【作者】 周秋娟；

【导师】 陈晓平；

【作者基本信息】 暨南大学 ， 工程力学， 2006， 硕士

【摘要】 软土变形的重要特征为具有时效性，其产生原因可归咎于软土在各种赋存环境中所具有的固结特性和蠕变特性。由于软土变形的时效性可能会使修建在软土地基上的建筑物产生不可忽视的工后沉降，并由此带来稳定性方面的问题，因此，研究软土变形的时效性的内在机理，探讨固结特性和蠕变特性，对建于软土地基上的工程有重要作用。 本文根据软土变形机理设计了不同的室内试验方案，分别对软土的固结特性、次固结特性、蠕变特性、应力—应变特性等进行了研究，主要内容和结论包括如下： 1．通过一维固结分级加荷试验可知，影响软土的主、次固结分界点的因素有：初级荷载、含水量、孔隙比、加荷比、土体固结效应、土的渗透性等；影响次固结系数的主要因素有先期固结压力、加荷比、含水率、预压力等，次固结系数在固结压力等于先期固结压力时有一峰值。通过预压固结试验可知次固结系数也与预压荷载有关：当固结压力小于预压荷载时，土体处于超固结状态，次固结系数很小；当固结压力接近于压力时，次固结系数开始急遽增大，说明预压荷载可以明显降低次固结变形。 2．由一维固结分别加荷试验可知，分级加荷与分别加荷情况下土样变形情况有较大差异，说明加荷方式的不同将会对土体的性质产生不一样甚至相反的结论：分别加荷下主、次固结的分界点随着固结压力的增大而越明显；而固结压力对次固结系数的影响不是很大，但次固结随着时间的增长有所变化；分别加荷时瞬时变形量随着固结压力的增加而增加，而分级加荷时由于固结效应特性的影响，瞬时变形增量越来越小；另外，分别加荷下的长期变形较明显，而分级加荷下几乎无长期变形，表明分别加荷可以更好的反映土体的次固结特性。 3．通过常规三轴试验可知：随着固结度的增大，土体排水条件越好，土体固结效应越明显，应力应变曲线的屈服点越往后，抗剪强度越高；剪切过程中排水条件下应力应变关系呈线性，抗剪强度较高，但无明显屈服点。 4．通过三轴蠕变试验可知：加荷速率对瞬时变形的影响较大；排水条件对更多还原

【Abstract】 Time-dependent characteristic is one of soft soil’s important characteristics, which imputes to its consolidation characteristics and creep characteristics in various circumstances. Time-dependent characteristic of soft soil may cause post-construction settlement in soft soil foundation, which brings about stability problems. As a result, study of the intrinsic mechanism of soft soil’s time-dependent characteristic and discussion on its consolidation characteristic and creep characteristic play an important role in projects which are built on soft soil foundation. By different laboratory test projects which are designed on basis of deformation mechanism of soft soil, the consolidation characteristics, second consolidation characteristics, creep characteristics, stress-strain characteristics, and other characteristics are investigated. The main content and conclusion presented in this thesis can be summarized as follows:1. Through one-dimensional consolidation tests, we can conclude as follows: Factors that affect the dividing point of primary-secondary consolidation are first load, water content, void ratio, load ratio, consolidation effect, permeability, etc. Factors that affect the secondary consolidation coefficient are preconsoildation pressure, load ratio, water content, preload, etc. When consolidation stress is equal to preconsoildation pressure, secondary consolidation has a peak value. Also, the results of preload consolidation tests show that secondary consolidation has a relationship with preload. When consolidation stress is lower than preload, soil is overconsolidated. and secondary consolidation coefficient is small. When consolidation stress is equal to preload, secondary consolidation coefficient starts to increase quickly, which indicates that preload can cause an obvious decrease in secondary consolidation deformation.2. Through one-dimensional consolidation tests loaded apart, we can conclude as更多还原