Experimental Study On Evolution Rule Of Water Content Of Silty Clay Slope Under Rainfall Condition

Silty clay slope is widely distributed in China.In the process of excavation,rainfall often occurs.Rainfall infiltration increases the soil moisture content of the slope,and decreases the matric suction,and reduces the shear strength of the slope soil.it may cause the slope instability.At present,the temporary protection measures such as turf or geotextile are often used in the project.Therefore,evolution law of slope moisture content in different protection measures is not clear.It is important to study the evolution law of slope water content in different protection measures,which is of great guiding significance for taking reasonable engineering protection measures.The silty clay slope is taken as the object of study in this paper.Indoor rainfall experiments were carried out on excavated bare slope,turf slope and geotextile slope model by using the self-made artificial rainfall simulation device.It can reveal the evolution law of slope soil moisture content in different protection measures,and provide technical support to take reasonable protective measures for slope engineering during construction.The main research contents and conclusions are as follows:(1)Experimental study on evolution law of moisture content in excavated bare slope under the condition of rainfall.The design and manufacture process of slope model is introduced.On condition that the rainfall intensity was 27mm/h,and the rainfall duration was 2h and 6h respectively by the physical model test,Studying on the evolution law of water content in excavated bare slope:when the rainfall begins,the soil moisture content of the slope surface changes most.In addition to the two measuring points inside,the change of water content of each measured points all conforms to the characteristics of rapid increase and then slow decline;the vertical direction of the slope:the more close to the top position of slope,the rain infiltration was more sensitive,and ith the increase of the vertical depth,the peak value of soil moisture content is much lower;the direction of parallel slope:the peak of moisture content in each measuring point has different degree of influence by rainfall,it decreases gradually along the slope.Rainwater is difficult to seep into the slope during the whole rainfall process.The data of each measuring point showed that the rainfall infiltration of slope has certain hysteresis.(2)Experimental study on evolution law of moisture content of turf slope under the condition of rainfall.The design and manufacture process of turf slope model is introduced.Based on the indoor model test,the evolution law of water content of it under the same rainfall condition was studied.The test found:when the rain started,the first to be affected is the surface soil of turf slope,and with the increase of the depth,it decreased;the maximum of the moisture content increase of the measuring point is in turn:slope surface?top of slope and slope interior;in addition to the internal measurement points,the shape of time varied curve is consistent,showing the change regulation of a wavy pattern,that is,firstly rapid increase and then slow down.Compared with the test results of bare slope,it was found that the rainfall infiltration rate is fast,and the moisture content of the slope decreases slowly after the rain stops.As rain falls and in the day after rain,the moisture content of each measuring point of the whole slope is maintained at a high level,which is unfavorable to the stability of the slope.(3)Experimental study on evolution law of moisture content of geotextile slope under the condition of rainfall.The design and manufacture process of geotextile slope model is introduced.Under the same rainfall conditions,we will imitate the rainfall infiltration process of geotextile slope by artificial rainfall device,so as to explore the change regulation of moisture content of geotextile slope in the rainfall conditions:in the whole process of the rainfall experiment,the water content changed obviously only at the foot of slope,having the characteristics of steep rise and fall.The change of moisture content of the measuring points in other locations is very small or unchanged.The location of each geotextile slope can not reach saturation.Compared with the bare slope,experimental results show that the geotextile has better anti-seepage effect and it is good for slope stability.It can be used as the first choice of protection measures in slope construction.