G MS THESIS_final version_Maxim Prokudin.pdf - Digital Repository ...

47In the areas where access was limited (closer to the walls), the method of soil compactionwas done by using a hand tamper (See Figure 21b). The hand tamper was equipped with aheavy steel tip 150 mm by 150 mm in size and was used to compact soil by pounding in arepetitive vertical motion. Also, due to small contribution of pore water pressureequilibrizaiton, a small level of compaction was induced via gravitational consolidation ofsoil under its own weight. The process lasted a period of three to four days.Particle Size DistributionParticle grain size distribution analysis for the loess was performed according with ASTMD422-63. However, since the test bed soil had to be removed and replaced multiple times,additional parameters like moisture content, density and undrained shear strength had to beevaluated. Moreover, test bed prepared for each phase of testing was used for placement ofmultiple number of piers and, therefore, the consistency and uniformity of the soil had to beensured.DCP TestWhile many research investigations have utilized the assumption of uniform initial relativeunit weight and initial void ratio throughout the entire test bed (Lim et.al., 2004), the soilparameters for this research were suspected to deviate throughout the entire test bed area and,therefore, were estimated for each pier placement location. Moreover, variation in soilconditions could have a significantly impact on pier modulus test results and, thus,jeopardizes findings and observations. To eliminate the uncertainty and access requiredinformation the first set of soil characterization tests was perfumed by using Dynamic ConePenetrometer (DCP) equipment. The DCP device was used to evaluate the level ofcompaction and stiffness of the loess. The evaluation of soil stiffness using DCP test wasperformed according with ASTM D 6951-03.