Inclination of houses induced by liquefaction in the 2018 Hokkaido Iburi-tobu earthquake, Japan

Abstract

Background: On September 6th, 2018, at 3:07 local time, a strong earthquake of magnitude Mw = 6.6 struck the east Iburi region in Hokkaido, Japan. Many serious damages such as landslide, liquefaction and collapse of houses occurred from this earthquake. Liquefaction caused road deformation and inclination of houses in Sapporo city, Hokkaido. In order to understand the damage caused by the earthquake, and find a solution to mitigate the liquefaction-induced damage in Sapporo city, a preliminary investigation of the 2018 Hokkaido Iburi-tobu earthquake was conducted from 18 to 20 September 2018. Results: The damages to the houses at Satozuka town and Utsukushigaoka town in Sapporo city are focused on. The damage at Satozuka was so enormous that the residents could not continue to live in their houses. Although the inclination of houses can be seen by visual inspection at Satozuka, there were few houses where the inclination can be judged visually at Utsukushigaoka. Therefore we did a field survey of inclined houses by using a digital angle meter at Utsukushigaoka. Conclusions: The inclination of 57 houses at Utsukushigaoka was measured, and the maximum value and direction of inclination are shown on the map. The houses located at the reclaimed land of the former river and former valley plain were inclined. Therefore, the old terrain greatly affected to the inclination of houses. These liquefactioninduced damage occurred in the same area where liquefaction occurred during the 2003 Tokachi-oki earthquake.

Structure–soil–structure interaction (SSSI) of adjacent buildings with shallow foundations on liquefiable soil

“…Earthquake‐induced soil liquefaction is one of the most devastating natural hazards. Despite advancements in seismic codes, structures founded on shallow foundations resting on saturated sandy soil have repeatedly been reported to experience excessive settlement, rotation, 1,2 or even complete toppling 3 as a result of liquefaction during major seismic events. In recent years, a variety of methodologies have been developed and employed in liquefaction research, offering significant progress in particular on the response of structures founded on shallow foundations.…”

“…Nevertheless, Ref. [31] indicate that inward rotation of adjacent structures may also occur, while inwards rotation has also been observed in the field, as in the example of Figure 1B from the 2018 Hokkaido Eastern Iburi earthquake in Japan 2 …”

“…[31] indicate that inward rotation of adjacent structures may also occur, while inwards rotation has also been observed in the field, as in the example of Figure 1B from the 2018 Hokkaido Eastern Iburi earthquake in Japan. 2 Although centrifuge modelling offers valuable insights, it cannot be efficiently used to conduct extensive par ametric studies. The experimental results can be used as benchmark to validate numerical models, which can then be used for to parametrically investigate the effects of SSSI on adjacent buildings, which is the key scope of the present paper.…”

Seismic Liquefaction Resistance Based on Strain Energy Concept Considering Fine Content Value Effect and Performance Parametric Sensitivity Analysis

“…The 1964 magnitude 9.2 earthquake in Alaska and the magnitude 7.6 earthquake in Niigata of the same year, prompted extensive research on this phenomenon. Soil liquefaction has also been observed in recent earthquakes in China [1], Japan [2], Indonesia [3] and the USA [4,5].…”

“…They assumed under cyclic loading approximately 0.01% for threshold strain and initial water pressure (u w ) increasing. After that, the shear strain was compared with 0.01 according to Serikawa et al [2] or 0.02 [3]. Next, water pressure was estimated through experimental graphs.…”