Excavation support – geotechnical failures in the context of design and execution errors as well as formal and economic conditions

摘要

Deep excavations carried out in the difficult ground conditions, demand particular care both in a design and execution phase, as well as reliably conducted supervision by personnel having the appropriate skill and experience, but also well-defined responsibility map. In the paper the consequences in omissions in some of these aspects are presented. Description of several deep excavation projects implemented with different techniques and in various ground conditions, in which failure or pre-failure state occurred are introduced. The results of the analysis failure causes analysis are characterized. On that basis, the tendencies in the scope of the most frequently occurring causes of failures in geotechnical project carried out in Poland are defined. Finally, an attempt is made to indicate the direction of changes needed in order to improve the situation – to reduce the number of construction failures in geotechnical projects. The paper contains also observations about uniqueness of the geotechnical structures comparing to other branches of civil engineering works and highlights risks and sources of problems in deep excavation projects. The discussion about vulnerability and high percentage of failure in that kind of projects in context of formal end economical conditions of public tender procedures is presented.