含根系土体水力特性的试验与理论研究

发布时间：2018-06-12 16:08

本文选题：垃圾填埋场覆盖层 + 植物根系　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：垃圾填埋场终场覆盖层的长期服役性能已经引起了越来越多关注,覆盖层在干湿循环的作用下会开裂,导致覆盖层的渗水能力增强。终场覆盖层通常种植植物,植物对裂隙的开展有一定的限制作用,但是至今没有对植物根系与裂隙同时存在对覆盖层水力特性的影响的研究。本文将研究含有植物根系与裂隙土体的水力特性。本文采用室内土柱试验来研究含有植物根系与裂隙土体的水力特性。设计了一套可以直接获取含植物根系现场土样,并能够直接进行室内土柱渗透试验的试验装置。试验装置包括降水装置、土柱主体、排水收集装置三部分。采用自主设计的试验装置,从室外试验场地获得了现场土样,进行了室内土柱渗透试验,并对试验结果进行了对比分析。室内土柱渗透试验分为四组,土样分别为重塑土样、不含根系含裂隙的室外现场土样、含狗牙根草根系的室外现场土样、含香根草根系的室外现场土样。四种土样在相同的降水条件下收集到底部渗水的时间不同,重塑土样在降水持续57.5小时收集到底部渗水,不含根系含裂隙的室外现场土样在降水持续12小时收集到底部渗水,含狗牙根草根系的室外现场土样在降水开始20小时收集到底部渗水,含香根草根系的室外现场土样在降水开始1.3小时收集到底部渗水。与室外不含根系的土样相比,狗牙根草根系能够提高覆盖层的防渗能力,香根草根系使室外覆盖层的防渗能力减弱。对比各组土样不同深度在相同基质吸力下的渗透系数,可以发现香根草根系对覆盖层渗透性的影响深度超出140 mm,狗牙根草与裂隙对覆盖层的影响深度不超过140 mm厚度。根据试验结果,结合已有计算非饱和渗透系数的公式,建立了计算含有草根土体的非饱和渗透系数模型,模型参数与草根参数直接相关。
[Abstract]:More and more attention has been paid to the long-term service performance of the landfill terminal overlay. The overburden will crack under the action of dry and wet cycle, which leads to the enhancement of the water seepage ability of the overburden. Plants are usually planted in the final covering layer, which has a limited effect on the development of cracks, but there is no research on the influence of the root system and the crack on the hydraulic characteristics of the cover layer at the same time. In this paper, the hydraulic characteristics of the soil with plant roots and fissures are studied. In this paper, laboratory soil column test is used to study the hydraulic characteristics of soil with plant roots and fissures. A set of experimental equipment was designed, which can directly obtain soil samples containing plant roots and directly carry out soil column permeation test in laboratory. The test device consists of three parts: dewatering device, soil column body and drainage collection device. The field soil samples were obtained from the outdoor test site with a self-designed test device. The indoor soil column permeation test was carried out, and the test results were compared and analyzed. The soil column permeation test was divided into four groups. The soil samples were remolded soil samples, outdoor soil samples without root cracks, outdoor soil samples with root system, and field soil samples with vetiver root system. Four kinds of soil samples were collected under the same precipitation conditions and the time of water seepage at the bottom was different. The remolded soil samples were collected to the bottom seepage in 57.5 hours of precipitation, while outdoor soil samples without root cracks were collected to the bottom seepage in 12 hours of precipitation. At the beginning of 20 hours of precipitation, the soil samples collected from the outdoor field with the root system of Herba doggeana were collected into the bottom seepage, while the soil samples containing the root system of Vetiveria root were collected to the bottom at 1.3 hours of precipitation. Compared with the soil samples without root system outside, the root system can improve the anti-seepage ability of the cover layer, and the root system of vetiver grass can weaken the anti-seepage ability of the outdoor cover layer. By comparing the permeability coefficient of soil samples at different depths under the same matrix suction, it was found that the influence depth of root system on overburden permeability was more than 140mm, and the influence depth of root and fissure on the overburden was not more than 140mm. Based on the experimental results and the existing formulas for calculating the unsaturated permeability coefficient, a model for calculating the unsaturated permeability coefficient of the soil with grass roots is established. The model parameters are directly related to the grass root parameters.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU411.4;TU993

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