华南非饱和红色问题土粒间吸力与抗拉张力学特性研究

The unsaturated problematic laterite, widely-distributed in South China, is prone to geological hazards and engineering problems. These hazards and accidents have been proved to be closely related to the mechanical behavior of tensile strength and interparticle suction of red soil. This project focus on the international difficulties of measurement of interparticle suction in unsaturated soils and the high correlation between interparticle suction and tensile strength behavior. The typical laterite in South China will be particularly studied. To establish the quantification and test methods for absorbed suction, the means of X-ray microcomputed tomography technology to reconstruct the three-dimensional structure of soil are used. And in other to build the quantification and test methods for variable structural suction, the following analysis methods are adopted: 3D structure reconstruction of the interface of the tensile failure crack (or fracture), the difference in tensile strength between the undistributed and remolded soil samples, and the composition of interparticle suction when tensile failure occurs. The aforementioned test methods contribute to the analyses of the mechanical behavior of the interparticle suction for the unsaturated problematic laterite. Meanwhile, by testing the mechanical behavior of tensile strength for undisturbed soil and remolded soil with different saturations, and by reconstructing the 3D structure of the interface of the tensile cracks (or fractures), the interparticle suction in unsaturated problematic laterite and its intrinsic and quantitative relation with tensile strength are investigated. This research will break through the international limitations that it has been difficult for a long period to consider the real 3D micro-geometrical structure when testing the interparticle suction of unsaturated soil, therefore, the expected outcomes will help establish a foundation for testing and investigating the absorbed suction, variable structural suction and their quantitative relation with tensile strength.

华南地区广泛分布的非饱和红色问题土易发生地质灾害及工程问题，与其粒间吸力及抗拉张的力学特性密切相关。本课题瞄准非饱和土力学中粒间吸力测试的难点及其与抗拉张力学特性的高度关联性，选取华南地区典型红色问题土，通过土的微观层析成像三维微观结构研究，构建非饱和土湿吸力的量化方法与测试方法；基于拉断面（张裂面）之间连接的三维微观结构重构、抗拉强度差值法的研究以及土样拉断时粒间吸力组成分析，构建可变结构吸力的量化方法与测试方法；测试分析红色问题土粒间吸力的力学特性；通过不同饱和度的原状土和重塑土的抗拉张力学特性测试及拉断面（张裂面）之间连接三维微观结构重构，阐明红色问题土抗拉张力学特性及其与粒间吸力的内在联系和量化关系。本研究将突破国际上较长时期以来非饱和土粒间吸力的测试方法难以考虑土颗粒间真实的三维微观几何结构的局限性，为人们测试研究非饱和土湿吸力、可变结构吸力及其与抗拉张强度的量化关系奠定基础。

华南地区广泛分布的非饱和红色问题土易发生地质灾害及工程问题，这与其粒间吸力及抗拉张的力学特性密切相关。本课题研究关注非饱和土力学中粒间吸力测试的难点及其与抗拉张力学特性的高度关联性，选取华南地区典型红色问题土，首先通过三维微观层析成像技术，对该典型问题土的三维微观结构进行了系统研究，构建了非饱和土湿吸力的量化方法与测试方法；在上述研究的基础上，又进一步开展了拉断面（张裂面）结构的三维微观结构重构、抗拉强度差值法的研究以及土样拉断时粒间吸力组成分析，建立了可变结构吸力的量化方法与测试方法，测试分析了红色问题土粒间吸力的力学特性，由此通过对不同饱和度的原状土和重塑土的抗拉张力学特性测试及拉断面（张裂面）之间连接结构的三维微观重构，阐明了红色问题土抗拉张力学特性及其与粒间吸力的内在联系和量化关系。本研究突破了国际上较长时期以来在非饱和土粒间吸力的测试方法中难以考虑土颗粒间三维微观结构影响的局限性，为人们测试研究非饱和土湿吸力、可变结构吸力及其与抗拉张强度的量化关系在测试技术及测试方法上奠定了坚实基础。