The Deposition Slope And The Peak Clipping Effect Of The Debris Flow After The Sediment Control Dam Experimental Study

Debris flow refers to the torrent carrying a large number of sediment and stones,which is caused by the heavy rain,heavy snow,or landslides because of other natural disasters in mountain areas or other valleys of deep valleys,terrain in steep areas.Debris flow is a disastrous geological phenomenon,and usually outbreak suddenly,ferocious,carrying huge stones,with a strong energy,and thus very destructive.Thus it is very important for the prevention and control of debris flow.Sediment control dam is one of the most important and effective engineering structures for the prevention and control of debris flow built on the debris-flow area of a transverse bed of artificial structures.An important parameter of the sediment control dam is the capacity,and the deposition slope of the debris flow after the sediment control dam is is a very important parameter in the design of the sediment control dam.At present,the research on siltation gradient of debris flow mainly focuses on the experience of small watershed,and the calculation method is chaotic,the calculation results are relatively large.The sediment control dam has the function of reducing the peak of debris flow and the sediment control dam body to intercept the coarse particles in the debris flow.Flood peak flow is one of the most important factors causing debris flow disaster.There are a large number of reservoirs,hydropower stations and sediment control dams in the southwest mountainous areas of our country.Therefore,it is very important to study the peak clipping effect of the sediment control dams to the debris flow in the downstream of the reservoirs or people living in the lower reaches of the sediment control dams.Due to the difficulty of field observation,there is a lack of theoretical calculation formula for Peak clipping effect.In this paper,based on the previous empirical formulas and conclusions,the relevant research factors are selected,and then the laboratory test is carried out to study whether the slope of the bottom slope,whether the overflow and the yield stress are on the siltation influences.And ths essay finally obtained calculation method of the deposition slope after the sediment control dam,and the use of Niuquan ditch,Xinqiao ditch,peach gully ditch of Wenchuan,Yinshan ditch of Shimian County and Yunnan Bridge River branch muddy ditch.This essay use these five cases to verify the comparison.In addition,the influence of the ratio of amount and the storage capacity and the yield stress on the peak clipping effect of the dam is studied by means of laboratory test.The experimental verification of the hunshui gully of Dayingjiang in Yunnan is studied.Mainly get the following conclusions:(1)Debris flow is greater than or less than the capacity of the case,the deposition slope is basically the same,there is no difference.Through comparative studies,the bottom slope do not affect the deposition slope.(2)The greater the yield stress of the debris flow is,the stronger the viscosity of the debris flow is.The greater the sedimentation thickness of the debris flow is,the deposition slope is bigger.The larger the coarse particles D90 in the debris flow is,the faster the settlement in the dam is,and the less the coarse particles on the surface of the debris flow in the dam is.Debris flow bulk density is getting smaller and smaller,and debris flow yield stress is getting smaller and smaller,and the deposition slope is getting smaller and smaller.The variation range of the bulk density ?g of the debris flow is small.Generally,the greater the bulk density is,the greater the yield stress of the debris flow is and the deposition slope is getting bigger.But the yield of stress growth is much greater than the growth rate of bulk density.We can obtain the dimensionless yield stress ?/(?g D90)with above parameters affect the deposition slope through the dimensionless.The dimensionless yield stress reflects the relationship between the characteristics of the debris flow and the deposition slope of the debris flow and it is a determining factors of the deposition slope.The greater the amount of non-dimensional yield stress is,the greater the deposition slope is.On the contrary,the deposition slope is getting smaller.A dimension harmonious formula of the deposition slope is got by this paper through the experimental study.This formula is:tan(?)=0.075?*0.317The results of the study were tested in the case of the four field investigation cases of Wenchuan,Niuquan ditch,Xinqiao ditch,Taoguan ditch,Yinshan ditch in Shimian county and Hunshui ditch in Yunnan Bridge River.The results show that the error is small and very close.(3)In the study of the peak clipping effect,the total library ratio(W/C)is one of the important factors affecting the clipping effect.The larger the total library ratio is,the worse the knocking effect is.At the same time,the dimensionless yield stress ?* is also one of the important factors that affect the clipping effect.The larger the ?* is,the worse the knocking effect is.(4)There is no flow that means the debris flow is stopped by the dam when amount of the debris flow and storage capacity(W/C)is less than 0.5.When the total library ratio is equal to 1,peak reduction that the dam for the debris flow effect is about 70%.(5)In the peak clipping of diluted debris flow and viscous debris flow,once the total library ratio is greater than 55?30.When the total library ratio(W/C)is between 1 and 55,the relationship between the dam flow and the pre-dam flow can be calculated as follows: When ?*<0.1 ?,When ?*?0.1 ?,...