Lele Liu
Key Laboratory of Gas Hydrate, Ministry of Land and Resources, Qingdao Institute of Marine Geology, Qingdao 266071, P. R. China.

Xiaobing Lu
Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, P. R. China.

Xuhui Zhang
Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, P. R. China.

Changling Liu
Key Laboratory of Gas Hydrate, Ministry of Land and Resources, Qingdao Institute of Marine Geology, Qingdao 266071, P. R. China.

Bin Du
Beijing J & C Geotechnical Construction Ltd., Beijing 100176, P. R. China.