Hariharan Vasudevan

Texas cone penetrometer (TCP) works on dynamic driving principles similar to of SPT, where a hammer is used to drive the cone device to a penetration of 12 inches. Results are typically reported in number of blows to drive 12 in. penetration depth (N12). Current correlations between N12 and soil strength properties are used to determine in situ shear strength properties of soils for geotechnical infrastructure design. Based on the data available, there is a research need to develop new relationships for TCP based on geology and stress histories. This paper presents new correlations development based on the data available in Dallas and Beaumont districts in Texas. In these relationships, undrained shear strength of CL clay is correlated to the depth and N12. Verification studies are conducted to assess the effectiveness of these new correlations.

An on-going research at the University of Texas at Arlington has attempted to develop correlations between Dynamic Cone Penetrometer (DCP) test measurements and strength results of cement and lime stabilized expansive soils. The DCP is used in this research since it is a simple, portable, fast and inexpensive method and can provide rapid assessments of strength enhancements with chemical treatments. The DCP device has a conical tip, which is connected to a series of slender rods along with a 15 pound sliding hammer. DCP tests were conducted on control (untreated), cement- and lime- treated soil specimens at four different time periods, 0, 3, 7 and 14 days after stabilization. The number of blows per selected depth of penetration was measured along the depth of treated soil specimen. The measured DCP data was correlated with laboratory strength measurements. Effects of stabilizer, dosages, and curing period on the DCP measurements were addressed. Both cement and lime treatments provided strong DCP correlations with high coefficients of determinations.