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公益財団法人深田地質研究所年報 第14号 2013


大坂城石垣石切丁場跡「天狗岩丁場」を訪ねて

Visit of Tengu Iwa Quarry site, One of the Stone Quarry Ruins for Osaka Castle

藤田勝代

FUJITA Masayo

要旨:香川県小豆島町岩谷地区にある大坂城石垣石切丁場跡(1972年国指定史跡)の天狗岩丁場には,大坂城に運ばれなかった残石が数多く点在している.2012年に新しく整備された天狗岩丁場の散策ルートを歴史探訪しながら,ルート沿いに見られるコアストーンやラミネーションシーティングといった花崗岩を特徴付ける風化帯構造の観察ポイントを紹介する.
キーワード:天狗岩丁場,大坂城石垣石切丁場跡,残石,花崗岩の風化帯構造,コアストーン,ラミネーションシーティング
Abstract: There are a number of remained cutting stones at the Tengu Iwa Quarry site, one of the Iwagatani Quarry Ruins for Osaka Castle (National historical relic site in 1972), at the area of Iwagatani, Shodoshima town, Shodoshima Island, Kagawa Prefecture. The Tengu Iwa Quarry site maintained a renewal path for public presentation in 2012. Along there, we can observe not only remained cutting stones but also core stones and lamination sheeting which compose of the weathering structure of granitic rocks.
Keywords: Tengu Iwa Quarry site, Stone Quarry Ruins for Osaka Castle, remained cutting stone,National historical relic site, weathering structure of granitic rocks, core stone, lamination sheeting
   p. 1- 13

箱根火山産三輝石安山岩(ピジオン輝石安山岩)の成因

Three pyroxene andesite (pigeonite andesite) from Hakone volcano

石井輝秋

ISHII Teruaki

要旨:ピジオン輝石斑晶を含む火山岩は非常に稀であり,世界で数例しか知られていない.箱根火山箱根峠産普通輝石-ピジオン輝石-紫蘇輝石安山岩(単に三輝石安山岩またはピジオン輝石安山岩と呼ばれる)は久野久先生による,偏光顕微鏡を駆使した詳細な研究論文(Kuno, 1935, 1936a)により世界的に有名である.本研究ではEPMAによりこのピジオン輝石安山岩の輝石晶出経路および輝石温度計で求めたマグマからの輝石晶出温度変化を解析し,その成因を検討した.初生的な水に富むソレアイト質高温マグマが,水に関し開いた二次的マグマ溜り中で三相の輝石を平衡晶出して形成された三輝石斑晶含有マグマ(温度は約1070℃)が,元の高温マグマ(温度は約1110℃)と二次的マグマ溜り中で混合して,ピジオン輝石安山岩を形成したという作業仮説を提出する.水に関し開いた二次的マグマ溜り中での,三種の輝石斑晶の平衡晶出の存在が鍵と成る.
キーワード:箱根火山,輝石地質温度計,ピジオン輝石,マグマ混合,三輝石安山岩
Abstract: Pigeonite phenocryst bearing volcanic rock is very rare in the world. Augite-pigeonite-hypersthen andesite (= three pyroxene andesite or pigeonite andesite ) from Hakone volcano is very famous according to the detailed studies on the pyroxenes using microscope by the late professor Kuno (Kuno 1935, 1936a). On the bases of the detailed EPMA analyses of the pyroxene crystallization sequences as well as estimated crystallization temperatures of pyroxenes and magmatic temperatures using pyroxene geothermometers for the pigeonite andesite, the author suggests the following working hypothesis, i.e. the pigeonite andesite was induced by magma mixing between three pyroxenes andesite magma (about 1070℃) originated from the primitive high temperature hydras tholeiite magma within secondary magma reservoir opened for water, and the high temperature magma (about 1110℃) in the secondary magma reservoir. The key concept is that cocrystallization of three pyroxene phenocrysts under open system for water in the secondary magma reservoir.
Keywords: Hakone volcano, pyroxene geothermometer, pigeonite, magma mixing, three pyroxene andesite
   p. 15- 28

学術研究船淡青丸KT-12-35研究航海の概要 -相模トラフ沿い沈み込み帯の構造と地震発生帯の関係の解明-

Preliminary report of the R/V Tansei Maru Cruise KT-12-35 - Geology and Tectonics between subduction zone and seismogenic zone along the Sagami trough and off Boso peninsula –

石井輝秋・川村喜一郎・小林励司・濱元栄起・山下浩之・安川和孝・大田隼一郎・名取孝人・吉田尊智・原口 悟・中村謙太郎・中野幸彦

ISHII Teruaki, KAWAMURA Kiichiro, KOBAYASHI Reiji, HAMAMOTO Hideki, YAMASHITA Hiroyuki, YASUKAWA Kazutaka, OHTA Junichiro, NATORI Takato, YOSHIDA Takanori, HARAGUCHI Satoru, NAKAMURA Kentaro, NAKANO Yukihiko

要旨:学術研究船淡青丸KT-12-35(2012年度第35次)研究航海は,研究課題名「相模トラフ沿い沈み込み帯の構造と地震発生帯の関係の解明」(代表研究者:川村喜一郎,山口大学大学院理工学研究科)のもと,房総沖,相模湾を調査海域として,平成24年12月23日(日)14:00~平成24年12月27日(木)10:00の5日間(東京台場出港~東京台場帰港)の日程で行われた.相模湾及び房総沖の海底下の地質構造及び地下温度構造を調べ,南関東の地震防災への基礎データを得ることを目的とする.そのために,ピストンコアによる柱状軟堆積物採取(4測点),ドレッジによる海底岩石(堆積岩・火成岩)採取(7測点),ヒートフローによる深海底の地殻熱流量調査(2測点)を行った.
キーワード:相模トラフ,地震発生帯,房総沖,ピストンコア,ドレッジ,地殻熱流量,淡青丸
Abstract: The R/V (Research Vessel) Tansei Maru KT-12-35 Cruise was performed from Sunday 14:00, December 23, 2012 (Daiba, Tokyo harbor) to Thursday 10:00, December 27, 2012 (Daiba, Tokyo harbor) in Sagami bay and off Boso area, to investigate “Geology and Tectonics between subduction zone and seismogenic zone along the Sagami trough and off Boso peninsula”, proposed by the chief scientist; Dr. Kiichiro KAWAMURA. The principal scientific objectives of the cruise were to collect basic scientific data sets for the prevention of earthquake disasters in the Minami Kanto area, according to investigation for geological and geothermal subbottom structure of deep-sea floor in Sagami bay and off Boso area. For those aims, scientific researches were performed at 2 stations of heat flow measurement, 7 stations of dredge to sample bed rocks including igneous as well as sedimentary rocks, and 4 stations of piston core to get sediment cores.
Keywords: Sagami trough, seismogenic zone, off Boso peninsula, piston core, dredge, (terrestrial) heat flow, Tansei Maru
   p. 29- 56

A review on the Cretaceous Raga Formation of the Miyako Group, and its related rocks in Japan

OBATA Ikuwo and MATSUKAWA Masaki

Abstract: The Cretaceous Raga Formation of the lowest Miyako Group is described and discussed in connection with the upperlying formations and the underlying rocks. Excluding the angular or subangular conglomerate (40 m ± in thickness) of the Raga Formation, there are alternating beds of rounded or subrounded conglomerates and conglomeratic sandstones (100 m± in thickness) of an unnamed formation in the Miyako area. As to the regional correlation of the latter alternating beds with four formations of the Miyako Group, a problem is noted herein.
Keywords: Raga Formation, Tanohata Formation, Hiraiga Formation, Aketo Formation, conglomerates, palynological analysis, Harachiyama andesite, Rikuchu Group
   p. 57– 65

橋梁基礎地盤調査における地質リスクの事例研究

Case study on risk of geological investigation for bridge foundation rock

宮島圭司

MIYAJIMA Keiji

要旨:橋梁基礎地盤調査における地質リスクを検討するため,中小橋梁および長大橋梁基礎の事例研究をおこなった.大部分の橋梁基礎において,地質予測の過大/過小評価が認められて地質リスクが発現した.その結果,コスト増が生じている.地質条件が複雑な場合に地質予測のずれが大きくなるので,基礎地盤の地質調査法および解析法の改善が必要である.
キーワード:地質リスク,橋梁基礎地盤,地質予測と実績,過大/過小評価,コスト損失
Abstract: Geological risk of bridge foundation rock is discussed on the basis of case study for short-span and long-span bridges. Over/underestimation of geological and geotechnical conditions arise for most of studied bridge foundations and this geological risk often produce cost loss. Because difficult geological conditions cause noticeable estimation error of bridge foundation rock, improvement of investigation and analysis method is necessary.
Keywords: geological risk, bridge foundation rock, geological estimation and practice, over/underestimation, cost loss
   p. 67- 75

蛇紋岩体分布地域の地すべり・地すべり地形 -その島弧日本列島における概観および小滝地区の例-

Landslides in the areas underlain by serpentinite or ultra-mafic rocks  – An overview on those landslides in Japanese islands and a case study at Kotaki areas, central Japan –

大八木規夫・内山庄一郎・土志田正二・清水文健・井口 隆

OYAGI Norio, UCHIYAMA Shoichiro, DOSHIDA Shoji, SHIMIZU Fumitake, INOKUCHI Takashi

要旨:最初に日本列島における蛇紋岩体の分布とそこに発生している地すべり・地すべり地形について概観した.蛇紋岩体は狭長ではあるが広く分布しており,とくに,東北日本では北海道の神居古潭帯,西南日本では蓮華帯・大江山帯が顕著である.これらより幅は狭いが蛇紋岩体は早池峰構造帯,三波川帯,黒瀬川構造帯などに延々と分布している.地すべり・地すべり地形はこれらの蛇紋岩体に多く発生している.それは葉片状蛇紋岩の部分に顕著であり,塊状蛇紋岩では発生が稀である.つぎに,詳細空中判読の対象として北アルプス北部の大所木地屋地すべり,および,その近隣の数箇所の地すべりを記載した.これらの作業を通して,蛇紋岩体における地すべりは,剪断帯などにおける葉片状蛇紋岩の部分あるいは他の地質体と断層接触している箇所において,著しく形成されていることが認められた.このことから,蛇紋岩における地すべり形成には地質構造,さらに,島弧形成にかかわるテクトニクスとの関係が重要であると考える.
キーワード:地すべり,蛇紋岩,地質構造,島弧,大所木地屋地すべり
Abstract: This paper is consists of two parts. Firstly, an overview is given for landslides on areas underlain by serpentinite and ultra-mafic rocks throughout Japanese island arcs. Major areas underlain by those rocks are Kamuikotan belt in Hokkaido, and Renge or Oeyama belt in western part of Honshu of the Inner Japan. Minor areas are found along Hayachine tectonic zone in northeast Tohoku of northern Honshu, Sambagawa belt, and Kurosegawa tectonic zone of the Outer Japan. Landslides are found in areas underlain by specific types of serpentinite in sheared zones, or contact zones with other rocks along faults. Secondly, detail aerial photo-interpretation is shown on Odokoro-Kijiya landslide at the northern part of North Alps of central Japan developed at the area composed of serpentinite and in addition a few landslides in the nearby areas underlain by similar rocks. A serpentinite rock body of scaly or phyllitic type in sheared zones, specifically contacting with other geologic bodies by faults, shows high susceptibility for landslides but very low of block type not contact with other geologic bodies. As the most of serpentinite rocks are considered as products of hydration of a wedge mantle along a Wadati-Benioff zone from a subduction of an oceanic plate, we have, through this study, approached in conclusion to an idea that those landslides on serpentinite rock bodies are fundamentally related to geologic structure and tectonics related to construction of island arcs.
Keywords: landslides, serpentinite, geologic structure, island arcs, Odokoro-Kijiya landslide
   p. 77-118

「若狭湾津波」の可能性の報道について

On the possibility of the occurrence of Tsunami in the Wakasa Bay at nearly 400 years ago

瀬戸口烈司

SETOGUCHI Takeshi

要旨:東日本大震災が起こった直後に朝日新聞は,1586年の天正地震にともなって若狭湾に津波が襲来し多大の被害が生じたことを記した文献が存在することを指摘した.朝日新聞の記事によると,『兼見卿記』に「丹後若狭ノ海濱津波ニ襲ワル」と記されている.原子力安全・保安院の指示にしたがい関西電力など電力3社は,若狭湾においてボーリング調査を実施して過去に津波被害が起きた痕跡があるかを検討した.その調査で,津波堆積物の指標となり得る砂層は認められないと結論された.地質学的には,1586年の天正地震にともなって若狭湾では津波は発生していないことが証明されたと言える.『兼見卿記』をあらためて検討すると,「波ヲ打上」と表現されているが,「津波」という語は使われていない.東京大学史料編纂所が『大日本史料』を編集し,『兼見卿記』を収録するにあたって係官が「丹後若狭ノ海濱津波ニ襲ハル」と注記した.その注記を朝日新聞は,あたかも『兼見卿記』の本文の記載であるかのように記事にまとめた.ルイス・フロイスの『日本史』でも,「大きな波浪」と表現されているが,津波という語は現れない.1586年に天正地震が起こったのと同じ時期に,季節風による高波が日本海を襲った,というのが実情であろう.「きわめて大きな波」を東大史料編纂所の係官が高波との区別をしないまま津波と表現した.そのあいまいな語の用法が,混乱を巻き起こした最大の原因と思われる.
キーワード:天正地震,若狭湾津波,兼見卿記,三方五湖,津波堆積物
Abstract: Soon after the Earthquake Disaster in the East Japan in 2011, the Asahi Shimbun reported the presence of the old documents that a tsunami following the Tansho Earthquake in 1586 hit the Wakasa Bay in Western Japan and the surrounding areas were suffered heavy damage. According to the article, the sentence that the beach along the Wakasa Bay in Tango District suffered by a tsunami is documented in “The Diary of Sir Kanemi”. According to the instructions from the Nuclear Safety Commission, Kansai Electric Power Co. Inc. and other two electric power companies conducted researches to get sediment cores by boring in the Wakasa Bay to clarify the presence or absence of seawater intrusion into the bay caused by the historically documented tsunami. Sediment cores from the Kugushi and Suga Lakes in the Mikata Five Lakes reveal the absence of such seawater intrusion into these lakes. Geologically speaking, these researches gave reliable evidences to deny the presence of supposed occurrence of “Wakasa Bay Tsunami following the Tensho Earthquake in 1586”. After reexamination of “The Diary of Sir Kanemi”, the words “the surging waves” were documented but the word “tsunami” was not used. When the Institue of Historiography of the University of Tokyo edited “The Historical Documents of Japan”, “The Diary of Sir Kanemi” was also involved in it and a historiographer commented annotation as “the beach along the Wakasa Bay in Tango District suffered by a tsunami”. Asahi Shimbun reported the presence of the sentence regarding the tsunami in the Wakasa Bay as if the sentence was appeared in “The Diary of Sir Kanemi”. In “The History of Japan” published by Luis Flois, the words “high waves” were expressed but the word “tsunami” was not appeared either. At the same time as the Tensho Earthquake occurred in 1586, heavy waves might have been generated by strong seasonal winds of winter time along the Japan Sea. Without clear discrinimation between tsunami and flood tide or high wave, a historiographer might have expressed the word “tsunami” for flood tide or high wave. An ambiguous usage of “tsunami” is regarded as the prime factor to introduce the confusion about the Wakasa Bay Tsunami.
Keywords: Tensho Earthquake, Wakasa Bay Tsunami, Diary of Sir Kanemi, Mikata Five Lakes, Tsunami Deposits
   p. 119- 137

家屋倒壊,および死者分布からみた大正関東震災(1923)の特徴

Characteristics of the 1923 Great Kanto Earthquake judging from distributions of house collapse and the dead person

都司嘉宣

TSUJI Yoshinobu

要旨:大正12年関東震災による当時の町村別の家屋全壊数と死者数を『大正震災志 上』(内務省社会局1926)から拾い出し,分布図を作成した.1町村当たりの家屋倒壊数が大きかったのは,(1)震源域の直上に当たる神奈川県平野部と房総半島最南端,(2)地質年代に湖水域であった甲府盆地や富士五湖地方,(3)江戸時代以前には利根川の氾濫平野であった埼玉県南東部,である.このうち,(1)と(3)では死者数も多かったが,(2)では死者数は少なかった.逆に,家屋倒壊数が少ない割に死者数が多かった場所が埼玉県北部の古利根川と荒川の自然堤防平野域に存在した.家屋倒壊数が多い割に死者数が少なかった場所では,家屋は長周期の緩やかな震動で倒壊したため,住人は倒壊するまでの間に十分に避難措置をとる時間的なゆとりがあったと考えられる.逆に,死者数が多かった場所では家屋は一瞬のうちに倒壊したものと考えられる.
キーワード:大正関東震災,家屋倒壊数,死者数,旧湖沼地の震災被害集中,自然堤防
Abstract: The numbers of the house collapse and the dead person according to the municipalities caused by the 1923 Kanto earthquake in “Taisho Shinsai Shi (The report of the Great Kanto Earthquake, edited by the Department of the Interior Social Welfare Bureau 1926) were collected and made distribution maps of them. The areas where the number of the house collapse was big in (1) the area just above the fault plane; plain areas in Kanagawa prefecture and on the top of the Boso peninsula, in (2) Kofu and Fuji Goko basins which had been parts of lake areas in geologically ancient years, and (3) in Southeast Saitama prefecture which had been was flooding plains of the Former Tone River before the beginning of 17the century. There were many death tolls in (1) and (3), too, but there were few death tolls in (2). On the contrary, the place where there were many death tolls although there was little number of the house collapse existed in the natural levee plains of the former Tone and Arakawa rivers in the area of the north part of Saitama Prefecture. In such area as the area (2), houses were collapsed by long period vibration so, the residents took enough time to refuge measures. On the contrary, it is thought that the house collapsed instantly at the place where there were many death tolls.
Keywords: the 1923 Great Kanto earthquake, the number of the house collapse, the death toll, earthquake disaster damage concentration in the former wetlands ground, natural levee
   p.139- 145

砂山崩し実験における連動性の観察

An observation of consecutive events in sandpile experiments

吉岡直人

YOSHIOKA Naoto

要旨:多角形の受け皿を用いて砂山崩し実験を行った.円ではなく多角形(八角形)を用いることにより,砂山は角錐となり,その斜面はいくつかのセグメントに分割され,それぞれを独立した斜面とみなすことができる.ナダレは1つのセグメントの崩壊として発生することも多いが,複数のセグメントが同時多発的に崩壊して大きなナダレになることも稀ではない.これを「連動」とみなす.どのセグメントが崩壊したのかを観察するために,WEBカメラで一定間隔ごとに写真を撮り,ナダレの前後を比較した.この結果,大きなナダレは隣接するセグメントが同時に崩壊して発生することが確かめられた.また,砂の落下点を受け皿の中心からずらすと,同じ部分が毎回崩れるため,ナダレの周期と大きさに規則性が現れるが,落下点を中心付にすると,周期も大きさも規則性が減少する.この場合,ナダレの起こる時期と大きさを予測するのはかなり困難であるが,複数のセグメントが連動する場合,その中心となるセグメントの変化は直前になって小さくなる(静穏化)ことが見いだされた.その詳しいメカニズムの解明は今後の課題である.
キーワード:砂山崩し実験,ナダレ,連動,セグメント,静穏化
Abstract: Sandpile experiments have been performed using, not a circular, but a polygonal (octagonal) disk. Thus the pile becomes a pyramid, the surface of which is divided into several segments. Each segment is considered to be an individual surface. Avalanches sometimes occur on a single segment and sometimes on several segments simultaneously, resulting in a large avalanche which is regarded as a consecutive event. We used an WEB camera which takes images of the sandpile with a constant interval, in order to identify the location of avalanches by comparing the two images taken before and after a large avalanche. A large avalanche occurs as a result of successive collapses of adjacent segments. We found that when the drop point of sand onto a sandpile misses the center of the disk, the occurrence of large avalanches becomes periodic and regular because the same segments collapse every time, whereas when it matches the center of the disk, it becomes irregular so that it is very difficult to forecast the time and the magnitude of the next avalanche. However we found that the main segment of the next avalanche becomes calm (quiescent) just before the avalanche. The elucidation of detailed mechanism of the quiescence will be a future work.
Keywords: sandpile experiment, avalanche, consecution, segment, quiescence
   p. 147- 156

第4回中央アジア地盤工学シンポジウム参加報告

Report on 4th Central Asian Geotechnical Symposium

藤井幸泰

FUJII Yukiyasu

要旨:第4回中央アジア地盤工学シンポジウムがウズベキスタン共和国のサマルカンドで開催された.シンポジウムは地盤工学と共に,遺跡や歴史的構造物の修復に関する討論や意見交換も行われた.サマルカンドはウズベキスタンにおける重要都市の一つである.世界遺産に指定された都市であり,市内には多くの歴史的構造物が現存する.しかしそれらのいくつかは軟弱地盤や塩類風化などの地質や地盤工学的問題を抱えている.この報告ではシンポジウムの概要を豊富な写真を交えて紹介する.
キーワード:遺跡,修復,保存,塩類風化
Abstract: 4th Central Asian Geotechnical Symposium was held in Samarkand. It intended to discuss and exchange ideas on geotechnical problems as well as conservation of heritage and historical sites. Samarkand is one of the most important cities and the World Heritage sites in Uzbekistan. There are many historical sites, and some of them contain geological and geotechnical problems, for example salt weathering and soft ground. This report introduces abstract of the symposium with abundant beautiful photographs.
Keywords: cultural heritage, conservation, preservation, salt weathering
   p. 157- 164

地盤工学における物理探査データのロックフィジックスをベースにした解釈技術に関する研究(その7) -物理探査データによる透水係数の推定-

Study on rock physical interpretation of geophysical data for geotechnical applications (Part VII) - Estimation of permeability of soils and rocks with geophysical data –

高橋 亨・田中莊一

TAKAHASHI Toru and TANAKA Soichi

要旨:物理探査データを利用して広範囲の透水係数を効果的に推定する手法の開発を目的に,物理探査データにロックフィジックスで提案されている岩石モデルを適用し推定した間隙率と粒径を用いてコゼニーカルマンの式から透水係数を求める手法の適用性を検討した.土質地盤における検討では,検層で得られたS波速度と比抵抗を用いて未固結砂岩モデルとアーチの式により土の粒径と間隙率を推定しコゼニーカルマン式で透水係数を計算した.現場透水試験による実測値と比較した結果,78%のデータで1桁以内の一致をみた.一方,砂質シルト岩に対する適用では,S波速度と密度検層結果に二粒子岩石モデルを適用し推定した粘土含有率から求めた粒径と,密度値から計算した間隙率を用いてコゼニーカルマンの式から透水係数を計算した.原位置透水試験による実測値と比較した結果,実測値との差が1桁以内のデータは53%にとどまった.
キーワード:ロックフィジックス,物理探査,透水係数,コゼニーカルマンの式
Abstract: For developing an effective method to estimate permeability of soils and rocks using geophysical data, we have studied the Koseny-Carman equation (K-C equation) with porosity and grain size estimated from geophysical data based on rock physics models. For application of the proposed method to saturated soils, S-wave velocity and resistivity logging data are input to the unconsolidated sand model and the Archie’s equation for estimating porosity and grain size of the soil, which are employed in K-C equation to calculate permeability. Comparison of estimated permeability with actual measurement by in-situ permeability test shows that permeability is estimated in accuracy less than one order of magnitude for 78 % of the compared data. For application to sandy siltstone, S-wave velocity and density logs are employed in the bimodal mixture model to estimate clay content, which can be used for calculating grain size. The grain size thus obtained and porosity derived from density are utilized for calculating permeability with K-C equation. Permeability estimated in accuracy less than one order of magnitude is only for 53% of the compared data.
Keywords: rock physics, geophysics, permeability, Koseny-Carman equation
   p. 165- 172

Voxler®を使用した河川堤防の物理探査結果の3次元可視化

3D visualization of geophysical data on a river embankment using Voxler®

金子 誠・高橋 亨

KANEKO Makoto and TAKAHASHI Toru

要旨:近年,河川堤防の詳細調査に3次元物理探査が適用され始めている.そこで,河川堤防における物理探査結果をわかりやすく表現するために,3次元データ表示ソフトVoxler® を使用して3次元可視化をおこなった.本稿では,物理探査結果表示に一般的に使われるパネルダイアグラムやブロック図の3次元表示のほか,等値面図や断面図作成のための操作手順および表示例を示す.
キーワード:Voxler,物理探査,河川堤防,3次元可視化
Abstract: In recent years, 3D geophysical exploration has begun to be applied to detailed investigation of river embankment. In order to present geophysical data on river embankment clearly, we performed 3D visualization of them using Voxler®, a 3D imaging software. This paper describes its operating procedures with some examples of 3D images such as block diagram, panel diagrams, isosurface views and cross-sectional views commonly used in presenting geophysical data.
Keywords: Voxler, geophysical exploration, river embankment, 3D visualization
   p. 173- 186

岩盤構造物の性能評価における課題 - 山岳トンネルにおける先進ボーリングの効果について -

On the Performance Evaluation of Tunnel and Underground Cavern - Rational Tunnel Construction using Advancing Boring –

亀村勝美

KAMEMURA Katsumi

要旨:山岳トンネルの建設工事ではまず事前に地質調査が実施され,その結果に基づいて地山分類が行われる.そして支保パターンと掘削工法が指針などに基づいて設定され,施工計画が立てられる.しかしながら,実施工においては,予期していなかった地山条件に遭遇し,支保の追加や補強,掘削工法の変更などを余儀なくされるケースは少なくない.結果として,トンネル周辺地山の掘削影響領域が拡大し,トンネル構造の性能の低下を招く.こうした状況を避けるためには,トンネル切羽で得られる地山情報を的確に評価し,適切な支保パターンにより施工することが重要である.ここでは,北海道で建設されたトンネルで実施された切羽からの先進ボーリングに基づく地山分類結果を詳細に分析し,その効果について検討した.
キーワード:山岳トンネル,岩盤分類,先進ボーリング,情報化施工
Abstract: In the construction of mountain tunnel, a rock mass is classified based on the pre-investigation result. Then support pattern and excavation method corresponding to a rock class is decided based on the specification, and construction is executed. However, there are many cases where reinforcement of supports, change of excavation method and re-excavation are necessary because of the difference of rock condition from the initial assumption. As a result, the performance of tunnel may deteriorate. In order to avoid this situation, proper evaluation of geological information which is obtained at tunnel face is essential. Here, the rock classification result based on the advancing boring from the tunnel face executed in the tunnel constructed in Hokkaido was analyzed in detail, and the effectiveness of advancing boring was examined. As a result, it was shown that the advancing boring was effective for a reasonable, economical tunneling work.
Keywords: mountain tunnel, rock classification, advancing boring, observational construction
   p. 187- 199