Bidirectional variation mechanical property testing instrument for contact surface between earth and structure

The invention discloses a testing instrument and a testing method for the dynamic property of a contact surface between an earth body and a structure under the effect of bidirectional vibration shear. The testing instrument structurally and mainly comprises a model bottom plate Y-direction stress loader, an X-direction stress loader, an X-direction displacement sensor, a Y-direction displacement sensor, a Z-direction stress loader, a Z-direction displacement sensor, a Z-direction pressure plate, square stacking rings and an earth containing box. The testing method comprises the steps such as installation of testing materials, installation of horizontal displacement and vertical displacement sensors, vertical stress loading and horizontal dynamic stress loading. The testing instrument and the testing method have the advantages that the structure is simple, the power transmission is reliable, the power loads which are randomly combined in the horizontal direction can be applied, the dynamic displacement of the earth body in the horizontal direction can be conveniently measured and the measurement accuracy is high.