Contract Management in EPBM Tunnels
Up to 90% of face pressured tunnels, most of them in urban environment, are using EPBM (Earth Pressure Balance Method Technology. Its safety management needs competence and experience both from designer and contractor. It all depends on the ground and on soil mix specifications. Bangkok Metro experience underlines importance of RMP (Risk Management Plan) and GBR (Geotechnical Baseline Report). Both documents shall be early implemented. Soil mix design tests shall be performed both external and at site laboratories. Slump performance studies with varying parameters are key for implementation. It is empirically recommended to target 15 cm (+/-) slump. Variations of sand/clay proportions and resulting soil mix design shall be recorded and interpreted.