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砂防ダム附近における流木阻止に関する実験的研究 An Experimental Study on Checking of Flow-Timbers neighbouring Check-Dam 佐々木, 八郎 Recentry in Japan, there are very often seen the destructions of many bridges and banks in flood which grow severer not only by sedimentmaterials, e. g. flow-stone and -sand, but also by float-materials, especially flow-timbers. Namely, these destructions are more intensified by the damupped backwater which is caused by flow-timbers checked by bridge piers at the peak time of a flood. The farther the river runs down, the heavier the damage becomes by flow-timbers. Therefore, if the peak time of flow-timbers can be retarded later than that of flood-discharge, the disaster on riverstructures will considerably be decreased. Accordingly, to check flow-timbers is as much important mission charged to the upper reaches of a river as to check flow-stone and -sand. The author consulted with the authorities concerned of Nagano Prefecture who have serious concerns about the above-mentioned and adopted the following proposals, A and B, as a practical plan for checking flow-timbers, and he tried a hydraulic experiment in using a model channel (see Fig. 1) to make it realize. A : a proposal to avail the sub-check-dam and set a leading gate, B a proposal to set a leading net. The results of the experiment may simply be stated as follows :A. (1) The checking-ratio=(U+W)/(T+U+V+W). Where, T :the number of the flow-timbers stopped on the bottom at the upper stream from the leading gate, U : do. drifting along the gate, V do. flowing down under the gate, W : do. caught into the pocket of the sub-check-darn. The details relating to U, V and W will be understood in Figs. 6～15 of this paper. Article 信州大学工学部紀要 13: 59-90 (1962) 信州大学工学部 1962-08-01 jpn departmental bulletin paper VoR http://hdl.handle.net/10091/11024 https://soar-ir.repo.nii.ac.jp/records/13124 0037-3818 AN00121228 信州大学工学部紀要 13 59 90 https://soar-ir.repo.nii.ac.jp/record/13124/files/Engineering13-03.pdf application/pdf 2.4 MB 2015-09-28