Xiaobing Lu

Numerical simulation on the marine landslide due to gas hydrate dissociation

Marine landslide due to gas hydrate dissociation is a kind of potential heavy hazards. Numerical simulation was processed to investigate the deformation, landslide and effects of main factors on the critical scale of dissociation zone to induce marine landslides during/after dissociation of gas hydrate. A simple method for analyzing the critical scale was presented based on the limit equilibrium method. It is shown that the maximum settlement is located near the upper side of the dissociation zone. The soil near the lower side of the dissociation zone uplifts. There is a critical scale of dissociation zone over which landslide will occur under given conditions. Expansion modes of the dissociation zone have obvious effects on the critical scale.

A dual percolation model for predicting the connectivity of fractured porous media

This paper presents a dual-percolation model coupling the percolation theory and the fracture percolation theory to study the conductivity of the fractured porous media. The Monte-Carlo method is used in the numerical simulation. First an appropriate computing scale by considering the calculation precision and elapsed time together is validated. Then, two parameters, A0 and D are presented in this model to determine the conductivity of the media. Generally the media can be blocked by itself in the condition of D > 2. However, the increase of pore connection and the randomness of fracture direction may release the selfblockage, increase the conductivity and make the dual porous media dissipated. A few long fractures can play a great role in the connection of media.

Numerical study on the stratum's responses due to natural gas hydrate dissociation

ABSTRACT Natural gas hydrate (NGH) dissociation can cause many kinds of potential hazards. Dimensional analysis is used first to obtain the controlling factors for NGH dissociation-induced stratums responses. And then the effects of the controlling factors on the deformation and stress distribution have then been numerically investigated. A simplified critical condition for judging the instability of gentle inclined stratum after NGH dissociation was proposed. It is shown that the maximum settlement is located near the upper part of the slide body while the soil uplifts near the lower part. The fast change of the stress and deformation is located at the interface between hydrate-bearing stratum (HBS) and over layer. The slope angle has the largest effects on the responses of the stratum. The effects of modulus and water depth on the stratums instability are small. There is a critical extension length of dissociation zone over which landslide will occur which is determined by the strength parameters, slope angle, friction coefficient and height of the over layer.