本研究為一個三年期計畫，旨在執行模型基樁水平單向與雙向反覆載重試驗，依據試驗瞭解並量化凝聚性土層中反覆載重對基樁水平承載行為之影響，並將分析結果整合成單樁與群樁基礎之非線性分析模式，並以實際工程案例進行側推分析，瞭解反覆荷載對基樁設計結果之影響，以應用於地震與海洋工程。第一年計畫將設計組立一套基樁水平反覆載重試驗設備，包括加載與反力系統，模型計測樁，控制與量測記錄系統與模型地盤準備設施。計畫將採曾文水庫之低塑性黏土(CL)以大型壓密儀製作過壓密重模試體，並執行兩組靜態極限水平基樁載重試驗，與六組考慮不同應力準位之單向與雙向水平基樁反覆載重試驗，推求凝聚性土層之靜態與動態之p-y 曲線。第二年計畫將改以低塑性之粉土(ML)作為試驗土樣，整體試驗規劃與第一年相同，目的為探討基樁於低塑性黏土與粉土試體中，其受靜態與反覆載重下之p-y曲線之變化與差異，以及作用周數t與應力準位SL對p-y曲線與累積位移影響之差異。第三年計畫將以EXCEL軟體撰寫國際規範與本試驗之p-y、t-z與q-z曲線以及基樁塑鉸非線性分析模組，整合這些分析模組至結構軟體LPILP和Group之輸入介面，建立單樁與群樁之非線性分析模式(地盤與基樁均為非線性)，再進行實際案例之非線性側推分析，以評估反覆載重效應對樁基礎設計之影響，建立一套反覆載重作用下樁基礎分析模式與程序，供工程實務應用。 ;This study is a three-year project. Its purpose is to investigate and quantify the effects of cyclic loads on the lateral and axial bearing behavior of a pile using model pile load tests. The non-linear analysis models of single pile and pile group will be established based on the test results. Using the above models, non-linear pushover analysis will be performed on real cases to explore the influences of cyclic loads on the design solution of piled foundation. The proposed analysis model and procedure for cyclic loads will be a useful guide to the practices of earthquake and ocean engineering. The first-year project is to design and assembly a set of equipment for performing model pile load tests under cyclic lateral loads. The equipment includes loading and reaction system, instrumented model pile, control and measuring system, and test specimen preparing device. In this study, the low-plasticity clay form Zengwen Dam will be used to prepare the test specimen to simulate in-situ strata, which is remolded by a pneumatic consolidation system. Two sets of static ultimate lateral pile load tests will be carried out first in the model grounds. Then, six sets of one-way and two-way cyclic lateral pile load tests will be performed by considering different stress level of cyclic load. The p-y curves of the cohesive soils will be deduced from the test results for static and cyclic loads. In the second year, the low-plasticity silt will be used as the test specimens. The test procedure is the same as the first-year project. The test results of low-plasticity clay and silt will be compared, including the differences of p-y curves under static and dynamic loads between. Furthermore, the influences of number of cycles and the stress level of cyclic load on p-y curves and the accumulated displacement at pile head will also be discussed. In the last year of this study, the p-y, t-z, and q-z curves from international standards and this study, as well as the curves of plastic hinges of different piles will be coded into an analysis module using EXCEL software. Non-linear models (both pile and ground are non-linear behavior) of single pile and pile group will be established using LPILP and Group software by integrating the results of EXCEL module into the input interface of LPILP and Group. The pushover analysis of the nonlinear models will be performed on real cases to evaluate the effects of cyclic loads on the design solution of piled foundation. Finally, a nonlinear analysis model and procedure for piled foundation under cyclic loads will be proposed for the use in the engineering practice.
