Study on Time-Dependent Behavior of Saturated Soils due to Loss of Structure based on Elasto-Plastic Mechanics

基于弹塑性力学的结构损失引起的饱和土时变行为研究

• 批准号: 12450190
• 负责人: ASAOKA Akira
• 金额: $ 8.77万
• 依托单位: NAGOYA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450190/
• 关键词: Natural deposit clay; Secondary consolidation; Soil structure; Overconsolidation; Anisotropy; Sanmpling; Elasto-plasticity; Soil-water coupled analysis; 弾塑性力学; 粘土; 圧密; せん断; 弾塑性構成式; 時間依存挙動

Natural deposit clay in highly structured, overconsolidated and anisotropy states is said to exhibit decrease of undrained shear strength due to sampling disturbance and time-dependent behavior such as "secondary consolidation/delayed compression" and "isotache" more remarkably than its remolded clay. In the present study, such behavior of the soil is investigated based on elasto-plastic mechanics and soil-water coupled analysis with experimental works. The main concluding remarks are as follows : 1) Colloidal clay reconstituted through self-weight consolidation in laboratory, which has significantly high water content, is highly structured, I.e. bulky compared with destructured/fully remolded clay. The clay approaches to destructured state as plastic deformations proceeds even in one-dimensional stress application. 2) In the numerical works, an elasto-plastic constitutive model for natural clays is newly proposed considering three concepts of soil structure, overconsolidation and anisotropy and their evolution rules. Furthermore, partially in the analysis, the v-lnp ' relationship is replaced by Inv-lnp ' to describe the self-weight consolidation process I.e. the large amount of compression behavior which occurs more remarkable in natural deposit soil, while v and p 'show specific volume and mean effective stress respectively. 3) Secondary consolidation of natural soil observed in oedometer tests if investigated from the numerical point of view. The behavior is attributed to not only high degree of structure of natural clay in itself but also increase/generation of overconsolidation accompanied with "sampling operation". Furthermore, in case that direction of sampling is different from that of axes of anisotropy, the secondary consolidation happens more easily.

在高度结构化、过度固结和各向异性状态下，天然沉积粘土的不排水抗剪强度会因采样干扰和时间依赖行为（如“二次固结/延迟压缩”和“等附”）而比重塑粘土更明显地降低。本文采用弹塑性力学和土-水耦合分析相结合的方法，结合试验研究了土的这一特性。主要结论如下：1)通过实验室自重固结重建的胶体粘土，具有显著的高含水量，具有高度结构化，即与破坏/完全重塑的粘土相比体积较大。即使在一维应力作用下，随着塑性变形的进行，粘土也接近破坏状态。2)在数值研究中，提出了考虑土体结构、超固结和各向异性三个概念及其演化规律的天然粘土弹塑性本构模型。此外，在分析中，v-lnp ‘关系部分被v-lnp ’关系所取代，以描述自重固结过程，即在天然沉积土中更为显著的大量压缩行为，而v和p '分别表示比体积和平均有效应力。3)如果从数值的角度研究土径计试验中观察到的天然土的次生固结。这种现象不仅与天然粘土本身的高度结构性有关，还与“取样操作”过程中超固结的增加/产生有关。此外，当取样方向与各向异性轴线方向不同时，更容易发生二次固结。

项目成果

A.Asaoka et.al.: "The decay of structure and the loss of overconsolidation"Proc. of The Fifteenth International Conference on Soil Mechanics and Geotechnical Engineering. 1. 19-22 (2001)

A.Asaoka 等人：“结构的衰变和超固结的损失”Proc。

Asaoka, A: "An Elasto-Plastic Description of the Difference between Sand and Clay"Proc of The 10th International Conference IACMAG. Vol.1. 263-270 (2001)

Asaoka, A：“沙子和粘土之间差异的弹塑性描述”第十届国际会议 IACMAG 的会议记录。

A.Asaoka: "Decay of structure and loss of overconsolidation"Proc. of The International Workshop on Deformation Of Earth Materials. 1. 109-118 (2001)

A.Asaoka：“结构的衰变和超固结的损失”Proc。

Noda T.: "'Sensitivity ratio' and 'sampling disturbance' of natural soils in terms of degradation of soil structure"Coastal Geotechnical Engineering in Practice, Proc. of The International Symposium IS-YOKOHAMA. 1. 113-118 (2000)

Noda T.：“天然土壤在土壤结构退化方面的‘敏感性比’和‘采样扰动’”沿海岩土工程实践，Proc。

Asaoka, A.: "An Elasto-Plastic Description of the Difference between Sand and Clay"Proc. of The 10th International Conference IACMAG. 1. 263-270 (2001)

Asaoka, A.：“沙子和粘土之间差异的弹塑性描述”Proc。