Study and Practice of Water Rock Physycal and Chemical Interaction in Redbeds Region
|School||Southwest Jiaotong University|
|Keywords||Special rock and soil Redbeds Water-rock interaction Engineering criterion Subgrade design|
The micro-middle engineering characteristics of water-rock physical and chemical interaction are researched for special engineering geological problems in redbeds region, such as embankment seepage, slope erosion, soluble salt corrosion, and so on. The methods of site geological survey, conventional tests, microscopic analysis, chemical analysis, physical simulation, chemical simulation, numerical simulation are used. The engineering criterion is established and new design principle is recommended about the water-rock physical and chemical interaction for redbeds subgrade project, firstly. The detail results as followed:(1)The engineering geological characteristics of redbeds are summarized on eight factors, including the distribution, stratigraphy, lithology, geological structure, attitude of rock formation, and structure of rock mass, geotechnical properties, engineering geological problems, which provides the basis for special geotechnical engineering study.(2)Based on the site investigation and analysis about thirty typical engineering examples, the engineering geological problems are concluded physical, chemical and mechanical effects.(3) It is proved that water-rock physical and chemical interaction is significantly through five hundreds and thirteen experiments. The physical effects engineering criterion is established, including the geotechnical parameters of the disintegration types, softening coefficient, cementation factor, the CBR softening coefficient, and free swelling rate. The chemical effects engineering criterion is established, including the geotechnical parameters of the PH, electrical conductivity and key components.(4) The real-time testing equipment for disintegration is design to test the disintegration rate and the disintegration discipline relation to time.(5) Through eighteen groups disintegration experiments for rough, like drying, dried-like and saturated redbeds mudstone samples, the different condition disintegration discipline and disintegration index are obtained.(6) Based on the California bearing ratio experiments about nine types roadbeds fills, the concept of California bearing ratio softening coefficient is suggested, the engineering criterion of roadbeds fills is established for fill water stability.(7) The percolation apparatus is design to test coarse fill horizontal and vertical permeability coefficient. The relation between horizontal and vertical permeability coefficient with compaction degree is obtained though the percolation apparatus.(8) Based on fifteen group physical and numerical simulation, the embankment seepage discipline is obtained with embankment geometry, compaction degree; fill type, head pressure, anisotropic permeability coefficient.(9) Through field investigation and field experiments, the basic characteristics of subgrade slope erosion are summarized and the method is advised to obtain the slope erosion depth.(10) Eighteen group immersion, chemical leaching tests are done, the law between alkaline redbeds geotechnical properties and the low salinity water, acidic water and carbonic water are obtained.(11) One hundred and forty eight group chemical tests are done, the redbeds geotechnical nature relation to PH, electrical conductivity and key components, are grasped.(12) Before and after decalcification free swelling comparison test, the change laws of swell and dispersion are obtained, while calcium carbonate content changes.(13)Based on five site investigation, the basic characteristics of soluble salt corrosion are summarized and the engineering measures are advised.