Principle and engineering application of geomechanics magnetic model test

Geomechanics magnetic model test is inspired by the idea of centrifugal model test, in which the centrifuge force field is used to simulate the gravity field. In uniform gradient magnetic field, material containing ferromagnet is subject to uniform magnetic force. Therefore, gravity can also be simulated by magnetic force. According to the basic principle of electromagnetism, a uniform gradient magnetic field generator is designed and manufactured. There are 2 000-turn coils in the solenoid, whose current ranges from 0 A to 16 A. The magnetic force of ferromagnetic material in the model can be increased 10 to 30 times of the gravity. A geomechanics magnetic model test is carried out using the high slope at left bank of Jinping-I hydropower station as an example. Results of the test are compared with numerical simulation results, which shows that the body force of the model can be increased to the multiple required by the similar ratio under a certain current value. Results of the physical model test are consistent with results of numerical simulation. In addition, if the current continues to rise, the overload process can be simulated, and thus the factor of safety under overload condition can be determined.