以離心模型探討土壤液化對具有淺基礎建築物之影響;Centrifuge modeling on the liquefaction-induced response of buildings with shallow foundations

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题名:	以離心模型探討土壤液化對具有淺基礎建築物之影響;Centrifuge modeling on the liquefaction-induced response of buildings with shallow foundations
作者:	董麗媛;Duyen, Dong Le My
贡献者:	土木工程學系
关键词:	One keyword per line;液化;淺基礎;SSSI;離心機建模;鄰近的建築物;One keyword per line;Liquefaction;shallow foundation;structure-soil-structure interaction;centrifuge modeling;adjacent buildings
日期:	2025-01-14
上传时间:	2025-04-09 15:55:19 (UTC+8)
出版者:	國立中央大學
摘要:	在地震發生期間,液化會對在飽和砂子上建造的結構造成重大風險,特別是在台灣等地震活動頻繁的地區｡本研究使用離心模型試驗探討液化作用下具有淺基礎的相鄰結構之行為｡實驗是在三個不同的峰值基底加速度(0.09 g､0.17 g 和 0.35 g)下使用不同間距的基礎進行的｡ CPT用於在地震前後評估鄰近建築物受液化影響後的土壤強度｡目的是評估不同的基礎間距如何影響地震後的沉陷､傾斜､超額孔隙水壓力 (EPWP) 和土壤強度｡結果表明，在 0.09 g 的輸入震動期間 (CAV = 0.43 g-s），基礎間距比較小(S<B)的模型土體沒有明顯液化，而基礎間距比較大(S>B)的模型則發生淺層液化。在 0.17 g 的輸入震動期間 (CAV = 0.89 g-s）土壤液化範圍加深，基礎間距比較小(S<B)的結構經歷了較大的沉陷，且受到更顯著的結構-土壤-結構相互作用（SSSI）效應影響；相比之下，基礎間距比較大(S>B)的結構受到的影響較小。輸入震動 0.35 g，(CAV = 1.77 g-s）液化情況加劇，基礎間距6公尺的結構雖然沉陷減少，但因大範圍液化而顯示出更大的脆弱性。基礎間距比較小(S<B)的結構因較強的SSSI效應導致基礎下方的土壤變形增強，造成沉陷增加；相比之下，基礎間距較大的結構（S > B）呈現更均勻的沉陷分佈，並在地震事件中提供更大的穩定性。兩種間距配置的結構傾斜方向在所有震動強度下均呈隨機性，這是由於液化期間應力重新分佈的不確定性及土壤反應的不均勻性所致。放大係數隨著震動強度的增加而降低，反映了土壤剛度的降低，而震動後重新凝結隨著時間恢復了土壤強度。最後，由於 SSSI 和液化效應的影響，相鄰結構下方的應力增量低於理論預測，這證實了 Boussinesq 等傳統模型在確定液化土中複雜荷載傳遞的侷限性。同時這項研究也應證了基礎間距在減輕液化造成的損害方面之重要性，並為密集建築的城市環境下的抗震設計提供了寶貴的見解。 ;Liquefaction causes a significant risk to structures built on saturated sand during seismic events, especially in regions prone to high seismic activity such as Taiwan. This study uses centrifuge experiments to investigate the liquefaction-induced behavior of adjacent structures with shallow foundations. The experiments were conducted with closer and wider foundation spacings under three input motions (0.09 g, 0.17 g, and 0.35 g). The CPT was employed before and after seismic events to assess soil strength affected by adjacent buildings after liquefaction. The aim was to evaluate how different foundation spacings influence the settlement, tilting, excess pore water pressure (EPWP), and soil strength after seismic events. The results indicate that during the input motion of 0.09 g (CAV = 0.43 g-s), structures with closer spacing (S < B) are not affected by the liquefaction while those structures with wider spacing (S > B) are affected by the shallow-layer liquefaction. Under the input motion of 0.17 g (CAV = 0.89 g-s), the structures with closer spacing (S < B) experience higher settlements and amplified SSSI effects compared to the structures with wider spacing (S > B). The input motion of 0.35 g (CAV = 1.77 g-s) intensified liquefaction, the structures with wider spacing (S > B) exhibiting lower settlements and greater vulnerability to widespread liquefaction. The increased settlement in closely spaced structures is attributed to stronger SSSI effects, which amplified soil deformation beneath the foundations. In contrast, structures with wider spacing (S > B) exhibit more uniform settlement providing greater stability during seismic events. Moreover, the tilting directions of structures in both spacing configurations are random across all seismic intensities, influenced by the unpredictable redistribution of stresses and uneven soil response during liquefaction. Amplification factors decrease with increasing seismic intensity, reflecting the reduction in soil stiffness, while post-seismic reconsolidation restores soil strength over time. Finally, stress increments beneath adjacent structures are lower than theoretical predictions due to the influence of SSSI and liquefaction effects, emphasizing the limitations of traditional models like Boussinesq’s in determining the complex load transfer in liquefied soils.
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