基于三轴试验的海底沉积物声速与物理和力学性质关系的实验研究

发布时间：2018-12-21 14:57

【摘要】：南中国海蕴藏着丰富的资源,是地球上资源最为丰富的地区之一,并且对于中国而言具有极其重要的战略地位。海底沉积物是海水与海底的交界面,是海洋物理探测和海洋工程装备支承基础,为此迫切地需要了解海底沉积物的物理及力学性质。介绍海底沉积物声学特性、物理和力学性质及其两者之间关系的国内外研究现状。描述了海底沉积物三轴试验及声速测量的实验原理及过程。设计了研究海底沉积物声速与物理和力学性质关系的实验方案,采用土力学中的三轴试验方法测量海底沉积物的力学性质参数,并同步进行声速测量。测量海底沉积物在三轴试验过程中的声速数据,分析声波在海底沉积物中传播的声速与实验围压的关系,得出海底沉积物声速同实验围压呈正相关关系的结论。测量海底沉积物的物理性质参数,分析海底沉积物声速与含水量、孔隙度、湿密度及中值粒径的关系,得出声速同含水量、孔隙度呈正相关关系,同湿密度、中值粒径呈负相关关系的结论。采用土力学中的三轴试验方法研究海底沉积物的力学性质,测量海底沉积物的破坏应力并绘制应力-应变曲线及破坏莫尔圆。测量海底沉积物的抗剪强度数据,得到海底沉积物的破坏点应力值与含水量、湿密度、中值粒径及孔隙度的关系曲线。分析得到海底沉积物破坏点应力值在含水量40%-45%之间以及在孔隙度50%-55%之间分别取得最大值的结论。对比分析表明实验的海底沉积物样品的力学性质与陆地的半脆性粘土相近。分析得出海底沉积物的声速同其破坏应力和摩擦角呈正相关关系,同粘聚力呈负相关关系。计算海底沉积物实验样品在三轴试验压缩过程中静弹性模量和动弹性模量,分析静弹性模量和动弹性模量与海底沉积物孔隙度和声速的关系。求得海底沉积物样品的等效固结模量和等效固结密度,建立沉积物声速双参数经验公式,绘制沉积物的固结声速曲面并进行预测声速与实验声速的误差比较。
[Abstract]:The South China Sea is rich in resources and is one of the most abundant resources on the earth, and has an extremely important strategic position for China. Seafloor sediment is the interface between sea water and seabed, and is the base of marine physical exploration and marine engineering equipment. Therefore, it is urgent to understand the physical and mechanical properties of seabed sediments. This paper introduces the research status of acoustic properties, physical and mechanical properties of submarine sediments and their relationship at home and abroad. The experimental principle and process of underwater sediment triaxial test and sound velocity measurement are described. An experimental scheme was designed to study the relationship between the velocity of sound and the physical and mechanical properties of submarine sediments. The mechanical properties of submarine sediments were measured by using the triaxial test method of soil mechanics, and the acoustic velocity was measured simultaneously. The sound velocity data of submarine sediment in triaxial test were measured and the relationship between sound velocity and experimental confining pressure was analyzed. The conclusion was drawn that the sound velocity of seabed sediment was positively correlated with experimental confining pressure. The physical property parameters of submarine sediment were measured, and the relationship between sound velocity and water content, porosity, wet density and median particle size was analyzed, and the positive correlation between sound velocity and water content, porosity and moisture density was obtained. The conclusion that the median particle size is negatively correlated. The mechanical properties of seafloor sediments were studied by means of triaxial tests in soil mechanics. The failure stress of seafloor sediments was measured, and the stress-strain curves and damage moire circles were drawn. The shear strength data of submarine sediment were measured, and the curves of stress value and moisture content, moisture density, median particle size and porosity of submarine sediment were obtained. The results show that the maximum values of stress at the point of submarine sediment failure are between 40% and 45% of water content and between 50% and 55% of porosity respectively. The comparative analysis shows that the mechanical properties of the samples are similar to those of the semi-brittle clay on land. The results show that the velocity of sound is positively correlated with the failure stress and friction angle, and negatively correlated with the cohesion. The static modulus of elasticity and dynamic modulus of elasticity were calculated during the compression process of marine sediment samples under triaxial test, and the relationship between static modulus of elasticity and dynamic modulus of elasticity with porosity and sound velocity of seabed sediment was analyzed. The equivalent consolidation modulus and the equivalent consolidation density of the sediment samples are obtained. The two parameters empirical formula of the sediment sound velocity is established. The surface of the consolidation sound velocity of the sediment is drawn and the error between the prediction of the sound velocity and the experimental sound velocity is compared.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P736.21;P733

【相似文献】