Expansive soil has been studied for eighty decades because it is prone to cause geotechnical engineering accidents. The results of the moisture content effects on the expansive pressure were not consistent in the literatures. In this paper, swelling deformation and pressure tests were conducted to clarify the effects of the initial water content on the swelling properties. The relation of expansive stress and initial moisture content was accurately described with a Gaussian distribution, unlike in the previously published studies. These results could be explained by the change in the microstructure with diverse moisture contents. In addition, dry density and vertical stress influences on expansive properties were analysed. With an increase in the vertical loading, the soil samples first expanded, and then the samples with a lower dry density collapsed; however, the samples with a higher dry density did not collapse, even under a considerable vertical loading. Furthermore, the relation between stress path and expansive pressure was examined. It was observed that the swelling pressures obtained from the constant volume tests were greater than the results from the swell under load tests. The relationship between the swelling pressure and swelling strain was also analysed.

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To investigate the seismic response of large-scale tunnel in compacted clay and effect of shock absorbing layer to the tunnel, a series of three dimensional (3D) shaking table model tests were carried out. The similarity ratio of the model is 1 : 8 and the size of the model container is 9.3 m (length) × 3.7 m (width) × 2.5 m (height). The cross-sectional diameter of the model tunnel is 0.9 m, and the thickness of the tunnel lining is 0.06 m. To simulate the clay soil surrounding condition, the container was filled with clay soil. During the tests, the concrete strain, acceleration, and dynamic soil pressure on the surface of the model tunnel were measured. The results show the existence of tunnel can decrease the maximum acceleration of the model in the X direction; the shock absorbing layer can further decrease the maximum acceleration, however, cannot change the dominant frequency of the ground motion. The longitudinal and hoop strain of the model tunnel with excitation of the input motion is mainly in tension state and the maximum hoop deformation of the model tunnel is located at the conjugate 45°. In addition, the shock absorbing layer has an effect on the strain and dynamic earth pressure of the model tunnel.

The brushless doubly fed machine is a new type of variable-speed, constant-frequency AC generator. In this paper, we combine the winding type rotor with a reluctance rotor and propose a new type of magnetoresistive effect of the wound rotor type. First, the three-dimensional finite element model is established using finite element analysis software, and the structure and principle of the model are introduced; second, based on the principle of sine winding, a new type of winding with a higher fundamental winding coefficient and a lower harmonic content is proposed, and its magnetic motive force is analyzed; third, a related analysis of its performance is conducted using finite element analysis software; fourth, based on the special characteristics of the rotor, the influence of the relative positions of the inner salient pole axis and the winding axis on the performance of the new type of brushless doubly fed motor is investigated; fifth, the ripple torque at different locations is analyzed; and finally, the correctness of the simulation is verified by experiments on a prototype.

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