摘要
针对级配碎石的动力特性以及颗粒破碎性质,采用室内动三轴试验,研究其在循环荷载作用下循环应力比(cyclic stress ratio,CSR)、围压以及加载次数对累积动应变、动弹性模量、颗粒形状系数和颗粒破碎的影响.研究结果表明,不同CSR条件下,加载次数达到10000 次时,累积动应变基本完成.随着加载次数的增加,不同CSR下的动弹性模量逐渐减小,滞回圈面积逐渐增加后保持稳定.低围压下,CSR对动弹性模量影响不显著,动弹性模量增加幅度较少;高围压下,动弹性模量随着CSR的增加而增长较大.循环荷载作用下,颗粒破碎方式主要为研磨;颗粒粒径越大,试验后的颗粒形状系数球度越大,颗粒越靠近球形,其轮廓线越圆滑.当CSR小于0.3时,影响颗粒破碎的主要因素为动应力大小,而围压影响不显著;当CSR大于0.3时,颗粒破碎主要因素受动应力和围压共同影响.
Abstract
The dynamic characteristics and particle breakage properties of graded gravel were investigated through dynamic triaxial tests.The effects of cyclic stress ratio(CSR),confining pressure and loading times on dynamic modulus,particle shape factor and particle breakage were researched.The results showed that the cumulative dynamic strain is basically completed when the loading times reach 10000 times under different CSR conditions.The dynamic modulus decreases with the increase of loading times under different CSR,and the area of hysteretic loop increases gradually and then remains stable.The increase ratio is smaller under the low confining pressure than that of high confining pressure.The effect of CSR on the dynamic modulus is insignificant when the confining pressure has a low level.The main type of particle breakage under cyclic loading is grind.The particle shape factor sphericity index is larger with the bigger size of particle.The shape of particle trends to sphericity,and the contour line of particle becomes smoother.When the value of CSR is smaller than 0.3,the important effect factor is dynamic stress rather than confining pressure on particle breakage.However,dynamic stress and confining pressure are combined impact factors on particle breakage when the value of CSR is larger than 0.3.
基金项目
国家自然科学基金项目(52178443)
国家自然科学基金项目(51878673)
国家自然科学基金项目(U1734208)
国家自然科学基金项目(U1934209)
国家重点研发计划(2019YFC1904704)
湖南省科学技术厅项目(S2021JJSSLH0088)
重载铁路工程结构教育部重点实验室开放基金项目(2021JZZ01)
重载铁路工程结构教育部重点实验室开放基金项目(2021JZZ02)
湖南省自然科学基金项目(2024JJ8021)
湖南省教育厅科学研究项目(22B0958)
湖南省自然科学基金项目(2021JJ60026)
NETL
NSTL
万方数据