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FIAT LUX UNIVERSITY OF LIVERPOOL SCHOOL OF ENGINEERING Year 1 Laboratories GSD Grain Size Distribution Test CIVE120: Geomechanics 1 Lecturer: Dr Paul Shepley Demonstrator Name: Demonstrator Email: UNIVERSITY OF LIVERPOOL Health and safety GSDLab Script // CIVE120 Instructions by lab demonstrators should be followed exactly and information regarding the labs fire instructions made known. Lab coats must be worn at all times during the experiment. This lab requires steel capped boots. You are reminded that you are required by law to comply with the School's basic rules of lab safety, as outlined at the start of the first year. 1 UNIVERSITY OF LIVERPOOL 1 Aims and objectives GSDLab Script // CIVE120 1.1 Aims This laboratory experiment aims to help students understand how to determine the grain size distribution of soils. 1.2 Objectives Prepare samples and measure the grain size distribution of soils. At the end of this lab experiment, students should be able to: • Conduct sieve analysis to determine and plot the grain size distribution of coarse- grained soils Describe the textural composition of the soil 2 Theory Because soils are a naturally occurring material, as engineers we must have established and common ways to describe and characterise materials found on sites. These will inform other engineers relying on the material to perform as anticipated, as well as contractors who are working on site to confirm the material is the material the design was intended for. At a basic level, soil description involves describing the material as it is found without using tools or equipment. But if soil samples are taken to the laboratory, one simple test to consider is to determine the particle size distribution of the sample. This is typically done for coarse-grained materials using the sieve shaker equipment shown in Figure 1. SIEVE SHAKER GORDIVINGAL QUMENT Figure 1 - Sieve shaker equipment and wire cloth sieves 2 2.1 UNIVERSITY OF LIVERPOOL Particle size distribution analysis GSDLab Script // CIVE120 This is to determine the proportion of different particle sizes within a soil to determine how 'sorted' - or single-sized – the material is. This is done with around 500g of dry, loose soil. Let M; be the mass of soil retained on the ith sieve from the top of the nest of sieves and M be the total soil mass. The percent weight retained is Mi M Retained on ith sieve == The percent finer is × 100% - Finer than ith sieve = (1 − Σ=1) × 100% M You can use weight instead of mass if you wish – but be confident with your units. 3 Experimental procedure You will determine the particle size distribution for two materials during this laboratory. Note - these are the same materials you will/have used during the PMB soil permeability laboratory. For the method, follow the procedure as: 1) Record the mass of the soil sample 2) Record the mass of the empty sieves 3) Stack sieves in order from smallest to largest, starting at the bottom, with the pan below the smallest sieve 4) Add the soil sample to the top sieve 5) Tighten the equipment to ensure that the sieve stack is held firmly in the shaker assembly 6) Set the sieve shaker to vibrate for 15 minutes 7) Take a few minutes to handle the dry soil provided and write a soil description for the sand. A BS5930:1999 chart has been provided to help you describe the material. Note the material type, colour and another other points of interest. 8) Determine and record the mass of the sieves with the retained soil 9) Repeat the test with the alternative soil type 4 Result recording Tabulate your results in the following tables. 3 UNIVERSITY OF LIVERPOOL Soil 1 description: GSDLab Script // CIVE120 Sample mass: g Sieve size (mm) Empty sieve mass (g) Sieve + soil mass (g) Mass of soil retained (g) Percent retained (%) Soil 2 description: Sample mass: g Sieve size (mm) Empty sieve mass (g) Sieve + soil mass (g) Mass of soil retained (g) Percent retained (%) Cumulative percent retained (%) Percentage finer (%) Cumulative percent retained (%) Percentage finer (%) 4