ROLE OF PHYSICAL COMPONENTS IN MECHANICAL BEHAVIOR OF MICROFINE CEMENT/SODIUM-SILICATE GROUTED SAND (STRESS-STRAIN CURVE, TRIAXIAL TEST, RESIDUAL STRENGTH, TENSILE).

摘要

A series of experimental parameter studies was performed to investigate the physical and mechanical properties of sand grouted with various mixtures of microfine cement and sodium silicate (MC/SS). Since there is very little nonproprietary information available for MS/SS grout, an investigation was undertaken with the objective of specifying proper mixtures of cement and silicate to produce desired gel times and grout strengths. Of all the mixtures investigated, one was selected for an in-depth study of the cohesive and adhesive strengths of grout under various stress conditions. Based on this study, the adhesive tensile strength was identified as the critical strength of grout. In addition to providing adhesion to the cohesiveless sand, grout also reduces the volume of voids within the sand matrix. Test results indicated that all MC/SS grouted sands behaved similar to a very dense sand, despite differences in initial density. The peak shear resistance and pre-peak stress-strain behavior of grouted sand, however, were both found to be controlled by the mechanical properties of the grout. The residual strength was found to be very close to that of ungrouted sand when drainage was allowed, but it tended to be higher under undrained conditions. Both the peak and residual strengths of grouted sand can be satisfactorily represented by a linear Mohr-Coulomb failure criterion, while a nonlinear failure criterion is needed for neat grout. Apart from the inherent grout strength, it has been found that the strength of grouted sand increases with increasing surface area of sand particles and confining pressure. Combining the critical strength of grout, the surface area of sand, and the confining pressure, an empirical strength model is proposed to predict the strength of grouted sand. Utilizing dimensionless parameters, the stress-strain behavior of grouted sand is analyzed by isolating the behavior of the sand matrix from the mixture dependent behavior contributed by grouting.