著者

福井 勝則 辻本 知範 大久保 誠介 松永 昌太

出版者

公益社団法人 土木学会

雑誌

土木学会論文集C (ISSN:1880604X)

巻号頁・発行日

vol.65, no.1, pp.19-28, 2009 (Released:2009-01-20)

参考文献数

13

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地震の前後に観測される電磁波の発生は興味深いことと考えられており,古くから研究されてきた.しかしながら,その現象は極めて複雑であり,電磁波の発生原因を明快に説明することは現状では難しいとされている.本研究では従来あまり検討されていない,AM波に混在する電磁ノイズに着目することとし,日本各地に設置されているAM波帯の電磁ノイズ観測装置による,過去の観測データを調べ,地震前後の電磁ノイズ発生状況の検討を行った.その結果,地震の2週間から5週間前より電磁ノイズは通常より多くなり始め,地震の1,2週間前に最大値を迎えた後,減少し,地震を迎える事例が多いことを示した.

著者

高 秀君 大久保 誠介 福井 勝則 金田 博彰

出版者

一般社団法人 資源・素材学会

雑誌

資源と素材 (ISSN:09161740)

巻号頁・発行日

vol.122, no.1, pp.26-34, 2006 (Released:2007-02-24)

参考文献数

20

被引用文献数

1 1

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For flood prevention, power generation and conveyance, the world's largest Three Gorges Dam was begun to construct in 1993. However, the problem of landslide around the Three Gorges reservoir has not been solved completely so far. Although a lot of geological investigations have been carried out in the field, the role of rock mechanical characteristics in the failure of rock slope has not been cleared thoroughly.In order to study the geological setting and the mechanical characteristic of the landslide area around the Three Gorges reservoir, field investigation and laboratory work including microscope observation, X-ray powder diffraction analysis and uniaxial compressive tests have been carried out. Rock specimens such as two muddy sandstones, a red mudstone, a limestone and a sandstone were collected and examined.The main mineral composition of examined rock specimens except for limestone is quartz. Under the air-dried condition, sandstone is the strongest and weathered muddy sandstone is the weakest. It is interesting to note that calcium contents (carbonate observed) in unweathered muddy sandstone are significantly decreased in weathered one. The decrease in strength for the weathered rock may arise from the dissolution of calcium. For all sample rocks, uniaxial compressive strength shows remarkable decrease under the water-saturated condition. It may be attributed to high content of clay minerals.Complete stress-strain curves were obtained. For all sample rocks, stress increased almost linearly with strain up to the peak strength and then dropped rapidly indicating brittle feature. Weakening under water-saturated condition and high degree of brittleness indicate that very careful and sophisticated measure is necessary to prevent landslide in the area.

著者

福井 勝則 大久保 誠介 羽柴 公博

出版者

東京大学

雑誌

基盤研究(B)

巻号頁・発行日

2007

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AM帯域に混在する電磁波の観測を行い, 地震発生の1ヶ月前から電磁ノイズが増加し始め, 10日前にピークに達し, その後低下し(空白期間といえる部分が存在), 地震に至るという例が多数見られることを示した. 岩石破壊試験を実施した結果, 電磁ノイズなどの予兆現象が地震のかなり前にピークを迎えることは解釈が難しく, 破壊の集中あるいは水の移動により, 空白期間が発生した可能性が高いことを示した.

著者

福井 勝則 大久保 誠介 森山 守 青木 智幸 小塚 孝 松原 誠

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ : journal of the Mining and Materials Processing Institute of Japan (ISSN:18816118)

巻号頁・発行日

vol.123, no.9, pp.467-474, 2007-10-25

参考文献数

14

被引用文献数

2

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The main drive of Hida Tunnel for Tokai-Hokuriku Highway was excavated by a world-largest-class TBM with the diameter of 12.84 m. The TBM have bored over 3.0 km of the tunnel through Nouhi Rhyolite, Granite Porphyry and Hida Gneiss. The uniaxial compressive strength of these rocks was found to be extremely high. Such high strength accompanied by high content of silicon dioxide resulted in significantly high wear rate of the disc cutters mounted on the TBM.<BR>In this study, cutter wear was carefully measured together with the operation conditions such as thrust force, penetration rate, cutter-head rotation rate and the rock properties such as uniaxial compressive strength, rock strength estimated from TBM cutting force, abrasivity obtained from turning operation test, chemical composition determined by X-ray analytical microscope.<BR>It was found that the extent of cutter wear largely depends on position of the disc cutter; cutter wear per unit rolling distance near the fringe of cutter head was extremely larger than that near the center of cutter head. A combination of rock strength estimated by TBM cutting force and length of wear flat in turning-operation test was found to be an excellent index to predict cutter wear rate.

著者

羽柴 公博 福井 勝則

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.136, no.1, pp.1-7, 2020-01-31 (Released:2020-01-31)

参考文献数

26

被引用文献数

2

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Time dependence, probability distribution, and size effect have been investigated by many researchers and are still important issues in rock engineering. These seem to be different characteristics of rock but were found to be closely related to each other through laboratory tests with rock specimens in recent studies. In this paper, the theoretical aspects on the time dependence, probability distribution, and size effect of rock strength were explained, and some of the theoretical results were compared with the previous experimental results. The theoretical formulae based on the rate process theory that represent the failure progression of rock were introduced, and their relation to the theories of visco-elasticity and visco-plasticity was described. The exact solutions of the loading-rate dependence of strength and the creep lifetime were derived from the formulae and were compared with the experimental results of andesite. In addition, the exact solutions of the probability distribution of strength and creep lifetime and their relation to the statistics of extremes were described; the exact solutions of the size effect of strength and creep lifetime and their relation to the comminution theory were also described. The authors clarified what issues have been or have not been verified in previous studies and presented the subjects of future investigation.

著者

福井 勝則 大久保 誠介 寺嶋 卓文

出版者

一般社団法人 資源・素材学会

雑誌

資源と素材 (ISSN:09161740)

巻号頁・発行日

vol.117, no.9, pp.703-710, 2001 (Released:2006-01-08)

参考文献数

21

被引用文献数

1 2

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A number of studies on electromagnetic wave emission from fractured rocks have been heretofore carried out. By many authors it was pointed out that rock fracturing or acoustic emission could be concerned with electromagnetic wave emission. However, the origin of electromagnetic wave emission is still not well understood.In this study electromagnetic wave from rocks was measured with a radio interference measuring apparatus during uniaxial compression testing under several kinds of loading conditions.Firstly, the uniaxial compression testing under constant strain rate of 10-4 s-1 was conducted for seven rocks. It was found that Inada granite, Honkomatsu andesite and Kuzuu dolomite emit electromagnetic wave. However electromagnetic wave cannot be detected for Sanjome andesite, Akiyoshi marble, Kimachi sandstone and mortar.Secondly, electromagnetic wave emission was investigated under several experimental conditions. It was found that Inada granite emits electromagnetic wave during uniaxial compression testing under a constant strain rate of 10-5 s-1 and under a constant rate of (stress-strain / Young's modulus).In most cases, electromagnetic wave emission was accompanied with sudden decrease of stress. By analysis on results of the uniaxial compression testing under constant strain rate, it was found that electromagnetic wave emission is closely related to cracking or crack extension.The main results in this study can be summarized as follows;1) Amplitude of electromagnetic wave is relatively large for strong rock.2) For Inada granite, the larger the stress drop occurred in uniaxial compression test is, the larger the amplitude of electromagnetic wave.

著者

福井 勝則 大久保 誠介 本間 直樹

出版者

一般社団法人 資源・素材学会

雑誌

資源と素材

巻号頁・発行日

vol.112, no.5, pp.303-308, 1996

被引用文献数

7

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A method to estimate rock strength with TBM cutting force is proposed. It is assumed that thrust force for a disc cutter increases linearly with product of rock strength and cutting depth. This assumption leads to the following equations:<BR>(Rock strength)&prop;(Resultant thrust force)/(Penetration rate)<BR>(Rock strength)&prop;(Resultant torque)/(Penetration rate) <SUP>1.5</SUP><BR>By the method, rock strength along Niken-goya tunnel was estimated. The tunnel mainly consists of sandstone and slate. Estimated rock strength well agreed with the results of geological investigation; extremely small strength in fragmented slate, on the other hand, very large while boring through massive sandstone. The estimated rock strength was compared with the results of Schmidt hammer test, and it was found that the correlation between the two was excellent. Correlation between estimated rock strength and rock classification was also examined. It was found that the correlation existed, however, the classification used was too rough to evaluate the proposed method precisely.<BR>The proposed method is relatively simple and requires only three values: thrust force, torque and penetration rate. It can be said that the proposed method is promising for real-time estimation of rock strength on the face.

著者

片岡 みなみ 羽柴 公博 福井 勝則

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.134, no.3, pp.41-45, 2018-03-31 (Released:2018-03-30)

参考文献数

27

被引用文献数

2

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It is known that the rock strength increases with an increase in loading rate. Many studies on the loadingrate dependence of rock strength have been performed under two environments, namely water-saturated and airdried conditions, and the loading-rate dependence has not been investigated well under the conditions of various water saturations observed in situ rock masses. In addition, the quantitative relation between the loading-rate dependence and water saturation has not been examined. In this study, the uniaxial compression test of Sanjome andesite under various water saturations was carried out and the dependence of the strength on the loading rate and water saturation was investigated. The test was performed with alternating two loading rates and the strength corresponding to each loading rate was determined from a single specimen. The test results show that the strength increase with a ten-fold increase in loading rate is almost the same under various water saturations and that the strength increases with a decrease in water saturation. Based on the test results, the theory to explain the dependence of the strength on the loading rate and water saturation was suggested. The variation in the strength was discussed to validate the theory.

著者

岩野 圭太 永江 純一 福井 勝則 羽柴 公博

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.134, no.2, pp.22-30, 2018-02-01 (Released:2018-02-27)

参考文献数

14

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Because blasting is a quite efficient and economical excavation method, it has been widely applied to tunnel excavation especially in hard rock. However, this method is rarely used to the tunnel site close to residential houses due to its environmental impact such as vibration and noise. Nowadays, the advanced electronic detonator, which was widely used in overseas mine site, was introduced to the tunnel site in Japan. This electronic detonator with accurate delay time (=ignition time difference between consecutive holes) has a potential to mitigate blasting vibration. In the past, many studies to lower the blasting vibration had been conducted and in some of them, several ways of simulation were implemented and the relations between vibration mitigation and arrangement of delay time were proposed. In this study, based on the past achievement and blasting test the authors had carried out, the appropriate method to determine the optimum delay time was proposed. In the case of electronic detonator in which each hole has different ignition time, the methods using autocorrelation and frequency analysis were found to be good expectation of delay time to lower the vibration. Also, in the case of conventional electric detonator in which ignition time has dispersion, the relation between vibration and ignition time dispersion was calculated, and the proper way to lower the vibration was proposed. This study gives practical method to set appropriate ignition time to lower blasting vibration.

著者

羽柴 公博 福井 勝則 小泉 匡弘

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.9, pp.223-229, 2017-09-25 (Released:2017-09-27)

参考文献数

92

被引用文献数

2

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Rock drills were developed about two hundred years ago, and hydraulic percussion rock drills are about half-century old. Performance and efficiency of rock drills have been increased by a number of researchers and engineers. Percussion energy was dramatically increased with changing the power source from pneumatic to hydraulic pressures; rods and rod joints were improved to endure the high percussion energy; carbide button bits were developed for hard rock drilling. This paper reviewed the previous studies and future issues on the drilling processes with hydraulic percussion rock drills. Studies on the stress wave propagation in rods and rod joints were based on theoretical and graphical methods and recently on numerical simulation. Studies on the interaction between a button bit and rock included crack propagation in rock, force-penetration relationship during drilling, and bit wear. Studies on the factors affecting drilling efficiency and drilling rate made a transition from simple to precise numerical simulations. Finally, important future issues were presented for the further progress of hydraulic percussion rock drills.

著者

岩野 圭太 永江 純一 福井 勝則 羽柴 公博

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.6, pp.123-131, 2017-06-01 (Released:2017-06-19)

参考文献数

24

被引用文献数

1

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Although blasting is a quite efficient and economical excavation method, it is rarely applied to tunnel projects close to residential areas due to its environmental impacts, especially with regard to vibration and noise. Two key controls used to mitigate the occurrence of noise and vibration due to blasting are the use of small instantaneous explosives charges and the use of precise delay times to initiate the blast design sequence. An advanced electronic detonator, which has its precision of 0.01% of designed delay time and has made it possible to achieve precise initiation control in blasting, was introduced and used in a tunnel construction site in Japan. Testing of the delay times during blasting was carried out, the test results revealed the specific features and performance of the detonator to control the blasting vibration especially within a short distance of the tunnel face. In previous studies, several ways of simulating blasting waveforms were used. One of these, the Monte Carlo method, in which the production wave was reproduced by superposing a single wave had the potential to give good predictions of the production waves that might occur. Therefore, in this study, a similar way of simulating production waves was carried out. Section peaks in the production waveforms correspond with the detonation of each blasthole. These section peaks were found to follow the Weibull distribution, even though the section peaks might be influenced by amount of explosives, drill alignment, and geological inhomogeneity etc. More detailed simulation with consideration of difference in travel time and the change of the Weibull parameters with distance gives further precise results compared with the real production waves. This study leads more precise method of predicting production waves and of optimum blasting design.

著者

片岡 みなみ 包 添書 羽柴 公博 福井 勝則

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.6, pp.107-115, 2017-06-01 (Released:2017-06-06)

参考文献数

28

被引用文献数

3

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The effect of water on the mechanical properties of rocks, such as strength and Young's modulus, has been investigated in many studies. To understand the mechanism of the effect of water on the mechanical behavior of rocks, not only these mechanical properties but also the stress-strain curve, which is one of the most basic data showing the mechanical behavior, should be focused on, and the change of the stress-strain curve with the different water conditions is needed to be known. In this study, the effect of water saturation on the uniaxial compressive strength and the stress-strain curve of rocks was investigated. The uniaxial compression test with alternating loading rate was performed using Sanjome andesite, Tage tuff, Kimachi sandstone and Akiyoshi marble. Inada granite was used for the uniaxial compression test with constant loading rate. The tests were conducted under various water conditions: oven-dried, vacuum-dried, air-dried, air-dried for one day, immersed in water and watersaturated conditions. The test results showed that the stress-strain curve of the andesite, tuff, sandstone and granite changed with the water saturation. On the other hand, the effect of water saturation on the stress-strain curve of the marble was not observed. From the test results, the increase in strength due to decrease in water saturation was discussed. A shift of the peak strength point with the water condition change was investigated, and the relation between the stress-strain curves under the different water conditions was considered based on it.