多因作用下南方红土区锚-土界面蠕变规律与锚固边坡蠕滑致灾机理及其应用

The intense infrastructure construction in red soil region of Southern China have formed a large number of high and steep (prestressed) anchored red soil slopes, of which, the creep characteristic of anchor and the long-term slope stability is relevant directly to the safety of infrastructure and the neighboring environment, even the people’s life and property. For this reason, this project is going to firstly develop element analysis-based testing technique and instruments for anchor-soil interface creep characteristic, and conduct a majority of creep tests to get the creep curve, the creep constitutive model, the creep equation, the relaxation equation, the long-term strength, and the trigger factor of creep-induced failure with its corresponding value for anchor-red soil interface subjected to multiple factors; secondly the creep pattern, the critical safe bearing capacity and the creep-induced failure mechanism for the engineering anchor under the application of multiple factors in the southern red soil region would be achieved through the anchor model test and numerical simulation analysis; then laboratory tests would be used to obtain the creep curve, the creep constitutive model, the creep equation and the long-term strength of typical red soil in southern red soil region; finally, by the employment of numerical simulation analysis, the creep mode and the disaster-inducing mechanism of the anchored red soil slopes with different retaining types subjected to multiple factors would be revealed, and the computational methods for the long-term stability analysis of anchored red soil slopes will be established. The research achievements can be applied to provide reliable theoretical reference for the stability evaluation of anchored red soil slopes and the calculation of new slope design in southern humid region.

我国南方红土区密集的基础工程设施建设，形成了大量高陡（预应力）锚固红土边坡，其中锚杆的蠕变特性和边坡的长期稳定性，直接关系到基础工程设施本身及其周边环境、甚至人民的生命和财产的安全。为此，本项目拟首先开发基于微元法锚-土界面蠕变性能测试技术和装置，通过大量蠕变试验获得多因作用下锚固体-红土界面的蠕变曲线、蠕变本构模型、蠕变方程、松弛方程、长期强度、以及蠕滑破坏触发因子及其临界量值；然后，基于锚杆模型试验和数值模拟分析，得到多因作用下南方红土区工程锚杆的蠕变规律、临界安全承载力和蠕滑破坏机制；其次，通过试验获得南方红土区典型红土的蠕变曲线、蠕变本构模型、蠕变方程和长期强度；最后，基于大量数值模拟计算，揭示多因作用下不同支护形式锚固红土边坡的蠕滑模式和致灾机理，并提出其长期稳定性分析计算方法。研究成果可为南方湿润区既有锚固红土边坡的稳定性评估和新边坡的设计计算提供可靠的理论依据。

我国南方红土区的密集工程建设形成了大量高陡锚固红土边坡。控制好锚杆锚固段在荷载、土体含水率变化等诸多因素作用下的蠕变变形是保证锚固红土边坡长期稳定的关键，而目前对此缺乏系统深入的研究。针对该难题，本项目从室内单元试验、模型试验、理论分析和数值模拟等方面入手，对红土土层锚杆在多因素作用下的蠕变特性展开了系统深入的研究，主要研究内容和重要结果如下：. （1）设计改装了土的三轴蠕变试验仪，以此开展了多因（包括土体含水率和干密度、围压等）作用下的红黏土三轴蠕变试验，获得了红黏土的长期强度随各影响因素的变化规律，建立了红黏土固结-蠕变耦合模型和多因作用的红黏土蠕变模型，如ANFIS神经网络蠕变模型和改进Burgers模型等。. （2）发明了模拟地层压力作用的锚-土界面粘结性能测试系统和桩/锚-土界面多工况扭剪特性测试装置。研制出锚-土界面蠕变特性和锚-土界面松弛特性测试装置，以此开展了多因（土体含水率和干密度、注浆压力）作用下锚固体-红黏土界面剪切蠕变试验和界面剪切松弛试验，揭示了锚固体-红黏土界面长期抗剪强度随各影响因素的变化规律，建立了多因作用下的锚固体-红黏土界面剪切蠕变模型，如基于分数阶导数的Burgers模型、RBF神经网络蠕变模型和基于Kriging方法的蠕变模型等。. （3）开展了水泥土中钢管拉拔模型试验，获得了水泥土锚杆拉拔P-s曲线。开展了红黏土层中全长粘结锚杆大尺度瞬时和蠕变拉拔模型试验，获得了红黏土土层锚杆瞬时拉拔P-s曲线、锚头位移蠕变曲线、轴力及剪应力沿锚杆杆体分布时变曲线等。. （4）提出了新的锚杆荷载传递分析模型和分析方法，以此开展了瞬时荷载下锚杆受力变形分析。引入锚-土界面剪切蠕变本构模型，以此开展了土层锚杆受力变形时变特性理论分析，由此获得了锚头拉拔蠕变曲线、锚杆轴力及剪应力沿杆体分布时变曲线的分析计算方法。. 本项目研究成果可为南方湿润区既有锚固红土边坡长期稳定性评估和新边坡的设计计算提供了可靠的理论依据。