by the drop hammer impact. Usually the diameter of the load plate is 300mm, the hammer weight is 10kg, the maximum impact force is 7.0 kN, and the load pulse width is 18mm. The test records the settlement of the plate during the impact of the drop hammer. Under the assumption that the impact force is constant and the Poisson’s ratio μ=0.21, the dynamic deformation modulus is calculated from the formula of the circular local load on the elastic isotropic half-space body:
Evd = 0.79(1-μ2) dσ/S
= 1.5rσ/S = 22.5/s (MPa)
In the formula: r—the radius of the bearing plate, here is 150mm;
σ—the maximum dynamic stress of the roadbed;
S—The sinking value of the bearing plate (mm);
1.5—The influence coefficient of the shape of the bearing plate

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