鋼構防砂壩承受土石流作用力之力學分析

Mechanical Analysis of Steel Check Dam Subjected to Loading of Debris Flow

林德貴(Der-Guey Lin) ； 黃郁博(Yu-Po Huang) ； 邱雅筑(Ya-Chu Chiu)

《中華水土保持學報》 54卷2期 (2023/06) Pp. 91-107

https://doi.org/10.29417/JCSWC.202306_54(2).0001

摘要

本研究針對華山溪格子型及曾文水庫加強B-型鋼構防砂壩（以下簡稱格子型及加強B-型鋼構壩）兩工程案例，進行整體結構承受土石流組合載重之3-D有限元素應力及變位分析。格子型鋼構壩頂部水平連結鋼管構件（或簡稱桿件）可串接所有單元結構，貫入兩側壩翼提供固定端束制作用，其能有效地將載重由壩心往壩翼傳遞，並限制各單元結構之桿件最大應力比（即剪力、撓曲、組合應力比）及最大水平變位之擴大發展，而由壩心往壩翼方向逐漸減小。反之，加強B-型鋼構壩各單元結構間無水平連結桿件串接，各自獨立承受載重而不會進行載重傳遞，因此各單元結構之桿件最大應力比及最大水平變位約略相同。鋼構壩上游側直立桿件及下游側水平桿件主要受拉應力控制，而下游側直立桿件及上游側水平桿件主要受壓應力控制。土石流巨礫撞擊力對兩鋼構壩案例造成之最大水平變位，皆符合國外之檢核要求，其值小於壩體有效高度之2%。在參數研究方面，鋼構壩之最大組合拉應力／壓應力比，對鋼管構件之徑厚比很敏感，會隨徑厚比之增加而明顯降低。

關鍵字

鋼構防砂壩 ； 單元結構 ； 鋼管構件 ； 最大組合拉應力／壓應力比 ； 最大水平變位 ； 徑厚比

並列摘要

This study performed three-dimensional finite element stress and deformation analyses on a grid-type steel check dam (i.e., grid-type dam) in Hua-Shan Creek and an enhanced B-type steel check dam (i.e., B-type dam) in Tseng-Wen Reservoir through debris flow loading. For the grid-type dam, two horizontal connection members were connected on the top run. The connection members stringed together the unit structures of the dam and penetrated the dam wing at fixed ends, which provided a restraint effect on the entire dam structure. The grid-type design could effectively transfer the loading from the unit structures at the dam center to those of the dam wing and prevent higher maximum stress ratios (e.g., shear, bending, and combined stress ratios). The maximum horizontal displacement of the unit structure gradually decreased from the dam center to the wing. For the B-type dam, all the unit structures only bore their own loading because no horizontal connection member was present to transfer the loading between structures. Consequently, each unit structure demonstrated similar maximum stress ratios and maximum horizontal displacement. Additionally, the maximum tensile stress occurred at the vertical upstream member and horizontal downstream member, whereas the maximum compressive stress occurred at the vertical downstream member and horizontal upstream member. In both cases, the maximum horizontal displacements occurred when the boulder impact force of debris flows was smaller than 2% of the effective dam height, which satisfied standard international inspection requirements. Moreover, the maximum combined stress ratio was sensitive to the diameter-to-thickness ratio of the steel-pipe member, which significantly decreased as the maximum combined stress ratio increased.

並列關鍵字

Steel check dam ； unit structure ； steel-pipe member ； maximum combined tensile-to-compressive stress ratios ； maximum horizontal displacement ； diameter-to-thickness ratio