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公益財団法人深田地質研究所年報 第15号 2014


火成岩岩石学における造岩鉱物解析の勧め -恩師久野久先生に導かれて-

Encouragement of precise investigation on rock forming minerals in the igneous petrology.With gratitude for the late professor Hisashi Kuno’s initiation and guidance

石井輝秋

ISHII Teruaki

要旨:恩師久野久教授の最後の学生であった筆者も,間もなく古希を迎え様としています.つまり,先生が亡くなられて早半世紀になろうとしています.本報告では私的側面にも触れながら,久野久先生に導かれた研究生活を振り返って,火成岩岩石学における造岩鉱物解析の重要性を提示し,推奨します.石井輝秋が1969年に先生から頂いた卒業論文のテーマは『箱根金時山型斜方輝石の研究』でした.顕著な帯状構造を示す輝石の解析とX線単結晶回折から,金時山型斜方輝石はピジオン輝石安定領域最下限(=PER-line)上で晶出したピジオン輝石が,中程度の徐冷下でホストの斜方輝石とラメラの普通輝石とに分解した,転移ピジオン輝石であると解釈しました.更に3種類の輝石地質温度計を開発して,溶岩の輝石晶出経路に適用し,lava flow trendとsubvolcanic reservoir trendの差異を明示しました.箱根火山OS,YS,CC全体の初生マグマとしては,ややwetな島弧ソレアイトマグマが考えられます.水に関してOS&YSは半開放系及びCCは閉鎖系のマグマ溜りの条件下で,初生マグマが結晶分化して形成されたと考えられます.
キーワード:久野久教授,箱根火山,輝石地質温度計,箱根金時山型斜方輝石,島弧ソレアイトマグマ,造岩鉱物, PER-line,lava flow trend,subvolcanic reservoir trend
Abstract: The author, who is the last student of the late Professor Hisashi Kuno, is approaching 70 years old, i.e., it means that almost a half century has passed since he passed away. I will report retrospective review of my research initiated and guided by Kuno-sensei including personal events. I would like to encourage for precise investigation on rock forming minerals in the igneous petrology. Kuno–sensei suggested to study on “orthopyroxene Kintoki-san type in Hakone”for Teruaki Ishii’s (Teru =shine =pyro, Ishi =stone =xene) graduation thesis in 1969. Analyses for zoned Ca-poor pyroxene and X-ray studies for single crystal suggest that the orthopyroxene of Kintiki-san type is inverted pigeonite, i.e., pigeonite crystallized along the lower stability limit of pigeonite field (=PER-line) decomposed into host orthopyroxene and exsolved augite lamellae under intermediate cooling. Three kinds of pyroxene geothermometer were proposed and were applied to the analyses on pyroxene crystallization sequences, and then lava flow trend and subvolcanic reservoir trend were established. Primitive magma of Hakone volcano for all OS, YS and CC stages may be assumed as semi-wet island arc thollite magma. OS&YS and CC magmas were induced under semi–open and closed conditions for water in magma reservoir, respectively.
Keywords: Professor Hisashi Kuno, Hakone volcano, pyroxene geothermometer, orthopyroxene of Kintoki- san type, island-arc tholeiite magma, rock forming minerals, PER-line, lava flow trend, subvolcanic reservoir trend
   p. 1-20

写真測量とコンピュータビジョンの最近の動向 -アンモナイトの三次元化に関して-

Recent trend about Photogrammetry and Computer Vision: 3D visualization from multiple 2D images of Ammonite Fossil

藤井幸泰

FUJII Yukiyasu

要旨:アンモナイト化石の三次元モデル化に関して,写真測量とStructure from Motion(SfM)の両技術の適用を試みた.どちらでも三次元モデル化は可能であるが,従来の写真測量は標定点の設置と測量など煩わしい作業も多い.近年のコンピュータビジョンの発展から生まれたSfMはとりあえず写真撮影すれば三次元モデルができてしまう.今後も技術の進展を見守りつつ,地質対象物への適用を試みていきたい.
キーワード:デジタルカメラ,画像処理,Structure from Motion,バンドル調整
Abstract: Photogrammetry and Structure from Motion (SfM), which is one of computer vision techniques, were applied to make three-dimensional (3-D) model of an ammonite fossil. Both techniques are useful to make 3-D models. On the one hand, it is needed to put control points and measure them for photogrammetry. On the other hand, it is very easy for SfM to make a 3-D model from multiple photo images. The technique related to photogrammetry and computer vision will be progressed in the future. It would be applied to geo-objects.
Keywords: Digital Camera, Image Analysis, Structure from Motion, Bundle Adjustment
   p. 21-26

Indoceras baluchistanense Noetling, 1897 from west Kohat, south of Peshawar, northern Pakistan

OBATA Ikuwo, OHUCHI Seiji and MATSUKAWA Masaki

Abstract: Newly collected oxycones from northern Pakistan is studied and described herein, with the geological setting. They show so many common features to those of type specimens of Indoceras baluchistanense. Coromandel coast including Pondicherry, Ariyalur etc., is illustrated as palaeostratigraphical and palaeobiogeographical figures on the southern India.
Keywords: Cauveri Basin, Uttattur (Ootatoor) Group, Trichinopoly Group, Ariyalur (Ariyaloor) Group, Pondicherry area, Valudayur beds, Trigonarca beds, Coromandel coast
   p. 27–38

筑波山塊を取り巻く岩屑堆積面とその堆積層

Piedmont slopes underlain by debris deposits surrounding Tsukuba Mountains, Kanto, Japan

大八木規夫・池田 宏・木村克己・大井信三・内山庄一郎・鈴木比奈子・清水文健・井口 隆

OYAGI Norio, IKEDA Hiroshi, KIMURA Katsumi, OOI Shinzou, UCHIYAMA Shoichiro, SUZUKI Hinako, SHIMIZU Fumitake and INOKUCHI Takashi

要旨:筑波山塊を取り巻く緩傾斜の岩屑堆積面の代表例5地区について記載し,形成時期,岩屑供給域との関係を考察した.これらの堆積面は赤城山起源テフラの鹿沼軽石層を含む火山灰起源のローム層に覆われる深さ20m以下の岩屑堆積物からなっている.その構成物は径5m以下の花崗岩類の角礫・亜角礫とマサおよび火山灰起源ローム土のマトリックスからなり,岩屑なだれ・土石流により形成された.その地表面は上位からU,H,M,および,Lの4面に区分される.これらのうち,H面が最も広く普遍的に発達している.このH面の岩屑堆積層形成時期について,これを覆う赤城山起源のテフラや火山灰層との関係,および,山体構成物から大量の滑落崩壊,緩勾配での移送・堆積を可能にする降水の強度と量に関して,最も可能性の高い時期はMIS 5e,すなわち,120ka前後と考えた.岩屑堆積面と岩屑供給域との面積比Asr/Adbを検討したところ,代表例のうち4地区は堆積域に対応する供給域が認められたが,残る1地区(猿田地区)は供給域が1/2であった.これは岩屑面形成時から今日までに谷の争奪があったか,あるいは,局所的に著しい削剥があったのかなどの問題が考えられる.この山塊には5系統のリニアメント(断裂系)が発達している,岩屑堆積面の中心軸はこれらリニアメントの制約を明瞭に受けていることから,岩屑の生産にもこれらの断裂系が強く関わっている.なお,筑波山塊の上部には岩屑堆積面形成後今日までに小・中規模の崩壊や浅層クリープなどにより生産されたと推定される岩屑が大量に認められることから,今後の斜面防災にむけた詳細な調査が必要である.
キーワード:緩斜面,岩屑堆積面,岩屑堆積層,岩屑供給域, MIS 5e,花崗岩類,断裂系
Abstract: As typical piedmont slopes underlain by debris deposits (PSD) surrounding Tsukuba Mountains composed of granitic rocks, five examples from those PSDs were described and discussed on their deposition stage and relation between the slopes and the debris source areas. The PSDs are underlain by debris ~20m thick with large angular blocks ~5m in length, and covered by brown soil ~2m thick weathered from volcanic ash intercalating so-called “Kanuma” pumice fall deposit (Ag-KP, a regional tephra in Kanto region) which were brought from Akagiyama volcano 90km west-north-west from Tsukuba Mountains. It is thought that the PSDs were formed by debris avalanches and/or debris flows. The surfaces of the PSDs are divided into four; U, H, M and L from upper to lower. The H-surfaces among them are the most smooth and found generally and widely in the study area. We suggest that the most probable stage of the debris deposition of the H-surfaces is MIS 5e (120ka ±), because of their relation with volcanic ash and of capability of expectedly larger volume and stronger intensities of rainfall needed to cause extreme number of landslides on the mountain, transportation and deposition of debris to construct the PSDs in the warmer stage than in other colder stages during the Late Pleistocene. The ratio of a source area to that of a PSD, Asr/Adb, is close to or larger than unity on four examples, but another one, Saruta PSD, is 1/2. It is considered that piracy of valleys or deeper erosion than other sites of PSDs would be caused during the development of the Saruta PSD. Five series of lineament (fracture systems) can be identified on the relief map of the study area produced from 10m-mesh-DM. Fracture systems may strongly concerned to produce great volume of debris, because the central axes of PSDs are constrained by those fracture systems. Reverse type and box type of weathering zone structure are found on the upper slopes of Tsukuba Mountains. It may be produced by development of fracture systems and by rapid erosion of the mountains during the formation of PSDs. As we found thick debris or unsteady creeping blocks produced probably after the formation of PSDs on several areas of the mountain, specifically upper slopes, it should be said to need detail survey on their distribution and volume on those slopes for mitigation of future disasters.
Keywords: piedmont slope, debris deposits, debris source area, MIS 5e, granites, fracture systems
   p. 39-68

安政東海・南海地震(1854),および宝永地震(1707)による大坂での地震・津波被害

Damage caused by the 1854 Ansei Tokai- Nankai and the 1707 Hoei Earthquakes-Tsunamis in the Osaka City zone

都司嘉宣

TSUJI Yoshinobu

要旨:紀伊水道から四国にかけての南方海域を震源として,およそ100年の繰り返し間隔で南海地震が起きている.この海域では1707年には宝永地震が,1854年には安政南海地震が起きている.南海地震が起きるたびに,大坂市中は地震の揺れと津波によって大きな被害が生じた.1854年の安政南海地震による大坂市中北西部での震度は5から6強であったと推定される.安政南海地震の本震発生の約2時間後,津波が市中の水路に浸入し,多くの避難民を乗せた船は上流に運ばれ,橋のところで転覆した.安政南海地震のさいには大坂全体で津波によって361人が溺死した.本研究では安政南海地震による大阪平野全体の詳細震度分布図を描いた.それによると,旧河内国の北部で震度がより強かったことが判明した.その領域は,弥生時代末期の四世紀ごろ消滅した河内湖の領域に一致していたことが判明した.西暦684年の白鳳南海地震以来,今日までに9回の南海地震が記録されているが,887年の仁和地震,1361年の正平南海地震,1707年の宝永地震の三つは特に大きく,この3回とも大坂には大きな津波被害をもたらしている.この3回の特に大きな南海地震の痕跡は四国・室戸岬の三段の海岸段丘として痕跡をたどることができる.
キーワード:安政南海地震,津波の河川遡上,歴史地震,干拓地の震度増加.
Abstract: A series of gigantic earthquakes called Nankai earthquakes occurs in the Pacific sea area south offing the Kii straits and Shikoku island in the intervals of about one hundred years. The earthquakes belonging to this series broke out in 1707 and 1854 called the Hoei and the Ansei Nankai earthquakes, respectively. Whenever a gigantic earthquake belonging to this series occurred, the city area of Osaka seriously damaged both by the shaking and by the accompanied tsunami. Seismic intensity of the 1854 Ansei Nankai earthquake was estimated at 5 to stronger 6 in the northwest section of the central Osaka area. About two hours after the occurrence of the main shock of the Ansei Nankai earthquake, tsunami waves rushed into the channels in the city and ships with many refugees carried upstream and wrecked at bridges. In total, 361 people were killed due to the tsunami of the 1854 Ansei Nankai earthquakes in Osaka. In the present study, the map of detailed distribution of seismic intensities was drawn for the whole area of the Osaka plains. It was clarified that there was an area of stronger shaking in the north part of Kawachi province, whose area coincides with the area of the ancient Kawachi Lake which had disappeared at the end of Yayoi period (4th century). Since the occurrence of the Hakuho Nankai earthquake of 684 AD, in total 9 events were recorded. The Nankai earthquakes of the 887 Ninna, the 1361 Shohei, and the 1707 Hoei were extraordinary gigantic ones and the accompanied tsunamis of those three events hit Osaka seriously. These events can be detected as the three steps at the marine terraces of the cape Muroto, Shikoku.
Keywords: the 1854 Ansei Nankai earthquake, tsunami waves ascending upstream a river, historical earthquakes, seismic intensity increasing on a reclaimed land.
   p. 69- 82

砂山崩し実験における連動性の観察(2)

An observation of consecutive events in sandpile experiments (2)

吉岡直人

YOSHIOKA Naoto

要旨:昨年に引き続き,八角形の受け皿を用いて砂山崩し実験を行った.すなわち,8つの斜面を独立したセグメントと見做し,その連動性を観察した.データは昨年同様,砂山全体の重量変化と,一定時間間隔で砂山上部から撮った写真である.データの採取方法や,解析方法にはかなりの改良を加えた.とくに,重量データと写真のデータを組み合わせた解析方法を開発し,各セグメントの状態の時間変化を追跡することが可能となった.この結果,大きな崩落は,グーテンベルグ-リヒター則に従う小さな崩落とは明瞭に区別すべきものであること,大きな崩落を起こしたセグメントは,その後余震活動を連想させる活発な砂移動を起し,全体としてそれが治まったころ次の大崩落が起きることが見てとれた.しかしながら,次の大崩落が,どの場所で,連動性を含めてどの程度の規模で起きるかを予測することは,極めて困難であることも明らかとなった.
キーワード:砂山崩し実験,連動,セグメント
Abstract: Following the last year, I have performed sandpile experiments using an octagonal disk. The pile is a pyramid having 8 independent surface segments. The consecutive events between them were observed. The data are the change in the total weight of the sandpile and the photographs of the pile taken from an above point with a constant time interval. The methods of data acquisition and data analysis were greatly improved. In particular, I developed the analytical programs in which the weight data and the photo data were assembled. Thus the time traces in the weight of each segment were able to be obtained. We found that the large events should be clearly distinguished from other small events which obey the Gutenberg-Richter law, and that the segments at which a large event occurred become very active after the event. This reminds us of aftershock activity. The next large event seems to occur when the activity becomes calm. However, it appears that it is very difficult to forecast where and how large the next large event will be.
Keywords: sandpile experiment, consecution, segment
   p. 83-90

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8) -物理探査データによる透水係数の推定(2)-

Study on rock physical interpretation of geophysical data for geotechnical applications (Part VIII) - Estimation of permeability of soils and rocks with geophysical data (2)-

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.不飽和土質地盤としての河川堤防上の地表探査で得られたS波速度と比抵抗を用いて未固結砂岩モデルとグローバのモデル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.開削断面で採取された試料の室内透水試験による実測値と比較した結果,砂質土,粘性土とも1桁程度の精度で一致した.硬質砂岩の室内試験で測定されたS波速度と比抵抗データに頁岩質砂岩モデルを適用し推定した粘土含有率から求めた粒径とアーチの式に基づき比抵抗から推定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.室内透水試験による実測値と比較した結果,多くのデータ(約75%)が実測値との差が1桁以内で推定された.
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 a method using the Koseny-Carman equation (K-C equation) with porosity and grain size estimated from geophysical data based on rock physics models. For an application of the proposed method to unsaturated levee soils, S-wave velocity and resistivity profiles across the levee are input to the unconsolidated sand model and the Glover’s model 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 laboratory permeability test of soils sampled on an excavated levee section shows that permeability is estimated in accuracy of around one order of magnitude for sandy and clayey soils. For an application to hard sandstone core samples, S-wave velocity and resistivity measurements in the laboratory are modeled by the shaly sand model and Archie’s equation to estimate clay content, which can be used for calculating grain size. The grain size thus obtained and porosity derived from resistivity with the Archie’s equation are utilized for calculating permeability with K-C equation. Many of compared data (about 75%) agrees each other in the accuracy less than one order of magnitude.
Keywords: rock physics, geophysics, permeability, Koseny-Carman equation
   p. 91-98

現場透気試験による亀裂性岩盤のスレショールド圧の評価

Evaluation of threshold pressure of fractured rock by in-situ gas-tightness test

下茂道人・島屋 進・前島俊雄

SHIMO Michito, SHIMAYA Susumu and MAEJIMA Toshio

要旨:亀裂性岩盤内のガスの移行特性は,LPG地下貯蔵,放射性廃棄物処分,CCS,メタンガス地山におけるトンネル掘削など,多くのエンジニアリング分野で問題となる.地盤内のガスや水の同時流(二相流)のシミュレーションにおいては,地盤固有の透過特性とともに相対透過率や毛管圧と水飽和度との関係が解析結果に大きく影響を与える.これらのパラメータは,現場試験結果に基づいて設定されることが望ましいが,試験技術が確立していないため,砂地盤や堆積岩の室内試験結果や既往の計算事例などを参考に,適用性を十分に確認しないまま亀裂性岩盤の解析に用いているのが現状である.なかでも,ガスが水と入れ替わる際に亀裂内の気液境界面に生じる差圧(スレショールド圧またエアーエントリー圧と呼ばれる)は,ガスの移動や分布に大きく影響するパラメータであるが,国内外において現場試験事例が非常に少ない.
著者らは,ボーリング孔を用いて亀裂性岩盤のスレショールド圧を測定する装置を開発するとともに,同装置を用いた複数の試験手法を考案し,LPG岩盤タンクの建設サイトにおいて適用性確認試験を行った.本論文では,現場試験で得られた試験技術の適用性や岩盤の透過率とスレショールド圧との関係などについて得られた知見について述べる.
キーワード:亀裂性岩盤,スレショールド圧,現場試験,気密性,二相流
Abstract: Gas transport characteristics of fractured rocks is a great concern to variety of engineering applications such as LPG underground storage, nuclear waste disposal, CCS, gas flooding in the oil field and tunneling excavation in the methane-bearing ground. Besides absolute permeability, the relative permeability and the capillary pressure as a function of water saturation, have direct influences to the results of subsurface two phase flow simulation, however, number of the in-situ test results on these parameters are limited. The authors have developed equipment and the procedures to evaluate the threshold pressure of fractured rocks and applied them to a series of in-situ tests in a granitic rock at the Namikata underground LPG storage site in Ehime prefecture, Japan. This paper discusses the applicability of the developed technologies for the measurement of the threshold pressure and also the relationship between threshold pressure and permeability of fractured rocks based on the in-situ test results.
Keywords: fractured rocks, threshold pressure, in-situ test, gas-tightness, two-phase flow
   p. 99-106

岩盤構造物の性能評価における課題 -先進ボーリング調査結果に基づく地山分類-

Some Issues On the Performance Evaluation of Tunnel and Underground Cavern - Rock Mass Classification based on Advancing Boring Results –

亀村勝美

KAMEMURA Katsumi

要旨:北海道の道路トンネルでは,設計施工要領によって全線にわたって切羽からの先進ボーリングを行うことが原則とされており,これによって施工中に地山に関する多くの情報が得られる.そこで先進ボーリングが実施された16のトンネル(全長31km)における事前調査結果,先進ボーリング結果と施工実績の関連性について検討を加えてきた.そしてこれまでに,ある程度の費用と時間を必要とするが先進ボーリングから得られる豊富な情報を用いることにより,予測と施工時の地山等級との一致率をかなり高くでき,最終的に合理的なトンネル施工が可能となることを明らかにしてきた.一方で,先進ボーリングにより得られる大量の情報のすべてが必ずしも地山分類評価に活かされておらず,現行の地質調査結果に基づく地山評価法(地山分類表)を見直すことによって,評価精度を向上させることが出来る可能性があることを示した.
キーワード:山岳トンネル,地山分類,先進ボーリング
Abstract: In the road tunnel in Hokkaido, an advancing boring from tunnel face has been regulated by the road tunnel design and construction guidelines. So a lot of information concerning to rock mass properties are acquired. Here, rock mass classification results based on the advancing boring of 16 tunnels (31 km in total length) are compared with constructed results. As a result, it is clearly shown that the accuracy of rock mass classification can be made higher by using advancing boring data. On the other hand, a lot of information acquired by advancing boring have not been properly used in rock mass classification, so the further study might be possible to improve the rock mass classification table.
Keywords: mountain tunnel, rock classification, advancing boring
   p. 107-115

堆積性泥質軟岩の物理・力学的特性評価手法に係る若干の考察

On the unique experiences for the characterization of rock basement in argillaceous soft or weak rock

田中莊一

TANAKA Soichi

要旨:岩盤内もしくは岩盤上に重要構造物を構築するにあたってはその基盤岩の地質学的・工学的特徴を十分に把握する必要があるが,構造物規模や工費によっては相応の調査・試験が常に行われるとは言い難い.その結果,建設中あるいは供用後に基盤岩に起因するトラブルが生じる例がしばしば見聞きされる.とりわけ軟岩基盤,特に堆積性泥質軟岩域では施工対応の容易さも相俟って等閑にされがちである.そこで,今後の参考に供すべくこれまでの経験をもとに岩盤構造物の特徴的で重要な岩の特性をまとめ,特に不均質性や時間依存性など泥質軟岩の物理・力学的性質について紹介した.野外調査,原位置もしくは室内試験を通して得られる岩の物性値は,対象岩盤に作用する外力とその履歴,地下水浸透と含水状況変化などに対する取り扱い方により異なる.それら差異は岩に作用する外力と発生ひずみ量の大きさと時間効果に影響され,作用速度と継続時間,岩内部の水の流動性,さらには岩盤構造物の形状と境界条件などにより説明できる.具体的には, ひずみ依存性と長期変形特性に関する大規模検討実験をもとに考察した.しかし,種々の調査・試験手法による差異を統一的に解釈し岩の特性を評価する方法について言及できる段階には至っていない.また,これらの物性値は点の情報(ミクロモデル)であって広域の領域を表現(マクロモデル化)できるものではない.広域へのアップスケーリングの考え方と具体的手順の確立が望まれる.そのためには物理探査法の活用が不可欠であり,ロックフィジックスの研究を核にしたミクロからマクロモデルへのアップスケーリングの考え方について述べた.
キーワード:泥質軟岩,岩相,物理・力学的性質,破壊規準,ひずみ依存性,長期変形特性
Abstract: The characterization of properties of rock basement in argillaceous soft/weak rock presents effective information to construct various structures in/on rock. However it is rather difficult to select adequate method out of means by several investigations and experiments. According to my experiences in the evaluation of physical and mechanical properties of argillaceous rock , several essential points are revealed as follows:(1) mechanical properties as strength and deformation moduli are depending on the strain level and on loading-velocity to surface of rock basement at in-situ experiment or to test pieces in the laboratory. (2)The different aspects of rocks as intact/crushed/sheared/weathered/crushed with clay/fault gouge indicate clearly differences in the criteria by power functional equation with strength parameter α,β.(3)Creep parameters α(on deformation) and β(on lapse time) indicate contracting tendency between in-situ creep test and creep test in laboratory. The reason of these differences is considered on the effects of the drainage of pore water and the different boundary condition of in-situ and specimen form. Anyway we can gain readily each micro models of rock basement by experiences, but we don’t know how to develop to macro models for wide area. So I emphasize it is very important to develop the upscaling technique.
Keywords: argillaceous rock, rock property, failure criterion, strain dependency, creep parameter
   p. 117-129