摘要
我国南海广泛分布着珊瑚礁砂地基,在海底油气管道等众多高温基础工程的建设中需要掌握温度对珊瑚礁砂力学性质的影响。对取自南海的珊瑚礁砂进行不同温度下的固结排水三轴剪切试验,通过与石英砂试验进行对比,深入研究高温对于珊瑚礁砂抗剪强度特性的影响机制,并分析温度效应对颗粒破碎、内摩擦角、临界状态的影响。结果表明:温度效应对于珊瑚礁砂和石英砂力学行为的影响机制显著不同,升温使石英砂孔隙水排出,土颗粒有效接触增多,从而表现出更强的抗剪强度和剪胀性;升温虽然使珊瑚礁体积压密,但升温也会使珊瑚礁砂颗粒破碎和重排列程度增加,导致其抗剪强度和剪胀性降低;存在一个温度门槛值,当温度大于该门槛值,温度升高使得珊瑚礁砂颗粒破碎和抗剪强度降低量明显增大;随温度增大,珊瑚礁砂颗粒破碎指标B_r增大,在p’-q平面的临界状态线略微向靠近p’轴的方向旋转;珊瑚礁砂的峰值和临界摩擦角与B_r存在负相关函数关系。
In the construction of many high-temperature infrastructure projects such as submarine oil and gas pipelines in South China Sea,it is necessary to master the effect of temperature on the mechanical properties of coral reef sand on which these projects are seated. The drained triaxial shear tests of coral reef sand from South China Sea were carried out under different temperatures,and the effects of high temperature on shear strength,particle breakage,friction angle and critical state of coral reef sand were studied in depth by comparing with the test results of quartz sand. It is shown that the effects of temperature on the mechanical behaviors of quartz sand and coral reef sand are quite different. Increasing temperature causes pore water discharge of quartz sand,increases the effective contact of soil particles and consequently increases the shear strength and dilatancy of quartz sand.However,increasing temperature results in a significant decrease in both shear strength and dilatancy due to particle breakage and rearrangement of coral reef sand. There exists a temperature threshold value. When the temperature is higher than the threshold value,increasing temperature causes the coral reef sand particles to break and the shear strength to decrease significantly. With increasing the temperature,the relative particle breakage index of coral reef sand increases,and the critical state line in the p’-q plane rotates towards p’-axis. The peak and critical friction angles of coral reef sand have a corresponding negative correlation function relationship with the relative particle breakage index of coral reef sand.
作者
何绍衡
夏唐代
李玲玲
丁智
单华峰
HE Shaoheng;XIA Tangdai;LI Lingling;DING Zhi;SHAN Huafeng(College of Civil Engineering and Architecture Zhejiang University,Hangzhou,Zhejiang 310058»China;Department of Civil Engineerings Zhejiang University City College Hangzhou,Zhejiang 310015,China;Institute of Coastal Environment and Geotechnical Engineerings Taizhou University Taizhou,Zhejiang 318000,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2019年第12期2535-2549,共15页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(51508506)
浙江省自然基金项目(LQ16E080008)
台州市科技局项目(1801gy22)~~
关键词
岩石力学
珊瑚礁砂
颗粒破碎
温度效应
抗剪强度特性
临界状态
rock mechanics
coral reef sand
particle breakage
temperature effect
shear strength characteristics
critical state
