摘要
植物根系经历生长―成熟―衰亡的生命周期,但这一动态过程对根-土复合体力学性能的影响却长期受到忽视。植物根系衰亡对根-土复合体力学性能的长期劣化作用是生态护坡工程耐久性评估的关键问题。以福建省武平县马尾松覆盖的斜坡为研究对象,通过单根拉伸试验与根土复合体大型直剪试验,系统探究根系衰亡动态过程中力学特性及根-土复合体抗剪强度的演变规律。结果表明:马尾松根系抗拉强度与极限抗拉力随衰亡历时呈指数衰减趋势,其中衰亡初期为快速下降阶段,抗拉强度降幅达30%~50%,衰亡后期退化速率趋于平缓。根-土复合体抗剪强度受根系衰亡影响显著,附加黏聚力随衰亡历时推进而逐步减小,而内摩擦角变化不显著。基于试验数据,建立了根系抗拉强度幂函数模型与抗剪强度指数衰减模型,并修正Wu模型引入附加黏聚力衰减系数,定量表征根系衰亡对根-土复合体抗剪强度的时变效应。研究揭示了根系衰亡削弱自身固土能力的机制,为生态护坡工程长期稳定性评估及维护决策提供了理论依据。
Plant roots undergo a life cycle of growth,maturation,and decay,yet the effect of dynamic process of this cycle on the mechanical behavior of the rootsoil composite have been largely overlooked.Long-term deterioration of rootsoil mechanical properties caused by root decay is a critical consideration in assessing the durability of ecological slope-protection structures.Using Masson pine-covered slopes in Wuping County,Fujian Province as the study subject,this paper employs single-root tensile tests and large-scale direct shear tests on rootsoil composites to systematically investigate the evolution of root mechanical properties during mortality dynamics and the corresponding changes in the shear strength of the rootsoil composite.The results show that the tensile strength and ultimate tensile force of Masson pine roots decrease exponentially with decay duration.In the early stage of decay tensile strength declines rapidly by 30%50%,after which the degradation rate gradually levels off.Root decay significantly affected the shear strength of the rootsoil composite:the root-conferred additional cohesion decreases progressively with decay duration,whereas the internal friction angle remains essentially unchanged.Based on the experimental data,we developed a power-law model for root tensile strength and an exponential-decay model for composite shear strength.We further modified the Wu model by introducing a cohesion-decay coefficient to quantify the decay-duration-dependent reduction in shear strength.These findings clarify the mechanism by which root decay undermines soil reinforcement and provide a theoretical basis for long-term stability assessment and maintenance planning of ecological slope-protection projects.
作者
吴宜龙
简文彬
林昀昭
朱祖腾
郑国明
WU Yi-long;JIAN Wen-bin;LIN Yun-zhao;ZHU Zu-teng;ZHENG Guo-ming(Institute of Geotechnical and Geological Engineering,Fuzhou University,Fuzhou,Fujian 350108,China;Key Laboratory of Geohazard Prevention of Hilly Mountains,Ministry of Natural Resources,Geological Engineering Survey inFujian Province,Fuzhou,Fujian 350002,China;Fujian Institute of Geological Survey,Fuzhou,Fujian 350013,China)
出处
《岩土力学》
北大核心
2026年第1期140-148,159,共10页
Rock and Soil Mechanics
基金
国家自然科学基金(No.U2005205)。
关键词
根系衰亡
根-土复合体
单根拉伸试验
大型直剪试验
浅层滑坡
root decay
root-soil composite
single-root tensile test
large-scale direct shear test
shallow landslide
