A Pluvial Deposition Method to Reconstitute Well-Graded Sand Specimens

Abstract

Stationary pluviators generally use one or more sieves to spread the sand flow exiting from the hopper through one or more holes over the desired area. On the other hand, traveling pluviators do not need a sieve or mesh because in this case it is possible to move an opening or a nozzle over the area of interest. Traveling pluviators are preferable to stationary pluviators, especially in the case of well-graded cohesionless soils, because they provide more uniform specimens. However, traveling pluviators have drawbacks, specimen layering being the most relevant. This technical note illustrates an experimental procedure to reconstitute large specimens of well-graded sands using a traveling pluviator. The effects of specimen layering on mechanical soil properties became negligible with this technique as it was possible to assess performing a series of CPT tests with both a standard cone and a 20-mm cone.

Response of Skirted Foundations Resting on Dry Medium Dense Sand

“…The use of this method for obtaining the required relative density has been reported by many researchers [9][10][11]. By using the raining technique, any density within the maximum/minimum density range can be achieved by controlling the intensity and the height of fall of the sand [12][13][14].…”

Comparison between Two Different Pluviation Setups of Sand Specimens

“…There are three methods for preparation of reconstituted sand specimens, tamping, vibration, and pluviation (Lo Presti et al 1992;ASTM 2006). Among these methods, pluviation has been widely used due to its ability to achieve a wide range of relative densities for sand bed (Rad and Tumay 1987;Fretti et al 1995;Choi et al 2010; Dave and Dasaka 2012;Gade and Dasaka 2015). Additionally, this method is mainly advantageous when it is needed to reconstitute large specimens for model tests or calibration chamber tests within a short time (Fretti et al 1995).…”

“…Among these methods, pluviation has been widely used due to its ability to achieve a wide range of relative densities for sand bed (Rad and Tumay 1987;Fretti et al 1995;Choi et al 2010; Dave and Dasaka 2012;Gade and Dasaka 2015). Additionally, this method is mainly advantageous when it is needed to reconstitute large specimens for model tests or calibration chamber tests within a short time (Fretti et al 1995). Kuerbis and Vaid (1988) reported that the method used to prepare a reconstituted sand bed should be able to produce a very loose to very dense bed, a uniform void ratio throughout the specimen, no segregation of soil particles (regardless of particle size or fines content), and replicable natural soil deposits.…”

“…Air-pluviation may be further divided into three groups depending on the type of opening under the sand storage or hopper. The first type is a single nozzle in which the soil is poured through the nozzle moving in a regular pattern (Fretti et al 1995). The second type is a curtain rainer in which the sand from the hopper is poured through a narrow slot in a thin sand curtain (Butterfield and Andrawes 1970;Gemperline and Ko 1984;Garnier and Cottineau 1988;Stuit 1995).…”

“…The relative density (RD) of sand reconstituted by air-pluviation depends on the height of fall (HF), the deposition intensity (DI), uniformity of raining sand, the porosity of the diffuser sieve, the opening width of the curtain in curtain technique, particle characteristics, and other parameters (Kolbuszewski 1948;Kolbuszewski and Jones 1961;Butterfield and Andrawes 1970;Rad and Tumay 1987;Vaid and Negussey 1988;Lo Presti et al 1992, 1993Fretti et al 1995;Lagioia et al 2006;Choi et al 2010;Dave and Dasaka 2012;Gade and Dasaka 2015).…”