報告書番号

381026

タイトル（和文）

有峰第三発電所地下空洞掘削時の周辺岩盤の力学的挙動

タイトル（英文）

MECHANICAL BEHAVIOUR OF ROCK MASS AROUND THECAVITY OF ARIMINE NO. 3 POWER STATION

概要 （図表や脚注は「報告書全文」に掲載しております）

有峰第３発電所は地下式であり，その地下空洞は高さ約２０ｍ，幅約１５ｍ，長さ約３０ｍである。周辺岩盤は花こう岩である。本空洞の特徴はいわゆる「きのこ型」ではなく，流線型の「卵型」空洞であり工法も吹付け工とロックボルト工を主体として施工され，本邦においては最初の卵型空洞となる。空洞掘削に際しては事前に掘削解析手法により挙動予測を実施し，施工時には各種計測を実施し，岩盤挙動の解明をはかった。掘削解析結果によればゆるみ領域はあまり大きくないが空洞と周辺トンネルの交差部に留意すべきことが判った。計測結果によればロックボルトの軸力は１５０～２７００ｋｇ／平方ｃｍであり，ロックボルトは掘削後早急に施工することがその効果を発揮するうえで肝要であることが判かった。上記の結果は今後空洞掘削にさいし空洞形上のデザインに関し有用な情報となるものである。

概要 （英文）

THE HOKURIKU ELECTRIC POWER COMPANY HAS CONSTRUCTED A LARGE EGG SHAPE CAVERN FOR A POWER STATION FOR THE FIRST TIMEIN JAPAN. THE AUTHORS CARRIED OUT FORECASTING OF THE BEHAVIOUR OF ROCKMASSES AROUND THE CAVERN DURING EXCAVATION BY THE NUMERICAL ANALYSIS METHOD DEVELOPED BY ONE OF THE AUTHORS. THROUGH THE EXCAVATION WORKS, MANY KINDS OF MEASURING WERE PERFORMED INCLUDING ROCK DEFORMATION, STRESSES IN SHOTCRETE, CONVERGENCE OF THE CAVERN, FORCES IN ROCK BOFTS ETC. THE FOLLOWINGS ARE SOME RESULTS OBTAINED. (1) SET TIMING OF ROCK BOLT: SET TIMING OF ROCK BOLTS HAS BEEN PROVED TO BE VERY IMPORTANT. ROCK BOLTS OF 3M LENGTH WERE SET IN THE EARLY TIME JUST AFTER THE EXCAVATION OF THE ARCH GALLERY, AND FORCES OF WHICH WERE 1300 3400 KG/SQUARE CM.FERCES OF 5M ROCK BOLTS SET AFTER THE FOLLOWING EXCAVATION OF THE ARCH PART WERE, HOWEVER,COMPARATIVELY LOW VALUES OF 0 600KG/SQUARE CM. THIS FACT SHOWS THE SET TIMING OF ROCK BOLTS IN THE ARCH PART SHOULD BE AS SOON AS POSSIBLE. (2) LENGTH OF ROCK BOLTS: FROM THE STRESS DISTRIBUTION IN ROCK BOLRS, THE 5M LENGTH WAS FOUND TO BE SUITABLE FOR THE DESIGN OF THECAVERN. THE POSITION OF MAXIMUM STRESS IN ROCK BOLTS LOCATED IN THE MIDDLE PART OF THE ROCK BOLTS IN CASE OF 5M LENGTH ROCK BOLTS. ON THE CONTRARY, IN CASE OF 3M ROCK BOLTS, THE POSITION WAS AT THE BOTTOM PART OFROCK BOLTS. THE FORMER CASE OF THE DISTRIBUTION IS DESIRABLE. (3) COMPARISON BETWEEN THE ANALYSIS AND THE MEASURING: RATHER GOOD AGREEMENT WERE FOUND IN THE DISTRIBUTION AND THE TIME HISTORY OF THE ARCH PART SETTLEMENTS, WHICH SHOWS THE ANALYSIS METHOD BEING USEFUL. THE ABOBE MENTIONED RESULTS WOULD BE VERY USUFUL IN THE FUTURE DESIGNING OF UNDERGROUNDCAVERNS.

報告者

キーワード