Modelling the mechanical response of gas hydrate bearing sediments has become a crucial issue in the environmental field. The scarcity of experimental data due to the instability of the gas hydrates makes it difficult to develop accurate mechanical constitutive models. This paper suggests a numerical homogenisation method to simulate the response of composite materials like gas hydrate bearing soils. The homogenisation technique is based on Fast Fourier Transforms and thus can be used with real images of soils. This method is applied here to both granular and fine soils for various volume fractions and types of gas hydrate inclusions.