深厚冲积层人工冻土水热迁移试验研究

发布时间：2018-06-30 04:58

本文选题：人工冻土 + 温度场　；参考：《安徽理工大学》2017年硕士论文

【摘要】：结合人工地层冻结技术在矿井建设中的杰出应用,两淮地区新建矿井穿越表土层的厚度不断增加。本文通过冻土的理论分析、人工冻土水热迁移的试验探究以及结合工程实例的双圈管冻结模型的数值模拟三种方式,对深厚地层土壤水热迁移规律进行系统的研究。结果对于掌握深厚地层土体的水热迁移规律以及深部矿井建设具有一定指导的意义。通过自行研制的一套能够进行大体积土样试验的冻胀试验装置,针对深厚冲积层黏土的含水率和冷端温度两个因素进行了补水条件下的单向冻结试验,通过试验得到了土壤冻结过程中不同高度处各土层温度场、水分场以及位移场的发展变化规律。对于深厚冲积层含水率相同的土体,冻结温度越低,温度场达到稳定的时间越快;冻结温度相同时,土体的含水率越大,温度场稳定所需要的时间越长;在同一冻结温度下,含水率越大的土体冻结锋面移动越慢;土体含水率相同时,冻结温度越低,冻结锋面移动速率越快;在对土体单向冻结过程中,靠近冷源的土体,基本发生的是原位冻结,水分迁移量很小,随着冻结锋面的向上推进,水分不断地向冻结锋面处迁移,冻结完成后,土体中仍有未冻水的存在;测试土体冻后含水率,可以发现,在相同冻结温度下,初始含水率大的,水分迁移量大,初始含水率相同时,冻结温度越高,水分迁移量越大,含水率最大值位置都在冻结锋面附近;在一定含水率范围内,冻结温度相同时,冻胀率随着土体含水率的增加,呈线性分布,含水率越大冻胀率越大;在一定冻结温度范围内,土体初始含水率相同时,土体冻胀率随着冷端温度的升高,呈线性分布,冷端温度越高冻胀率越小。利用COMSOLMultiphysics模拟了两种模式下的双圈管冻结工程,并与现场实测值进行了对比分析,通过比较可以发现,冻结管偏斜对温度场以及冻结壁的发展具有较大影响,冻结管无偏斜时,冻结交圈较有偏斜时较早;模拟的温度场与冻结壁的发展规律与实测规律大致趋势基本相同,计算数据非常接近。结果表明利用COMSOLMultiphysics模拟双圈管冻结过程中温度场的发展是可靠的,对深部矿井建设具有一定的指导意义。
[Abstract]:Combined with the outstanding application of artificial stratum freezing technology in mine construction, the thickness of new mines crossing the surface soil layer in Lianghuai area is increasing continuously. Based on the theoretical analysis of frozen soil, the experimental study of water and heat transfer in artificial frozen soil and the numerical simulation of double loop pipe freezing model in combination with engineering examples, this paper makes a systematic study on the laws of soil water and heat transfer in deep strata. The results have certain guiding significance for mastering the law of water and heat transfer of deep stratum and soil mass and the construction of deep mine. Through a set of frost heaving test equipment which can carry out mass soil sample test, unidirectional freezing test was carried out under the condition of rehydration and cold end temperature, aiming at two factors of deep alluvial clay soil moisture content and cold end temperature. The temperature field, moisture field and displacement field of soil layer at different height during soil freezing were obtained by experiments. For the soil with the same moisture content in the deep alluvial layer, the lower the freezing temperature, the faster the time for the temperature field to reach stability; when the freezing temperature is the same, the larger the moisture content of the soil is, the longer the time required for the stability of the temperature field; at the same freezing temperature, When the moisture content of the soil is the same, the freezing front moves faster and the freezing temperature is lower. In the process of unidirectional freezing of the soil, the freezing process of the soil near the cold source is basically in situ freezing, and when the moisture content of the soil is the same, the freezing temperature is lower and the velocity of the freezing front moves faster. The amount of water migration is very small. With the upward advance of the freezing front, the water moves continuously to the freezing front. After the freezing, there is still unfrozen water in the soil. When the moisture content of the frozen soil is measured, it can be found that, at the same freezing temperature, there is still unfrozen water in the soil. When the initial moisture content is large, the water migration is large, and when the initial moisture content is the same, the higher the freezing temperature is, the greater the moisture migration is, and the maximum moisture content is located near the freezing front; in a certain range of moisture content, when the freezing temperature is the same, the maximum moisture content is near the freezing front. With the increase of soil moisture content, the frost heaving rate is linear distribution, the larger the water content is, the greater the frost heaving rate is, and when the initial moisture content of soil is the same, the frost heave ratio of soil is linearly distributed with the increase of cold end temperature. The higher the temperature at the cold end, the smaller the frost heave rate. By using COMSOL Multiphysics, the double loop tube freezing engineering in two modes is simulated, and compared with the field measured values. By comparison, it can be found that the deflection of the freezing tube has great influence on the temperature field and the development of the freezing wall, and when the freezing tube has no deflection, The simulated temperature field and the freezing wall have the same trend and the calculated data are very close to each other. The results show that it is reliable to use COMSOL Multiphysics to simulate the development of temperature field in the freezing process of double-loop pipes, and it is of certain guiding significance to the construction of deep mine.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD265.3

【参考文献】