Impact of ground conditions and excavation depth on selection of excavation support system

Inappropriate selection of an excavation support system (ESS) may lead to delays, cost overruns and quality and safety problems. Soil conditions, excavation depth and groundwater level are important factors that significantly affect the selection of ESS. However, a guideline that determines the effects of these three factors and accounts for their variation in the selection of ESS is not available. To evaluate such effects, a questionnaire was sent to excavation support experts worldwide. The results of the conducted survey are presented and discussed in the current paper to determine the favourable soil conditions and maximum excavation depths for ESS in dry and wet soils. The focus is on the soldier pile, secant pile, diaphragm and jet grout walls because of their common use worldwide. Clear guidelines that can help in the selection of an appropriate ESS for given site conditions could be established. The obtained findings are compared with the conditions and adopted ESS of reported case histories.