Discrete element simulation analysis of damage and failure of hydrate-bearing sediments

Abstract

It is of great significance to study the mechanical properties of hydrate-bearing sediments for safe exploration. To date, the majority of the related research has focused on the analysis of conventional mechanical parameters of hydrate-bearing sediments, while research on the failure modes and damage process is very limited. In this work, simulation models that consider the hydrate saturation (SH) and hydrate distribution heterogeneity, were generated by using the discrete element method, following which the triaxial undrained shear of these models were simulated. The results show that hydrate-bearing sediments have the damage and failure characteristics of brittle rocks, the higher saturation and the lower distribution heterogeneity, the more obvious characteristic is. In addition, the existence of hydrate significantly changes the failure mode of sediments. With the increase of saturation and the uniformity of hydrate distribution, the distribution of microcracks changes from disorder to order, and finally connects to form a main failure surface with an angle of 45° to the loading direction. What's more, taking crack initiation stress and damage stress as characteristic parameters to describe the progressive failure process of hydrate-bearing sediments has good feasibility.