基于流固耦合分析支撑架对云杉抗风性的影响  

Effects of support frame on wind resistance of spruce based on fluid⁃solid coupling analysis

作　　者：吴圣众 吴克勤 曾钦志[1] 周建斌 吴美强 饶久平[1] WU Shengzhong;WU Keqin;ZENG Qinzhi;ZHOU Jianbin;WU Meiqiang;RAO Jiuping(College of Material Engineering,Fujian Agriculture and Forestry University,Fuzhou,Fujian 350108,China;Fuzhou Leyi Ecological Technology Co.,LTD,Fuzhou,Fujian 350007,China)

机构地区：[1]福建农林大学材料工程学院,福建福州350108 [2]福州乐亿生态科技股份有限公司,福建福州350007

出　　处：《森林与环境学报》2023年第4期442-448,共7页Journal of Forest and Environment

基　　金：福建省科技计划项目“节能环保装配式立体绿化新技术研究”(2021Y4009);福建农林大学横向项目“绿化种植容器用可降解耐候型木塑复合材料的研发”(KH190224A)。

摘　　要：在强风作用下新移栽的树木可能发生歪斜、倒伏等破坏,造成经济损失与人员伤亡,因此,树木的抗风性以及提高树木抗风性研究具有重要意义。以云杉为例,对设立支撑架前、后的云杉分别进行三维简化建模,树高8 m,冠幅4 m,主干基部直径0.3 m,并赋予模型对应的力学性能,再进行流固耦合数值模拟。结果表明:无支撑时,云杉树梢位移、枝干所受剪切应力和树底弯矩均随着风速的增强而增大。在20 m·s^(-1)风速下,云杉横纹方向剪切应力最大值为2.6 MPa,大于云杉横纹抗剪强度的85%,云杉可能发生剪切破坏,通过后处理发现破坏危险点位置在1级分枝与主干的交界处,云杉的枝干易被折断。分别在云杉树高的1/8、2/8、3/8处设立支撑架,对比无支撑架时云杉的风致响应,云杉的树梢位移、枝干所受剪切应力和树底弯矩均有所减小,云杉发生横纹剪切破坏的风险降低,发生倒伏的概率大幅下降。当支撑架置于树高2/8处时云杉所受的剪切应力最小,相对无支撑架时减小了50%,云杉枝干被折断的风险大幅下降。然而,处于支撑架上方的云杉部分随风摆动的振频较无支撑时有所增大,云杉的稳定性下降,长时间的高频振动亦会增大枝干折断的风险。计算机数值模拟风致树木响应具有很强的自定义性,其模拟结果对树木的抗风性及其支撑架的设计应用具有一定的参考价值。Under strong winds,newly transplanted trees can tilt or fall,causing economic losses and injuries.Therefore,studying the wind resistance of trees and methods to enhance their wind resistance is of great significance.In this study,3D simplified models of spruce were built before and after the installation of support frames in them.The trees were 8 m in height,4 m in crown diameter,with a trunk diameter of 0.3 m at the base.Corresponding mechanical properties were assigned to the models and fluid⁃solid interaction was numerically simulated.The results showed that without support,the displacement of the spruce treetop,shear stress on branches,and bending moment at the base increased with increasing wind speed.At a wind speed of 20 m·s^(-1),the maximum shear stress in the transverse direction of spruce was 2.6 MPa,exceeding 85%of its transverse shear strength.This indicates that there is a possibility of shear failure in the tree with the failure point at the junction of the primary branch and the main stem.Supporting the tree at 1/8,2/8,and 3/8 of its height reduced the displacement of the treetop,shear stress on branches,and bending moment at the base,ultimately lowering the risk of shear failure and falling.When the support frame was placed at 2/8 of the tree′s height,the shear stress on the tree was minimized,reducing the risk of branch breakage by 50%.However,the part of the tree above the support frame had an increased wind⁃induced oscillation frequency compared to the unsupported tree,reducing the tree′s stability and increasing the risk of branch breakage owing to prolonged high⁃frequency vibration.Numerical simulation of wind⁃induced tree response is highly customizable,and its results have reference value for studying wind resistance of trees and designing support frames for trees.

关 键 词：流固耦合 树木支撑架 抗风性 云杉 

分 类 号：S761.2[农业科学—森林保护学] O242[农业科学—林学]