摘要
对取自西沙群岛的珊瑚砂试样分别开展侧限压缩、三轴压缩、单向剪切和循环剪切4种试验,研究不同加载方式和应力水平下颗粒破碎及粒组转化关系,讨论珊瑚砂颗粒破碎优势区间的分布规律。提出通过颗粒破碎增长率来描述颗粒破碎程度随循环剪切次数的变化情况,发现随着循环次数的增加珊瑚砂颗粒破碎增长率由初始值迅速向0衰减,应力的升高会导致颗粒破碎增长率的衰减加快,颗粒破碎越快趋于稳定。提出当颗粒破碎增长率低于某很小值时视为颗粒破碎已经达到极限值,可在实际工程中将此极限破碎状态下珊瑚砂的力学参数用作设计上的极值,以此作为颗粒破碎影响下最不利或最有利情况。颗粒接触力较高但颗粒之间相对运动不充分的试样发生颗粒破碎后粒组转化缺乏规律性,充分的颗粒相对运动使得颗粒破碎后粒组转化呈现明显的相似性和规律性。粒组含量变化趋势在粒径0.25 mm处由波动变化转换到稳定增长,此阈值粒径随着颗粒之间接触力的增加而减小。颗粒破碎在整个粒径范围内并非均匀分布,而是存在典型的粒径增长区间和粒径丢失区间。在相同的粒径坐标模式下,典型破碎优势区间对应于颗粒级配曲线的转折区域。
The relationship between particle crushing and grain group transformation under different loading conditions and stress levels of coral calcareous sand（CCS） from Xisha islands is investigated in this study. A series of tests were carried out,such as the oedometer test,triaxial compression test,simple shear test and cyclic shear test. The growth rate of particle crushing is adopted to analyze the crushing behavior of particles. The results indicate that the crushing growth rate of CCS decreases rapidly to zero with the increasing of loading cycles. The increasing of stress level accelerates the reduction of the growth rate of particle crushing,and arrives at the stable state of crushing sooner. It is proposed according to the test results that the particle crushing reaches its limit when the particle crushing growth rate is less than a small value. The limit value can be used in engineering practice. The mechanical parameters of the CCS corresponding to the limit value can be used as the extreme value in the design for the most unfavorable or most favorable situation in real project. Samples with higher contact force but insufficient relative motion between particles are lack of regularity in particle group transformation after crushing,while the samples with full relative motion between particles have the particle group transformation with obvious similarity and good regularity. The particle size of 0.25 mm is a critical point where the grain group content will be changed from variation to a stable growth state. The distribution of particle crushing can be divided into domains of particle size increasing and particle size losing. The particle size losing domain is correspond to the inflection interval of particle distribution curve under the same coordinate model of particle size.
作者
纪文栋
张宇亭
裴文斌
左殿军
JI Wendong;ZHANG Yuting;PEI Wenbin;ZUO Dianjun(National Engineering Laboratory for Port Hydraulic Construetion Technology,Tianjin Research Institute for Water Transport Engineering,M.O.T.,Tianjin 300456,China;Key laboratory of Harbor and Marine Structure Safety,Ministry of Communications,Tianjin Research Institute for Water Transport Engineering,M.O.T.,Tianjin 300456,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2018年第8期1953-1961,共9页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金面上项目(41572297)
中央级公益性科研院所基本科研业务费专项资金项目(TKS–150103)~~
关键词
土力学
珊瑚砂
颗粒破碎
破碎率
加载方式
循环剪切
soil mechanics
coral calcareoussand
particle crushing
cmshing rate
loading condition
cyclicshear
