海相含砂黏土层的变形机理及大变形固结模型研究

Marine deposits usually contain coarse particles, and they possess a high void ratio as well as a low shear strength. Therefore, the prediction of post-construction settlement of the marine deposits due to self-weight and surcharge loading is crucial for safety of infrastructures on which they are constructed. It is well recognized that the coarse aggregates significantly affect the compressibility of sand-clay mixtures. However, quantitative evaluation of the evolution of internal structure during consolidation analysis has been seldomly reported, and the existing models do not incorporate the change of internal structure, which may lead to a significant error in computing the compressibility of sandy clay. Additionally, previous models do not incorporate the finite strain analysis, which is coupled with the permeability properties and the evolution of the drainage boundaries. This project is proposed to solve the above problems: make quantitative analysis of inter-aggregate skeleton based on CT tests, and propose a new model incorporating the sand fraction effect with application to finite strain analysis. The model will improve our basic understanding of the deformation mechanism of sandy deposits, offer a reference for engineers and researchers.

海相沉积物通常包含一定量的砂颗粒。由于海洋特殊的沉积环境，沉积层通常具有高压缩性和低强度，直接威胁建造在海床上建筑物的安全。大量的研究结果表明，砂颗粒的存在对含砂黏土的固结变形有显著的影响。由于对砂骨架在非均匀土体固结过程中的形成和演变缺乏定量研究，以往的模型并没有考虑固结过程中土体结构的影响，同时也没有考虑大变形引起的土体渗透性和排水边界的改变，因而计算结果与实际沉降存在较大的偏差。该项研究旨在解决传统模型存在的上述两个根本问题，利用CT实验探讨含砂黏土中砂骨架的形成和演化机制，在此基础上建立考虑大变形和砂骨架结构演变的本构模型。通过与室内物理模型试验的对比验证其有效性。模型的提出将深化对含砂黏土层变形机理的认识，为工程师和研究人员提供参考。

海相沉积物通常包含一定量的砂颗粒，且具有高压缩性和低强度，直接威胁建造在海床上建筑物的安全。大量的研究结果表明，砂颗粒的存在对含砂土体的固结变形有显著的影响。以往的弹粘塑性模型并没有考虑固结过程中砂骨架结构的影响，因而计算结果与实际沉降存在较大的偏差。通过该项目解决了传统弹粘塑性模型存在的上述根本问题，通过室内实验和数值模拟探讨含砂黏土中砂骨架和黏粒桥的形成和演化机制，在严格理论推导的基础上建立了考虑大变形和砂骨架结构演变的弹粘塑性本构模型，并提出了海相含砂黏土层的沉降计算方法。模型的提出深化了对含砂黏土变形机理的认识，为工程师和研究人员提供参考，有望进一步改善现有的设计方法。