摘要: |
The Presumpscot clay is a soft, low plasticity, sensitive silty clay deposit that covers significant portions of southern and coastal and lowland Maine. The deposits low strength, sensitivity, and presence of heterogeneity (e.g., silt and sand seams) presents challenges to site characterization, engineering design, construction, and long-term stability. Currently site investigation practice is limited by cost and engineering parameters are often obtained from discrete soil property measurements. These include highly variable profiles of in situ vane shear strength, correlations based on soil composition, and on limited data from laboratory testing of undisturbed tube samples. A new method for more rapid and comprehensive subsurface profiling to obtain a wider range of engineering parameters is needed for more reliable and efficient design. Cone penetration testing with pore water pressure measurement (CPTU) provides near continuous profiles of subsurface resistance (tip and sleeve) and penetration-induced pore pressure that are used to indicate layering, lateral and depth heterogeneity, and relative soil composition (e.g., "soft" clays, "stiff" sands). Seismic testing can be incorporated (i.e., SCPTU) to measure shear wave velocity for earthquake design. Notably, the CPTU/SCPTU can be used to determine soil engineering parameters across a site, however these profiles must first be calibrated to engineering properties determined from laboratory testing on undisturbed tube samples. This proposed research initiative is aimed at developing a framework for using SCPTU profiling in Presumpscot clay. |