Study On Water Retention Characteristics And Water Stability Of Modified Solidified Soil Under Wetting And Drying Cycles

In southwest China,there are a large number of red layer soft rocks which are difficult to be used directly for engineering construction.The red layer soft rock refers to the red layer soft soil containing the clay rock interlayer.many scholars at home and abroad of red layered soil characteristics and distribution range of doing the research,it is concluded that the red bed weak rock containing a certain amount of clay mineral,happen when exposed to water hydration,expansion and dispersion,contraction after dehydration,repeatedly to collapse and water stability performance is poor.Due to rainfall and drought in summer and the rainy season in south China,over and over again in the red bed weak rock slope with water after the disruption,a large number of soil,washed down the slope blocking drains,buried roads,affect the normal operation of highway.At the same time,it causes soil and water loss along the road,the ecological environment deteriorates,and the slope is receding and shuddering.If it is not dealt with promptly,the slope erosion will further develop,leading to the collapse and landslide of the slope.So red bed weak rock under the condition of natural strength to meet the project requirement,need artificial measures to cure of soil,the use of physical,chemical and biological measures to change the internal structure of the soil,so as to improve the performance of soil,increase soil strength and stability,and satisfies the requirement of engineering construction and ecological environment protection,etc.Therefore,in this article,through indoor test to find the best improved material,and test,the effect of the modified solidified soil and consideration of the soil under the condition of dry-wet circulation of improved water stability performance and water features.The specific contents and conclusions are as follows:(1)water stability test.Through indoor unconfined compressive strength and the disintegration of immersion test to determine the soil improvement effect,eliminated some unavailable specimen,and further by dry-wet cycle test,verify the dry-wet circulation of solidified soil resistance ability.By dry-wet cycle test to select the most suitable for the engineering application of specimen dosage,and then simulated conditions of slope surface runoff water stability test,verify with the specimens in the field of engineering practicability,and the optimal dosage.The properties of composite solidified soil are better than those of other two kinds of solidified soil.The composite solidified soil can reach the maximum strength of 80%after curing 7d,and the softening coefficient is above 95% after soaking.The strength of the mixture solidified soil with the optimal dosage in the curing agent 1% and the cement above 4% increased the maximum,and the strength loss rate was also relatively low after immersion,and the increase in the increase of the amount of mixing was not obvious.Composite cement solidified soil solidified soil contrast dry-wet circulation resistance stronger,can resist 15 times of the dry-wet cycle,less strength loss,part of the specimen with a small number of soil falls off phenomenon,related to the cement content,the higher the dosage of cement,dry-wet circulation resistance is poor.The optimum dosage of soil is good in simulated surface runoff influence test.At least the soil mass above 25 cm thickness should be processed.After curing,the surface sediment yield of soil is very small,and the effect of runoff has little effect on soil erosion.(2)water holding characteristics test.Filter paper method is used to determine soil water characteristic curve of soil,the determination of soil and solidified soil under routine conditions of soil water characteristic curve and the dry-wet circulation solidified soil under the condition of soil water characteristic curve,through the analysis of the curve and observation under dry-wet circulation is stabilized soil,the soil water-holding capacity attenuation,with matlab and origin software simulation analysis was carried out on the data.It can be seen from the soil water characteristic curve that the water holding capacity of the soil is improved after solidification,and the solidification effect is obvious.The soil water characteristic curve of solidified soil is also hysteretic,and the hysteretic curve is more obvious than plain soil.Under the influence of dry-wet circulation,the soil water characteristic curve of soil still lag,two kinds of humidity under the path curve both under what cycle times are far higher than that of soil water characteristic curve of soil.After 15 dry and wet cycles,the water holding characteristics changed,but the water stability remained stable,and the water holding characteristics of the soil were much better than that of the soil.With the increase of the number of dry and wet circulation,the hysteresis loop is shrinking,and the hysteresis phenomenon gradually weakens with the increase of the number of dry and wet cycles.This effect makes the soil water storage capacity worse and worse,but the more times the difference is not obvious,indicating that the soil in the back is more and more stable,which is not affected by this situation.The correlation coefficient of all soil water characteristic curve fitting is greater than 0.9990,which is close to 1.The results show that using VG model to fit the data of soil water characteristic curve is very good,and there is a good correlation between the experimental data and the model,and the fitting results are all in accordance with the requirements.