Ge Zhang
Institute of Applied Physics and Computational Mathematics, Beijing 100088, P. R. China

Yudong Zhang
Institute of Applied Physics and Computational Mathematics, Beijing 100088, P. R. China

Aiguo Xu
Institute of Applied Physics and Computational Mathematics, Beijing 100088, P. R. China

Yingjun Li
State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083, P. R. China