نشست ساختمان با فونداسیون سطحی ناشی از روانگرایی
Abstract
1- Introduction
2- Field observation
3- Observations from laboratory experiments
4- Concluding remarks
References
Abstract
In order to examine relative importance of key parameters affecting liquefaction-induced settlement and tilting of buildings with shallow foundations, earthquake reconnaissance studies and centrifuge experiments were made and their results were compared with those of similar previous studies. It is shown that: (1) The liquefactioninduced relative settlement and tilting of shallow foundations tend to increase with increasing contact pressure and ground settlement, and with decreasing groundwater table depth and thickness of the non-liquefied crust; (2) The tilt angle of the building also tends to increase with increasing eccentric mass and distance ratio; and (3) The safety factors against vertical load and dynamic overturning moment are key indicators to estimate liquefaction-induced damage to buildings with rigid shallow foundations.
Introduction
During the 2011 Tohoku Earthquakes, extensive soil liquefaction occurred in many reclaimed lands of the Tokyo Bay area and along the Tone River basin, causing excessive settlement and titling of many residential wooden houses and low-rise reinforced concrete (RC) buildings founded on shallow foundations. Similar damage to residential houses was also observed not only on reclaimed lands but also on natural deposits during recent earthquakes such as the 2011 Christchurch and 2016 Kumamoto earthquakes. Despite many reconnaissance and laboratory studies on soil liquefaction (e.g., [3,6,8,9,11,13,14]), the various factors and their effects leading to settlement of buildings with shallow foundations have not been thoroughly understood to date. In addition, most of the previous studies concentrated only on building settlement, overlooking building tilt failure which is equally or even more important when considering the serviceability of the building after the quake, i.e., performance-based seismic design of buildings with shallow foundations. The objective of this paper is therefore to examine relative importance of key parameters affecting not only settlement but also tilting of buildings with shallow foundations founded on liquefiable soils based on both field observation and laboratory experiments.