Study on Engineering Properties of Deep Marine Soft Clay in Guangdong-Hong Kong-Macao Greater Bay Area

Abstract

A large number of Marine soft clay are distributed in the Pearl River Delta region of China. The soft clay features mainly on high water content, high sensitivity, high compressibility, low density, low strength and low perviousness, which dramatically restricts local project construction. These features often cause engineering problems such as subgrade settlement, pavement cracking, house cracking, tilting and insufficient bearing capacity of the foundation. Therefore, analyzing the soft clay engineering properties in this area is of great significance for guiding engineering design and construction. Based on the statistic analysis of a large amount of in-situ exploration and experimental data in the western central urban area of Zhuhai, this paper focuses on the distribution and engineering properties of the deep Marine soft clay. The results suggests that the thickness of soft clay is at a range of 10m~ 55.1m. The average water content of soft clay is as high as 68.05%, the plasticity index is 28.16, the fast shear cohesion is only 4.93 kPa, and the internal friction angle is 3.26°. Statistical analysis of layered soft clay shows that the parameters of soft clay vary greatly in depth. The preconsolidation pressure and unconfined compressive strength increases with depth. The water content, liquid limit, plastic limit and plasticity index increase first and then decrease with depth, and the average values reach the maximum values at the depth of 10m ~ 25m. However, the direct shear strength index is on the contrary, and shows a track of decreasing first and then increasing. The minimum values of cohesion and internal friction angle come out at the depth of 10m-25m, with the values of 4.83kPa and 3.10° respectively. The results of in-situ test can better reflect the true mechanical properties of soft clay.