基于旋切触探技术的层状岩体力学性质的尺寸效应研究

The size effect of rock mass mechanics properties is one of the most challenging task in rock mass engineering. The current field test method for the size effect of rock mass is very difficult, expensive and time-consuming, and only a small amount of targeted results. In order to create a kind of fast and accurate field test method to study the size effect of the complex layered rock mass, the rotary penetration technology is used in this project. The relationship between the penetration parameters (drilling pressure, torsional moment, drilling rate, rotating speed and location), rock mass mechanics parameters (elastic modulus, compressive strength, cohesive force, and internal frictional angle) and the geometric features of the structural plane are analyzed. Combined the theoretical analysis with the result of laboratory test, then we research the effect of the geometric features of the structural plane on the size effect of the rock mechanics parameters and REV size of rock mass. The theoretical model for size effect of rock mass is established. Finally, the correlation between the REV size of rock mass and penetration parameters are investigated in the process of the rotary cutting penetration. The method for the representative element volume (REV) determination is proposed under the influence of many factors including the thickness, spacing and density of structure surface. Rational, scientific, reliable and fast determination of the rock mechanical parameters can provide a scientific basis for rock mechanical research, and engineering design and construction.

岩体力学性质的尺寸效应一直是岩体工程中最具有挑战性的课题之一。目前开展岩体尺寸效应的现场原位试验费用高、时间长、且难度大，只有少量针对性成果。本项目基于本团队研发的现场岩体力学参数快速确定技术，以层状岩体为研究对象，分析旋切触探参数（钻压、扭矩、钻速、转速和位移）、层状岩体力学参数（弹性模量、抗压强度、粘聚力和内摩擦角）与岩体几何特征之内在关系；结合概化室内标定试验，研究结构面几何特性对岩体力学参数的尺寸效应和岩体REV尺度的影响规律，建立岩体尺寸效应的理论模型；研究旋切触探参数与岩体REV尺度的关联，提出基于旋切触探技术的岩体REV尺度的确定方法，合理、科学、可靠、快速地确定岩体力学参数，为岩体力学科学研究与岩体工程设计、施工提供科学依据。

岩体力学性质的尺寸效应是工程岩体稳定性评价中岩体力学参数选取的一个关键，也是当前岩体工程理论和实践中亟待解决的重大科学问题之一。本项目探寻了旋切触探参数对岩体结构面几何特征的响应特性，研究了旋切参数与RQD之间的映射关系，提出了基于旋切参数的RQD分级标准，解译了旋切参数定量评价节理岩体非连续性、完整性、基本质量与力学性质，提出了基于旋切参数岩体各向异性评价方法，揭示了岩体结构面的几何特征对岩体力学性质的尺寸效应的影响规律，建立了岩体力学参数随岩体尺寸和结构面几何特征变化的数理模型，阐明旋切触探参数与层状岩体REV尺度之间的关联机制，构建旋切触探参数与岩体REV尺度之间的数学关系，提出了基于旋切触探技术的岩体REV尺度的确定方法，研发了深部岩体旋切试验设备，开发了旋切系统监测软件，为岩体尺寸效应的现场测试提供新的理论与技术。