Study on geotechnical characteristics of marine soil at Hong Kong–Zhuhai–Macao tunnel

Abstract

The Hong Kong–Zhuhai–Macao Bridge (HZMB) immersed tunnel is part of the HZMB, connecting three vibrant cities and crossing the Lingding Sea in South China. It is at the west channel of the Pearl River Estuary and the Tonggu West Channel. The stratum in this area includes deep soft soil with large differences in soil distribution. Based on geotechnical investigation data on marine soil at the HZMB tunnel, the spatial distribution of physical and mechanical properties of deposit soils was statistically analyzed. A field investigation revealed that deposit soils could be subdivided into four strata: Holocene marine deposit stratum, late Upper Pleistocene continental, mid Upper Pleistocene marine alluvial deposit, and early Upper Pleistocene alluvial deposit stratum. Field and laboratory test results indicate that Holocene marine deposit soils had a high water content (42.5% < < 81.2%), large void ratio (1.21 < < 2.43), flow-plastic state ( > 1), high compressibility ( < 5 MPa), low shear strength (2.5 kPa < < 28.5 kPa), and low bearing capacity (58.9 < < 120 kPa); therefore, they could not be used as a natural foundation. The late, mid, and early Upper Pleistocene continental deposit strata had low water content (1.5% < < 40.5%), high bearing capacity ( > 120kPa), low void ratio (0.41 < < 1.24), and low flow-plastic to liquid state ( < 0.95), Additionally, the results of regression analysis showed that the compression ratio was positively correlated with natural water content. Finding from field and laboratory tests provide a basis for immersed tunnel design and construction.