【作者】 李丽；

【导师】 邓亚虹；

【作者基本信息】 长安大学 ， 地质工程， 2013， 硕士

【摘要】 汾渭盆地是我国乃至世界上地裂缝最为发育，灾害最为严重的地区。区内地裂缝多发育于黄土介质中，黄土的物理力学性质和地层结构为地裂缝的发育提供了独特的孕裂基础。研究隐伏地裂缝在近地表的破裂扩展模式，对地裂缝的预测预警和工程灾害防治具有重要的理论和实际意义。以往对地裂缝成因机制和破裂扩展机理的研究大都基于经典弹塑性力学和弹性断裂力学理论，大型物理模型试验和数值模拟结果均显示隐伏地裂缝的破裂扩展具有反倾特征，这与实际地裂缝剖面结构揭示的倾向一致性不符。这就需要考虑在漫长的地质历史过程中，黄土的蠕变及长期强度等力学特性对地裂缝的破裂扩展模式的影响。基于此，本文以汾渭盆地地裂缝为研究背景，以西安地区长安地裂缝（fc1）金滹沱探槽东壁的Q₃原状黄土为研究对象，开展了地裂缝带Q₃原状黄土的三维流变本构及长期强度的研究。首先，通过常规三轴压缩试验，揭示了地裂缝带Q₃原状黄土的应力应变关系曲线特征及其破坏模式，并得到了不同应变量对应的抗剪强度值及其对应的抗剪强度参数。其次，通过三轴循环加卸载蠕变试验，分析了地裂缝带Q₃原状黄土的蠕变曲线及应变速率与时间关系曲线特征，并基于统一流变力学模型理论，得到了地裂缝带Q₃原状黄土的三维流变本构模型，建立了模型的本构方程，辨识出了模型参数。最后，基于蠕变试验结果，构建了地裂缝带Q₃原状黄土的“分数-线性”形式的长期强度曲线，获得了相应的长期强度方程，进而得到了长期强度及其强度参数。上述成果为隐伏地裂缝破裂扩展模式及其力学机理的理论和数值模拟研究，为隐伏地裂缝场地灾害的预测预报以及建（构）筑物的合理避让和灾害防治奠定了基础。更多还原

【Abstract】 The Fen-Wei basin can be the most developed area of ground fissures and the associatedgeo-hazard in China and even in the world. Most of ground fissures development in the loessmedium. The physical and mechanics properties and stratigraphic structure of loess provides aunique pregnancy basis for the growth of ground fissures. Studying fracture extension modelin near surface of the concealed ground fissures will be significance of theoretical andpractical for forecasting and early warning and engineering disaster prevention and control. Inthe past, most of the study of ground fissures formation mechanism and fracture extensionmechanism were based on the classical elastic-plastic mechanics and elastic fracturemechanics theory. The numerical simulation and physical model test come to a conclusionthat the concealed ground fissures in the near-surface rupture expansion were counter-inclined,which not agree with the actual profile structure. This will need to consider in the longgeological history process, the creep and the long-term strength mechanism of loess influencethe crack fracture extension model.Based on this, the paper take the ground fissures of Fen-Wei basin as the researchbackground, on the object of Q₃undisturbed-loess which is located in the east of Jin Hutuoexploratory trench wall of Chang an ground fissure （fc1） in Xi’an region, researched onthree-dimensional rheological constitutive and long-term strength of Q₃undisturbed-loess inground fissure belt. First, through the conventional triaxial compression test, revealedcharacteristics of the stress-strain relationship curve and failure mode of Q₃undisturbed-loessin ground fissure belt, and got shear strength values in different variables and the shearstrength parameters. Second, through the triaxial cyclic loading and unloading creep test,analyzed characteristics of the relation test curve of Q₃undisturbed-loess in ground fissurebelt, and based on uniform rheological mechanics theory, obtained the three-dimensionalrheological constitutive model of Q₃undisturbed-loess in ground fissure belt, established theconstitutive equation of the model and identified the model parameters. The last, based on thecreep test results, built the long-term strength curve in forms of "scores-linear" of Q₃undisturbed-loess in ground fissure belt, obtained the long-term strength equation, and then got the long-term strength and the strength parameters.These achievements for study of concealed ground fissures extension model andmechanical mechanism of the theory and numerical simulation, for concealed ground fissuresprediction and the build （structure） of the reasonable avoidance and hazard prevention laid afoundation.更多还原