Study on shaking phenomenon of branches by strong wind and windbreak structure.

在青森县，9119号台风造成许多苹果掉落，果树受损严重。在本研究中，我们首先研究了近地面风的湍流特性，阐明了大风导致树枝摇动的现象，得出以下结论：(1)水平风速是低频和高频相结合的结构；(2)水平风速和垂直风速的湍流强度随水平风速的增大而增大；(3)苹果枝条的杨氏模数E=2.4-4.0gf/cm~2，与其他果树(梨、柿、桃)的杨氏模数相同；(4)苹果来回风向波动较大，大于升降方向。(5)风对苹果波动的影响大于对风速的影响。(6)树枝和苹果的摇动与阵风有关。(7)防风网后苹果的波动不受风速和强度的影响。

Many apples dropped by a Typhoon 9119 in Aomori Prefecture, and fruiters sustained great damege.In this studies, first, we studied on the turbulent characteristic of wind near the ground, we elucidated a shaking phenomenon of branches by the strong wind, and considered the windbreak structure.As the result of them we obtained the following the concluding remarks.(1) Horizontal wind velocity is the structure to combine the low frequency and the hight frequency.(2) The turbulent intensity of horizontal and vertical wind velocity increases as horizontal wind velocity increases.(3) The Young's modulus of the branches of apple was E=2.4-4.0gf/cm^2 in the like-values for another fruit trees (pear, persimmon and peach).(4) The fluctuations of apples by wind are large in the direction of back and forth are larger than the direction of rise and fall, right and left.(5) The fluctuations of apples by wind influenced on the magnitude of fluctuating velocity more than the magnitude of velocity.(6) The shaking branches and apples were related to the gustiness.(7) The fluctuations of apples behind the windbreak net were not influenced by the strength and the fluctuations of the wind speed.