Postsurcharge Secondary Compression Characteristics of Marine Clay from Piezocone Penetration Tests on a Low-Volume Road

Secondary compression is a major concern for road construction situated on marine clayey soil conditions in the eastern and southeastern provinces in China. Marine clay characterization in the field is hence an important step in the design of low-volume roads. Piezocone penetration tests (CPTu) were conducted for site investigation of a low-volume road situated in Lianyungang, Jiangsu Province, China. The compressibility of relatively homogeneous marine clay at the site was analyzed, with a focus on the postsurcharge secondary compressibility. The primary compression index (C-CL) was obtained from odometer tests on undisturbed samples. The postsurcharge secondary compression index (C-alpha epsilon) was backcalculated from the settlement curves and defined with the time-dependent strain response. The ratio of C-alpha epsilon/C-CL, fell in the range of 0.05 +/- 0.01, indicating that high secondary compressibility is associated with the clay deposits. Finally, regression analysis was performed to correlate the C-alpha epsilon to the CPTu normalized cone tip resistance (Q(tn)). A modified empirical correlation between and C-alpha epsilon and Q(tn) was further developed on the basis of comprehensive evaluation of data from Lianyungang marine clay and the literature.