site characterisation study - phases 1 and 2 - HKU Libraries - The ...

- 90 -B3 CONCLUSIONSThe main conclusions from the review of relevant literature are as follows:(i) Shallow seismic reflection may be useful in mapping the baseof extensive fill bodies. Seismic refraction is unlikely to besuccessful in identifying instability indicators other than thebedrock level. Surface wave methods could be useful in themapping of weathering profiles if a relationship existsbetween stiffness and weathering grade.(ii) Resistivity imaging may be useful in the location of shearzones or faults and the mapping of zones of elevated moisturecontent and high clay content. Void mapping may also bepossible. The self potential method could be utilised in thedetection of leaking services.(iii)Both frequency-domain and time-domain electromagneticmethods could be utilised in the mapping of zones of highmoisture content, location of voids and the location of shearzones and altered dykes.(iv)It is unlikely that gravity or magnetic methods would beparticularly useful in Hong Kong.(vi) It is possible that GPR will be able to determine the thicknessof retaining walls, detect clay filled discontinuities,hydrothermally altered zones, voids and zones of enhancedmoisture content. The combined use of GPR andthermography may also be useful in mapping voids andelevated zones of moisture behind hard surface protection toslopes.B.4 RECOMMENDATIONS(a) The applicability of the following non-invasive engineering geophysical methodsshould be tested in Hong Kong:(i) Shallow Seismic Reflection;(ii) Spectral Analysis of Surface Waves;(iii) Resistivity Imaging;(vi) Self Potential;(v) Electromagnetic Methods;