We thank Dr Taylor for his interest in our paper and for bringing to our attention the results of his own work in the same general subject area. He has concentrated in his discussion on the behaviour of relatively coarse residues from the coal industry. We would agree with him that the behaviour of coarse and fine residues, even from the same mining operation, cannot readily be equated, and, therefore, it is quite possible that he observed trends which differed from those apparent in China Clay tailings. We have also been careful to stress that particle shape may not, in the majority of cases, have a strong influence upon liquefaction susceptibility compared to the effects of density and grading. In the case of coal residues it seems that chemical effects may also be significant.
Regarding the degree of compaction of the China Clay tailings during lagoon construction, the majority of the material in the lagoon has been hydraulically deposited and has then consolidated under its own self-weight. Therefore, our approach in testing these materials was to simulate the in situ consolidation process as closely as possible in order to achieve realistic densities (hence our use of anisotropic consolidation).
One point in Dr Taylor's discussion with which we find difficulty is his reference to a ‘liquefaction failure’ in his test on the remoulded west Wales tailings (stress path 6 in his fig. 1 since at the end of the test path the sample is still carrying appreciable effective stresses.
- © The Geological Society, London 1978