【作者】 郭璇；

【导师】 赵成刚；

【作者基本信息】 北京交通大学 ， 岩土工程， 2007， 博士

【摘要】 单一变形机制已不能满足描述实际岩土颗粒材料复杂变形特征的要求。本文第一部分从理论和试验入手,在Houlsby等人单一变形机制理论框架的基础上,建立适用于描述率独立耗散岩土材料多变形机制的热力学建模方法,给出理论方法的具体应用例子,对扩展的热力学建模方法应用于岩土材料其限制条件及适用性进行了理论推导及相应讨论,通过选择特例对理论的合理性进行了初步论证。多变形机制描述的超塑性理论方法可保证提供形式紧凑,一致性强的统一理论体系,并保持理论的开放性。该理论方法允许在更广泛的范围模拟岩土材料新的变形机制而不失满足热力学一般性的关系和要求。第二部分致力于发展率独立耗散岩土材料多变形机制热力学建模方法下的具体模型。遵循第一部分的理论方法,发展了超塑性结构损伤双面模型;引入广义非线性强度理论实现了建议模型的三维化,进行了三维应力状态下土体强度特性的初步研究;并对模型进行各向异性修正,通过热力学方法建立了各向异性旋转硬化模型;分别给出系列模型完整的增量反应,数值分析和对比验证。数值模拟结果与试验结果吻合较好,初步表明了遵循多变形机制热力学建模途径进行土体应力分析的实用性及有效性。最后,对率独立耗散岩土材料多变形机制热力学建模方法的理论有效性及限制进行了总结和说明。本文工作的总体思路首先是建立适用于率独立耗散岩土材料多变形机制描述的热力学建模方法,进而发展方法下的具体模型,并对模型进行了相应修正等工作,分别给出各模型具体的理论组成部分。通过模型的模拟预测和试验结果对比,初步说明了本文所提出多变形机制率独立耗散岩土材料热力学建模方法的应用前景及潜力。更多还原

【Abstract】 It is obviously that the single deformation mechanism cannot satisfy the needs for describing geomaterials complicated behaviour.Based on the First/Second Law of Thermodynamics,a systematic constitutive presentation of 32 possible ways within the multi-mechanisms thermodynamical framework for rate-independent geomaterials description is built in part I.The proposed multi-mechanisms thermodynamical framework assures to develop the coherent,compact and open system to simulate concrete behaviour for geomaterial without violate the Law of Thermodynamics. Application examples and the restrict conditions are discussed in detail separately for the proposed framework in appendix.Several integration schemes are investigated and evaluated for the new approach.It appears that a series of these basic studies is helpful to build rational governing equations for geotechnical materials.By the series of theory work built in part I,the innovative idea of multi-mechanisms thermomechanical approach is proposed to develop the families of models to describe the multi-mechanisms response for rate independent frictional dissipative geomaterials.As an application of the new method,the concrete series of models are developed in the part II.Account for the structural damage and dissipative nature of soil,the damage and structural rearrangement behaviour are chosen to present the concrete multi-mechanisms modeling methods for geomaterial.Model prediction results fit the GDS and conventional experimental data of Zhengzhou and Beijing naturally clay very well.It indicates that the proposed isotropic hyperplastic structural damage dual-surface model effectively can be used in describing the bearing capacity for some structured soils.To reflect more real stress characteristic description,a three-dimensional model is realized by introduced the generalized non-linear strength theory in chapter 5.To take frictional and anisotropy response into account,a rotational hardening model is proposed in chapter 6 by following the multi-mechanisms thermodynamical approach. Through evaluation and compared the model simulation to the experimental results,the applicability of the series of proposed models are preliminary validated.It shows that the rational estimation ability for predicting the deformation of the hardening granule geomaterials in the condition of small strain scope and low confine pressure.The practicability and availability of the multi-mechanisms thermodynamical approach was indicated farther.The summarization and expectation of future research in modeling method for geomaterials are presented in the partⅢof the paper.The series of models in proposed approach satisfy the laws of thermodynamics and possible can account for more structural or complicated factors for soil behaviour description.It is believed that the proposed new energy approach would help better understand for more perplexing aspects of soil behaviour and the further application of the proposed approach should be developed in the next step.更多还原