報告書番号

383056

タイトル（和文）

岩盤内半地下発電所における地震観測─その２近距離強地震による挙動（１９８３年８月）─

タイトル（英文）

EARTHQUAKE OBSERVATION AT THE SITE OF SEMI-UNDERGROUND POWER STATION IN ROCK MASS (2) -BEHAVIOR DURING NEAR STRONG EARTHQUAKE (AUGUST, 1983)-

概要 （図表や脚注は「報告書全文」に掲載しております）

半地下式原子力発電所の耐震性を実証することを目的として，直径１５ｍ，深さ２２ｍの岩盤円筒ピット型水力地下発電所で地震観測を実施している。昭和５８年８月に震央距離約１４ｋｍ，マグニチュード６．０で最大加速度１１８ガルの地震とその余震が観測された。得られた成果のおもなものは以下の通りである。１）円筒ピットの地上部に対する底部の最大加速度比は，半径方向で１／２～１に，鉛直方向で７／１０～１に分布し，標高差として約１９ｍではあるが，地中にいくにしたがい加速度の低減効果が現れている。２）円筒ピットの周波数応答関数，つまり地下から地上への伝達関数は，半径方向で３．５Ｈｚ付近および８～１５Ｈｚに，鉛直方向で１１～１４Ｈｚに顕著なピークを有する。今後，観測点を増加し，観測を継続の予定である。

概要 （英文）

THE SEISMIC OBSERVATION HAS BEEN CARRIED AT A SEMI-UNDERGROUND HYDROELECTRIC POWER STATION INSTALLED IN A CYLINDRICAL PIT OF 15M IN DIAMETER,22M IN DEPTH IN ROCK MASS IN PURPOSE OF EVALUATING THE EARTHQUAKE RESISTANCE OF SEMI-UNDERGROUND NUCLEAR POWER PLANTS. THE BEHAVIOR OF THE CYLINDRICAL PIT HAS BEEN ANALYSED MAINLY BY THE OBSERVED SEISMIC WAVES OF THE NEAR STRONG EARTHQUAKE OF HYPOCENTRAL DISTANCE 14KM, MAGNITUDE 6.0,MAXIMUM ACCELERATION 118 GAL IN AUGUST,1983,AND ITS AFTERSHOCKS. AND FOLLOWING RESULTS WERE OBTAINED. 1) RATIOS OF SUBSURFACE MAXIMUM ACCELERATIONS TO SURFACE MAXIMUM ACCELERATIONS WERE ALMOST IN RANGE FROM 1/2 TO 1 IN RADIAL DIRECTION AND 7/10 1 IN VERTICALDIRECTION. 2) FREQUENCY RESPONCE FUNCTIONS, THIS IS THE TRANSFER FUNCTION FROM THE SUBSURFACE TO THE SURFACE, HAVE REMARKABLE PEAKS OF ABOUT 3.5HZ AND 8 TO 15HZ IN RADIAL DIRECTION, AND 11 TO 14HZ IN VERTICAL DIRECTION. THE POWER SPECTRUM IN HIGH FREQUENCY DOMAIN FOR MORE THAN 8HZ IN RADIAL DIRECTION AND MORE THAN 11HZ IN VERTICAL DIRECTION DECREASE ACCORDING TO THE DEPTH FROM THE GROUND SURFACE. 3) SPECTRAL INTENSITIES ARE OCASSIONALLY IN USE BESIDES MAXIMUM ACCELERATIONS AND MAXIMUM VELOCITIES AS AN INDEX PRESENTING THE SEISMIC MOTION INTESITY FOR STRUCTURES.RATIOS OF SUBSURFACE SPECTRAL INTESITIES TO SURFACE SPECTRAL INTESITIES WERE IN RANGE FROM 2/3 TO 1. IT IS RECOGNIZED FROM THIS RESULT THAT SEISMIC FORCES AT THE SUBSURFACE IS LESS THAN THOSE AT THE SURFACE.

報告者

キーワード