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植物是天然的工程师,拥有防止浅层滑坡和地表侵蚀的潜能,并具备低投入、易养护、绿色环保和生态平衡等优点。目前国内外的研究和工程实践大多只考虑植物根系的力学加筋作用,而忽略了更为重要的水力作用。植物蒸腾能增加土体吸力,从而降低土体渗透系数且增加抗剪强度,所以能提高边坡稳定性和防止地表侵蚀。笔者的跨学科研究团队结合高等非饱和土力学理论和植物特征,从根本上研究了大气–植被–土体的相互作用机理;提出了新的理论模型,可预测植被土的持水能力;构建了考虑植物根系形状影响的地下水渗流与地表径流耦合运移的新模型;推导了计算植被边坡吸力分布与稳定性安全系数的解析解,引入了指数形、三角形、均布形和椭圆形4种典型的根系形状;并自主研发了用于离心机模型试验的人造根,能够模拟不同形状的植物根系的水力作用和力学加筋作用,并利用其揭示了根系形状对边坡的变形与破坏机理的影响。为保证研究的基础性和实用性,选取了百慕大草和鸭脚木树两种代表性植物,并考虑了种植间距与真菌等因素的影响。主要研究结果揭示:(1)植物在干燥与降雨条件下均能明显提高土体吸力,提高边坡稳定性;(2)植物引起的土体吸力可以用叶片面积指数和根表面积系数等植物特征参数量化,并且鸭脚木树的叶片面积指数和根表面积系数之间存在着线性关系;(3)真菌能显著提高植物根系的抗拉强度,加强植物的力学加筋作用;(4)所研究的4种根系形状中,指数形根最有利于提高边坡稳定性。上述研究包括室内试验、现场监测、离心机试验和理论建模等方面,建立了一套科学合理的理论框架与测试方法,并为植物护坡的工程实践和“海绵城市”的建设提供科学依据。
Plants are natural engineers and have the potential to prevent shallow landslides and surface erosion, with the advantages of low input, easy maintenance, green and ecological balance. At present, most researches and engineering practices both at home and abroad only consider the mechanical reinforcement effect of plant roots, while neglecting the more important hydraulic effects. Plant transpiration can increase the soil suction, thus reducing the soil permeability coefficient and increasing the shear strength, so it can improve the slope stability and prevent the surface erosion. Based on the theory of unsaturated soil mechanics and plant characteristics, the author’s interdisciplinary research team studies the interaction mechanism between atmosphere, vegetation and soil fundamentally, proposes a new theoretical model to predict the water holding capacity of vegetation soil, A new model of groundwater seepage coupled with surface runoff considering the influence of plant root shape is derived. An analytical solution to calculate the safety distribution of suction distribution and stability of vegetation slope is derived. The exponential, triangular, uniform and oval 4 And the typical root shape. The artificial root used in the model test of the centrifuge was developed independently, which can simulate the hydraulic effect and the mechanical stigma of the roots of different shapes, and revealed the deformation and destruction of the slope by the root shape Mechanism of influence. In order to ensure the basicity and practicability of the study, two representative plants, Bermudagrass and Aralia elata, were selected, and the effect of planting spacing and fungi was considered. The main results show that: (1) The plants can significantly improve soil suction and improve slope stability under dry and rainfall conditions; (2) Plant-induced soil suction can be characterized by plant features such as leaf area index and root surface area coefficient Parameters were quantified, and there was a linear relationship between leaf area index and root surface area coefficient of A. canadensis; (3) fungi can significantly increase the tensile strength of plant roots and strengthen the mechanical reinforcement of plants; (4) Of the four kinds of root shape, exponential root shape is most conducive to improving slope stability. The above research includes a set of scientific and reasonable theoretical framework and testing methods in laboratory test, on-site monitoring, centrifuge test and theoretical modeling, and provides scientific support for plant slope protection engineering practice and “sponge city” construction in accordance with.