丛生竹根系抗拉力学特性

摘要

竹林是具有水土保持功能的一种重要植被,其地下根系力学性能好坏是影响竹林固土力学作用的重要因素.为了了解丛生竹林地下根系的抗拉力学特性,利用自制的植物根系抗拉力学特性野外便携实验系统,对料慈竹、绿竹、龙竹、香竹4种丛生竹根系进行了现场拉伸实验,测量这4种丛生竹不同直径根系的抗拉力、应变,并通过计算得到抗拉强度和弹性模量.结果表明,4种丛生竹根系最大抗拉力与根直径的关系呈幂函数正相关增长,抗拉强度与根直径的关系呈幂函数负相关增长.根系平均抗拉力分别为料慈竹(59.47 N)、香竹(58.65 N)、龙竹(43.51 N)、绿竹(40.80 N),平均抗拉强度依次为龙竹(30.24 MPa)、料慈竹(23.14 MPa)、绿竹(22.83 MPa)、香竹(18.14 MPa),平均极限应变较为接近,在14％～18％之间,平均弹性模量值为龙竹(169.86 MPa)、料慈竹(166.37MPa)、绿竹(158.36MPa)、香竹(135.56 MPa),最高峰值达到350 MPa.4种丛生竹相比,龙竹根系的综合抗拉力学性能最好,其次是料慈竹和绿竹,最后是香竹.与常见造林树种油松、落叶松、白桦相比,丛生竹根系具有较好的抗拉力学性能.%Bamboo plays an important role as a kind of vegetation with contribution to soil and water conservation,Mechanics property of roots play a crucial role in mechanics of soil-reinforcement.In order to find the tension properties of the bamboo roots underground,the tensile experiment for the roots of four kinds of sympodial bamboo Bambusa distegia,Dendrocalamopsis oldhami,Dendrocalamus giganteus,and Chimonocalamus dumosus,was implemented in the field.The experiment employed our own portable experimental equipment for testing tensile characteristics of root.Tensile force and strain rate of roots with different diameters was tested for these four kinds of bamboo.Then,their tensile strength and elastic modulus were obtained through calculation.The experimental results show that the tensile force of sympodial bamboo root increases regularly by the power function regulars the increase of the root diameter,and the tensile strength of root reduces along with the increase of root diameter by the power function.The average anti-tension of these four bamboo roots is Bambusa distegia (59.47 N),Chimonocalamus dumosus(58.65 N),Dendrocalamus giganteus(43.51 N)and Dendrocalamopsis oldhami(40.8 N),and their average tensile strength isDendrocalamus giganteus (30.24 Mpa),Bambusa distegia (23.14 MPa),Dendrocalamopsis oldhami(22.83 MPa)and Chimonocalamus dumosus (18.14 MPa),the ultimate strain has limitation from 14％ to 18％.The average elastic modulus is Dendrocalamus giganteus(169.86 MPa),Bambusa distegia(166.37 MPa),Dendrocalamopsis oldhami(158.36 MPa) and Chimonocalamus dumosus (135.56 MPa).Compared to the four kinds of bamboo,Dendrocalamus giganteus root has the best comprehensive tensile properties.Next are Bambusa Distegia root,Dendrocalamopsis oldhami root,and Chimonocalamus dumosus root respectively.Compared with the common afforestation tree Pinus tabulaeformis,Betula platyphylla,Larix gmelinii,clumping bamboo roots have better tensile mechanical properties.