加载速度及含水率对四种植物直根抗折强度的影响

Effect of Loading Rate and Moisture Content on the Anti-fracture Strength of Straight Roots of Four Plant Species

以3~4年生柠条、沙柳、沙棘、白沙蒿为研究对象,采用TY8000系列伺服控制材料试验机,研究加载速度及土壤含水率对直根抗折强度的影响。结果表明：4种植物直根的抗折强度与加载速度呈正相关,1.5~2.0mm及3.0~3.5mm 2个径级的直根在承受瞬时折断力（加载速度500mm/min和860mm/min）时的抗折强度显著高于相同径级的根在缓慢折断力（加载速度10mm/min）时的抗折强度,其中加载速度500mm/min时2个径级直根抗折强度为柠条（（58.30±7.45）MPa,（49.21±3.45）MPa）〉沙柳（（23.21±1.88）MPa,（19.12±2.95）MPa）〉沙棘（（7.79±1.06）MPa,（6.61±1.05）MPa）〉白沙蒿（（5.51±0.66）MPa,（4.43±0.38）MPa）,相同径级的根在缓慢折断力时的抗折强度分别为上述强度的87.1%、83.7%,82.8%、86.8%,79.2%、81.8%,90.0%、73.6%。4种植物直根抗折强度随着土壤和根系含水率的增加呈减小趋势,2.0~2.5mm的直根在土壤干旱（含水率为0.0%）时的抗折强度为柠条（（60.05±7.00）MPa）〉沙柳（（25.99±2.88）MPa）〉沙棘（（8.52±1.17）MPa）〉白沙蒿（（5.85±0.63）MPa）,在土壤含水率饱和（含水率为25.6%）时的抗折强度分别为上述强度79.1%、73.0%、74.3%、65.1%。

The anti-fracture strength of straight roots of four plant species were measured by the Multifunctional Electronic Pull Test Machine of TY8000 in vigorous loading rates and vigorous moisture content seasons.The four plant species were the vegetation species of Caragana korshinskii,Salix psammophila,Artemisia sphaerocephala and Hippophae rhamnides.For the four plant species,the roots were selected from the corresponding plant age of 3-4-year-old.The results showed that the anti-fracture strength of straight roots of four plant species were positively correlated with the loading rate.The anti-fracture strength of the root under instantaneous breaking force（the loading rate of 500mm/min and 860 mm/min）was significantly higher than that of the root under the slow breaking force（the loading rate of10mm/min）with the same diameter.Under the loading rate of 500mm/min,the anti-fracture strength of 1.5-2.0mm and 3.0-3.5mm diameter class roots followed the sequence of Caragana（（58.30±7.45）MPa,（49.21±3.45）MPa）Salix（（23.21±1.88）MPa,（19.12±2.95）MPa）Hippophae（（7.79±1.06）MPa,（6.61±1.05）MPa）Artemisia（（5.51±0.66）MPa,（4.43±0.38）MPa）;comparing with the strength of the roots mentioned above,the anti-fracture strength of the same diameter class occupied 87.1%and 83.7%for Caragana,82.8%and 86.8%for Salix,79.2%and81.8%for Hippophae,90.0%and 73.6%for Artemisiaunder the loading rate of 10mm/min.With the increase of soil moisture content,the root moisture content of four plant species increased and the anti-fracture strength had a tendency to reduce.The anti-fracture strength of 2.0-2.5mm straight roots for the four species followed the sequence of Caragana（（60.05±7.00）MPa）Salix（（25.99±2.88）MPa）Hippophae（（8.52±1.17）MPa）Artemisia（（5.85±0.63）MPa）under drying soil（soil moisture content was 0.0%）.The anti-fracture strength of the same diameter class occupied79.1%for Caragana,73.0%for Salix,74.3%for Hippophae and 65.1%for Artemisia.