Dr. Kenneth H. Stokoe, P.E.
Dr. Ken Stokoe, II is a world-renowned expert in the area of nondestructive testing of geotechnical and pavement systems with stress waves. He joined the faculty of the College of Engineering at UT Austin in 1973. He is presently the holder of the Jennie C. and Milton T. Grave Chair in Engineering. He was instrumental in developing the in situ crosshole seismic method for shear wave velocity measurement to the method that has been adopted as the standard by the American Society for Testing and Materials (ASTM D4428M) and the method that is used by geotechnical engineering firms. He has also developed a torsional shear/resonant column system, which is now used by many universities and private firms in the U.S., Europe and Asia to evaluate dynamic material properties.
In the last fourteen years, Dr. Stokoe has conducted major research efforts in the areas of: 1. nondestructive testing of pavements, runways and geotechnical systems, and 2. laboratory evaluation of soil stiffness under cyclic and dynamic loading conditions. He and his colleagues have developed the Spectral-Analysis-of-Surface-Waves (SASW) method for pavement and subgrade testing. This work has been performed mainly with funding from TxDOT. The laboratory studies with which Dr. Stokoe has been involved can be divided into two groups. The first group has dealt with the use of resonant column/torsional shear equipment to evaluate the nonlinear shear modulus and material damping of soils. The second group has dealt with axially pulsed or cyclically loaded equipment for measurement of Young’s, resilient and constrained moduli. This work has been conducted primarily with funding from the Air Force Office of Scientific Research, the United State Geological Survey, the Electric Power Research Institute, California DOT, and TxDOT. Much of the recent work has been performed in conjunction with resilient modulus testing of subgrade soils. Furthermore, Dr. Stokoe has developed synthetic specimens which the SHRP project used in the evaluation of resilient modulus equipment.
Over the past eight years, Dr. Stokoe has been involved in the development of the Rolling Dynamic Deflectometer (RDD) with funding from TxDOT and the United States Air Force. The purpose of this device is to perform continuous profiles of pavement stiffness “on-the-fly.” This deflectometer operates at speeds around 2 km/hr (about 1.2 mph) and presently represents a “one-of-a-kind” piece of equipment. Most recently, the RDD has been used to profile several runways at the Dallas-Fort Worth (DFW) Airport and various highway pavement sections around Houston, Orange, Waco, Wichita Falls, and Sulphur Springs, Texas.