【作者】 陈海洋；

【导师】 汪稔；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2005， 硕士

【摘要】 钙质砂是一种海洋生物成因的、富含碳酸盐类物质的特殊岩土介质,在我国南海海域有着广泛的分布。随着南海诸岛的开发和保卫的需要,尤其近十几年来对南海石油资源的勘探和开采以及岛礁旅游业的开发,岛礁和海上现代化工程数量将日趋增多,规模将更大。因此对钙质砂的试验与理论研究,对于指导钙质砂实际工程的设计、施工与安全性检查,对于我国的政治、经济的发展都具有十分重要的意义。钙质砂由于在沉积过程中大多未经长途搬运,保留了原生生物骨架中的细小孔隙等原因,形成了土颗粒多孔隙(含有内孔隙)、形状不规则、强度低易破碎等特点。已有的研究表明:在进行常规土力学试验时,由于内孔隙的存在,钙质砂表现出明显区别于其它陆源砂的特性-易破碎、难饱和、高压缩等。深入研究钙质砂的内孔隙,揭示其分布特性,进而建立微观孔隙与宏观力学性能之间的关系,对于更好的分析、理解和研究钙质砂所表现出来的特殊的工程力学性质具有重要的意义。基于此,本文对钙质砂颗粒及其内孔隙做了一系列试验研究,主要工作包括:1、确定内孔隙试验方法。由于钙质砂颗粒强度较低,且颗粒内含有完全封闭的内孔隙,常规土力学制样方法无法达到孔隙试验要求。本文采用了飞秒激光冷切割法获得颗粒平整的断面,且保留了颗粒内孔隙的分布特性,满足了试验研究要求。2、对钙质砂内孔隙显微试验图像进行分析,获取内孔隙的主要孔隙参数,揭示内孔隙的分布特性。本文借助Matlab图像处理软件,定量化对内孔隙进行了分析,并利用分形理论对内孔隙的大小及分布特征进行了定量测定。3、将微观孔隙试验结果应用于颗粒强度分析。此次研究从钙质砂内孔隙的大小及其分布特性出发,分别运用分形理论和JAYATILAKA-TRUSTRUM分析方法对不同粒径的钙质砂颗粒进行了强度分析。试验结果表明:钙质砂颗粒强度符合Weibull分布特征,由内孔隙特征出发得到的Weibull模量m能很好的满足结果分析要求。4、初步探讨了钙质砂内孔隙对试样制饱和的影响。钙质砂在进行力学试验时,由于试样的反复使用,最初出现的试样难以饱和问题已不明显。结合本次研究得到的内孔隙参数,通过理论推导结合试验结果,初步分析了内孔隙对试样制饱和的影响。5、对本文的工作进行了总结,并对钙质砂的研究方向进行了展望。更多还原

【Abstract】 The calcareous sand is a special rock and soil medium which composes much carbonate and is generated in marine environment,and it is wise distributed in South China Sea. With the requirement of the exploitation and defence in the islands,especially for the requirement of the fossil oil exploration and tourism,much more projects will be built in the sea and the scale will be larger. It is very significant to study the calcareous sand for supervision of design、construction and security check.So is to the development of our politics and economy.Without long distance transport and kept with small pore in the grain,calcareous sand has typical mechanics,such as much inner pore、irregularity shape、low strength.It is found that with the existence of the inner pore,calcareous sand has obvious characters ,such as easy breaking、hard saturation and high compression.So it is very needed to study the inner pore and establish the relationship of the inner pore and mechanical property for comprehension of the typical property in calcareous sand.The main work can be concluded as follows:1、Experimental method of the inner pore is found. Because of the low strength and inner pore in shape,calcareous sand is hard to get a smooth cross-section.Laser cold chipping is used and a smooth cross-section is obtained.2、The inner pore is found.With the image analysis software,the image is digital analysed and the parameters of the inner pore are obtained.And the fractal theory is used to the distribution of the inner pore.3、The result of the inner pore is applied in particle strength.With the characters of the inner pore in size and distribution, the theory of fractal and JAYATILAKA-TRUSTRUM is used to analysis of particle strength.The results indicate that the particle strength of calcareous sand exhibits Weibullian behavior,and the Weibullian modulus obtained to the distribution of the inner pore can much meet the need of the strength analysis.4、The influence of the inner pore in saturation of the calcareous sand is preliminary analysed.Because of the reuse of the calcareous sand,the phenomena of hardness saturation become unconspicuous.With the results of the inner pore and theoretical derivation, the influence of the inner pore in saturation is preliminary analysed.5、The achievements of this study are summarized,and the research direction of the calcareous sand is also presented.更多还原