Research On The Mechanics Characteristics Of Calcareous Sand-Limestone Mixture

Calcareous sand is a special marine and carbonate-rich geotechnical medium, which is widely spread throughout the oceans near Nansha Island.It has obvious different mechanical properties from the general sand. In the process of national defense and development of ocean resources, a comprehensive and deep study on sand-limestone mixture of mechanical properties to guide the design and construction of the calcareous sand and to solve the related problem of island road construction has become very important.Based on the summarizing the research history of calcareous sand, the main physical property of testing material such as composition and particle shape are presented. The mechanical properties are researched and analyzed through the compression test and shear test. sand-limestone mixture is composed of fine particles and coarse particles and has a certain graduation. Reference to the previous research achievements of cohesionless soil such as soil-aggregate mixture, the modified compaction test, surface vibration compaction test and penetration test are researched and analyzed with changing the ratio of coarse particles and maximum particle size. The main work can be concluded as follows.(1) The basic physical properties of calcareous sand were analyzed. chemical composition, shape, carbonate content and specific gravity of calcareous sand were tested through laboratory test.The compression characteristics of calcareous sand were analyzed. Different initial void ratio of calcareous sand were analyzed under one-dimensional compression tests and was compared with isotropic compression.(2) The shear properties of calcareous sand were analyzed. Shear properties under direct shear test and triaxial tests was analyzed and compared, at the same time, the shear properties under high pressure of calcareous sand and quartz was compared.(3) The compaction properties of calcareous sand were analyzed. Based on the fabric characteristics and the scaling principle, the mix proportion was carried out.The content of coarse grain、the moisture content and the maximum size of mixture were taken into accounted both in heavy compaction and the surface vibration compaction and analyzed its compaction properties and broken law.(4) The penetration properties of calcareous sand were analyzed. The density, uniformity coefficient, coefficient of curvature, maximum size and content of P5 was considered in the penetration test and on the basis of these, the permeability coefficient of calcareous sand model was put forward.