Wang Peng, Tang Yin, Ren Peng, Zhang Hua
Geotechnical Engineering Institute, Sichuan Institute of Building Research, Chengdu, 610081, China.
Sichuan Engineering Research Center for Mechanical Properties and Engineering Technology of Unsaturated Soils, Chengdu University, Chengdu, 610106, China.
Sci Rep. 2024 Mar 25;14(1):7057. doi: 10.1038/s41598-024-56488-2.
Creep is one of the typical mechanical properties of clay, and studying the creep mechanical properties of clay is of great significance to construction projects in clay sites. This study conducted creep tests on Chengdu clay and found that the soil mass underwent elastic deformation, decay creep deformation, steady-state creep deformation, and accelerated creep deformation. The isochronous stress ratio-logarithmic strain curves and their mathematical models were proposed to thoroughly analyze clay creep mechanical properties. Creep automatic feature points, such as linear elastic extreme point, initial yield point, long-term strength point, and plastic point, were identified on the curve. Considering the hardening and damage effects during creep loading, linear elastic and viscoelastic elements considering the time-dependent damage, a viscoplastic element considering the load hardening effect, and viscoplastic and plastic elements considering the load damage effect were established based on the element model and the Riemann-Liouville fractional derivative. Based on the mechanical properties of the whole clay creep process, the creep mechanical feature points, and the established element model, a clay creep model was proposed considering the hardening and damage effects. The rationality and regularity of the creep model were verified using the creep test data. This research accurately revealed the creep mechanical properties of clay and facilitated soil deformation prediction, thus providing technical guidance and references for construction projects in clay sites.
蠕变是黏土典型的力学性质之一，研究黏土的蠕变力学性质对黏土场地的建设工程具有重要意义。本研究对成都黏土进行了蠕变试验，发现土体经历了弹性变形、衰减蠕变变形、稳态蠕变变形和加速蠕变变形。提出了等时应力比 - 对数应变曲线及其数学模型，以深入分析黏土的蠕变力学性质。在曲线上识别出了线性弹性极点、初始屈服点、长期强度点和塑性点等蠕变自动特征点。考虑蠕变加载过程中的硬化和损伤效应，基于元件模型和黎曼 - 刘维尔分数阶导数，建立了考虑时间相关损伤的线性弹性和黏弹性元件、考虑荷载硬化效应的黏塑性元件以及考虑荷载损伤效应的黏塑性和塑性元件。基于黏土整个蠕变过程的力学性质、蠕变力学特征点以及所建立的元件模型，提出了考虑硬化和损伤效应的黏土蠕变模型。利用蠕变试验数据验证了蠕变模型的合理性和规律性。本研究准确揭示了黏土的蠕变力学性质，有助于土体变形预测，从而为黏土场地的建设工程提供技术指导和参考。
