This paper describes the measures taken to stabilize the slope above a tunnel portal during construction. In Takasaki Tunnel, Chiba Prefecture, geology of the portal section is very poor, which consists of highly weathered mudstone. Vartical earth stitching bolts were installed prior to the tunnel excavation to minimize the influence of excavation on slope stability. The behavior of the ground and support works including earth stitching bolts were monitored during construction. The observed data indicate that vertical earth stitchng boltseffectively worked to reduce the subsidence of the ground and then to maintain slope stability.

抄録全体を表示

This study aims to analyze university admission trends in the Chiba prefecture. The government decided to keep limited numbers of those entering a university in twenty-three wards of Tokyo. The policy’s aim is to not admit too many Tokyo students. Admission in a university in the Chiba prefecture is affected by admission to university in Tokyo because the Chiba prefecture is next to the capital, Tokyo. This study analyzes successful candidate and enrollment student data by comparing the data from Chiba Prefecture and Tokyo. The results indicate that successful candidates have high academic abilities that increase in the Chiba Prefecture; however, student enrollment is decreased. Nevertheless, student enrollment is increased in Tokyo

抄録全体を表示

Various samples of river waters representing various geological formation in their sources in Kwanto district were taken, and their silicic acid contents were estimated by the Isaacs method, modified slightly ; found that the river waters, same in the geological formation of river source, were nearly similar in regard to the silicic acid content. The following approximate data were obtained : [table]

抄録全体を表示

本研究は従属栄養性微生物群を主生物相と想定した活性汚泥の異化代謝作用に関するもので, まず摂取されたTOC成分の酸化率の推定方法に関して酸素比摂取速度のかわりにTOCとTN各成分の比摂取速度を利用した算定方法の概念を述べ, 次に完全混合連続式及び半連続式の活性汚泥法の試験結果から基質供給方式, 基質C/N比そしてSRT等の各因子が摂取されたTOC成分の酸化率に及ぼす影響を検討するものである.

抄録全体を表示

The Akita-Komagatake, located in the central part of the Ou Back-Bone Range, northeast Japan, is a Quaternary volcano with two calderas. The tephra, younger than 13,500 y.B.P., erupted from this volcano, are stratigraphically divided into thirteen formations, namely AK-13 to AK-1 in ascending order, on the basis of buried soil and loess intercalated. The tephra consists of three types of lithologies: such coarse-grained essential materials as pumice and scoria (type 1), well-sorted black to brown sandy ash (type 2), and fine-grained ash frequently including accretionary lapilli (type 3). These lithologic types are resulted from different styles of volcanic eruption: Plinian to subplinian style eruption (type 1), vulcanian to phreatoplinian style eruption (type 2) and phreatoplinian style eruption (type 3). ¹⁴C measurements on humic soil or woods just below or above the tephra reveal the tendency that the explosive eruptions at the Akita-Komagatake volcano occured during three stages; 13,500 to 11,600 y.B,P., 10,000 to 7,100 y.B.P. and 4,000 to 1,000 y.B.P. In the first stage, AK-13, main part of which is called the Koiwai Pumice, and AK-12, the Yanagisawa Pumice, were erupted. During the eruption of the Koiwai Pumice, the Obonai Pyroclasitic Flow Deposits was produced. The volumes of erupted materials for the tephra including the pyroclastic flow deposit are more than 0.6 km³, and two calderas are thought to have been formed in this stage. In the second stage, AK-11 to AK-6 were erupted. AK-9, the Arasawa Pumice (newly named in this paper), and AK-8, the Horikiri Pumice, are dominated by pumice and scoria (lithologic type 1), and their volumes of erupted materials are more than 0.1 km³. The volumes for other tephra in this stage is more than 0.046km³. Through the second stage to the last stage, the volumes of erupted materials tend to become smaller than 0.046km³.

抄録全体を表示