Study On Soil-water Characteristic Curve And Wetting Characteristics Of Red Clay

Red clay, widely distributing in the western part of China, is classified as poor soil due to its undesirable physical mechanics and poor water-physical property. With the fast development of infrastructure in the western area, how to utilize red clay as the subgrade bearing layer, roadbed stuffing and so on has been major problems since red clay is commonly seen in those construction regions. This essay will do researches of red clay in the southeastern area of Gui Zhou province upon its soil-water characteristics and wetting characteristics based on experiments and theories.By investigating field work, researching relevant references, collecting existing geological materials and analyzing the hydrogeological and poor engineering geological phenomenon in detail and getting samples using cutting rings and spade, also with a series of experiments including the screen grade testing, liqui d- plastic limits test and compaction test, the particle size distribution, plastic limit, liquid limit, the best moisture content and maximum dry density and other physical parameters of red clay were determined. Combined with the determination of the sc reening test and plastic-liquid limit test results, the red clay in the southeastern area of Gui Zhou province is defined as inactive clay.The focus of this essay is the effect that dry-wet cycle acts on red clay’s properties,and there are obvious volume change during the process. Experiments were done on the samples with the dry-wet cycle and got the contraction curve under different tomes of cycles. Three phases linear volume change phase, volume change slowing down phase and steady dehumidifying phase are discovered. Fitted equation is raised based on Peng X contraction curvilinear model and the experimental data to make related experiments, researches and constructions convenient.Adopting revised filter paper to discuss the impacts that degree of compaction, methods of controlling moisture content and dry-wet cycle act on soil-water characteristic line, found that with the increase of compaction degree, the matric suction of soil at the same moisture rate increase too, and the soil-water characteristics curvilinear of dehumidifying route is above that of the moistening path which shows obvious hysteresis quality; but with the increase of times of dry-wet cycle, the effects of those factors on soil-water characteristics curvilinear is weakened. Comparing the imitative effects of Fredlund Xing model with that of Van Genuchten model on soil-water characteristics curvilinear, results show that Fredlund Xing model is more in line with the fitting of data from filter-paper methods.And applying on Fredlund Xing’s mathematical model to relatively match the soil-water characteristics of moisture percentage per volume and per weight,and to match related parameter and linear regression, then to provide reference to real construction design.Revised weighing methods is adopted to do experiment on red clay,and the feasibility of this method is validated. Discuss the influences of original moisture percentage, degree of compaction, moisture line, and times of dry-wet cycle on red clay’s slaking property is discussed. The experiment demonstrates that increasing original moisture percentage and the degree of compaction can restrain red clay’s slaking,and the minimum slaking amount happens at the place with the highest moisture percentage. In the dry-wet cycle, soil samples which humidifying experienced first slakes faster than those which experienced dehumidifying phase first and with the times of dry-wet cycle increases, soil’s fracture development is obvious, which makes the red clay’s slaking degree also increase.