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Model test on hydraulic characteristics of soil slopes with geotextile belts and vegetation
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摘要: 目前关于植被护坡机理的研究多集中于植被根系的力学效应上，关于其水文效应的研究大多也仅针对于单株植物的根系吸水及蒸腾作用。为了探究在多植株条件下植株间距对土体水力特性的影响，以植被联合植筋带（持水加筋带）构成的植物护坡形式为基础，开展了植株间距分别为20、30和40 cm模型的干燥和降雨过程的模型试验观测，测定不同埋深处土体的吸力及含水率的变化过程。试验结果表明，在植株间距为20 cm的模型试验中，干燥工况下吸力最大值比植株间距为30和40 cm的试验组分别高出5.3%和43.3%，说明植株间距越小，植株间水分竞争越激烈，吸力增大越明显。在植被的根系深度范围内，土体的吸力及体积含水率变化幅度较大，且变化幅度随着土体深度的增加而减小，根系深度范围以下的土体基本不受影响。降雨工况下，雨水优先沿裂隙渗入土体内部，因此应防止边坡开裂。由于植筋带埋设于植株根系两侧，株距实际上就是竖向植筋带的埋设间距，所以在采用植筋带进行护坡设计时，植筋带间距应根据经济性和灌木的株距，按照“细而密”的原则进行布置。Abstract: At present, the research on the mechanism of vegetated slope mostly focuses on the mechanical effects rather than the hydrological effects of vegetation roots, and even there are some studies focusing on the hydrological effects, and most of them only focus on the water uptake and transpiration of single plant roots. In order to investigate the effect of plant spacing on hydraulic characteristics of the vegetated soil, such as the soil suction and water content at different depths, in multiple plants conditions and the drying-wetting processes, monitoring on the soil suction and water content at the observation points were carried out in the model tests composed of the vertical geotextile belts (water-retaining and reinforcement belts) and vegetation, in which the plant spacing was 20, 30 and 40 cm respectively. The model test results show that the maximum suction of the soil in the test with a plant spacing of 20 cm was 5.3% and 43.3% higher than that of the test group with a plant spacing of 30 cm and 40 cm respectively during the drying process. It can be concluded from the model test results that the smaller the plant spacing is, the more intense the water competition between plants, and the more obvious increase of suction in the soil. Within the root depth of vegetation, the suction and volumetric water content of the soil decrease with the depth of the soil, and the soil below the root depth is basically unaffected. Under the rainfall condition, rainwater preferentially infiltrates into the soil along the cracks, so the slope should be prevented from cracking. Since the vertical geotextile belts are installed on one or both sides of the plant root system, the plant spacing is actually the distance between the vertical geotextile belts. When the geotextile belts are used for slope protection, the distance between geotextile belts should not be too large, and they should be arranged under the principle of “fine and dense” in accordance with the cost and the spacing of plants.
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Key words:
- vegetated slope /
- the geotextile belt /
- plant spacing /
- hydraulic characteristics /
- model test
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图 4 干燥阶段不同株距测点1（10 cm埋深）处吸力的变化
Figure 4. Change of suction force at plant distance measurement point 1 (10 cm buried depth) in the drying stage
图 5 干燥阶段不同株距测点2处（20 cm埋深）吸力的变化
Figure 5. Changes of suction at plant distance measurement point 2 (20 cm buried depth) during the drying stage
图 6 干燥试验前后不同株距的吸力沿深度的变化
Figure 6. Variation of suction of different plant spacings along depth before and after drying test
图 7 干燥过程中不同株距的株间A点处不同埋深测点的体积含水率变化曲线
Figure 7. Variation curve of volumetric water content at different burial depth measuring points at the middle point A of different plant distances during the drying process
图 8 降雨过程中不同株距的株间A点处不同埋深测点的吸力变化情况
Figure 8. Changes of suction at different buried depth measuring points at the midpoint A of different plant distances during wetting process
图 9 降雨过程中三植株中心点B处测点吸力的变化情况
Figure 9. Changes in suction at the measuring point at center B of three plants during wetting process
表 1 土体的物理力学参数
Table 1. Physical and hydraulic parameters of the soil
渗透系数/
(cm·s−1)液限/
%塑限/
%最大干密度/
(g∙cm−3)最优含水率/
%8.15×10−5 33.7 20.0 1.746 17.0 
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