Study On Disintegration And Scourability Of Loess Improved By Fly Ash And Rodadyes

Loess is widely distributed in the northwest of China.Its water sensitivity characteristics has brought many problems of subgrade and slope engineering based on loess.Therefore,improvement measures are often necessary taken for loess.The flyash has poor effect for the improvement of water stability of loess,so it needs to be mixed with lime and cement.However,with the change of environmental protection requirements,it is urgent to find a replacement of lime.Roadyes is a new type of polymer material which is gradually popularized in Loess Area in recent years.It has the characteristics of green environmental engineering and is now in the stage of application research.Taking fly ash and roadyes as the research object,analyzing the water sensitivity characteristics of improved loess,which can provide theoretical basis for the popularization and application of roadyes in loess area.In order to explore the water sensitivity of improved loess,this study has carried out indoor physical mechanics tests and model tests,which mixed flyash and roadyes into Malan Loess in Weinan area.Based on the analysis of compaction characteristics,strength variation law,sensitivity index,disintegration characteristics and scour characteristics of the the optimal combination of different dosage and maintenance time is found,which provides a reference for the improvement of water sensitivity of loess.The main test results are as follows:(1)Using a light compaction test,it was found that the mixture of fly ash will reduce the maximum dry density and increase the optimal moisture content of the improved loess,while roadyes will increase the maximum dry density and decrease the optimal moisture content of the improved loess.The optimal combination level of the two curing agents at the maximum dry density of the sample is obtained.(2)The unconfined orthogonal test shows that the unconfined compressive strength of the Loess improved by roadyes has little change compared with that of the plain loess,and the strength of the improved soil mixed with fly ash has increased significantly.The best quality ratio of two curing agents has been confirmed?(3)The stability of the disintegrating water of the mixed improved soil is better than that of the plain loess and the single solidified agent improved soil.When the water stability of the mixed improved soil with fly ash and roadyes performs its best condition,the mixing amount is 15%and 0.05%respectively.Compared with the plain loess,the stability of the disintegrating water of the mixed improved soil with the best mixing amount is about 4 times higher.The disintegration test shows that the disintegration curve of plain loess and roadyes improved soil is linear,and the model parameter P can represent the corresponding disintegration rate.The disintegration curve of fly ash and mixed improved soil conforms to the exponential growth trend.The water stability index q is defined by the Logarithmic model,which can reflect the ability of improved soil to resist static water erosion.(4)The erosion test of plain loess slope and the improved loess slope with the most appropriate mixture degree was simulated manually.The influence of slope angle and slope water flow on the erosion characteristics of slope was studied.The relationship between the runoff intensity and the amount of soil particles in the runoff with time was analyzed,and the corresponding empirical model was established.It is found that the critical slope of the plain loess slope and the improved loess slope is 45°,and the anti erosion water stability of the improved loess slope is about 60%higher than that of the plain loess slope.