英文篇名
On the Design and Construction of Structure and Geotechnical Engineering for the Southern Branch of the National Palace Museum
作者
黃心泉、俞清瀚、沈崇瑜
關鍵字
基礎隔震、隔震器、液化潛能、液化側潰、擠壓砂樁、打擊式PC樁
摘要
國立故宮博物院南部院區座落於嘉義縣太保市,係國家重大文化政策,除定位為「亞洲博物館」,亦同時具有平衡南北文化權的目標。博物館主體建築之設計意念,採中國書法不同筆法以流線量體交織而成;其結構體設計,除配合流線量體概念採鋼構二元結構及三D曲線框架結構,為維護古蹟文物安全,以2500年地震迴歸期為考量,於基礎版下配置隔震系統。因應土壤液化,博物館採打擊式PC基樁貫穿液化砂土層達良好承載層,以提供充分之基礎承載;並藉基樁打設對地層之擠壓夯實,增加抗液化能力。針對砂性土層液化狀況,基樁垂直承載力設計時考量樁身極限摩擦力折減及液化土層沉陷引致之負摩擦力影響;而側向承載力則同時考量群樁效應及液化土層側向支撐之折減。基於地形幾何特性,博物館南側臨至善湖區域,以擠壓砂樁進行地盤改良,防止液化可能引致之側向流動,確保博物館基礎整體穩定。擠壓砂樁改良前先進行試作區施工及成效檢驗,確認設計參數與施工方法;全面施工後之改良成效檢驗均滿足設計目標,惟針對黏性土壤夾層則進一步檢核。試樁分兩階段進行,均同時採靜載及PDA動載試驗,先期階段之靜力載重試驗成果有效驗證原設計極限承載力,且動載試驗結果與靜載行為相當一致;而工作樁之試樁結果亦均符合設計承載要求。此外,PDA試樁亦驗證: 本基地所打設基樁之樁體均具良好完整性;打樁引致之地層擾動與靜置後承載力回復效應則相當顯著。
英文摘要
The southern branch of the National Palace Museum is located at Tai Po City Chiayi County. The new branch represents a major cultural policy established by the Executive Yuan. In addition to positioning as the museum as an "Asian Museum", the Executive Yuan is also pursuing the goal of balancing the cultural rights between the northern and southern areas of Taiwan. The design concept of the architecture of the museum adopts Chinese calligraphy with different strokes to represent intertwined fluid forms. To meet the mentioned design concept, a 2D steel structure and 3D curve frame structure were chosen for museum architecture. Moreover, the base isolation system is set up with the seismic standards of a 2500 year return period to ensure the safety of collections. In view of the problem of soil liquefaction, driven PC piles will serve as the foundation of the Museum. Compaction effects induced during pile installation are expected to increase resistance against liquefaction. For pile design under soil liquefaction, influence of reduction for ultimate skin friction of liquefied layers and potential negative skin friction induced by the settlement of liquefied layers are considered for the vertical capacities; while both the reduction of group-pile effect and lateral resistance of liquefied soils are adopted for the lateral capacities. In addition, the south side of the museum along the lake area are improved by sand compaction piles to prevent lateral spreading and also ensure the overall stability of the museum. The pilot test area for the sand compaction piles was established to verify the design parameters and construction specification before massive construction. Verification of the effectiveness of sand compaction piles meets the design requirements well, but the effectiveness of the interbedded clay layers must be assessed further. Pile load tests, which employ static load and PDA simultaneously, are performed in two stages. First, the preliminary static load tests are conducted to verify the ultimate capacity of the design piles and the test results of PDA are very consistent with the pile behaviors obtained in static load tests; furthermore, the load test results verified on the working piles meet the allowable bearing capacity of the design. In addition, the integrity of working piles are validated by the PDA tests; and the effect of recovery in pile capacity due to the soil disturbance caused by pile-driving is significant in this project site.