Centrifuge Model Tests of Tieback Anchors and Drainage Pipes for Stabilization of Slopes under Earthquake Loads

Tieback anchors are widely used for the stabilization of natural and manmade slopes in Japan. The interactions between tieback anchors and slopes under seismic loading need to be understood to develop rational design concepts and installation methods in earthquake prone areas. We conducted centrifuge model tests to examine the characteristics of dynamic and residual loads on tieback anchors installed in slopes subjected to seismic loads. If the model slope contained a saturated zone, circular failure occurred even with pre-tensioned tieback anchors, and the amplitude of the oscillating loads on the tieback anchors was very high. This suggested that excess pore water pressure may cause the design capacity of the anchors to be exceeded, depending on the stability of the slope and intensity of the earthquake. Additional tests were therefore conducted with model slopes with drainage pipes installed (perforated plastic tubes). The drainage pipes significantly reduced pore water pressure, which in turn enhanced the stability of the slope and reduced the loads on the tieback anchors. We conclude that installation of drainage pipes in earthfill slopes would enable the selection of smaller ground anchors and potentially reduce overall construction costs

Clinical significance of gastrointestinal bleeding history in patients who undergo left atrial appendage closure

Background and Aim: Anticoagulant users with nonvalvular atrial fibrillation (NVAF) sometimes suffer from gastrointestinal bleeding (GIB) and have difficulty continuing the medication. Left atrial appendage closure (LAAC) has been developed for such situations. We aimed to clarify the clinical significance of a history of GIB in comparison to other factors in patients who had undergone LAAC. Methods: From October 2019 to September 2023, patients with NVAF who underwent LAAC at our hospital were enrolled. We investigated the percentage of patients with a history of GIB who underwent LAAC and compared the incidence of post-LAAC bleeding in these patients compared to those with other factors. Results: A total of 45 patients were included. There were 19 patients (42%) with a history of GIB who underwent LAAC. In a Kaplan–Meier analysis, the cumulative incidence of bleeding complications after LAAC was significantly higher in patients with a history of GIB in comparison to patients with other factors. There were eight cases of post-LAAC bleeding in total, and seven cases had GIB. Conclusions: We need to recognize that GIB is a significant complication in patients who undergo LAAC. The management of GIB by gastroenterologists is essential to the success of LAAC

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本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである京都大学0048新制・論文博士博士(工学)乙第10506号論工博第3543号新制||工||1192(附属図書館)UT51-2000-P673(主査)教授 中條 善樹, 教授 田門 肇, 教授 平尾 一之学位規則第4条第2項該当Doctor of EngineeringKyoto UniversityDFA

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京都大学0048新制・課程博士博士(理学)甲第12174号理博第3068号新制||理||1457(附属図書館)24010UT51-2006-J167京都大学大学院理学研究科生物科学専攻(主査)教授 正高 信男, 教授 三上 章允, 教授 林 基治学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA