Rainfall Test And It's Infiltration Rule Evaluation Of Binary Stratigraphic Slope In Longdong

As a national strategic reserve of oil and gas field,its development cannot do without a large number of stations,pipelines and industrial construction projects.However,due to the local land requisition coordination problems leading that most of the land expropriation in the oil area is on the slope,resulting in existence of a large number of natural slope and the slope formed by excavation or filling in the oil area.Rainfall induced landslides has become one of the serious many factors of oil and gas stations,pipelines and industrial production construction and operation safety.In this paper,a typical binary stratigraphic slope in Longdong area is selected as the research object.By using the self-designed "sweep-spray" precipitation simulation system,three large-scale field rainfall experiments are designed and conducted under different rainfall conditions.Slope water content,matric suction and slope erosion are monitored.Slope erosion characteristics are further analyzed.Geo-studio finite element software SEEP/W module is used to carry out numerical calculation.The changes of seepage field under rainfall infiltration and different rainfall intensity are studied.The curve of rainfall infiltration depth with time in Longdong area is obtained,which will be helpful to the practical engineering application.The main conclusions are as follows:1.Aiming at the shortages of artificial rainfall device in the current slope rainfall test,a"sweep-spray" artificial rainfall device is proposed,which achieves the rainfall requirement by controlling the duration of rainfall.The rainfall time can be extended as far as possible in the mode of rainfall operation,which can more effectively approximate the rainfall intensity and rainfall that simulate actual light rain,moderate rain,heavy rain and rainstorm.2.The law of slope erosion on the binary stratigraphic slope is obviously different from that of the homogeneous slope.The phenomenon of slope erosion on the upper soil is more obvious than the lower soil,which is related to the permeability and strength of the two kinds of soils.Because of the big permeability,the fast water infiltration,the small soil strength and the less soil particle migration energy of the upper soil,as the upper soil slorpe erosion phenomenon is obvious.The permeability coefficient of the lower soil is relatively small,the water infiltration is slow,the response time of the volume water content is long,and the water infiltration in the lower layer is obviously lagged.3.The infiltration of binary stratigraphic slope shows a certain rule,the infiltration speed of slope shoulder is the fastest,the slope is the second,and the slope foot is the slowest.The response time of the volumetric water content of the lower soil is obviously lagging behind that of the upper soil.The appearance of the phenomenon is closely related to the property of the lower soil.The lower soil has smaller permeability coefficient,lower water infiltration and longer response time to volumetric water content,which is obviously different from that of homogeneous soil slope.4.In the numerical results,under different conditions,the variation law of the volumetric water content at each measuring point in the slope is basically the same as the variation law of the volumetric water content at each measuring point in the field test.