Generalization of Elastoplastic Model Using p and q for Geomaterials Based on the SMP Criterion

1. 三维应力下岩土材料的弹塑性模型。将扩展SMP准则的三维判据应用于黏性-摩擦材料弹塑性模型，提出了基于该判据的转换应力，将判据在转换的主应力空间中变成以轴为空间对角线的锥体来确定转换应力。在此基础上，建立了岩土材料的弹塑性模型，该模型考虑了岩土材料的三个特性。首先是三维应力下岩土材料的强度和变形特性；二是土工材料的剪胀特性；三是强度与变形的围压依赖性。所提出的模型能够在三维应力和大范围内预测岩土材料的应力应变关系，包括黏结-分型材料和颗粒材料。该模型在堆石坝数值分析中的应用。为了将该模型应用于实际工程，采用有限元法推导了弹塑性本构张量。以现有堆石坝为例，验证了该模型在有限元分析中预测土工材料在路堤荷载作用下变形的有效性。该模型计算的地基沉降和侧向位移与实测结果吻合较好。非饱和土的三维弹塑性模型。采用基于扩展SMP准则的转换应力张量，建立了非饱和土的弹塑性模型。模型中考虑了吸力对非饱和土力学行为的影响，将吸力应力加入净应力中形成有效应力，并将屈服应力和模型参数关联起来。该模型所需的材料参数很少，可以很容易地从常规试验的结果中确定，例如测径和直剪试验或双轴试验。它可以预测非饱和土在三维应力和恒定或变吸力条件下的应力-应变-强度行为。利用吸力可控三轴试验装置，对非饱和压实黏土进行了大量的三轴压缩和拉伸试验，研究了在吸力恒定和吸力减小的不同应力路径下的应力-应变特性。该模型的预测结果与非饱和土在恒吸力和减吸力条件下的三轴压缩和三轴拉伸的实测行为吻合较好，这可能导致不可恢复的体积压缩（崩塌）。少

1. An elastoplastic model for geomaterials in three-dimensional stresses. For applying a three-dimensional criterion the Extended SMP criterion to elastoplastic models for cohesive-frictional materials, a transformed stress based on the criterion is proposed, which is determined by making the criterion become a cone having the axis as the space diagonal in the transformed principal stress space. Furthermore, an elastoplastic model for geomaterials is presented, which takes the following three characteristics of goematerials into consideration. The first is the strength and deformation characteristics of geomaterials in three-dimensional stress; the second is the dilatancy characteristics of geomaterials; the third is the confining-pressure dependency of strength and deformation. The proposed model is capable of predicting the stress versus strain relations of geomaterials including cohesive-factional materials and granular materials in three-dimensional stress and a wide range of the c … More onfining pressure.2. Application of the proposed model to numerical analysis of rock-fill dam. In order to apply the model to practical engineering by using FEM, the elastoplastic constitutive tensor is derived. An example of the existing rock-fill dam was selected to demonstrate the usefiilness of the model in the finite element analysis for predicting deformation of geomaterials under embankment loading. The settlement and the lateral displacement of foundation computed by the proposed model fairly agree with the observed results.3. A three-dimensional elasto-plastic model for unsaturated soil. Using a transformed stress tensor based on the Extended SMP criterion, an elasto-plastic model was proposed for unsaturated soil. The influences of suction on the mechanical behavior ofunsaturated soil are taken into account in the model by using a parameter named as suction stress, which is added to net stress to form an effective stress, and associating a yield stress and model parameters with it. The proposed model needs few material parameters, which can be easily determined from the results of the ordinary tests, for example, oedometer and direct shear tests or biaxial test. It can predict the stress-strain-strength behavior of unsaturated soil under the conditions of three-dimensional stresses and constant or variable suction. A considerable number of triaxial compression and extension tests on unsaturated compacted clay were performed by using a suction controllable triaxial apparatus, to measure the stress-strain behavior under different stress paths with constant and decreasing suction. The prediction by the proposed model shows good agreement with the measured behavior of unsaturated soil not only in triaxial compression but also in triaxial extension under the conditions of constant suction and reduction in suction, which may induce an irrecoverable volumetric compression (collapse). Less