Horizontal Dynamic Cone Penetrometer: A New Device for Estimating Engineering Properties of Vertical Soil Wall in SP Soils

摘要

Despite the high performance of dynamic penetration tests such as dynamic cone penetrometer (DCP) for assessing the engineering properties of site materials, they are not efficient for vertical soil walls. To deal with this issue, an automatic portable time-saving horizontal dynamic cone penetrometer (HDCP) was invented in this study. A set of HDCP model tests were performed on the Tehran young alluvial sediments at different depths and various relative densities, which indicated the high repeatability of the developed equipment with the coefficient of variation (COV) ranging from 7 to 16 %. Multiple correlations were developed between the HDCP output, i.e., dynamic penetration index (DPI), and the parameters including relative density, Young's modulus, shear modulus, subgrade reaction coefficient, ultimate bearing capacity, and internal friction angle. The results revealed that the equations had a high coefficient of determination (R-2 approximate to 0.9). In addition, to compare the results of HDCP with standard DCP, a DCP test with a 4-kg hammer under the same conditions as those of HDCP was performed to provide an energy level equivalent to that of HDCP (about 21 J). As a result, a relationship between HDCP and standard DCP was obtained using the energy ratio of the standard DCP to DCP4kg. Considering the obtained high coefficient of determination (R-2 approximate to 0.95) between HDCP and DCP indices, the HDCP index can be converted to DCP index. So, the proposed DCP-based equations can be used for evaluating the engineering parameters of vertical soil walls with different materials.