13.1 Introduction

In recent years，excavation accidents have occurred constantly，and many in cities China such as Shanghai，Guangzhou and Hangzhou.These accidents include the collapse of foundation pits，water seepage，ground surface settlement，tilting of adjacent buildings，leaking of nearby water or gas pipes，and even explosions.The accidents warn us that the construction of the underground excavation has huge risks and that potential danger must be taken care of.The cost of the accident is high and painful.Engineers should learn the lessons from the accident cases.The following excavation failures selected are well known for their impact on the geotechnical community.