论文标题:人工冻土融沉特性及其预报模型研究
The Studying of Artificial Frozen Soil"s Thaw Settlement Character and Forecasting Model
论文作者
论文导师 杨平,论文学位 硕士,论文专业 森林工程
论文单位 南京林业大学,点击次数 236,论文页数 68页File Size19898K
2006-06-01论文网 http://www.lw23.com/lunwen_379067/
artificial frozen soil; influence factor; thaw settlement character ;water migration; forecasting model
本论文首先根据土工试验方法标准(GB/T 50123-1999)要求,自行研制了一套人工冻土冻胀融沉试验装置。其中,冻胀量试验装置由试样盒、恒温箱、温度控制系统、温度监测系统、补水系统、变形监测系统、加压系统组成。融沉试验装置由加热传压盖、试样盒、恒温箱、温度控制系统、温度监测系统、变形监测系统、加压系统组成。在自行研制的试验装置上,针对南京地区典型土质淤泥质粘土、粉质粘土、粉砂,选择影响人工冻土融沉特性的冷冻温度、含水量、干密度、荷载等因素进行不同水平的单因素试验和正交试验,获得了冷冻温度、含水量、干密度和荷载对各种土质融沉系数、融化压缩系数的影响规律。指出淤泥质粘土、粉质粘土和粉砂在单向冻结温度场中产生融沉变形,其融沉系数均随含水量增大而增大;融沉系数与干密度变化规律中存在一个临界干密度,临界干密度对应土体最小的融沉系数;土体开敞型单向冻融时,其融沉系数随温度增大而增大;荷载在50～300KPa变化时,对融沉系数的影响最大;正交试验表明,影响融沉系数的第一主因是含水量,其次是干密度和冷冻温度;当含水量较小时,融沉系数值与冻胀率接近,含水量较大时,融沉系数远大于冻胀率。在试验数据的基础上,建立了融沉预报模型,模型建立时,采用各因素对融沉影响的相加、相乘模型分别来反映其对融沉的综合作用,通过对各种模型评价,淤泥质粘土、粉质粘土、粉砂推荐使用相加模型来预报冻土地层中融沉大小,该模型可用于预报南京地区典型土层冻土融沉系数。本文还分析了土体冻融后的水分迁移特征,指出冻结过程和融化过程都会导致水分在土体内迁移积聚,引起土体内的水分重分布,冻结过程和融化过程一样,土体内的水分都是由土体暖端向土体冷端迁移。最后,本文对人工冻结法在城市地下工程应用中减小融沉的措施提出了许多建议。
According to geotechnical testing methods standards (GB/T 50123-1999), the author developed a set of testing devices that can perform frozen swollen experiment and thaw settlement experiment of artificial frozen soil. The frozen swollen testing devices are composed of specimen boxes, thermostatic box, temperature control system, temperature monitoring system, supply water system, deformation monitoring systems, pressure system and can perform frozen swollen experiment under the conditions of different temperatures, different water content, different dry density, different pressure and different freezing conditions. By the frozen swollen testing devices we can discover the relationship between the rate of frozen swollen and soil category, dry density, temperature, water content, pressure, freezing conditions and establish the corresponding models. The melt settlement testing devices are composed of pressing and heating cover plate, specimen boxes, thermostatic box, temperature control system, temperature monitoring system, deformation monitoring systems and pressure system. Aiming at three kinds of soil of Nanjing region—silt clay, mealy clay and mealy sand—the paper selected refrigeration temperature, water content, dry density and pressure as four factors to perform different levels singer-factor tests and orthogonal tests at the self-developed testing devices and found the influence laws that refrigeration temperature, water content, dry density and pressure have on all kinds of melt settlement coefficient and thaw compression factor. The paper shows that silt clay,
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