受三趾马红土控制的黄土滑坡滑带土的非饱和蠕变特性研究

In northwest China, the loess landslides controlled by hipparion red clay are usually with wide distribution, large scale and strong harmfulness. The formation of this type loess landslide is closely related to the creep behaviors of Pliocene hipparion red clay as the sliding-zone soil. At present there are fewer researches on the quantitative relationship between creep characteristics of hipparion red clay and evolution mechanism of landslide formation, but all on the engineering geologic features of hipparion red clay with qualitative analysis. Therefore, based on the typical loess landslides controlled by hipparion red clay in northwest China, the hipparion red clay is taken as the research object with a method of combining experimental test and theoretical analysis in order to study the creep characteristics and long-term strength of hipparion red clay. Then an unsaturated creep test will be conducted to obtain the creep characteristic and long-term strength indicators of hipparion red clay under different matrix suctions. Based on this, by the theory of unsaturated soil mechanics, rheological mechanics, creep models, an unsaturated creep constitutive model involving stress-strain-time-matrix suction would be established, and an unsaturated long-term strength formula for hipparion red clay would be deduced, which will provide some theoretical explorations and test accumulations for analysis of creep mechanism , stability evaluation and time prediction for instability of the loess landslides controlled by hipparion red clay.

我国西北地区受三趾马红土控制的黄土滑坡分布广、规模大、危害性强，其滑带通常为上新世三趾马红土，此类黄土滑坡的形成与三趾马红土的蠕变行为有密切的联系，但目前针对三趾马红土的研究基本以定性分析其工程地质特性为主，定量开展其蠕变特性及其与黄土滑坡形成演化机理内在联系的研究鲜见。为此以我国西北地区典型受三趾马红土控制的黄土滑坡为例，选取三趾马红土为研究对象，运用试验测试与理论分析相结合的方法详细研究其蠕变特性及长期强度问题。重点开展三趾马红土的非饱和蠕变试验研究，在充分掌握三趾马红土不同基质吸力下的蠕变特性及长期强度指标基础上，利用非饱和土力学、流变力学、蠕变模型等理论，建立其包含应力-应变-时间-基质吸力的非饱和蠕变本构模型，并推导出三趾马红土的非饱和长期强度公式，为此类滑坡蠕滑机理分析、稳定性评价、滑坡失稳时间预测提供理论探索和试验积累，具有重要的理论意义和实用价值。

我国西北地区受三趾马红土控制的黄土滑坡分布广、规模大、危害性强。本课题以我国西北地区典型受三趾马红土控制的黄土滑坡为例，选取三趾马红土滑带为研究对象，运用试验测试详细研究其非饱和特性，重点开展三趾马红土的非饱和蠕变试验研究。通过开展三趾马红土水敏特性研究、非饱和强度特性研究、非饱和蠕变特性研究、非饱和长期强度研究，取得以下研究成果和发现：（1）三趾马水敏特性研究表明，三趾马红土含水状态对其土水特性、吸水特性、崩解特性、固结变形与失水干缩特性影响显著，分别影响其基质吸力变化、崩解速率、吸水质量、固结变形尺度与裂缝愈合速度；（2）三趾马红土非饱和强度特性研究表明，随含水率减小、干密度及围压的增大，三趾马红土应力-应变曲线由应变软化型向应变硬化型转化，试样峰值应力及弹性模量均增加；（3）三趾马红土非饱和蠕变特性研究表明，三趾马红土蠕变特征明显，蠕变曲线呈现非线性，含水率及干密度对蠕变特性影响显著。分别建立并对比分析 Singh-Mitchell蠕变模型、Mesir蠕变模型、自定义模型以及元件模型对三趾马红土蠕变行为的预测精度，发现元件模型很好拟合三趾马红土的蠕变特性；（4）获取了三趾马红土不同状态下的长期强度，表明其在长期荷载作用下强度衰减特征显著，干密度、含水率、围压均对长期强度损失率有明显影响。研究成果为分析与评价受三趾马红土控制的黄土滑坡蠕滑机理、稳定性评价、滑坡失稳时间预测提供理论探索和试验积累，具有实用价值。