林木风致动态响应特征的试验研究

Study on characteristics of wind-induced dynamic response of forest

首先对1株新疆杨进行了阻风效应试验,得出了新疆杨对降低风速及风压的效应很明显的结论;然后通过对5株新疆杨进行实验室条件下的模拟自然风的动力加载试验,得出了新疆杨的风致动态位移及风致动态应变特征曲线;其次通过对4株新疆杨进行野外真实风条件下动力加载试验,得到了风致动态应变、风致动态位移、风致动态速度及风致动态加速度响应特征曲线;最后对室内和野外两种试验条件下的新疆杨动态响应特征曲线进行了对比.试验及分析表明:新疆杨树干上同一方向的上、下两测点位置的位移、速度及加速度具有明显相关性;在随机风荷载激励下,林木的外表层纤维交替处于拉压状态;随着林木高度的增加,林木的风致动态位移越大.本文对林木防风减灾及林木保护具有重要的理论意义和实用价值.

Firstly,the wind-resistance effect test was carried out with one P.bolleana in this article,and a conclusion was arrived at that P.bolleana was obviously effective to reduce wind speed and wind pressure.And then through dynamic loading test of five P.bolleana under laboratory condition simulating natural wind power,the characteristic curves of wind-induced dynamic displacement and wind-induced dynamic strain were acquired.In the dynamic loading test of four P.bolleana under the condition of true wind power outdoors,characteristics curves of wind-induced dynamic strain,wind-induced dynamic displacement,wind-induced dynamic speed and wind-induced dynamic acceleration response were also obtained.Finally,a comparison was carried out on the dynamic response characteristic curves of P.bolleana under both indoor and field test conditions.Test and analysis showed that displacement,velocity and acceleration had obvious pertinence on the upper and lower measuring point position in the same direction of stem of P.bolleana,and in the random wind load excitation,the forest fibers of outer surface were in alternating tension-compression state,and with the increase in forest height,wind-induced dynamic displacement of forest was larger.This article has the important theorelical significance and practical value to wind resistance,disaster alleviation and protection of forest.