温度梯度诱导的冻土非均质机制及力学响应研究

冻结壁 温度梯度 非均质机制 非均匀变形破裂 稳定性
赵晓东 2014-01 项目
The engineering background of the current application is the stability control of thick frozen shaft with non-uniform temperature. The heterogeneities induced by thermal gradient present the non-linear behavior, and that can not be obtained by the current test method or theories. The key scientific issue of the current application is aiming at the action mechanism of thermal gradient to the deformation fracture of frozen soils. In this application, we will take the heterogeneities induced by thermal gradient on as the basic object, and the emphasis will be put on the existing form of the heterogeneities and the evolution laws. The comprehensive research approaches including frozen hollow cylinder test with single radial thermal gradient, numerical simulation tests on the frozen hollow cylinder with combinatorial radial thermal gradients based on the 3D deformable distinct element method, physical simulation test on the frozen shaft (frozen hollow cylinder with combinatorial radial thermal gradients) ,and theoretical analysis will be all under consideration. In addition, the K0DCGF (K0 consolidation, freezing with thermal gradient under loading) method, distribution strain measurement sensors composed by carbon black and silicon rubber, and digital photography technologies will be adopted according to the distinguishing features of the object investigated. On the basis of above mentioned, we will then carry out the investigation on the basic characteristics and basic laws for the formation and variation of the cracked frozen structures with non-uniform temperature. Furthermore, both the local and total deformation and strength for the frozen hollow cylinder will be further studied. In the end, the responses of non-uniform deformation-local fracture- the overall instability of the frozen hollow cylinder to the thermal gradient will be obtained. The anticipated achievement will provide a scientific and fundamental support for the stability dynamic control of the frozen shaft in thick alluvium.
课题以非均匀温度厚冻结壁稳定控制为背景;针对现有试验方法和理论不能揭示温度梯度诱导的冻土非均质特性及其非线性力学行为的现状;紧紧围绕温度梯度对冻土体变形破坏的影响机理这一关键科学问题;以温度梯度诱导的冻土非均质效应为研究对象;以非均质性赋存形态与演变规律为研究重点;采用径向单一温度梯度冻结圆筒试验、基于三维可变形离散元理论的径向组合温度梯度冻结圆筒数值试验、冻结壁物理模拟试验与理论分析相结合的综合研究方法;应用K0DCGF(K0固结-保持荷载冻结-形成温度梯度-再试验)、基于炭黑-硅橡胶复合导电传感元件的分布式变形测量、数字照相等技术与手段;研究冻结圆筒中非均匀温度冻土破裂体形成、演化的基本特征与基本规律;明确冻结圆筒变形-承载性能与温度梯度之间的相互关系;揭示冻结圆筒非均匀变形-局部破裂-整体失稳过程对温度梯度效应的力学响应机制。研究成果将为特厚冲积层中冻结壁稳定性动态调控提供科学依据。