Study On The Dynamic Characteristics And Law Of Water And Salt Migration In Chlorine Saline Soil

Qinghai is one of the main provinces with inland saline soil,which has a large amount of saline soil,covering almost all types of saline soils.There are distinct differences in engineering properties of different types of saline soil.At present,most studies on water-salt migration in saline soil still use trad itional capillary testers,which cannot satisfy the requirements of project practice well.Meanwhile the study of barriers has not formed a comprehensive system yet,which are mainly selected by experience without corresponding theoret ical guidance.The study on the dynamic characteristics of over-saline soil under different control conditions is little,the analysis of the failure causes under traffic loads has not formed a system.But natural saline soil is often used as roadbed filling,which will cause road diseases that affect the use u nder the influence of external changes of environment.Therefore,not only does the analysis of the influence factors on the water-salt migration law as well as dynamic peculiarities of saline soil through this research have certain importance for perfecting the research of saline soil,but also supply a theoretical guidance for engineering practice in similar areas.This article mainly relies on the National Highway 215 Sebei to Chaerhan section of the highway project,taking the natural chloride saline soil used in the project as the research object.Firstly,the capillary tester was used to carry out the water-salt migration test under different water content at room te mperature,and the problems and shortcomings of this method were found.Secondly,based on the principle of standpipe test,chloride saline is finished the water-salt migration tests under freeze-thaw cycles and normal temperature to gain the change curves of migration height with time under different working conditions,which to explore the law of water-salt migration under multiple test conditions and different working environment.Again,the dynamic stress-dynamic strain,dynamic shear modulus,dynamic damping ratio and other parameters of soil dynamics reflections of chloride saline soil under different test conditions are obtained by applying sinusoidal cyclic d ynamic loads under different working environment based on the GDS dynamic triax ial test system,which is used to discuss the law of the saline soil dynamic peculiarities of saline soil under traffic load.Finally,combining the results of the water-salt migration test and the dynamic triaxial test,factors impact on the stability of the roadbed is analyzed,and reasonable disposal measures are proposed.The main conclusions are as follows:(1)The saline soil in the Qarhan Salt Lake area is a perchlorinated saline soil,there is also a little amount of sulfate expect lots of chlorine salt as well.The type of saline soil is easily dissolved in water and has strong er cementing ability and hygroscopicity,the presence of a large amount of chl oride in the soil will make the soil insensitive to temperature changes,resulting in a si gnificant drop in the freezing point of the soil.(2)The traditional capillary tester has a small caliber,which leads to size effect of the model existed,it is difficult to control t he compaction extent to simulate different grades of roads.It is difficult to apply temperature to finish water and salt migration test under the condition of changing temperature.The test error is too large to meet the requirement precision.(3)Water-salt migration tests under normal temperature and freeze-thaw cycle conditions show that treatment of high-salinity groundwater and repeated freeze-thaw cycles can promote the migration of water,salt and ions in the soil.The higher groundwater level,the stronger migration of water and salt.The gravel barrier used in the research can effectively block the upward m igration of water and salt of the soil,achieving the expected e ffect.(4)Through carrying on the dynamic triaxial tests under different contro l conditions,founding that the dynamic stress increases with the increase of dynamic strain under different confining pressure,moisture content and fr equency,but dynamic shear modulus and dynamic damping ratio is contrary.This basis is to be used analyze the causes o f dynamic stress-dynamic strain curve,dynamic shear modulus and dynamic damping ratio under different factors.