Tactile pressure sensors in centrifuge testing

Assessing vertical and lateral earth pressure is important in geotechnical and foundation engineering. Vertical stresses are easy to calculate assuming a geostatic stress condition. However, characterizing the lateral earth pressure is primarily based on judgment and empirical correlations that assume a lateral earth pressure coefficient based on the shear strength parameters of the soil. Effects of factors such as overconsolidation, geologic age, and pre-shaking on the lateral earth pressure magnitude and distribution are difficult to assess using only the empirical correlations found in literature. Direct measurements of the lateral earth pressure in the field, full-scale, and centrifuge models are required to fully characterize these factors. This paper discusses the use of grid-based tactile pressure sensors in centrifuge models to study the effects of overconsolidation and pre-shaking on the lateral earth pressure. A new preparation and calibration procedure for the tactile sensors is discussed in detail. A series of five centrifuge tests were performed using dry and saturated sand in normally consolidated, overconsolidated, and pre-shaken deposits. The measured lateral earth pressure distributions are plotted and evaluated. Precautions and recommendations for the use of tactile sensors in centrifuge experiments are given.