基于颗粒破碎尺寸效应的岩堆体剪切强度理论研究

项目名称： 基于颗粒破碎尺寸效应的岩堆体剪切强度理论研究

项目编号： No.41472251

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 地质学

项目作者： 徐永福

作者单位： 上海交通大学

项目金额： 103万元

中文摘要： 随着土地资源越来越稀缺，岩堆体地基将在我国今后的工程实践中经常遇到，岩堆体的剪切强度是地基承载力和稳定性分析的最基本参数，在工程设计中首当其冲地需要。以往确定含巨砾岩堆体的剪切强度是进行缩尺处理，根据缩尺后试料的剪切强度外推估算岩堆体剪切强度，外推估算遇到缩尺试料选择难、拟合参数离散等难题。本项目在建立颗粒破碎的分形模型和假设剪切强度为颗粒间的摩擦力的基础上，建立岩堆体剪切强度理论，导出颗粒破碎强度的尺寸效应，由此根据细颗粒岩堆体的剪切强度计算含巨砾岩堆体的剪切强度，并采用颗粒破碎强度和岩堆体剪切强度试验数据验证提出的剪切强度理论，颗粒破碎强度采用单颗粒压缩试验确定，剪切强度通过不同尺寸的直剪仪和三轴仪测量。本课题提出的剪切强度理论中的计算参数包括颗粒破碎的分维、破碎强度和细粒料的内摩擦角，计算参数物理意义明确，参数取值范围确定，确定方法规范，易于实际工程应用，并用试验数据进行广泛验证。

中文关键词： 岩堆体；剪切强度；颗粒破碎；尺寸效应；分形模型

英文摘要： Shear strength of coarse granular materials, widely used in civil works, is seldom measured because of severe practical experimental limitations. The lack of knowledge in shear strength of coarse granular materials often leads to severe accidents including failures in civil works built by coarse granular materials. This project presents an original method for evaluating the shear strength of coarse granular materials, based on fractal crushing of particles in coarse granular materials. Shear strength is defined as the friction stress at contact points due to particle mobile. Contact points between particles in granular materials are fractally distributed in shear plane. According to fractal distribution of contact points between particles, the shear strength envelope of granular materials can be deduced, and expressed by a power function, in which parameters are expressed by fractal dimension of the particle distribution, the particle tensile strength and inner friction angle of granular materials. According to fractal particle crushing of granular materials, the size effect of particle tensile strength can be derived. Through the size effect relation operating on the shear strength envelope, it is possible to determine the shear strength of a coarse-grained granular material from the measured shear properties of a finer-grained granular material made of the same mineral and having parallel particle size distributions. In this project, the method is explicitly proved, taking into account the statistical distribution of the crushing strength of particles with different sizes, within materials that can be considered as physically similar, particularly having parallel grain size distributions. A wide set of independent experimental results is shown to validate the method consistently.

英文关键词： Rockfill;Shear strength;Particle crushing;Size effect;fractal model