Volume 6 – Geotechnical Manual, Site Investigation and Engineering ...

Chapter 4 LABORATORY TESTING FOR SOILS
measured under conditions of zero lateral strain, and the difference is most pronounced for
overconsolidated clays and compacted soils.
c. Hydraulic Consolidation Cell (Rowe Cells Consolidation Test)
The conventional oedometer enables one to determine the consolidation characteristics in the
vertical direction only. With some modifications, the hydraulic consolidation cell (Rowe cell) with
radial drainage can measure the horizontal consolidation properties. The Rowe cell is an incremental
loading test similar to a conventional oedometer test with a reasonably long testing duration. These
cells, in which load is applied to the sample hydraulically, offer many advantages and considerably
widen the scope of laboratory testing. In addition, the hydraulic loading system gives accurate
control of applied loads over a wide range, including high pressures on large diameter samples.
(a) Schematic Diagram of Oedometer
(b) Hydraulic Consolidation Cell
Figure 4.4 Consolidation Test Apparatus
4.6.6 Shear Strength Tests (Total and Effective Stresses)
The principal tools available for strength determination include the California Bearing Ratio (CBR)
apparatus, the Franklin Point Load Test apparatus (Franklin et al. 1971; Broch and Franklin 1972),
the laboratory vane apparatus and various forms of direct shear and triaxial apparatus. For the
purpose of relevance and application to DID related works, only the vane apparatus and the direct
shear and triaxial tests are presented herein.
Laboratory vane test
The principles involved in the vane test are discussed in Section 3.3. Whilst the field vane typically
uses a blade with a height of about 150 mm, the laboratory vane is a small-scale device with a blade
height and width of about 12.7mm. The small size of the laboratory vane makes the device
unsuitable for testing samples with fissuring or fabric, and therefore it is not very frequently used.
The laboratory vane test is described in BS 1377: part 7:1990, clause 3.
Direct shear test
The vane apparatus induces shear along a more or less predetermined shear surface. In this respect
the direct shear test carried out in the shear box apparatus (Skempton and Bishop 1950) is similar.
Fig. 4.5 shows the basic components of the direct shear apparatus; soil is cut to fit tightly into a box
which may be rectangular or circular in plan (Akroyd 1964; Vickers 1978; ASTM Part 19; Head 1982;
BS 1377:1990), and is normally rectangular in elevation. The box is constructed to allow
displacement along its horizontal mid-plane, and the upper surface of the soil is confined by a
loading platen through which normal stress may be applied. Shear load is applied to the lower half of
4-10 March 2009