長樁模型於飽和粉土質砂土中之樁土互制反應

SOIL-PILE INTERACTIONS IN SATURATED SILTY SAND FROM MODEL LONG PILE TEST

張文忠(Wen-Jong Chang) ； 蕭廷翰(Ting-Han Hsiao) ； 周仕勳(Shih-Hsun Chou)

《中國土木水利工程學刊》 30卷4期 (2018/12) Pp. 305-313

https://doi.org/10.6652/JoCICHE.201812_30(4).0007

摘要

考量台灣海峽地質與環境等因素，群樁基礎為離岸風機較佳之基礎型式，基樁受側向載重之反應為設計時主要控制因素之一，但基樁側向載重傳遞機制複雜且具高度不確定性。本研究結合非線性數值模擬及實體基樁縮尺模型，以原用於CPT標定之標度槽，作為可分層控制側向邊界應力之土槽，加入模型基樁及樁頂側推機構，由數值模擬計算基樁側推位移時邊界應力，以施加補償應力方式降低邊界效應，結合樁身反應及界面應力量測系統，進行不同側向加載條件下飽和粉土樁土互制行為基礎研究，結果顯示本土離岸海床主要組成之粉土層其p-y曲線不宜直接採用砂土p-y曲線，應隨深度或壓密應力進行p-factor折減，且須於進行基樁側向抵抗分析時多加留意其壓縮性影響。

關鍵字

標度槽 ； 長樁模型試驗 ； 粉土質砂 ； 樁土互制反應

並列摘要

Due to the thick silty soil layers and seismic effects in the western sea floor of Taiwan, group pile foundations are preferred for offshore wind turbine foundations. Because of the high uncertainties and complexities of soil-pile interactions in laterally loading conditions, the needs for proper understanding the soil-pile interactions in silty soils have raised. This paper presents the results of long pile push-over tests in a saturated silty sand under different stress conditions. A layered calibration chamber for CPT study is converted to apply compensated boundary stresses during the push-over phase to reduce the boundary effects in model tests. A model pile with bending strain gauges and tactile sensors for interface stress monitoring are embedded in the field simulator and lateral loads are applied on the pile top with different constrained conditions. The results reveal that the typical p-y curves for sand and clay are not applicable to local silty soils. The p-factor reduction from the sand curve should consider the field stress conditions and the compressibility of silty sand.

並列關鍵字

calibration chamber ； long pile model test ； silty sand ； soil-pile interaction