| This paper analyses the similar requirements for the material used in this experiment. The requirements include the mechanical properties of demands and rational water quality. The mechanical property requirements include heavy and compressive strength requirement. The calculation is based on the similarity theory and the basic equation of elastic mechanics. Rational water quality requirements include permeability coefficient, water absorption and softening coefficient. The calculation is based on similarity theory and the basic differential equation of seepage flow mechanics, earth pressure theory, parameter definition itself, etc.After determining the requirement of similar material, we choose the similar material components. Considering the nature of the water-rock coupling similar material in water should be stable, we choose cement as main gelling material. Referring to other studies, we choose Vaseline and silicone oil as to regulate the water rationality of similar material qualitative material.In the experiments, this paper makes full use of the orthogonal experiment method to determine the main influence factors of the different characteristics. We find that weight requirement is mainly affected by the content of barite, strength is mainly affected by cement content, also affected by the content of vaseline in periods of low cement content. Permeability coefficient is affected by the cement content vaseline content and silicone oil content. Softening coefficient is mainly related to the cement content and silicone oil content.After determining the factors of the similar material mechanical properties and water quality, we do extensive experiments and data analyses to determine the fitting formula of each property affected by the content of raw materials. These formulas are: weight changes over barite content fitting formula, strength changes over the cement content and the vaseline content when the cement content is less than 4%, strength changes over the cement content and the vaseline content when the cement content is more than 5%, permeability coefficient changes over cement content vaseline content, silicone oil content and softening coefficient changes over the cement content and silicone oil content. The combination of the fitting formula according to the need, can guide the model test to determine the geological environment of underground coal mine in each layer of different raw material composition to meet the similar characteristics. |
