Liquefaction and Residential Foundations: Lessons learned from Past Earthquakes

摘要

For more than 50 years, engineers have recognized that seismically-induced soil liquefaction can cause significant damage to structural foundations, particularly shallow foundations. As a result, many modern building codes such as the International Building Code require geotechnical engineers to analyze and address liquefaction and its potential effects when designing new structures in seismic-prone areas. However, potential liquefaction hazard is often ignored for new residential structures in many parts of the United States, which are often designed in accordance with the International Residential Code. This article presents some of the inconsistencies and dangers associated with neglecting liquefaction hazard mitigation for residential structures. Lessons learned from past liquefaction case histories involving residential structures are reviewed. Commonly observed reasons that engineers and building inspectors often give for neglecting liquefaction mitigation for residential structures are discussed, with concerns over cost identified as the most common reason for this neglect. A comparative study is presented in which two forms of liquefaction mitigation are considered for a hypothetical new residential development. The results of the study show that the cost to structurally strengthen the foundation of each house was only 21% of the cost to improve the soil for each house through the installation of stone columns.