Engineering Geological Characteristics and Cause Analysis of Grayish-white Clay in Beihai

A very stiff grayish-white clay layer containing quartz particles is widely distributed within the depth of 40 m below seabed in Beihai, Guangxi. The soil has low water content, high density, small specific gravity, small void ratio, low compressibility, high shear strength in natural state, and very weak permeability. It has characteristics of swelling due to water absorption and softening, and cracks due to water loss and shrinkage, which will quickly disintegrate to the peptized state after immersion in water again. Mathematical statistical analysis was conducted on the indoor physical and mechanical test results of 200 grayish-white clay samples from 49 boreholes in the sea area. The engineering geological characteristics of the grayish-white clay layer in Beihai was comprehensively analyzed. XRD mineral composition analysis, carbonate content, soil corrosion, 950°C loss on ignition were carried out selectively. The internal factors are evaluated combined with Guangxi geological data and previous research results on Beihai clay, from the formation of soil and material composition, which provide a scientific basis for the rational evaluation of the engineering geological properties of this type of soil, and also provide reference for its development, utilization and engineering management.