Laboratory Study On The Influence Of Root System On Properties Of Expansive Soil Under Acid Rain

Slope Vegetation solid soil erosion prevention destabilization often depends on the slope of the slope in the vegetation root strength,disintegration property and permeability coefficient of the amplitude increase,in the special expansive soil,it is also necessary to observe the improvement range of the expansive properties.As one of the acid rain problem facing today’s environment,and the coverage and harm are increasing;vegetation protection is an important measure for the treatment of expansive soil slopes;In recent years,vetiver has entered the field of vegetation slope protection research as an excellent slope protection plant.It is generally believed that the planting of vetiver can be the key research in the protection project of the difficult to control expansive soil.Vegetation protection can not only stabilize the soil moisture and temperature,vegetation root reinforcement can also increase the shear strength and permeability of the soil,reducing the swelling characteristics of the expansive soil,and increase the slope resistance against sliding,play the role of soil consolidation and slip resistance,thereby improving the stability of expansive soil slopes.This article is based on the existing research results and research conditions,the main acid rain conditions vetiver roots Reinforced soil basic pH ysical properties of the expansion,the anti-expansion characteristics and disintegration property and experimental Study of micro-structural characterization by XRD diffractometer expansive soil for impact,the following conclusions:(1)Comparing the liquid limit plasticity limit value in acidic environment with the liquid limit plasticity limit value in neutral environment for experimental research,concluding as follow:Liquid Limit Interval at pH 3～7 with pH increase exhibits "S" type tends to increase;The plastic limit changes between the two ends of the acidic environment pH=3～7,the law of change is small at both ends,big in the middle;The plasticity index in the acidic environment increases in direct proportion to the pH value in the range of pH=3～7.(2)Through the test of the unloaded swelling rate of the reinforced root～soil complex of vetiver fibrous root system under acidic environment,it is found that:The unloaded swelling rate of composite expansive soil reinforced with different plant roots is less than that of plain soil,and there is an optimal root content;The unloaded swelling rate of the root～soil composite sample under the acidic environment increases with the decrease of the pH 值 value of the acidic environment;The order of the influence intensity of root parameters on unloaded expansion rate is root number>length>distribution>diameter.(3)Through the test of the disintegration characteristics of the reinforced root～soil complex of the vetiver root system in an acidic environment,it is found that the increase of acid rain concentration has a promoting effect on the disintegration ability;root diameter,root length,root coefficient amount and root distribution method have a corresponding increase in the ability to resist collapse,length has the most significant effect,factors affecting the strength of the order of a length>the PH 值 value>Distribution>the number>diameter.(4)For the same conditions and the same age,the minerals of expansive soil in acidic environment will not change much,Only the diffraction peak of the peak size will have an impact,thus causing the amount of substance to decrease;For the expansive soil under acidic conditions,The decrease in the occurrence of cementitious substances will affect its microstructure and the overall trend will decline,and with the strengthening of the acidic environment,trends fortified.