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目前对土坝或地基进行动力反应分析时所需土的动模量E_d及阻尼比λ参数,有的是通过现场由波速法测定;有的是在室内通过试样测定。当测定是在室内进行时,对应变范围较大情况下的E_d和λ,一般都是通过振动三轴仪或振动单剪仪对土样进行往复加荷,测定其在不同激振频率与固结应力状态下的应力、应变波形曲线,然后从该波形中取出某一周的应力、应变波形,绘出该周期的应力-应变滞回圈,如图1。从而计算出动模量E_d=(AB)/(OB),阻尼
At present, the dynamic modulus E d and the damping ratio λ parameter of soil required for dynamic response analysis of earth dams or foundations are measured by the wave velocity method in the field; some are determined by the samples in the room. When the measurement is performed indoors, the E_d and λ in the case of a large variation range are generally determined by oscillating triaxial apparatus or vibration single shear apparatus to reciprocate the soil sample and measuring the excitation frequency at different excitation frequencies. The stress and strain waveforms under the stress state, and then take out the stress and strain waveforms of a certain week from the waveform, and draw the stress-strain hysteresis loop of this period, as shown in Fig.1. In this way, the dynamic modulus E_d=(AB)/(OB) is calculated.