盐生植物根系增强土体抗剪强度效应试验研究

以大柴旦盐湖区及其周边地区作为试验区,选取海韭菜、芦苇2种优势盐生植物作为供试种,通过对2种盐生植物根—土复合体试样和素土试样进行剪切试验,探讨了盐生植物根系对土体抗剪强度增强作用以及土体抗剪强度的影响因素。结果表明:2种植物根—土复合体试样粘聚力值为13.48~21.87kPa,不含根系素土试样粘聚力值为8.45kPa,与不含根系素土相比,根—土复合体的粘聚力值增长量为5.03~13.42kPa,其增长幅度为59.53%~158.82%;海韭菜根—土复合体试样粘聚力值大于芦苇,2种盐生植物根—土复合体试样粘聚力值与2种盐生植物在一定范围内的根系含量之间呈正相关关系,同时一定程度上表明了试验区2种植物根系增强土体强剪强度的机制表现为,在一定范围内根—土复合体中根系密度和数量愈高则其对土体抗剪强度增强程度相对愈显著,且海韭菜对土体粘聚力的增强作用显著大于芦苇。该研究成果对研究区以及与该区地质条件相类似的其他地区利用盐生植物增强土体抗剪强度,以实现有效地防治地表水土流失、浅层滑坡等地质灾害具有理论研究价值和实际指导意义。

Study on Reinforcement Effect by Halophyte Roots in Increasing Soil Shear Strength

Da Qaidam Salt Lake and its surrounding areas were selected as the test sites.And two predominant halophytes (Triglochin m aritimum L.Claus.and Phragrnites australis (Cav.) Trin.ex Steud) were selected as the test samples.By direct shear tests on soil without root samples and rooted soil samples for the two halophytes,the influences of the roots of the two halophytes on increasing shear strength of soil were investigated.The test results show that the cohesion forces of rooted soil for the two halophytes were 13.48～21.87 kPa,and the cohesion force of soil without roots was 8.45 kPa.In contrast to soil without root,the increment in cohesion force of rooted soil was 5.03 ～ 13.42 kPa,with the corresponding incremental rate of 59.53％～158.82％.The cohesion force of rooted soil for T.maritimum was greater than that for P.australis.Moreover,the cohesion forces of rooted soil for the two halophytes were positively correlated with root content in some extent.And in some extent,the mechanism of roots for the two halophytes in increasing the shear strength of soil was exhibited in the following.To a certain extent,the increased amount of roots and root density meant the increased effect of roots in increasing shear strength of soil,and the contribution of root for T.matitimum in increasing shear strength is relatively greater than that for P.australis.The obtained conclusion has the theoretical value and practical significance in increasing shear strength by roots of halophytes {or Da Qaidam Salt Lake area and other areas with the similar geological condition,and meanwhile,the conclusion is conducive in the control of geological hazards like water loss and shallow landslides.