Suitability of sands from different locations at Nsukka as backfill material for vibroflotation

Abstract

Soil stabilization using vibroflotation method requires material backfill for smooth operation of the process and effective densification. Backfill materials fill the voids created by the vibroflot and acceptable backfill is sand with less percentage of fines. This study assesses the suitability of Nsukka sand for backfill purpose in vibroflotation. Samples of Nsukka sand were tested in the laboratory for their physical, mechanical and electro-chemical properties. The suitability numbers (SN) were determined and a linear regression analysis carried out to correlate the values of SN with the properties of the sand. Tests results showed that Nsukka sand is "Good" backfill material for vibroflotation with a mean SN of 15. The samples indicated narrow percentage of fines value of 0.34-4.81% and are generally classified as poorly graded sand (SP) with mean fineness modulus of 2.12. They have low salt content with electrical conductivity values between 1090-1950µS/cm and mean pH and chloride content values of 6.8 and 98.5ppm respectively. Dry compaction test reveals mean MDD value of 1809kg/m 3 for standard Proctor compaction. Linear regression analysis reveals that SN is dependent on D10 and D30. The efficiency of the model was tested with separate results and the differences between the actual and the predicted SN were small and acceptable. This study concludes that Nsukka sand is a good material for vibroflotation densification.

Comparison and Cost Analysis of Soft Soil Foundation Treatment Schemes in Port Construction

“…In vibroflotation construction, if broken stone is used as backfilling material, weathered stone or semi-weathered stone should not be used as much as possible. In the course of vibroflotation construction, the strength and permeability of piles formed by vibroflotation become lower and worse because of broken weathered stone and semi-weathered stone caused by vibroflotation [22,23]. Equation ( 5) can be used to estimate the amount of backfill to be filled in per unit volume of sand foundation:…”

Effect of precipitation on received water at a sewage treatment plant

“…This approach could also be applied when observing data arrangements or transitions into other fields, including visitor and lodger quantitative evaluations (Yoda 2017). To discuss the relations among precipitation, received water, and water quality parameters, a matrix of Pearson correlation coefficients was analyzed in Microsoft Excel 2011, as discussed in previous articles (Chigor et al 2012;Pogu et al 2018). Our obtained data were the actual nonaveraged values; therefore, their standard errors or deviations were not computed and the graphs are presented without error bars.…”