This paper addresses the interpretation of plate load tests bearing on double-layered systems formed by an artificially cemented compacted top soil layer (three different top layers have been studied) overlaying a compressible residual soil stratum. Applied pressure-settlement behavior is observed for tests carried out using circular steel plates ranging from 0.30 to 0.60 m diameter on top of 0.15 to 0.60-m-thick artificially cemented layers. The paper also stresses the need to express test results in terms of normalized pressure and settlement—i.e., as pressure normalized by pressure at 3% settlement ( p/ p3% ) versus settlement-to-diameter ( δ/D ) ratio. In the range of H/D (where H= thickness of the treated layer and D= diameter of the foundation) studied, up to 2.0, the final failure modes observed in the field tests always involved punching through the top layer. In addition, the progressive failure processes in the compacted top layer always initiated by tensile fissures in the bottom of the layer. ...

Plate load tests were carried out on un-reinforced sand and sand reinforced with fibres, compacted at relative densities (DR) of 30%, 50% and 90%. For the reinforced sand, 24 mm long polypropylene fibres were added, a concentration of 0·5% by dry weight. The analysis of the results indicates that the soil load-settlement behaviour is significantly influenced by the fibre inclusion, changing the kinematics of failure. The best performance was obtained for the densest (DR = 90%) fibre-sand mixture, where a significant change in the load-settlement behaviour was observed at very small (almost zero) displacements. However, for the loose to medium dense sand (DR = 30% and 50%), significant settlements (50 mm and 30 mm respectively) were required for the differences in the load-settlement responses to appear. The settlement required for this divergence to occur could best be represented using a logarithmic relationship between settlement and relative density. The overall behaviour seems to support the argument that inclusion of fibres increases strength of sandy soil by a mechanism that involves the partial suppression of dilation (and hence produces an increase in effective confining pressure, and a consequent increase in shear strength).

This paper describes the development and validation of an empirical model for predicting the International Roughness Index (IRI) over time. The model is designed to balance mathematical complexity and ease of implementation in network-level pavement management systems. The predicted pavement roughness is modeled as a function of the initial IRI (post construction or treatment) and pavement age. The model accounts for the effects of climate, subgrade, treatment type, pavement type, traffic loading, and functional system (urban or rural) through the use of calibration coefficients. Representative roadway sections are selected from a 10-year (2005 to 2014) pavement management database provided by the Texas Department of Transportation (TxDOT). To validate the model, the IRI data observed in 2015 is compared with the 2015 predicted IRI. The reasonableness and sensitivity of the model are also evaluated. The results show that the proposed model can be a useful tool for predicting IRI in network-level pavement management systems.