Study on Cone Penetration Test of Sand Layer along Southwest Coast of Hainan Island

Coastal dunes are widely distributed along the southwestern coast of Hainan Island paralleling to the coastline. Cone penetration test is a commonly used in-situ testing method in geotechnical engineering, it has strong advantage in sand layer which is difficult to obtain undisturbed sample. Through the cone penetration tests and the laboratory test on sand with different densities and grain size distributions, the correlation between in-situ test index and laboratory test index was analyzed. It is found that the hit number of standard penetration test is linearly correlated with the tip resistance of cone penetration test, so the density of sand can be judged by the value of tip resistance. The content of silt and clay in sand has a great influence on side friction and friction ratio of cone penetration test, and the friction ratio is linearly related to the content of silt and clay. For different sand with same geological origin, the particle-size distribution has great impact on the friction ratio, the larger the main particle size is, and the smaller the friction ratio is. For same sand with different geological origin, the content of silt and clay of sand is different, and the cone penetration test curve and the particle-size distribution curve are also different.