Cyclic behavior of gravel–steel interface under varying rotational shear paths

Cyclic rotational behavior of a soil–structure interface is imperative for understanding the three-dimensional behavior; this requires testing the interface under systematically varying rotational shear paths. A series of cyclic tests were conducted on the gravel–steel interface along linear, elliptical, and circular shear paths by systematically varying the orthogonal amplitude shear displacement ratio. The resultant peak shear stress was observed to be independent of the shear direction and dependent on the shear path. The interface demonstrates a coupling response among the orthogonal shear directions during the rotational shear, which governs the three-dimensional shear mechanism. Owing to such coupling, during the cyclic shear, the unloading extent from the resultant peak loading state at different quarters of a shear cycle diminishes as the shear path changes toward a circle; this leads to the monotonous shear proceeding in a circular route with an insignificant change in the shear direction. Significant dilatancy is induced by rotational shear, which can be divided into irreversible and reversible components. The final compression of the irreversible dilatancy increases as the area under the rotational shear path increases. The reversible dilatancy diminishes as the shear path becomes a circle. The interface evenly demonstrates aeolotropy under the rotational shear condition.

Numerical Analysis on the Effects of Binary Interaction between Typhoons Tembin and Bolaven in 2012

The binary interaction is one of the most challenging factors to improve the forecast accuracy of multiple tropical cyclones (TCs) in close vicinity. The effect of binary interaction usually results in anomalous track and variable intensity of TCs. A typical interaction type, one-way influence mode, has been investigated by many studies which mainly focused on the anomalous track and record-breaking precipitation, such as typhoons Morakot and Goni. In this paper, a typical case of this type, typhoons Tembin and Bolaven, occurred in the western North Pacific in August 2012, was selected to study how one typhoon impacts the track and intensity of the other one. The vortex of Tembin or Bolaven and the monsoon circulation were removed by a TC bogus scheme and a low-pass Lanczos filter, respectively, to carry out the numerical experiments. The results show that the presence of monsoon made the binary interaction more complex by affecting the tracks and the translation speeds of the TCs. The influence of Bolaven on the track of Tembin was more significant than the influence of Tembin on the track of Bolaven, and the looping track of Tembin was also affected by the external surrounding circulation associated with Bolaven. The absence of Tembin was not conducive to the development of Bolaven due to stronger vertical wind shear condition and the less kinetic energy being transported to upper troposphere. Note that the above analysis demonstrates the interacting processes between TCs and sheds some light on the prediction of binary TCs.