Design of a three-dimensional earth pressure device and its application in a tailings dam construction simulation experiment

The basic principle of the three-dimensional stress state test is deduced based on the relationship between the normal stress and the conventional stress state, and the relationship between the total stress state and the effective stress state is given based on Terzaghi’s effective stress principle. On this basis, we made a three-dimensional earth pressure device by using a pedestal obtained by 3D printing technology, 6 micro earth pressure cells, a pore pressure cell and an attitude sensor. Considering the effect on the tested values of the dynamic change in the normal stress direction, the conversion relationship between the absolute test direction and the relative test direction of the test device is deduced, which can be used to dynamically test the three-dimensional total stress state and three-dimensional effective stress state. In addition, a method to calculate the K0 value is proposed based on the earth pressure device comparing with the direct test result by the K0 oedometer and indirect test results by direct shear test and triaxial test in laboratory. Two three-dimensional earth pressure devices are used in a simulation experiment of tailings dam construction, and the results show that with the increase in pore pressure, the calculated errors of the three-dimensional stress state caused by rotation angles will be more noticeable. This study has engineering value for in situ geotechnical testing and soil strength prediction.