An experimental study of miniature CPTU dissipation test on a kaolin clay in a large model container with surrounding instrumentation of pore pressure transducers was carried out with various OCR values. Then it followed a numerical simulation under finite difference analysis, where the cone penetration was modeled by a proposed excitation mechanism, termed as "Plane Strain Cone" analogy, and the soil model used was Modified Cam Clay Model. Although the numerical simulation still embraced errors for soil elements localized near the cone, in a global point of view, it was found that the simulation gave quite comparable trends with the experimental results for both NC and OC cases. The experimental and numerical results also suggested that the CPTU dissipation occurred mainly under a reco...[ Read more ]

An experimental study of miniature CPTU dissipation test on a kaolin clay in a large model container with surrounding instrumentation of pore pressure transducers was carried out with various OCR values. Then it followed a numerical simulation under finite difference analysis, where the cone penetration was modeled by a proposed excitation mechanism, termed as "Plane Strain Cone" analogy, and the soil model used was Modified Cam Clay Model. Although the numerical simulation still embraced errors for soil elements localized near the cone, in a global point of view, it was found that the simulation gave quite comparable trends with the experimental results for both NC and OC cases. The experimental and numerical results also suggested that the CPTU dissipation occurred mainly under a recompression manner. An interpretation method was hence proposed, where the position of the normalized dissipation curve was found to be the closest to the one proposed by Levadoux & Baligh (1986) in the normalized time and normalized pressure space, but the shape of the curve was found almost identical to the one proposed by Teh & Houlsby (1991). It was also found that the influence of rigidity index Ir had negligible effects on the dissipation curve. The proposed interpretation method was verified by Rowe cell test results, as well as the CPTU dissipation data described in Lee & Ng (1999) for a Hong Kong marine deposit, and was found to be reasonable. The variation of dissipation curves with OCR values was also studied and it was found both experimentally and numerically that the dissipation curve could still be monotonically decreasing even under in-situ highly OC condition. However, the dissipation rate increased with OCR values.