Experimental Study On Compression-seepage Coupling Characteristics Of Sandstone-mudstone Particle Mixture

This paper conducts the confined step loading compression consolidation-penetration coupled test based on GDS consolidometer on the common civil engineering material of sandstone-mudstone particle mixture of the upper reaches of the Yangtze River, Aimed at researching the deeper connection between the consolidation characteristic and permeability characteristics of sandstone-mudstone particle mixture. According to the results of experiments, this paper explores the effects of particle size distribution, particle content of mudstone and dry density of the sample for the consolidation and permeability characteristics of the sandstone-mudstone particle mixture, analyzes the experimental phenomena from the theoretical point, to some extent, explains the mechanism of the connection discussed above. Taking the alternate affection of compression and consolidation and permeation into account, under the conditions of interaction of two processes, the variable regular of compression characteristics and permeability characteristics was studied, The specific contents and conclusions are as follows:(1) Using the GDS oedometer, conducts the confined step loading consolidation-penetration coupled test under the conditions of different distribution of particle size, sand-mudstone mixture ratio, dry density of the sample for the saturated sandstone-mudstone particle mixture. The effectiveness of the experiment datas were insured by parallel tests. According to the datas of experiments, this paper explores the effects of the characteristic particle size, content of mudstone and dry density of the sample on the characteristics of the compressibility and permeability o f the sandstone-mudstone particle mixture.(2) Playing the advantage of the test system, and considering the interaction of compression and penetration process, this paper studied the form of permeability coefficient k of sandstone-mudstone particle mixture varying with the compression loading. Meanwhile, to probe the influence of penetration process for the compression characteristics of saturated sandstone-mudstone particle mixture, the deformation law under step loading of the samples with and without oriented percolation, which had the same consolidation time was had been compared.(3) Based on the regular of the rapidly decrease and then stabilized of permeability coefficient k with the step compression load, proposed the nonlinear model of percolation: lg[ei/(e0-e)]-lgk. Fitting the test results with nonlinear permeability model existed, include lge-lgkv, lg[kv(1+e)]-lge, lg(1+e)-lgkv、lg[ei/(e0-e)]-lgk.. The results prove that the model of lg [ei /(e0-e)]- lgk is in the best agreement with the experiment result.(4) Compared with the results of test with the Terzaghi one-dimensional consolidation theory, further understanding the mechanism.of compression deformation of sandstone-mudstone particle mixture has been gained.This paper completes the determination of the compression of sandstone-mudstone particle mixture and permeability parameters using the GDSCTS. Considering the inter action of soil compression and seepage process, explains the deformation of mixture an d the mechanism of permeability and also further deepens the understanding for the material of sand and shale.