Effect of structural boundaries and stress history on at-rest soil pressure of sand

Abstract

The knowledge of lateral earth pressure is a required input to many issues in geotechnical design and analysis. The determination of lateral earth pressure at rest is often based on a coefficient of earth pressure at rest (K0) for which there is no theoretical basis for its determination. This paper addresses three issues that have direct influence on the measurement of lateral earth pressure at rest: pressure measurement technique, presence of a structural boundary and stress history. The testing was carried out using two different pressure measurement techniques: null gauge technology and deflecting membrane technology. The tests were carried out under two different boundary conditions: free-field conditions and conditions adjacent to a structural boundary. The tests included multiple load–unload cycles. The data generated in this study have indicated that the small deflections required to produce output signals when using deflecting membrane transducers have significant impact on the recorded response. The null soil pressure measurement technique precludes deflection and is therefore inherently more suitable. The effect of a structural boundary must be considered when determining horizontal pressure at rest; the presence of a structural boundary alters the development of vertical soil pressure which is reflected in the magnitude of lateral soil pressure.