Registration of three soil stress gages at 0 through 28 MPa (4000 psi)

A series of static tests were conducted on three soil stress gages. The gages tested were the currently accepted SE soil stress gage (34 MPa (5000 psi) range), a modified high range SE (HRSE) soil stress gage (138 MPa (20,000 psi) range), and the Waterways Experiment Station Medium Level (WML) stress gage. The tests consisted of multiple static loadings of two different soil types (Reid-Bedford sand and buckshot clay) which contained four HRSE gages, four WML gages, and eight SE gages. The loading range was from 0 to 28 MPa (4000 psi). The test chamber was 1.17 m (46 in.) in diameter by 1.07 m (42 in.) deep. Representative outputs from all three gage types are presented. Of special concern are the recorded outputs from the standard SE gages. These measured the loading of both soil types reasonably well, but consistently over-registered during unloading in the sand. Hysteretic-type behavior was not observed on the other two types of gages. The results imply that for dynamic tests in some soils the standard SE gage will indicate higher impulses than had actually occurred.