• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Experimental study and constitutive modelling of stress-dependent coupled hydraulic hysteresis and mechanical behaviour of an unsaturated soil.
【24h】

Experimental study and constitutive modelling of stress-dependent coupled hydraulic hysteresis and mechanical behaviour of an unsaturated soil.

机译：应力相关的水力滞后与非饱和土力学行为耦合的试验研究和本构模型。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The principal objectives of this research were to investigate and to model coupled hydraulic and mechanical characteristics of an unsaturated expansive soil.; 17 triaxial tests were carried out to investigate hydraulic and mechanical behaviour of the unsaturated expansive soil along various stress paths, including wetting-drying, compression and shearing. In each test, sufficiently long duration was permitted to ensure suction equalization. The longest duration of one test was up to seven months. Irreversible swelling upon wetting, irreversible contraction upon drying and accumulated swelling after a wetting-drying cycle were observed. These volume changes decreased with an increase in net mean stress. Based on double-structure concepts proposed by Gens & Alonso (1992), an SD (suction-decrease) yield curve was identified from the irreversible swelling upon wetting and was found to be inclined at an angle of 30° to the net mean stress axis, smaller than the assumption made in Barcelona Expansive Model. Irreversible contraction upon drying indicated yielding on SI (suction-increase) yield curve proposed by Alonso et al. (1990). Identified yield suction upon drying was significantly lower than the maximum experienced suction, indicating coupled movements of SD and SI yield curves. Reagarding hydraulic behaviour, at suctions less than 100 kPa, both absorption and desorption rates decreased as net mean stress increased. At suctions larger than 100 kPa, soil-water characteristics were not influenced by net mean stress. Suction history was found to produce a significant influence on isotropic compression and shear behaviour. This was caused by changes of soil state (both void ratio and degree of saturation) resulting from cyclic wetting-drying. Smaller degree of saturation made the soil become more resistant to yield, exhibiting a hardening effect on mechanical behaviour.; Two new constitutive models (Model-A and Model-B) were developed. Model-A was intended to improve existing elasto-plastic models for simulating the coupling of hydraulic and mechanical behaviour of unsaturated soils. This model was modified from a state-dependent elasto-plastic model proposed by Chiu & Ng (2003). Two main improvements were considered, i.e. to simulate hydraulic hysteresis and stress-dependent soil water characteristics and to capture observed key features of deformations in cyclic wetting-drying. Reasonable agreement between model predictions and test results was achieved.; Model-B was developed to explore the possibility to capture the influence of suction history on mechanical behaviour. This model was modified and extended from an elasto-plastic model presented by Wheeler et al. (2003). Two main improvements were considered, i.e. to simulate wetting-induced plastic swelling and to consider soil behaviour at deviator stress state. This model is able to simulate the observed influence of suction history on compression and shear behaviour. This is because that plastic change of degree of saturation was regarded as another hardening parameter for mechanical behaviour in addition to plastic volumetric strain.
机译：这项研究的主要目的是研究和模拟非饱和膨胀土的水力和力学特性。进行了17次三轴试验，以研究不饱和膨胀土沿各种应力路径（包括干湿，压缩和剪切）的水力和力学行为。在每个测试中，允许足够长的持续时间以确保吸力均衡。一项测试的最长持续时间长达七个月。观察到润湿时不可逆的溶胀，干燥时不可逆的收缩和润湿-干燥循环后累积的溶胀。这些体积变化随着净平均应力的增加而减小。根据Gens＆Alonso（1992）提出的双结构概念，从润湿时的不可逆溶胀确定了SD（吸减量）屈服曲线，并发现其与净平均应力轴成30°角倾斜，比巴塞罗那扩展模型中的假设要小。干燥后不可逆的收缩表明了Alonso等人提出的SI（吸力-增加）产量曲线上的产量。 （1990）。干燥后确定的屈服吸力明显低于最大吸力，表明SD和SI屈服曲线的耦合运动。在吸力小于100 kPa时，重新获得水力行为，吸收和解吸速率均随净平均应力的增加而降低。当吸力大于100 kPa时，土壤水特征不受净平均应力的影响。发现吸气历史对各向同性压缩和剪切行为产生重大影响。这是由于循环干湿导致的土壤状态变化（孔隙率和饱和度）引起的。较小的饱和度使土壤对产量的抵抗力增强，对机械行为表现出硬化作用。开发了两个新的本构模型（模型A和模型B）。模型A旨在改进现有的弹塑性模型，以模拟非饱和土壤的水力和力学行为耦合。该模型是根据Chiu＆Ng（2003）提出的状态依赖的弹塑性模型进行修改的。考虑了两个主要改进，即模拟水力滞后和应力相关的土壤水分特征，并捕获观察到的循环干湿变形的关键特征。在模型预测和测试结果之间达成合理的共识。开发模型B是为了探索捕获抽吸历史对机械行为的影响的可能性。该模型是对Wheeler等人提出的弹塑性模型进行了修改和扩展。 （2003）。考虑了两个主要改进，即模拟润湿引起的塑性溶胀和在偏应力状态下考虑土壤行为。该模型能够模拟观察到的抽吸历史对压缩和剪切行为的影响。这是因为除了塑性体积应变之外，塑性饱和度的变化被认为是机械性能的另一个硬化参数。

著录项

  • 作者

    Chen, Rui.;

  • 作者单位

    Hong Kong University of Science and Technology (Hong Kong).;

  • 授予单位 Hong Kong University of Science and Technology (Hong Kong).;
  • 学科 Engineering Civil.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 397 p.
  • 总页数 397
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 建筑科学;
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号