沙柳直根抗拉特性对循环荷载的响应

doi:10.13866/j.azr.2022.03.23

摘要/Abstract

摘要：

为揭示风力侵蚀区植物长期遭受大风使其根系反复受力后的固土性能,以神东矿区广泛分布的水土保持植物种沙柳（Salix psammophila）为研究对象,采用TY8000伺服式强力机对1~5 mm径级沙柳直根进行轴向循环荷载试验,探究直根抗拉特性对模拟大风拉拔产生的反复加载-卸载作用的响应。结果表明：（1）承受循环荷载后直根极限抗拉力与根径呈幂函数正相关,抗拉强度与根径呈幂函数负相关,与单次荷载下直根抗拉力、抗拉强度-根径关系相似。（2）承受循环荷载后各径级直根抗拉力、抗拉强度较单次荷载均有所增强且差异显著（P<0.05）,1~2 mm、2.5~3.5 mm、4~5 mm直根抗拉力、抗拉强度分别增长了60%、60%,48%、50%,31%、32%。（3）直根力-位移曲线在循环过程中表现出明显的周期循环特征,随循环次数增加,滞回环间距逐渐闭合,由加载段-卸载段曲线组成的滞回环面积随之减小,抵抗塑性变形能力越来越差,最后趋之稳定。直根累计伸长率随循环次数的增加而增长,分为快速增长阶段和缓慢增长阶段。（4）承受单次荷载和循环荷载后,直根弹性应力、极限应力、弹性模量与根径呈负相关,累计弹性应变、极限应变与根径无关系;承受循环荷载后,直根弹性应力、极限应力、累计弹性应变明显增大,极限应变则表现为：单次荷载>循环荷载,弹性模量在不同荷载下无规律性。综上所述,沙柳根系在承受一定程度的营力低周循环荷载后,能够更加适应外界环境,增强对侵蚀营力的抵抗能力,更有利于植物根系发挥固土效能。

关键词: 直根段, 循环荷载, 抗拉强度, 变形特征, 沙柳

Abstract:

To clarify mechanical properties of straight roots in response to repeated loading and unloading induced by simulated high wind drawing, an axial cyclic load test was applied to straight roots of Salix psammophila. These roots had a diameter of 1-5 mm in the Shendong mining area and a TY8000 servo-type strong force was used to reveal the soil-fixing ability of plants in wind-eroded areas after their roots were repeatedly stressed by strong long-term winds. Results show the following: (1) the tensile force of straight roots after cyclic loading was positively correlated with the diameter based on a power function; the tensile strength after cyclic loading was negatively correlated with root diameter based on a power function, which was similar to the relationship between tensile force, tensile strength, and root diameter under a monotonic load. (2) Compared with the monotonic load, the tensile force and tensile strength after cyclic loading of straight roots of all diameters were significantly enhanced (P<0.05), and the tensile force and tensile strength of 1-2 mm, 2.5-3.5 mm, and 4-5 mm roots increased by 60%, 60%, 48%, 50%, and 31%, 32%, respectively. (3) In the cycle process, the force-displacement curve of straight roots showed obvious cycle characteristics with increasing cycle number; the hysteresis loop spacing is gradually close to closing; and as the area decreases, the capacity of resistance to plastic deformation becomes worse, which tends to be stable. The accumulated elongation of straight roots increases with increasing cycle number, which can be divided into a rapid growth stage and a slow growth stage. (4) The elastic stress, ultimate stress, and elasticity modulus of straight roots was negatively correlated with root diameter after monotonic load and cyclic load, and the accumulated elastic strain and ultimate strain have no relationship with root diameter. The elastic stress, ultimate stress, and accumulated elastic strain after cyclic loading of all diameters was enhanced, the ultimate strain was monotonic load > cyclic load, and the elastic modulus has no relationship under different loads.

Key words: straight roots, cyclic load, tensile strength, deformation characteristic, Salix psammophila

胡晶华,刘静,白潞翼,张欣,兰鹏波,袁亚楠. 沙柳直根抗拉特性对循环荷载的响应[J]. 干旱区研究, 2022, 39(3): 900-907.

HU Jinghua,LIU Jing,BAI Luyi,ZHANG Xin,LAN Pengbo,YUAN Yanan. Straight root tensile properties of Salix psammophila in response to cyclic loading[J]. Arid Zone Research, 2022, 39(3): 900-907.

图/表 6

图1

图2

图3

图4

图5

表1

参考文献 26

[1]	Wang S M, Du H D, Wang S Q. Analysis of damage process and mechanism for plant community and soil properties at northern Shenmu subsidence mining area[J]. Journal of China Coal Society, 2017, 42(1): 17-26.
[2]	Bordoni M, Meisina C, Vercesi A, et al. Quantifying the contribution of grapevine roots to soil mechanical reinforcement in an area susceptible to shallow landslides[J]. Soil & Tillage Research, 2016, 163(1): 195-206.
[3]	Capilleri P P, Motta E, Raciti E. Experimental study on native plant root tensile strength for slope stabilization[J]. Procedia Engineering, 2016, 158(8): 116-121. doi: 10.1016/j.proeng.2016.08.415
[4]	Capilleri P P, Cuomo M, Motta E, et al. Experimental investigation of root tensile strength for slope stabilization[J]. Indian Geotechnical Journal, 2019, 49(6): 687-697. doi: 10.1007/s40098-019-00394-2
[5]	白潞翼, 刘静, 胡晶华, 等. 紫穗槐直根力学性质研究[J]. 干旱区研究, 2021, 38(4): 1111-1119.
	[ Bai Luyi, Liu Jing, Hu Jinghua, et al. Deformation characteristics of the straight roots of Amorpha fruticosa[J]. Arid Zone Research, 2021, 38(4): 1111-1119. ]
[6]	Boldrin D, Leung A K, Bengough A G. Effects of root dehydration on biomechanical properties of woody roots of Ulex europaeus[J]. Plant and Soil, 2018, 431(3): 347-369. doi: 10.1007/s11104-018-3766-7
[7]	刘昌义, 胡夏嵩, 赵玉娇, 等. 寒旱环境草本与灌木植物单根拉伸试验强度特征研究[J]. 工程地质学报, 2017, 25(1): 1-10.
	[ Liu Changyi, Hu Xiasong, Zhao Yujiao, et al. Strength characteristics of single root tensile test of herbs and shrubs in cold and arid environments[J]. Journal of Engineering Geology, 2017, 25(1): 1-10. ]
[8]	Ouyang Q, Yang W, Zhou X, et al. Root tensile properties of the herbaceous plants for slope protection in earth-rocky mountain area, northern China[J]. Science of Soil and Water Conservation, 2017, 15(4): 35-41.
[9]	Boldrin D, Leung A K, Bengough A G. Root biomechanical properties during establishment of woody perennials[J]. Ecological Engineering, 2017, 109(11): 196-206. doi: 10.1016/j.ecoleng.2017.05.002
[10]	Saifuddin M, Osman N, Rahman M M, et al. Soil reinforcement capability of two legume species from plant morphological traits and mechanical properties[J]. Current Science, 2015, 108(7): 1340-1347.
[11]	Zhang C B, Chen L H, Liu Y P, et al. Triaxial compression test of soil-root composites to evaluate influence of roots on soil shear strength[J]. Ecological Engineering, 2010, 36(1): 19-26. doi: 10.1016/j.ecoleng.2009.09.005
[12]	申紫雁, 刘昌义, 胡夏嵩, 等. 黄河源区高寒草地不同深度土壤理化性质与抗剪强度关系研究[J]. 干旱区研究, 2021, 38(2): 392-401.
	[ Shen Ziyan, Liu Changyi, Hu Xiasong, et al. Relationships between the physical and chemical properties of soil and the shear strength of root-soil composite systems at different soil depths in alpine grassland in the source region of the Yellow River[J]. Arid Zone Research, 2021, 38(2): 392-401. ]
[13]	Kim, Weon J, Jae Y, et al. Effect of loading rate on the fracture behavior of nuclear piping materials under cyclic loading conditions[J]. Nuclear Engineering and Technology, 2016, 48(6): 1376-1386. doi: 10.1016/j.net.2016.06.006
[14]	吕春娟, 陈丽华, 赵红华, 等. 油松根系的轴向疲劳性能研究[J]. 摩擦学学报, 2013, 33(6): 578-585.
	[ Lyu Chunjuan, Chen Lihua, Zhao Honghua, et al. Axial fatigue properties of Pinus tabulaeformis root[J]. Tribology, 2013, 33(6): 578-585. ]
[15]	穆枫, 程子敏, 李玉灵, 等. 太行山区林木根系单根固土生物力学及疲劳特性研究[J]. 西北林学院学报, 2019, 34(2): 14-21, 55.
	[ Mu Feng, Chen Zimin, Li Yulin, et al. Study on the biomechanics and fatigue characteristics of single root soil and soil of tree roots in Taihang Mountain[J]. Journal of Northwest Forestry University, 2019, 34(2): 14-21, 55. ]
[16]	李瑞燊, 刘静, 王博, 等. 反复施加拉剪组合力对小叶锦鸡儿直根材料力学特性的影响[J]. 水土保持学报, 2019, 33(5): 121-125.
	[ Li Ruishen, Liu Jing, Wang Bo, et al. Effects of repeated combined tension and shear forces on mechanical properties of Caragana microphylla root materials[J]. Journal of Soil and Water Conservation, 2019, 33(5): 121-125. ]
[17]	盖小刚. 林木根系固土力学特性研究[D]. 北京: 北京林业大学, 2013.
	[ Gai Xiaogang. Study of Mechanical Properties of Tree Root Reinforcing Soil[D]. Beijing: Beijing Forestry University, 2013. ]
[18]	Hales T C, Miniat C F. Soil moisture causes dynamic adjustments to root reinforcement that reduce slope stability[J]. Earth Surface Processes and Landforms, 2017, 42(5): 803-813. doi: 10.1002/esp.4039
[19]	Zhang C B, Zhou X, Jiang J, et al. Root moisture content influence on root tensile tests of herbaceous plants[J]. Catena, 2019, 172(8): 140-147. doi: 10.1016/j.catena.2018.08.012
[20]	张乔艳, 唐丽霞, 廖华刚, 等. 多花木蓝根截面微观结构对其抗拉特性的影响[J]. 植物生态学报, 2019, 43(8): 709-717. doi: 10.17521/cjpe.2019.0112
	[ Zhang Qiaoyan, Tang Lixia, Liao Huagang, et al. Effect of microstructure in cross section on tensile properties of Indigofera amblyantha[J]. Chinese Journal of Plant Ecology, 2019, 43(8): 709-717. ] doi: 10.17521/cjpe.2019.0112
[21]	Jaffe M J. Thigmomorphogenesis: The response of plant growth and development to mechanical stimulation: With special reference to Bryonia dioica[J]. Planta, 1973, 114(2): 143-157. doi: 10.1007/BF00387472 pmid: 24458719
[22]	王萍花, 陈丽华, 冀晓东, 等. 4种常见乔木单根拉伸的应力应变曲线分析[J]. 水土保持通报, 2012, 32(3): 17-22.
	[ Wang Pinghua, Chen Lihua, Ji Xiaodong, et al. Analysis of stress-strain curves for four common arbor root systems[J]. Bulletin of Soil and Water Conservation, 2012, 32(3): 17-22. ]
[23]	Liu Y B, Li S X, Yu D M, et al. Experiment on single root tensile mechanical properties of typical herb species in loess region of Xining Basin[J]. Transactions of the Chinese Society of Agricultural Engineering, 2018, 34(15): 157-166.
[24]	朱海丽, 胡夏嵩, 毛小青, 等. 护坡植物根系力学特性与其解剖结构关系[J]. 农业工程学报, 2009, 25(5): 40-46.
	[ Zhu Haili, Hu Xiasong, Mao Xiaoqing, et al. Relationship between mechanical characteristics and anatomical structures of slope protection plant root[J]. Transactions of the Chinese Society of Agricultural Engineering, 2009, 25(5): 40-46. ]
[25]	蒋坤云, 陈丽华, 盖小刚, 等. 华北护坡阔叶树种根系抗拉性能与其微观结构的关系[J]. 农业工程学报, 2013, 29(3): 115-123.
	[ Jiang Kunyun, Chen Lihua, Gai Xiaogang, et al. Relationship between tensile properties and microstructures of three different broadleaf tree roots in North China[J]. Transactions of the Chinese Society of Agricultural Engineering, 2013, 29(3): 115-123. ]
[26]	许金泉, 郭凤明. 疲劳损伤演化的机理及损伤演化律[J]. 机械工程学报, 2010, 46(2): 40-46.
	[ Xu Jinquan, Guo Fengming. Mechanism of fatigue damage evolution and the evolution law[J]. Journal of Mechanical Engineering, 2010, 46(2): 40-46. ]

加载方式	根径/mm	弹性应力/MPa	极限应力/MPa	弹性应力占比/%	弹性应变/%	极限应变/%	弹性应变占比/%	弹性模量/MPa
单次荷载	1~2	6.31	24.69	21	0.94	13.67	7	8.95
	2.5~3.5	6.24	20.16	31	1.28	13.36	10	8.81
	4~5	6.06	15.53	38	0.80	14.58	6	7.81
循环荷载	1~2	15.71	38.92	40	2.58	10.73	23	11.61
	2.5~3.5	15.41	29.11	61	2.45	11.11	24	8.20
	4~5	10.61	21.64	49	3.28	14.25	26	3.74