現地傍壓儀試驗應用在軟弱岩石內基樁之行為模擬

Abstract

台北國際金融大樓為超高層建築物，建築於岩盤面起伏甚大之軟弱岩層上，基樁受載重之行為極為重要。現有之基樁理論中，主要基於基本土壤力學理論，根據土壤採樣做室內試驗或做現地試驗所求得之工程參數做分析，較大型工程通常也使用現場基樁載重試驗來驗證設計之安全性。然而，現地載重試驗花費較高，採用合理且較經濟的現地試驗遂為較佳選擇，因此，本研究之模擬方法係針對基樁榫入岩盤之行為做模擬，採用量取軟弱岩層工程特性較理想之現地試驗方法－傍壓儀試驗 (Pressuremeter Test, PMT) 資料作為分析之依據，並以最佳化程式Simplex分析PMT資料，求取合適之參數，藉由撰寫FLAC程式以模擬樁受載重之行為。並將剪動時產生之膨脹角與隨應變量改變之岩石的楊氏模數，融入模擬機制中，提出與現場樁載重試驗相當接近之模式，以期能提供合理之模式模擬樁榫入軟岩之行為。

For Taipei financial center, a high-rise building built on the waiving soft bedrock, the loading behavior of pile is very important. The existing study of the pile behavior is based on the experience of small diameter of socket pile and the theory of soil mechanics with the safety factor according to the building code. Therefore, for large scale constructions, it is required for the Pile-load test to get the more reliable pile-rock interaction. However, due to high coast of tests, a more efficient and cheaper methods should be found to replace. Hence, the purpose of this study takes advantage of Pressuremeter Test (PMT) data using the optimization program Simplex to get the parameter of rock as input for the numerical modeling program, FLAC. Combining the dilate angle when soft rock sheared and Young’s module according to the increasing of shear strain into the modeling mechanism, a more reasonable and accurate model was presented.