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A new research and development path to more accurately detect the resonant frequency of soil samples.

The resonant column is a commonly used instrument for measuring the dynamic characteristics of soil. The traditional resonant column is generally a Stokoe-type resonant column with a fixed bottom and a free top. When using a traditional resonant column to measure the dynamic characteristics of soil under a certain shear strain (excitation voltage), since the resonant frequency of the soil under this strain is unknown in advance, it is necessary to find the resonant frequency. By applying different excitation frequencies to the soil sample, the excitation frequency with the maximum amplitude is used as the resonant frequency of the soil under the shear strain. Then the soil sample can be measured with this resonant frequency. This process is referred to as "sweeping frequency". The resonant frequency under each shear strain needs to be obtained by sweeping the frequency, and each sweep will cause the soil sample to produce hundreds of pre-vibrations. When the measured shear strain is large, the hundreds of pre-vibrations during the sweeping process will have a significant impact on the properties of the soil, greatly increasing the shear modulus of the soil and reducing the damping ratio of the soil, resulting in inaccurate measurement values. The Energy Injected Virtual Mass (EIVM) resonant column does not require frequency sweeping. The system can quickly and automatically vibrate at the resonant frequency of the soil sample, which greatly reduces the impact of pre-vibration and makes the measurement more accurate.