Investigation on Pile Foundations of High-Rise Buildings Inclined Largely in the Hyogoken-Nambu Earthquake

Abstract

he damage to p 孟 1e丘)undations of high・ rise apartment buildings 血 at tnted large 亙 y towards south 孟 n a liquef Σ ed area du頁ng the 1995 Hyogoken − Nambu earthquake is investiga 耄ed ， The bui工 dings ， designed 壬 md constrllct¢ d in early 1980s， were supportcd on bored pre −cast conc 祀 te piles 500 in diameter and 26 m ( 13m＋ 13m)long ． An 8 − m 踊 。k layer 。f reclaimed fi11 caps a marine deposit of Holo 。。ne soll which is underlain ， at 24 − m dep畄． by a stiff layer of Pleistocen 。 sand ha舳 g N −values gr 已ater 出 an 40．凸 e 齟 肛 e and d。forrnation patterns of the p ま 1es above and below the excavated ground are observed d廿eot 達 y and with a plumb bob ， and wi 止 aborehole camera and an inc 賎nometer both 孟 nserted 至 nto the hoUow spaces ofthe piles ． respecUvely ．跏 e pile heads are fbund to have bcen displaced westwards by 40 cm ． with fa 且ures and cracks near the pile heads and around 孟 0 ・ m depth at all pnes as well as wi 血 severe outofB at about 5−m depth except fbr 血e piles in the no 曲 row 、 the dete 。ted 制 塒 e and de飾matl 。 n rnodes would be induced by the inertia force and ground displaeement in the west direction ， togeth 已r with the southward ground movem 已nt that occurred on the south 已m pa 貢 Qfthe site．

Study of Ground Lateral Flow on Piles Foundation due to Soil Liquefaction

“…Half span of building was considered to be effected by lateral spreading induced by liquefaction in waterfront ground. Density of filling soil was assumed to 2.7 from the formula N value was supposed to 12 by referenced from histogram [1,2] and relevant criterion [6,7] . The inner friction angle of the liquefiable soil was supposed to φ by the Ozaki formula [6] and the active lateral pressure wedged on pile was considered as .…”

“…The shear and pressure damage, which were found to be focus in the top of pile foundation, was the mainly destructive forms in the past investigation. The latest excavated reports indicate that more and more pile foundations in liquefiable soil were damaged with the top part of pile foundation being in good condition while superstructure subsidence or decline occurred concurrently [1][2][3][4]. So the viewpoint of cracking and failure of piles due to large bending moments maybe has developed in the field close to the boundaries between liquefied and non-liquefied soil layers has been brought forward.…”

“…So the viewpoint of cracking and failure of piles due to large bending moments maybe has developed in the field close to the boundaries between liquefied and non-liquefied soil layers has been brought forward. Both field observations and analysis suggest that a complex soil-structure interaction damage phenomenon occurred underground with much uncertainty, how to quantify and incorporate the various factors into engineering evaluation procedures is still an important problem need to be researched [1][2][3][4][5][6][7][8][9] .…”