【作者】 胡建华；

【导师】 汪稔；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2004， 博士

【摘要】 本文从路堤的填土改良——粒径级配改良,以及控制大气降水下渗——水平排水板的共同作用,研究一种应用于多年冻土地区的新型路堤结构形式,即级配改良结构性路堤,设计了原位模型试验,分析其作用机理,研究结果表明级配改良结构性路堤,将是一种低成本有效保护冻土的路堤结构形式。1.研究了多年冻土区路基工程的主要冻害类型,成因和有效的防治措施,认为只要合理控制土质、温度、地下水三个因素的作用,就能够有效的控制多年冻土区路基工程的冻害,保护冻土。2.土的导热性能内在因素主要受含水量、孔隙度、干密度以及粒径级配的差异控制,其导热系数大小与土含水量、干密度存在一定的数学关系。3.查明试验段工程冻土地质类型,确定路基设计原则和填土室内物理力学试验基础上,开展了在青藏高原多年冻土区的级配改良路堤原位模型试验。4.成功运用光纤光栅传感技术,对多年冻土路堤的变形进行监测,结果表明,与通风管路堤比较,减少冻胀变形和最大冻胀发生的区域,以及缩短冻胀变形的冻结阶段时间;温度监测结果分析发现,级配改良结构性路堤中,粗颗粒级配砾石层中存在着对流换热,在冷、热条件下具有明显的热开关效应;但碎石中颗粒级配层的导热性能冬夏差异较小,其孔隙率低于粗颗粒层,同时密实度高。5.在级配改良路堤中,细粒土级配层能够形成降水下渗的缓冲层,与水平排水板横向排水共同作用,改变大气降水下渗路径,形成水平向迁移,减少了冻土地下冰的水分来源,减少冻胀量的增加;并且水平排水板具有加筋作用,有利于改善路堤的不均匀变形。6.根据热力学的基本原理,建立了级配改良结构性路堤的数值计算模型,运用非线性有限元方法,分析年增温率为0.04℃/a条件下,级配改良结构性路堤的温度场的发展规律,认为此种路堤形式能够有效的保护多年冻土,延缓多年冻土的退化。更多还原

【Abstract】 In the paper, a new embankment structure is studied that is the improved graded structured embankment. In this embankment, the filling soil is improved on particle grade and laid horizontal drain board. An in situ model testing was designed on Beiluhe testing field in the Qinghai-Tibetan railway, and its mechanism is analyzed to heat exchange and moisture migration. The results showed that improved graded structured embankment is a kind of effective structure forms to protect permafrost.1. It is studied about the styles and causes of damage of roadbed, effective measures to protect roadbed in the permafrost regions. It is thought that the key is the actions of soil, temperature and water to control the damages of roadbed, if one of the three factors is mended, the damages will be controlled and the measure can protect the permafrost.2. The influencing factors are moisture content, porosity, dry density and particle graded of soil to the thermal conductivity, and the value of the thermal conductivity is related the moisture content and dry density of soil.3. The engineering geology condition is surveyed in Beiluhe testing field in the Qinghai-Tibetan railway, the design principle is confirmed to the embankment, and on the basis of the results about the physics and mechanical examination of the filling soil in the room, it was built to the test model of improved graded structured embankment for testing in the suit of Beiluhe testing field in the Qinghai-Tibetan railway.4. The application is succeeded to the fiber grating strain sensor for monitoring the deformation in the model embankment, and the fiber grating strain sensor would be used the long-term monitoring the deformation in the permafrost. The results of the monitoring deformations indicated that the frost heave deformations and the frost heave area is reduce, and the time of freezing phases during the frost heave is shorten, to compare with the ventilation duct in the roadbed. At the same time, the results of the temperature monitoring confirmed that the gravel coarse granule graded layer has the heat exchange form of the convection, in the diversity conditions to the cold and hot season, and the layer manifests the effect of the on-off to thermal. But to the macadam medium granule graded layer, the thermal conductivity difference doesn’t be in evidence in the cold and hot season, because the porosity in this layer is less than and the dry density is more than the gravel coarse granule graded layer, in this layer, the heat exchange form is conduction.5. In the improved graded structured embankment, the pathway of the precipitation seep downward is changed toward the horizontal lateral seep, due to the together effect to the fine granule soil graded layer, the amortize layer can be formed to the precipitation seep downward,更多还原