傲慢与偏见作者
摘要
含水量对黄土强度特性影响的研究
文章作品摘要
黄土高原地区易发生滑坡、崩塌等地质灾害，极大地危害了人类的生命安全，同时给经济发展带来惨重损失，因此研究黄土的强度特性及黄土滑坡的诱发机制具有重要意义。究其本质，黄土是一种土颗粒间黏结作用力易受外界因素影响的粉质土-粉质黏土。作为一种特殊土，黄土具有大孔隙、垂直节理发育、遇水湿陷、沉积层理不明显等特点，同时，由于黄土层与其下覆地层（如风化泥岩层、河流冲积黏土层等）物理性质、水理及强度变形方面的差异性，在降雨或灌溉等水的作用下，易发生滑坡。
本文从水对黄土强度特性影响的角度出发，以泾河南塬典型黄土为主要研究对象，在对黄土滑坡灾害进行野外地质调查、室内试验基础上，系统研究了水对黄土强度弱化的作用规律，最后结合典型黄土滑坡实例，分析其滑动特征，并探讨其诱发机制。本文主要内容如下：
（1）通过对探井不同深度处原状土样的直剪试验，研究了土体在不同含水率状态
下的变形破坏特征和强度弱化规律，分析发现：土体含水率升高时，土体的应变特征
逐渐由应变软化型过渡到应变硬化型，且固结正应力水平的提高使土体的应变硬化特
性更加明显；水对低含水率土样的抗剪强度软化效应比对高含水率土样更明显，水分
对黄土强度弱化作用的内在机制是使黄土颗粒间的胶结作用弱化，并且水对土颗粒间
错动时的摩擦阻力大小无影响。
（2）通过开展原状土体的残余剪切试验，研究了土体的残余强度及变形特征，发
现研究区内的天然黄土第一次剪切破坏时不具有应变软化特征；土体的强度随剪切位
移呈增长趋势，并且土体的残余强度特性主要取决于土粒颗粒间的胶结作用，而不受
颗粒错动时摩擦阻力影响；原状土体的重塑过程使土体的残余黏聚力降低，残余摩擦
角则基本不变。
（3）通过对重塑土样的直剪试验，研究了黄土的结构强度特征，发现土体含水率
越低，结构强度越高；当土体呈现应变软化特性时，土体具有结构强度，呈现应变硬
化特征的土体不具有结构强度。
（4）通过野外地质调查，针对一个典型的滑坡实例，系统分析了高速远程黄土滑
坡的滑动特征，认为对于此类黄土滑坡的诱发机制可以从上部拉裂破坏区、中部剪切
破坏区、下部饱和土体静态液化区三个方面分析。
上述研究成果对研究水入渗作用下黄土强度的弱化规律具有一定的实用和指导价值，并加深了黄土滑坡形成机理的认识。
关键词：黄土滑坡；含水量；抗剪强度；残余强度；结构强度；高速远程滑坡
INFLUENCE OF MOISTURE CONTENT ON SHEAR
STRENGTH OF LOESS
ABSTRACT
Landslides, falls and other geo-hazards are very common in the Loess Plateau, which can bring great harm to the safety of human life and economic development. Therefore, a study of shear strength characteristics of loess and causative mechanism of loess landslides is esntial. Loess is
a kind of silt-silty clay, which is easily influenced by the external factors. Characterid by the large pores, vertical joints, collapsibility due to wetting, loess is a kind of problematic soil. In addition, due to the differences in physical properties, hydraulic properties and strength parameters between Loess and its underlying strata, such as weathered mudstone, alluvial red clay, loess landsliding is prone to occur under the condition of rainfall or irrigation.
From the perspective of the influence of moisture on shear strength of Loess, I lected the Loess in the south of Jingyang as the main rearch object, the relationship between shear strength with the moisture contents has been systematically investigated bad on geological survey and laboratory tests. Finally, the causative mechanism and physical of a typical loess landslide were analyzed.
黄河文化First, the deformation and failure characteristics of shear strength parameters were studied through direct shear tests on undisturbed loess samples with different moisture contents taken at different depth, and it can be concluded that the stress-strain behavior of the soil changed from strain softening to the strain hardening, with an increa in moisture content. Also, the increa of the normal stress renders the strain hardening of the soil more obvious .The effect of moisture content on the soil shear strength of the soil sample with low moisture content is more obvious compared with the soil sample with high moisture content. In short, the intrinsic mechanism of the weakening ef
fect of moisture content on shear strength of loess is to weaken the cementation between the particles, rather than the friction between particles.
Second, bad on the of reversal direct shear tests of undisturbed soil, the residual strength has been studied. It can be concluded that at first shear failure of the Loess, the strength of the soil increas with the shear displacement, and the residual strength of the soil is controlled by the cementation between the soil particles, rather than the friction resistance of the particles.The destruction of soil can lead to a decrea in the residual cohesion, while the residual internal friction angle remains unchanged.
Third, the structural strength of loess is studied by direct shear tests on soil samples, and it can be concluded that the lower the soil moisture content, the higher the structural strength ; Furthermore,when the soil of strain softening behavior, the structural strength can be played.
Finally, bad on the field geological survey, causative mechanism and physical process of a typical high speed landslide-with long runout distance were analyzed. The failure process can be divided into tensile damage zone in the upper part, the shear damage zone in the middle part and the saturated static liquefaction zone in the lower part.
少林达摩
KEY WORDS: Loess landslide;Moisture content; Shear strength; Residual strength；Structural strength;High-speed landslide with long runout distance伦敦的景点
目 录
摘要........................................................................................................................................... I ABSTRACT ................................................................................................................................ I 1 绪论. (1)
1.1研究背景和意义 (1)
1.2问题的提出 (1)
1.3国内外研究现状及存在问题 (2)
1.3.1 黄土的物理性质研究 (2)
1.3.2 黄土微观结构特征研究 (2)
1.3.3 原状黄土的结构性研究 (3)
总胆汁酸偏高的原因
1.3.4 饱和黄土的渗透性研究 (4)
1.3.5 饱和、非饱和黄土的力学特性研究 (4)
1.3.6 土体细观特性的数值试验研究 (7)
1.3.7 基于研究现状的思考 (8)
1.4研究内容 (9)
1.5技术路线 (9)
形容彩虹的诗句
2 研究区地质环境条件 (11)
2.1研究区工程地质条件 (11)
2.1.1 地理位置 (11)
2.1.2 地形地貌 (11)
2.1.3 地层岩性 (11)
2.1.4 地质构造 (13)
2.1.5 气象水文 (13)
2.1.6 水文地质条件 (14)
2.2黄土的基本物理、水理性质 (14)
2.2.1 试验取样 (14)
2.2.2 基本物理性质 (15)
2.2.3 水理性质 (20)
2.3小结 (21)
3 黄土抗剪强度的试验研究 (23)
3.1不同含水量条件下黄土强度特性试验研究 (23)
3.1.1 试验方案 (23)
3.1.2 剪切破坏行为 (26)
3.1.3 不同含水量条件下抗剪强度变化特征 (29)
3.2黄土残余强度特性试验研究 (34)
3.2.1 试验方案 (34)
3.2.2 土样埋深对残余强度特性影响 (34)
3.2.3 含水率对残余强度特性影响 (38)
3.2.4 土体结构性对残余强度特性影响 (42)
3.3黄土结构强度特性试验研究 (43)
3.3.1 试验方案 (44)
3.3.2 重塑土剪切行为 (44)
contractual3.3.3 水对土体结构性影响 (45)
3.4小结 (47)
4 高速远程型黄土滑坡的滑动特征及诱发机制分析 (49)
4.1基本概况 (49)
4.2滑坡特征 (50)
4.2.1 滑坡形态特征 (50)
4.2.2 拉张裂缝 (53)
4.2.3 前缘挤压 (53)
4.2.4 地下水位 (54)
4.2.5 盐分 (55)
4.3滑动机制 (55)
4.3.1 上部拉裂区 (56)
4.3.2 中部剪切区 (56)
4.3.3 下部静态液化区 (59)
4.4小结 (60)
5 结论及展望 (61)
5.1结论 (61)
5.2展望 (62)
攻读硕士期间的学术论文及参与项目 (63)
致谢 (65)
参考文献 (67)
