ABSTRACT:

From the viewpoint of low tensile strength and brittle character of improved soils by the conventional CDM technique, a series of laboratory unconfined-compression and splitting-tension tests was conducted on fiber/cement/alluvial soil composite to evaluate the influence of fiber inclusion on the static response of CDM soils. The mechanical properties of interest were unconfined compression strength, Yield splittingtensile strength, and the ductility. The parameters used in this study were cement dosage, fiber content, and fiber length. Results of the experiments indicated that fiber inclusion influenced the response of CDM soils by increasing the unconfined compressive and yield tensile strength and significantly increased the ductility index. However, the influence of fiber inclusion was dominantly affected by cement dosage. At lowest cement dosage the influence of fiber inclusion on the peak compressive and yield tensile strength was small regardless of fiber parameters but the ductility index was highest at the same fiber parameters. As cement dosage increased the effectiveness of fiber inclusion increased on the compressive and tensile peaks and decreased from the viewpoint of the ductility. For the same cement dosage, increasing fiber content or length significantly increased the ductility. The contribution of fiber length to the peaks showed opposite influence at different cement dosages. The enhanced behavior of reinforced alluvial soil due to fiber inclusion may lead to safe-economic new design of Reinforced Cement Deep Mixing ground.

INTRODUCTION

The purpose of ground improvement from the viewpoint of Geotechnical Engineering is to improve the properties of soft ground to increase its bearing capacity, as a foundation, or to increase the required safety factors and its stability under different load conditions. Among the different techniques, Deep Mixing Method (DMM) is considered a major and has been proved its effectiveness as a reliable technique for largescale soil treatment.

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