【作者】 张全胜；

【导师】 杨更社；

【作者基本信息】 西安科技大学 ， 岩土工程， 2003， 硕士

【摘要】 在寒区岩土工程中，岩体中含有一定量的水，冻结后，水冰相变体积膨胀，产生巨大的冻胀力，岩体成为水、冰、岩，气的多相损伤介质。这种不均匀的冻胀力和冻胀变形对岩体工程稳定性产生重要的影响。本文的主要工作就是在国家自然科学基金(10072047，10202019)的资助下，针对西部大开发中的岩石冻融这一突出问题而提出来的。从细观损伤力学理论出发，利用CT识别先进的试验技术研究岩石在冻结融化过程中，水分的迁移，冰的形成，内部细观损伤扩展机理及相应损伤结构的变化。在研究过程中本文主要做了以下工作：(1)针对岩石损伤变化较小时，运用CT均值和方差分析不方便的缺陷，本文提出运用对CT数范围划分区段的方法，根据各区段统计频率的变化规律来分析损伤扩展状况；(2)针对岩石受到外部作用的多变性，本文提出了基准损伤，正损伤，负损伤的概念，在某种程度上考虑了岩石受到外部作用时的压密情况；(3)现有的基于CT数的损伤变量大多需要用到岩石基体的CT均值，这实际上是很难观测到的，因此本文建议了一个可运用岩石初始状态CT均值的损伤变量，由于现有的勒迈特教授应变等价原理使用上的不便，本文在其基础上进行了推广；(4)建议了一个可用岩石初始状态CT数和弹性模量的单轴损伤本构方程，并用算例进行了验证；(5)对两种不同岩石在开放环境下受到冻融循环作用且融化过程中补水时，内部损伤随冻融循环次数增加的扩展规律进行了探讨，主要运用了常规的CT均值和CT方差的分析方法进行分析，试验发现：对于孔隙率和含水率较高，密度和强度较低的软弱岩石，冻融循环次数对损伤结构的扩展有明显的影响，而对于孔隙率和含水率较低，密度和强度较高的硬岩，冻融循环次数对其损伤结构扩展初期由于含水率低的原因，影响不是太大，而后期由于水补给后，含水率较高的原因，冻融影响逐渐增大；(6)运用了本文提出的区段划分和统计频率的方法，深入地分析了开放环境下的线性温度变化的冻融循环次数，冻结温度，冻结速度不同岩石作用时，其内部损伤随冻融循环次数，冻结速度和冻结温度变化的扩展规律，需要指出的是除了在试验前饱水外，冻融过程中没有补水。试验发现，对于强度较大，颗粒孔隙闭合程度较高时最初的几次冻融循环对损伤的扩展起着主导作用，而后逐渐趋于恒值;而对于强度较低，孔隙贯通程度较高，离散性较大的软砂岩，随着冻融循环次数的增加，损伤变量增大，由于本次试验冻融次数有限，未能观察到冻融循环次数较高时的损伤变量变化情况。试验研究表明冻结温度对损伤有一定的影响。主要是由于岩石中的水融有一定量的盐类物质，盐类物质的存在及其含量的差异使的水分的冰点具有一定的可变性，而岩石材料本身具有热胀冷缩的性质。对于强度较高，孔隙连通性低且含水率较低的的硬岩，在冻结过程中基本上是以岩石的收缩占主导地位。而对于次硬岩，由于层理面的存在，水分很容易散失掉，在冻结过程中由饱水到冻结到0℃时是以水分的迁移散失占主导地位，而在冻结到一10℃和一20℃时都是以岩石的收缩占主导地位。至于孔隙率较高且连通性较高的软砂岩则以颗粒重组和收缩占主导地位，岩石密度增大。研究表明冻结速度对岩石损伤扩展也有一定影响。对于岩石强度较大，孔隙贯通程度较小的硬岩，冻结速度对其影响最大，冻结后岩石整体上密度呈增大的现象，但增大的程度跟冻结速度成反比。具有层理结构的次硬岩内部损伤扩展也受冻结速度的影响，整体上岩石密度呈减小的现象，但减小的程度跟冻结速度成反比。强度较低，颗粒间粘结力较弱，孔隙贯通程度较高的软砂岩在受到冻结时其密度会有所增加，但增加程度几乎不受冻结速度的影响。(7)一定假设的基础上运用弹性理论分析了软岩体在冻结后及冻融循环后的冻胀力大小，由于现场情况和本文假设的理想情况有一定的出入，所以本文计算的结果只能定性代表冻胀力发展趋势。更多还原

【Abstract】 In the cold geotechnical engineering, when the rock containing a mount of water was frozen, the inner water swells, and the freezing swollen force is emerged, in turn the rock became a multi damage material containing water, ice, air, rock. The freezing force and deformation have a important role in the stability of rock engineering. In this paper, the major work is posed according to the accentuated problem in the west development. The research method is concerned with freezing test, CT scanning and damage mechanics analysis. Based on the damage mechanics theory, during the freezing and thawing, the CT measurement technology is used to observe the water transference, ice formation, inner microdamage propagation principle and the corresponding damage structure variability. The following is done:(1)it is difficult to analyzed damage variables which is very little, therefore, a new method of CT number division is put foreword, in which damage evolution is reflected by the statistical frequency. (2)because of the variability of rock subjected to outside action, three new conceptions: postive damage basic damage and negative damage, are suggested, which can deal with the condition that rock density became large.(3)the present damage variables based on CT number mostly include CT average number of the rock without damage, which is difficult to measure, so a new damage variable, which includes the average CT number is proposed, on the other hand, strain equal theory is generalized because the one put foreword by Lemaitre is not good enough to use. (4)a axial damage constitutive equation is proposed and testified. (5)with the circle times, the damage propagation laws of two different rocks, subjected to circle of freezing and thawing, are studied, and in the analysis process, traditional analysis method including average CT number and is used, some important conclusions are reached: inner damage of soft rock containing a large mount of apertures is largely propagating with the time increasement of circle, however, at the preliminary time, the hard rock containing a small mount of aperture is a little propagating, at late time, the influence become large ;(6)zone separation and statistics frequency put forward is used to analysized the three different damagepropagation in the open circumstance, when they are subjected to the different circle times of freezing and thawing, in which the temperature variability is linear, different freezing rate, and different freezing temperature, and no water is supplied during the test. In the study, what’s more, some particular experiment phenomenon are explained by means of theories, such as water move, the change of water and ice. In the test, the preliminary propagation of the hard rock containing a small mount of aperture is dominant during the test, inner damage of soft rock containing a large mount of apertures is largely propagating with the time increasement of circle, because the circle time is limited, the damage propagation can not be observed during enough times. The study also indicates that the freezing temperature has a part influence on the damage propagation. As is known that the water in the rock contains a mount of salt, and the kind and content in turn make the water freezing temperature variable. On the other hand, rock material will shrink when frozen, and expand when warmed. For the hard rock containing a small mount of aperture, the shrink of rock material is superior to the expansion of water. For the second hard rock with layer, when freezing temperature is at 0 , the water disappearance is dominant, however, when at -10 and -20 , the water shrink is dominant. For the soft rock, the shrink of material and reconstruction of particle is dominant, and density of rock is large. The freezing rate also influences the rock damage propagation. In the whole, the density get large when frozen, and the freezing rate is reverse rational to the degree of the density enlargement. The density get small when frozen, and the freezing rate is reverse rational to th更多还原