硬粘土深挖方边坡长期软化机理及其数值模拟

Longterm seepage and displacement coupled simulation will be conducted on the deep cut slopes in stiff clay in this research. The consitutive relationship in which strain softening features of stiff clay is simulated, and a corresponding computation method in which rapid convergence can be reached will be studied. The act effect of wet and dry cycles on softening of cut slopes will be explored. The lonterm displacement and failure mechanism of will be discussed with consideration of the over consolidation effect, evaporation and infiltration, unsaturated seepage, cracks and excavation process.

本项目拟进行深挖方条件下的硬粘土开挖边坡长期渗流和变形的耦合模拟，研究能够反映硬粘土应变软化特性的本构模型和与之适应的数值上快速收敛的软化过程计算方法，探索干湿循环对硬粘土边坡软化发展的贡献机制。研究工作将全面考虑超固结特性、蒸发和入渗、非饱和渗流、裂缝、开挖过程等对硬粘土深挖方边坡长期软化过程的影响，探索边坡的长期变形和破坏机制。

项目系统研究了密度、干湿循环、裂缝发展等对渗透和强度等特性的影响规律，开展了人工控制干湿循环大比尺硬粘土边坡物理模型试验，建立和追踪了干湿循环过程的全域精细变形场及发展历程，考虑了非饱和渗流过程、加卸荷循环、蒸发入渗强度、裂缝发展，分析了超固结、裂缝、胀缩特性等硬粘土固有特性等对边坡性态的影响，揭示了干湿循环引起变形累积的边坡破坏机制。开展了不同初始应力条件下循环球应力作用导致的土体变形累积机制试验研究，发现了循环球应力历史可能导致组构变化，进一步导致体积变形和剪切变形累积。研究了施工过程中无保护条件下硬粘土边坡的稳定性和应力变形演化过程，引入亚塑性模型模拟了土体非线性响应过程，形成了考虑蒸发入渗循环与应力变形耦合的硬粘土边坡模拟方法，对衬砌和加筋等加固防护条件下硬粘土开挖边坡性态发展和加固机理开展了数值分析，为工程中加固措施的采用提供了科学依据。