The formation of Fe (OH)3 implies t

The formation of Fe (OH)3 implies that the Lianyungang marineclay had experienced an oxidation condition at the depth of 6 m and10 m during the past deposition period.5. Geotechnical properties5.1. In-situ testFig. 7 shows the variation of in-situ CPTu tip resistance, localfriction and pore pressure with depth. Fig. 8 shows the variation ofthree geotechnical parameters (su, OCR, and K0) derived from CPTutest results as expressed by Eqs. (1) to (3). The values of NΔu and Bq arealso shown in Fig. 8. Except for the depth of 6.0 m and 10.0 m, OCRvalues are nearly equal to 1.0, indicating that the Lianyungang marineclays at this depth are normally consolidated. However, OCR values atthe depth of 6.0 m and 10.0 m are close to 2.0, indicating that the soilsat these two depths are overconsolidated. The variation of K0 isconsistent with that of OCR. Except for the depth of 6.0 and 10.0 m, theK0 value is close to 0.6. K0 values of the soils at the depth of 6.0 m and10.0 m are higher than those at other depths. The reason of thisphenomenon may be mainly attributed to the relatively highercontent of Fe3+ at these two depths, as will be discussed in the latersection.