【作者】 兰常玉；

【导师】 张向东；

【作者基本信息】 辽宁工程技术大学 ， 工程力学， 2009， 博士

【摘要】 随着我国铁路网建设的高速发展,穿越季节性冻土区的铁路数量及行车速度都在不断提高,高铁地基沉降所引发的危害也愈加严重,虽已引起人们的重视,但相关研究尚未深入,尤其从量化季节性冻土结构性角度研究高铁地基沉降问题目前国内外未见相关报道。论文以哈大线高速铁路沈阳段为研究实例,结合现场监测、室内试验、冻融循环试验、季节性冻土动三轴试验,利用应变能、J积分、土体动力学、热力学、能量转化等相关理论知识和MIDAS数值模拟软件,从量化季节性冻土结构性角度完成了季节性冻土区冻融循环与列车动载耦合作用下高铁地基沉降规律研究。建立了综合考虑季节性冻土变温冻结、恒温冻结、变温融化、恒温融化等过程的结构性量化指标,实现了考虑土体结构性的三场耦合;利用施工期的实际沉降监测值验证了量化指标计算地基土体沉降量的合理性;指明了土体结构演化过程中,结构可稳性与结构可变性同时存在于同一状态下的土体中,只是不同状态变量(荷载、含水量、孔隙比等)下,结构可稳性与结构可变性的强弱不同;在半对数坐标下,得出结构性量化指标与土体应变满足线性相关的结论,并确定了相关系数;通过冻融过程土体微结构观察得出在没有补给水源的情况下,土中水分在冻结过程中也会出现局部的分凝现象以及土中盐类经一个冻融循环后发生重新分布的结论;将冻融循环次数引入量化指标方程,利用其计算出不同冻融循环次数对应的冻融循环与列车动载耦合作用下高速铁路地基的累积沉降量,并与MIDAS数值计算结果相对比,证明了量化指标计算冻融循环与列车动载耦合作用下高速铁路地基沉降的可行性;通过均匀设计试验,得出季节性冻土区换填法防冻害措施的最佳值为:置换层深度在冻融影响范围内50%～60%;置换层厚度为冻融影响范围的20%～25%;地下水位应在冻融影响范围之外。更多还原

【Abstract】 With the high speed development which our country railway network constructs, the railroad traversing seasonal frozen soil area quantity and the running speed are enhancing increasingly. The high-valence railroad roadbed subsidence initiates the harm even more seriously, although it has brought attention to people, the related studies has not yet penetrates. Especially,to studies the high-valence railroad roadbed subsidence question from the quantification seasonal frozen soil constitutive has not been reported in domestic and foreign at present.In the paper,taking the high-speed railroad in Shenyang as the study example , on the base of the scene examination, the indoor large-scale thaw-freeze cycle experiment and the seasonal frozen soil vibration triaxial test, using theoretical knowledges which include strain energy, J integral, soil body dynamics, thermodynamics, conversion of energy principle and the MIDAS numerical simulation software, it has completed the study on settlement law of high-speed railroad foundation under freeze-thaw cycles coupled with train dynamic load. The structural quantitative indicator including variable-temperature freezing, temperature freezing, variable-temperature melting, temperature melting is established,achieved coupling with three field Taking into account to the soil structural and verified the reasonable which calculate the amount of foundation soil settlement by structural quantitative indicator using the actual monitoring in the period of construction .It was pointed that stability and variability exist in the same state of the soil in, quantitative indicators and soil structural strain to meet the linear correlation. By observation of soil micro-structure in freezing and thawing process ,it can be achieved that Soil will also be a partial segregation phenomena during the freezing process without water supply and soil salts will be redistributed by a freeze-thaw cycle. Freeze-thaw cycles were included the quantitative indicators of equations, which is used to calculated the settlement of foundation under different freeze-thaw cycles and compared the numerical results with it .The result prove it feasibility . Through the uniform design experiment, the anti frost damage measures is obtained that fill the best values in the seasonal frozen soil area are: replacement of frozen-thawed layer depth is 50% ~ 60%in the sphere of influence,the thickness is 20%～25% of the affected areas ,the water table should be outside the scope of freeze-thaw effects.更多还原