| 摘要: | 板樁牆系統已廣泛應用於開挖、臨水結構及擋土牆結構中，具有成本低，施工方便和可重複使用的優點。此外，台灣處於地震頻繁地區。遂在本研究中進行了一系列的離心試驗，以研究在動態荷載作用下河邊的板樁牆行為。在這項研究中，板樁由鋁合金製成。透過霣降法構建相對密度為70％的細石英砂土層模型。試體中彎矩應變的量測由樁上安裝數個應變計，並且安裝了兩個雷射位移計(LDT)，以觀察壁的橫向位移和旋轉，並用線性差動位移計(LVDT)和雷射掃描設備量測表面沉陷。
結果顯示，當地震加速度為0.16 g時，帶有錨壁的牆中，位移和傾斜角均位於安全範圍內。LVDT和雷射掃描設備量測下，最大沉陷位於牆後0.04H和錨定板後0.1H (其中H為開挖深度)。在沒有錨的牆中，橫向位移和傾斜角接近坍塌範圍的閾值，也就是說地震後板樁牆極需修復。對於0.33 g和0.45 g的地震加速度，單錨壁和雙錨壁中，錨固拉桿距離是單錨壁的兩倍，在0.33 g地震加速度下壁面塌陷；即使在遭受嚴重地震（0.45 g地震加速度）的情況下，在具有與單個錨定牆相同錨固拉桿距離的雙錨定牆，牆仍能維持不被破壞。與單錨壁相比，使用雙錨壁將減少一半的彎矩。雙錨牆的錨固拉桿距離是單錨牆的兩倍，其橫向位移、傾斜角、彎矩、回填沉陷則是單錨牆的三分之一。在工程實踐上，將錨固拉桿施作為雙錨固壁並增加錨固拉桿的數量可以明顯提高壁的穩定性。
;Sheet pile wall system has been widely employed in excavation, waterfront structure, and retaining structure with the outstanding advantages of low expenses, favorable in construction, and reusability. Besides, Taiwan locates at the active seismic zones that the earthquakes occur regularly. Therefore, a series of centrifuge tests in this research was conducted to study the behavior of the sheet pile wall at the riverside subjected to dynamic loading. In this research, the sheet piles were made of aluminum alloy. The model was constructed by a pluviation method with fine quartz sand, which has a relative density of 70%. The bending moment was measured by several strain gauges attached along with the pile. Two LDTs were installed to observe the lateral displacement and the rotation of the wall. The surface settlement was detected by using LVDTs and a laser scanning device.
The results indicated that the displacement and the tilting angle stayed in the safety zone in the wall without anchors in the case of seismic loading of 0.16 g. The maximum settlement measured by both LVDTs and a laser scanning device was located at 0.04H behind the wall and 0.1H behind the anchor plates (where H is the excavation depth). In the wall without anchors, the lateral displacement and tilting angle closed to the threshold of the near-collapse range that the wall needs to repair after the earthquake. For the seismic loading of 0.33 g and 0.45 g, in the single anchored wall and double anchored wall with the anchor tie rod distance is double of the single anchored wall, the walls collapsed at the seismic loading of 0.33 g. Otherwise, in the double anchored walls with the same anchor tie rod distance of the single anchored wall, even subjected to the severe earthquake (seismic loading of 0.45 g), the wall still sustains. Besides, using a double anchored wall would reduce half of the bending moment as compared single anchored wall. Using a double anchored wall with anchor distance is a double of a single anchored wall, the lateral displacement, tilting angle, bending moment, the backfilled settlement was one third compared to the single anchored wall. In engineering practice, arranging the anchor tie rods as double anchored walls and increasing the number of anchor tie rods can improve the stability of the walls. |
