OR/14/052 Laboratory testing
| Boon, D, Kirkham, M, and Scheib, A. 2014. Physical properties of till deposits from Anglesey, north west Wales. British Geological Survey Internal Report, OR/14/052. |
Samples were tested following the methods described in the British Standard for Soil Classification (BS1377:1999) and Head (2008)[1].
Soil density
Soil density analysis was undertaken using Procedure 3 of the linear measurement method described in British Standard BS 1377: Part 2: 1990, test 7.2. The ring is inserted into the soil, (see Figure 16), the sample is excavated and the top and base surface trimmed flush with the ring and wrapped in cling film to retain moisture. In the Lab the ring and soil are weighed wet, and then oven dried to 110° overnight, left to cool in a desiccator, and weighed again dry. The ring is then weighed and mass (g) of the soil sample is calculated. The volume of the sample is calculated by the average radius and length, determined from the average of six calliper measurements of the internal diameter, D, and three of the Length, L. The Bulk Density and Dry Density (Mg/m3) are then calculated by dividing the soil mass by the interior volume of the ring, calculated by measuring.
Shear strength
The drained shear strength of poorly cemented sand from Cemlyn Bay was determined by a set of three direct shear box tests. The ‘undisturbed’ block sample was carefully excavated from the cliff by hand, as shown in Figure 2, and contained in a tin to maintain the integrity of the sample so as to not introduce artificial fractures or other disturbance. Three samples were prepared from one block in the BGS labs with care taken not to create new fractures. Tests were performed over a range of effective normal stresses 50, 100 and 200 kPa. Test procedure described by Head (2008)[1] was followed. The same test procedure was then repeated with reworked sand (same sand compacted to similar density) in order to determine the effective shear strength without the cement.