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柴达木盆地4种盐生植物根系力学特性及根—土复合体抗剪强度研究
1, 1, 1, 1, 1, 2

(1.qinghaidaxue dizhigongchengxi, xining 810016; 2.zhongguokexueyuan qinghaiyanhuyanjiusuo, zhongguokexueyuan yanhuziyuanzonghegaoxiaoliyongzhongdianshiyanshi, xining 810008)

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Study on the Mechanical Properties of Roots and the Shear Strengths of Four Halophytic Plants in Qaidam Basin
XU Tong1, LIU Changyi1, HU Xiasong1, ZHOU Linhu1, SHEN Ziyan1, YU Dongmei2

(1.department of geological engineering, qinghai university, xining 810016, china; 2.key laboratory of comprehensive and highly efficient utilization of salt lake resources of cas, qinghai institute of salt lakes, cas, xining 810008, china)

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以柴达木盆地柯柯盐湖地区作为研究区,选取芦苇(Phragmites australias Trin.)、盐爪爪(Kalidium foliatum Moq.)、无脉苔草(Carex enervis C.A.Mey.)、盐地风毛菊(Saussurea salsa Spreng.)4种优势盐生植物作为供试种,开展室内单根拉伸、剪切试验,及根—土复合体试样直接剪切试验。结果表明:4种盐生植物平均单根抗拉力由大至小依次为盐地风毛菊(20.511 N)、芦苇(2.227 N)、盐爪爪(1.944 N)、无脉苔草(0.642 N); 平均单根抗剪力由大至小依次为盐地风毛菊(25.243 N)、芦苇(12.035 N)、盐爪爪(9.073 N)、无脉苔草(3.484 N),4种盐生植物其单根抗拉力、抗剪力与根径之间均符合指数函数关系; 平均单根抗拉强度由大至小依次为芦苇(281.208 MPa)、无脉苔草(114.798 MPa)、盐爪爪(33.159 MPa)、盐地风毛菊(14.824 MPa); 平均单根抗剪强度由大至小依次为无脉苔草(157.428 MPa)、芦苇(110.836 MPa)、盐爪爪(26.657 MPa)、盐地风毛菊(9.105 MPa),单根抗拉强度、抗剪强度与根径之间均呈幂函数关系。进一步研究表明,随着试验区地表以下取样深度的增加,4种盐生植物根—土复合体黏聚力c值呈逐渐减小的变化趋势,芦苇、盐爪爪、无脉苔草、盐地风毛菊分别降低了60.3%,60.1%,10.2%,28.3%; 在50 kPa,100 kPa,200 kPa,300 kPa垂直压力下,4种植物根—土复合体抗剪强度均显著大于素土,表现在地表以下0—20 cm深度处根—土复合体黏聚力c值增加幅度为9.9%~213.0%。该项研究结果对于通过盐生植物来防治盐渍土地区地质灾害现象的发生,具有一定的研究价值和实际指导意义。
Four dominant species of halophytes growing in Keke Salt Lake area of Qaidam Basin were chosen as experimental species. Four dominant species of halophytes were Phragmites australias Trin, Kalidium foliatum Moq, and Carex enervis C. A. Mey., Saussurea salsa Spreng. The indoor tensile test and shear test of single root, as well as the indoor direct shear test of four kinds of plant root-soil composite system were conducted. The results showed that the average single root tensile forces of the four halophytes from big to small were Saussurea salsa Spreng.(20.511 N), Phragmites australias Trin.(2.227 N), Kalidium foliatum Moq.(1.944 N), and Carex enervis C. A. Mey.(0.642 N); the average single shear forces descended in the order: Saussurea salsa Spreng.(25.243 N), Phragmites australias Trin.(12.035 N), Kalidium foliatum Moq.(9.073 N), and Carex enervis C. A. Mey.(3.484 N); the relationship between single root tensile force, single shear force and root diameter of four halophytes could be described by the exponential function; the average tensile strength of single root decreased in the order: Phragmites australias Trin.(281.208 MPa), Carex enervis C. A. Mey.(114.798 MPa), Kalidium foliatum Moq.(33.159 MPa), and Saussurea salsa Spreng.(14.824 MPa); the average shear strength of single root decreased in the order: Carex enervis C. A. Mey.(157.428 MPa), Phragmites australias Trin.(110.836 MPa), Kalidium foliatum Moq.(26.657 MPa), and Saussurea salsa Spreng.(9.105 MPa), the relationship between single root tensile strength, shear strength and root diameter could be described by the power function. Further studies showed that with the increase of sampling depth below the surface of the test area, the c values of the cohesion of the root-soil composite system of the four halophytes showed a trend of gradually decreasing, and decreased by 60.3%, 60.1%, 10.2% and 28.3% under Phragmites australias Trin., Kalidium foliatum Moq., Carex enervis C. A. Mey. and Saussurea salsa Spreng., respectively. Under the vertical pressures of 50 kPa, 100 kPa, 200 kPa and 300 kPa, the shear strengths of the root-soil composite system of the four plants were significantly higher than those of the sample of soil without roots, indicating that the c value of the root-soil composite system increased by 9.9%~213.0% in 0—20 cm layer below the ground. These results of this study have important theoretical values and practical significance for the effective prevention and control of soil erosion and other geological disasters by using halophytes in the study area.
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