Study On Macro - Microcosmic Characteristics Of Red Soil Under Different PH Values

Based on the comprehensive analysis on the harm of soil pollution, macroscopic property research of soil pollution, the soil microstructure research, pollution of soil corrosion mechanism. Clear of the current problems existing in the research of contaminated soil, in view of the Yunnan laterite, selection of hydrochloric acid and sodium hydroxide to adjust the pH of the solution, to conduct research on the effects of pH change on Yunnan laterite properties. Research mainly includes the compaction characteristics of lateritr, direct shear, compression characteristic, microstructure, and effect mechanism for effective prevention and control of water environmental safety and provide theoretical basis to the safety of infrastructure project.Macro and micro characteristics of compacted laterite showes:if infiltration time is a fixed value, with the increase of pH value, the maximum dry density of laterite there is a maximum and a minimum, the optimal moisture content decreases. If pH value is a fixed value, there are two maximum and a minimum values in laterite’s maximum dry density a, there are a maximum and two minimum values in optimal moisture content with infiltration time prolonging. Along with the increase of pH value, from acidic to alkaline process, the compaction of laterite microstructure image shows the characteristics of density variation, microstructure parameters of the corresponding porosity increases, the number of particles decrease, the particle size distribution fractal dimension there is a great value, the grain orientation degree reduced.Macro and micro characteristics of direct shear laterite show:if infiltration time is a fixed value, with the increase of pH value, the shearing strength, cohesion, internal friction Angle of laterite there is a great value. If pH value is a fixed value, with the extension of curing time, the laterite in the shear strength and cohesion, internal friction angle are diminishing. Acidic or alkaline conditions, cutting laterite microstructure images showed deterioration shear characteristics, micro-structural parameters corresponding porosity increases, the number of particles is reduced, particle size distribution and particle orientation of the fractal dimension decreases. With the extension of curing time, the micro-pore structure of clay increases, reducing the number of particles, particle size distribution and particle orientation of the fractal dimension decreases.Macro and micro characteristics of compressed laterite showes:if infiltration time is a fixed value, under acid condition, the laterite is not easy to be compressed; the alkaline concentration is low, laterite is not easy to compress, alkaline concentration is high, laterite is easy to compress. If pH value is a fixed value, with the extension of curing time, the laterite became easy to compress. With the pH value increases, from acidic to alkaline process, the micro-structure of the compressed image compression laterite exhibit enhanced features, the corresponding micro-structural parameters of porosity increases, the number of particles is reduced, reducing the particle size distribution-dimensional points, orientation of particles decreases. With the extension of curing time, the micro-pore structure of laterite increases, reducing the number of particles, particle distribution and orientation of the fractal dimension decreases.PH change on the compaction characteristics, the shear properties andcompression feature of laterite, effect from infiltration and different pH values between laterite, erosion, hydrolysis cementation, dissolution explained. The corresponding microstructure characteristics and chemical composition has been changed.