UH模型超固结状态演化分析及离心模型试验验证

Evolution analysis of over-consolidated state with UH model and verification of hypergravity centrifuge experiments

本构模型是土力学求解强度变形问题的关键。研究揭示了剑桥模型在超临界侧强度过高、超固结状态下无法应力三维化、应力应变关系发生突变等存在的问题,分析了UH模型建立的超固结状态耦合演化机制及在弹塑性理论框架下实现的超固结状态与正常固结状态计算理论的统一,并基于三轴试验预测证明了UH模型能更加合理地描述超固结状态下土的应力应变关系。通过开展载荷板离心模型试验以及数值模拟验证可以发现,相较于剑桥模型,UH模型计算的地基土荷载变形曲线、侧压力系数分布更加准确,其本质是单元的应力应变关系更加科学、合理。研究证明UH模型的应用能显著提高超固结状态土体强度变形计算的准确性和实用性,对复杂岩土工程问题的计算求解具有重要理论价值和实践意义。

Development of a proper constitutive model is the key to solving the strength and deformation problem in soil mechanics.It is revealed that the conventional Cam-clay model would exhibit unrealistically high strength on the supercritical side and sudden changes in stress-strain relations,and it is incapable of extending the stress tensor to three dimensions at the over-consolidated state.The coupling evolution mechanism in the over-consolidated state is introduced in a state-of-the-art UH constitutive model and the unification of calculation formulas in the over-consolidated and normal-consolidated states based on the elastoplastic theory.Through comparisons with the triaxial compression test results,it is verified that the UH model can satisfactorily describe the stress-strain relations of the over-consolidated soil.The validations against supergravity tests on the vertical behaviour of a circular plate,in terms of the load-deformation curve and lateral pressure coefficient distribution of the soil,demonstrate the significant advantage of the UH model over the Cam-clay model.The essence is that the stress-strain relations of the soil element can be described in a more scientific and rational manner in the UH model.It is well proved that the UH model significantly improves the accuracy and practicability in assessing the strength and deformation problems of the over-consolidated soil,thus capturing important theoretical value and practical significance in solving complex geotechnical engineering problems.