泥石流沟活跃程度的评价方法

EVALUATION METHOD FOR ACTIVE DEGREE OF DEBRIS FLOW GULLY

根据甘肃陇南等地 50条泥石流沟资料 ,建立了判别泥石流沟活跃程度的表达式N =(A/1 0 0 )(J/0 .0 6) 0 .375·F0 .4 ,以及泥石流侵蚀模数式E =B +0 .33(A/1 0 0 ) (J/0 .0 6) 0 .3

Analysis discovers that the active degree of debris flow gully mainly relates to the stability of solid material in tributary, which can be measured by its shearing stress. Thus, following the forms of shear stress γ HJ , and thinking the unit gravity of soil mass ( γ ) is constant, let A /100 stand for H , J/0.06 for J where 0.06 is the equilibrium gradient and F 0.4 for the transportation and erosion capability ( F is the gully area). After analysing of the data of 50 debris flow gullies, the author get the distinguishmental formula N=(A/100)·(J /0.06) 0.375 · F 0.4 ,and find that when N <2,the occurring frequeney P <10%, When 2≤ N ≤7, P is between 10% to 50%, when N>7, P ≥100%. Through comparison, the correct ratio of this formula reaches 90%, this formula has brief structure and high utilizing value. The further analysis discovers that the function intensity of debris flow has relation-ship with occurrence frequencies,namely N . But when the erosional modulus (10 4m 3/km 2·a -1 ) stand for function instensity and consider the influence of F , picking up 8 debris flow gullies in Gansu and Yunnan, we get E=B+0.33A/100·(J /0.06) 0.375 ,where B is 0.90 in Yunnan, and 0.20 in Gansu.