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山岳トンネルの安全かつ経済的な施工には，切羽前方の地山状況を精度よく予測して，必要に応じて予防保全的な対策工を講じる事が重要である．これまでに筆者らは，日常の施工管理の一環として，簡易に実施できるトンネル天端部の傾斜計測によって，切羽前方地山の硬軟変化を予測する手法を考案し，数値解析や現場計測試験で妥当性と有効性を確認してきた．本論文では，提案手法によって切羽前方地山予測を実現できる条件を明確化する目的で，土被りや地山剛性をパラメータとした感度解析を実施した．また，傾斜計測による地山状況予測結果を，変形余裕量の設定や補助工法の検討に対して実務的に活用することを目指して，傾斜角度から天端沈下量を定量的に推定する方法を検討し，現場実装試験の事後評価で有効性を確認した．, Safe and cost-effective excavation of mountain tunnels requires accurate prediction of geotechnical condition ahead of the tunnel face and preventive auxiliary methods or appropriate support members should be adopted correspondingly. Authors have so far developed a method to predict the change in ground stiffness ahead of the tunnel face by means of inclination monitoring which can be applied without any hindrance to the construction. Applicability and validity of the method have been verified through numerical simulation and field measurement tests. This study performs parametric numerical simulations in which ground stiffness at the face under excavation and ahead of the face, and tunnel overburden are considered as variables in order to clarify the geotechnical condition required for the application of the proposed prediction method. The study also discusses a quantitative estimation method for the tunnel crown settlement by measured inclination. This leads to further effective use of ground prediction results in which allowable deformation volume and appropriate auxiliary methods required can be determined beforehand. Effectiveness of the estimation method is investigated through the post-evaluation of field measurement data.

Purpose: For more than a century, ionizing radiation has been indispensable mainly in medicine and industry. Radiation research is a multidisciplinary field that investigates radiation effects. Radiation research was very active in the mid- to late 20th century, but has then faced challenges, during which time funding has fluctuated widely. Here we review historical changes in funding situations in the field of radiation research, particularly in Canada, European Union countries, Japan, South Korea, and the US. We also provide a brief overview of the current situations in education and training in this field. Conclusions: A better understanding of the biological consequences of radiation exposure is becoming more important with increasing public concerns on radiation risks and other radiation literacy. Continued funding for radiation research is needed, and education and training in this field are also important.

Safe and cost-effective excavation of mountain tunnels requires accurate prediction of geotechnical condition ahead of the tunnel face and preventive auxiliary methods or appropriate support members should be adopted correspondingly. Authors have so far developed a method to predict the change in ground stiffness ahead of the tunnel face by means of inclination monitoring which can be applied without any hindrance to the construction. Applicability and validity of the method have been verified through numerical simulation and field measurement tests. This study performs parametric numerical simulations in which ground stiffness at the face under excavation and ahead of the face, and tunnel overburden are considered as variables in order to clarify the geotechnical condition required for the application of the proposed prediction method. The study also discusses a quantitative estimation method for the tunnel crown settlement by measured inclination. This leads to further effective use of ground prediction results in which allowable deformation volume and appropriate auxiliary methods required can be determined beforehand. Effectiveness of the estimation method is investigated through the post-evaluation of field measurement data.

日本原子力研究開発機構は、新第三紀堆積軟岩を対象とした高レベル放射性廃棄物の地層処分技術に関する研究開発を目的として、北海道天塩郡幌延町において幌延深地層研究計画を進めている。幌延深地層研究所周辺の地質は、珪藻質泥岩の声問層や珪質泥岩の稚内層で構成され、どちらも珪藻化石を多量に含んでいる。これらの岩石は高い空隙率と低い透水性を示すことから、多孔質弾性論に基づく岩盤挙動の検討が重要であると考えられる。しかしながら、幌延深地層研究所周辺に特徴的な珪藻質泥岩や硬質頁岩については、低透水性であるという岩石の特徴や試験時の制御が容易ではないこと等を要因に、多孔質弾性パラメータの測定実績は多いと言えない状況である。そこで、珪質泥岩(稚内層)を対象として、多孔質弾性パラメータの測定実績を蓄積し、既往の研究で示唆されている拘束圧に対する依存性を確認することを目的として、多孔質弾性パラメータを取得するための岩石三軸試験を実施した。その結果、多孔質弾性パラメータのうち、排水体積弾性係数は拘束圧の増加に伴い大きくなる関係性が確認された。一方、Biot-Wills係数およびSkemptonの間隙水圧係数は、拘束圧の増加に伴い小さくなる傾向が確認された。また、岩石供試体の葉理方向によって拘束圧依存の程度が若干異なることが示唆された。, The Japan Atomic Energy Agency (JAEA) has conducted with the Horonobe Underground Research Project in Horonobe, Teshio-gun, Hokkaido for the purpose of research and development related to geological disposal technology for high-level radioactive wastes in sedimentary soft rocks. The geology around the Horonobe Underground Research Laboratory (HURL) is composed of the Koetoi diatomaceous mudstone layer and the Wakkanai siliceous layer, both of which contain a large amount of diatom fossils. Since these rocks exhibit relatively high porosity but low permeability, it is important to investigate the poro-elastic characteristics of the rock mass. For this objective, it is necessary to measure parameters based on the poro-elastic theory. However, there are few measurement results of the poro-elastic parameters for the geology around HURL, and the characteristics such as dependence on confining pressure are not clearly understood. One of the reasons is that the rocks show low permeability and the pressure control during testing is difficult. Therefore, a poro-elastic parameter measurement test was conducted on the siliceous mudstone of the Wakkanai formation to accumulate measurement results on the poro-elastic parameters and to examine the dependence of the parameters on confining pressure. As a result, some dependency of the poro-elastic parameters on confining pressure was observed. Among the measured or calculated poro-elastic parameters, the drained bulk modulus increased, while the Skempton's pressure coefficient, and the Biot-Wills coefficient in the elastic region decreased with the increase in confining pressure. The measurement results also inferred that the foliation observed in the rock specimens might impact a degree of dependency of those parameters on confining pressure.