【作者】 马士举；

【导师】 曹净；

【作者基本信息】 昆明理工大学 ， 岩土工程， 2008， 硕士

【摘要】 随着城市化进程的加快,人口的剧增和社会经济的快速发展,城市下伏土体资源的数量和质量正在发生深刻的变化,从而产生一系列的环境工程问题。国内外学者对此的研究缺乏系统性,很少从“场”的角度去分析土体的环境效应。本文从城市环境下伏土体性状变化的基本影响出发,通过查阅大量资料,结合理论计算,从“场”的角度探讨当前城市环境下土体变异的各种诱因。城市下伏土体环境效应包括四个方面:附加应力场效应、地下水化学场效应、温度场效应、电磁场效应。建筑物的荷载是通过基础传给地基,上部荷载在地基土层中引起附加应力,建筑物基底的附加应力不仅发生在基础之下的地基土中,而且会在基础以外相当大范围内扩散分布,当在区域内修建建筑物群时,附加应力叠加效应明显,形成区域性地面沉降。此外,岩土工程施工引起的卸荷和加载也会导致土体应力重分布,形成附加应力场效应。地质环境的变化造成了城市环境下地下水化学场的变异,结合室内试验结果,分析表明地下水化学场的变化将对土体产生影响,地下水中的组分将对土体产生物理的、化学的作用,影响了土体的矿物成分,改变了土体的结构,宏观上表现为土体物理、力学性质的改变。城市化进程加快,城市热岛效应愈来愈显著,扰动了城市下伏土体温度场。通过探讨热作用-化学-力学反应三者之间的相互作用,以温度为驱动力,通过改变土中孔隙液的组份及其含量的室内试验,揭示了不同粒间连接粘性土热效应的显著性。科技的发展使城市环境发生了电磁污染,在城市区域产生了城市附加磁场,使得土体土颗粒表面负电荷的密度和双电层结构发生变化,从而导致土体的细观结构形态特征发生相应的改变。更多还原

【Abstract】 With accelerating the progress of urbanization、the sharp increase of the population and the rapid development of social economy, the quantity and quality of the resource of urban soil are profound changing. Thus it caused a series of environmental engineering problems. The research by native and foreign scholars lack systematicness, because they seldom analysis the soil’s environmental effect from the angle of field directly. Starting with basic effects of the character change of urban soil, by consult a great deal of literature and datum and combined with theory calculation, all inducements of changing about the soil under city environment are discussed from the angle of field.Environmental effects of urban soil includes the following four factors: the effects of the field of additional stress、the effects of hydrogeochemical field、the effects of thermal field、the effects of superimposed magnetic field. The additional stress is induced by the loading of building on the foundation, and it spread distributes in great rang of the soil beyond the foundation. When building group is formed in some region, additive effect of additional stress is obvious and regional land subsidence is appeared. in addition, unloading and loading in geotechnical engineering also can induce stress redistribution in the soil, and result in the effects of the field of additional stress. The geo-environmental changes result in the change of hydrogeochemical field. Based on the test results, the geo-environmental changes can influence the structure and mineral composition of soil by chemical action and physical action. Macroscopically, physical and mechanical properties of soil are changed. With accelerating the progress of urbanization, the urban heat island effect has an important effect on the thermal field of soil. Based on discussion the interaction between thermal, chemical and mechanical mechanism, temperature to be driving force, though changing the component and content of porosity fluid in the soil, the experiment reveals the significance of the effects of thermal field. Urban electromagnetic pollution is produced with the development of technology. The superimposed magnetic field on city produces an effect on electric double layer and changes on the surface of cohesive particle, thus causing change of mesostructure conformational feature of cohesive soil.更多还原