人工林杨木的用途选择——实木或单板层积材

实木材性对单板层积材强度的贡献率可衡量单板层积材强度中源自实木材性的份额，是人工林杨木单项用途选择的基础。本文以３个无性系实体杨木和由３种不同厚度杨木单板分别组配的单板层积材为对象，以由贡献率引出的实木与单板层积材的份率差值为依据，研究得出人工林杨木的最终用途选择。结果表明：６９杨、７２杨和６３杨３个无性系杨木的平均份率差值分别为５７％、－１５％、－２９％，说明６９杨宜用作实木，７２杨和６３杨宜用作单板层积材；杨木用作不同组配结构的单板层积材时，实木与３５６５ｍｍ、２６１４ｍｍ、１５４５ｍｍ３种厚度单板组配的单板层积材的平均份率差值分别为４３％、－１３％和－４３％，说明实木与较厚的３５６５ｍｍ单板组配的单板层积材相比，杨木宜用作实木，与较薄的２６１４ｍｍ和１５４５ｍｍ单板组配的单板层积材相比，杨木宜用作单板层积材。不同荷载作用的结果下用途选择结果显示，在抗剪强度、弹性模量和冲击韧性３项性能上的份率差值为正，此时杨木宜用作实木；在抗弯强度、抗压强度和硬度３项性能上的份率差值为负，此时杨木则宜用作单板层积材。

END\|USE SELECTION OF PLANTATION POPLAR \_\_SOLID WOOD OR LAMINATED VENEER LUMBER (LVL)

The contributivity of solid wood properties to LVL strength can measure how much LVL strength is originated from solid wood properties. The proportion of end\|use selection and their difference values, which were calculated by contributivity between solid wood and LVL, were used to judge the end\|use selection of plantation poplar as solid wood or LVL in this paper. The results showed that the different values of Poplar 69, Poplar 72, Poplar 63 were 57% , -15%, -29%, respectively, and indicated that Poplar 69 was suitably used in solid wood, Poplar 63 and Poplar 72 in LVL. When 3 kinds of LVL were assembled with veneers of 3.565mm, 2.614mm and 1.545mm in thickness, their differences were 43%, -13%, -43%, respectively. These indicated that poplar was suitably used in solid wood compared with LVL with thick veneers, but in LVL compared with LVL with thin veneers. In addition to all of 6 properties, poplar was suitably used in solid wood to the properties of shear strength, modulus of elasticity and impact toughness because of their positive differences, but in LVL to the properties of modulus of rupture, compressive strength and hardness because of their negative differences.