摘要
白砂岩是戈壁沙漠地区输水渠道常见土料,其物理力学性质决定了渠道的安全稳定。开展了一系列室内试验发现白砂岩特殊的物理力学性质,主要如下结论:①白砂岩的土体分类为粉土质砂,主要矿物成分为石英,质量占比为66%,黏土矿物为蒙脱石和高岭石,质量占比之和为17%,特殊的矿物成分和颗粒级配使得该土料性质较为特殊,其中,液塑限特性方面接近于低液限黏土;渗透系数数量级为10^(-6)cm/s,接近于淤泥土和黏土。②白砂岩无论是疏松还是密实状态,应力都表现为应变硬化型,体变无剪胀发生。黏聚力随着压实度的增加显著增加,压实度为96%时,c=41k Pa,接近于黏土;内摩擦角则几乎与压实度无关,不同压实度下基本都为31.8°。③白砂岩的e–lnp平面内的临界状态线呈现出的规律与易碎散粒材料如珊瑚砂甚至堆石料相同;且临界状态应力比并非为定值,而是受到围压和初始密度的影响。这都与普通砂土的临界状态特性存在显著差异。
The white sandstone is a commonly used soil material in the Gobi canal.In order to study its physical and mechanical properties,a series of indoor tests are carried out.The following conclusions are drawn:(1)The white sandstone can be classified as the silty sand,its main mineral composition is quartz sand with the mass percent of 66%,and the clay mineral is montmorillonite and kaolinite,accounting for 17%.The special mineral composition and grain size distribution of the silty sand makes it have special behavior,which is similar to that of sand and clay.Among them,the liquid plastic limit closes to that of the low liquid limit clay.The permeability coefficient is on the order of 10^(-6)cm/s,closing to that of silt and clay.(2)Whether it is in loose or dense state,the stress of the white sandstone sand is shown as strain hardening,and no volume dilatation occurs.The cohesion increases significantly with the increasing compaction degree,when the compaction degree is 96%,c=41 kPa,which is close to that of the clay.The internal friction angle has little relation with the compaction degree,which is basically 31.8°under different compaction degrees.(3)The critical state line in the e-lnp space of the white sandstone is the same as that of brittle granular materials such as coral sand and even rockfills.Moreover,the critical state stress ratio is not a constant,but affected by the confining pressure and the initial density.All of those are significantly different from the critical state characteristics of the ordinary sandy soils.
作者
邓铭江
蔡正银
郭万里
黄英豪
张晨
DENG Ming-jiang;CAI Zheng-yin;GUO Wan-li;HUANG Ying-hao;ZHANG Chen(Department of Water Resources of Xinjiang Uygur Autonomous Region,Urumchi 830000,China;Key Laboratory of Failure Mechanism and Safety Control Techniques of Earth-rock Dam of the Ministry of Water Resources,Nanjing 210024,China;Geotechnical Engineering Department,Nanjing Hydraulic Research Institute,Nanjing 210024,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2020年第S01期1-5,共5页
Chinese Journal of Geotechnical Engineering
基金
国家重点研发计划重点专项(2017YFC0405102)
国家自然科学基金项目(51909170)
中央级公益性科研院所基本科研业务费专项资金项目(Y319010)
中国博士后科学基金项目(2018M640500,2019T120443)
关键词
白砂岩
粉土质砂
三轴试验
临界状态
强度变形
white sandstone
silty sand
triaxial test
critical state
strength-deformation characteristic
