Hydraulic Erosion Experimental Study On Grass Getting On 3D-Geomat Reinforced Slope Protection Under The Condition Of Rainfall

Soil erosion has already become a big problem to our country and the situation is more serious.In recent years,the economic of our country have a rapid development,the government increased investment in water conservancy、roads、and railways.Along with the excavation construction,appeared a lot of bare slopes,which under the action of its own gravity and rainstorm,easy to cause natural disasters threatening human life such as landslide and debris flow.Three-dimensional geonet mat grass slope protection as a new type of ecological slope protection type has been widely applied in engineering practice.But its stability which affected by factors such as rainfall and slope is still lack of in-depth research.This text taking advantage of the method included simulating rainfall experiment indoor and theory analysis,choosing several different slope and rainfall intensity,researches the influence of the characteristics of overland flow on the slope protected by 3D-geomat and grass jetting on it.Reveal the hydrodynamics characteristics, erosion characteristics and the law of flow and sediment reduction,and the research results can provide certain theoretical basis and technical support in engineering design, construction and maintenance.1. Slope flow velocity was evaluated by tracer method analyzing the correlation between the mean velocity of slope and the rainfall intensity> slope and flow path,the results show that the mean velocity of slope were significantly associated with rainfall intensity,slope and flow path.2. This article used the concept of flow Reynolds numbe to identifying overland flow type,the result show that overland flow was the turbulent flow (the upper part exists transition flow);The Froude number of overland flow in each section of on average are all greater than 1,showed the flow pattern of whole overland flow belongs to the category of the rapids.The relationship between drag coefficient and slope length show diminishing power function,drag coefficient has increasing trend with the slope increasing;The relationship between Reynolds number and the Froude number is power function, and the relationship between resistance coefficient and Reynolds number is power function, the Froude number and Resistance coefficient are related.3. Determining of runoff erosion and sediment content by pycnometer method:with the increase of rainfall intensity and slope.the slope surface sediment concentration was small.After a certain period of time.with the development of runoff,sediment concentration tended to increase,and then sediment concentration decreases gradually,finally turn to be stabilized. Cumulative erosion increases with the increase of rainfall intensity, and the rainfall erosion accounts was more than 60% of the whole test process in early 20 min of the testing.4. Under the protection of 3D-geomat and grass jetting on it,sediment concentration and cumulative erosion both far less than those in bare solpe comparison test,the infiltration of slope surface Increased by nearly 20%,and the mean sediment discharge reduce as much as 85%,showed that the function of 3D-geomat and grass jetting on it on reducing runoff and sediment is obviously.