黄土的孕灾力学行为与工程灾变机理研究

A variety of geology disasters of loess is closely related to the special medium structure, geological structure of medium and many external action including moisture increasing and loading etc. According to the evolvement of structural property of loess and its geological structure interface characteristics, the relationship among structure index of loess, the degree of water sensitivity, the degree of disturbance sensitivity and the soil characteristics is explored by considering the influence of hydraulic action, submerging ,wetting, loading, and dry-wet, freeze-thaw cycles, corrosion. In order to reveal the structure property and the change law of strength, deformation and hydraulic corrosion with reflecting the gestating disaster mechanism, the relationship between the structure index, degree of water sensitivity, degree of disturbance sensitivity.and the water sensitivity, rheological character, anisotropic character, damaging and so on reflecting the gestating disaster mechanics behaviors is also explored by the many kinds of experiments. Moreover, the geology disaster behaviors including the collapsibility, fissures, erosion, creep, cracks is investigated by the model testing and numeric method. The strength theory, the constitutive model and hydraulic erosion of structural loess under the action of water and force is proposed, so as to analyzing the development mechanism of slip, landslide,collapse, subsidence, ground fissures, and the catastrophe evolution of the loess foundation, slope, tunnel under watering (submerging, wetting, hydraulic power),loading (excavating, wet weight, penetration force) and weathering (drying-wetting cycle, freeze-thaw cycle, corrosion). For the collapse loess foundation with filling soil stratum, loess tunnel with large section and loess excavating high slope, the disaster evolvement mechanism is studied by considering the disturbance mechanism of loess engineering and geological structure. The preventing and controlling theory for loess engineering disaster is explored.

黄土的多种灾变与其介质的特殊结构和地质结构，以及湿、载等多种外在营力作用密切联系。从反映黄土的结构性及其地质结构面特性出发，考虑水（浸水、增湿、水力）、力（卸荷、湿重、渗透力）加载作用，以及风化作用（干湿循环、冻融循环、矿物溶蚀），研究黄土构度及其浸水灵敏度和扰动性灵敏度与土性之间的关系，以及构度、浸水灵敏度和扰动灵敏度与水敏性、流变性、各向异性和破损性等孕灾力学特性之间的关系及其湿陷、裂隙、冲蚀、蠕变和裂缝等灾变行为，揭示黄土结构性与反映孕灾力学行为的强度、变形、水蚀特性变化规律，建立水与力作用下结构性黄土的强度理论、本构模型、水蚀演变关系；进而研究水、力和风化作用下，考虑黄土地质结构体响应的土体工程的滑移、崩塌、塌陷、沉陷、地裂缝等灾害的孕育机制，以及针对黄土高填方地基、挖方高边坡、大断面湿陷性黄土隧道为主要对象的工程灾变演化，为应对黄土工程灾变建立防控理论基础。

黄土在水力（入渗、增湿）、水理（侵蚀、崩解、溶蚀）和加载（卸荷、湿重）耦合作用下的结构性演变、地质结构面发育，表现出湿陷、塌陷、地裂、滑移的孕灾力学行为。从反映黄土的结构性与地质结构面特性出发，考虑研究黄土构度及其浸水灵敏度和扰动性灵敏度与土性之间的关系，以及构度、浸水灵敏度和扰动灵敏度与水敏性、湿陷性、各向异性和破损性等力学特性之间的关系，揭示黄土结构性和结构面与强度、变形、侵蚀特性变化规律，建立水与力作用下结构性黄土的强度理论、本构模型、侵蚀演变关系；进而考虑黄土地质结构体响应的土体滑移、崩塌、塌陷、沉陷、地裂缝等灾害的孕育机制，研究黄土挖填方高边坡、大厚度湿陷性黄土地基及其隧道工程的工程演化，建立黄土工程灾变分析方法与防控技术，具有重要的理论与实践意义。.在土的综合结构势原理基础上，提出了黄土结构性的构度指标，揭示了其与黄土物理性质指标之间的关系。建立了黄土构度与压缩屈服关系基础上的边界面本构模型，以及构度与土水特性和压缩屈服关系基础上的非饱和黄土本构模型。通过水气运动规律考虑与否的途径，建立了增湿结构性衰减演变的总应力渐进破坏分析方法和双应力状态量的固结湿陷渐进破坏分析方法。分析了黄土高边坡增湿作用下变形发展规律和构度分布场特征，黄土隧道应力场分布、构度场分布和塌陷破坏力学机理，以及黄土地基的湿陷变形变化规律。提出了非饱和黄土的总应力强度准则和考虑基质吸力变化影响的净应力强度准则。在平面应变条件下提出了反映黄土构造裂隙特征的土压力公式，论证了黄土直立边坡存在的条件，和浸水增湿可能崩塌的内因。揭示了黄土隧道湿陷变形与衬砌结构的相互作用，隧道地基湿陷变形的附加作用和结构破坏特征。为揭示黄土工程中侵蚀冲沟发育、不均匀湿陷变形诱发地裂缝发展、滞水带软化剪切滑移、结构面发展和潜在滑移面形成的孕灾演变力学机制，提供了理论基础。