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Establishment of a suitable dynamic formula for the construction control of driven piles and its calibration for Load and Resistance Factor Design

機譯：為打入樁的施工控制建立合適的動力公式，并進行荷載和阻力系數設計的標定

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Dynamic pile driving formulas have been available for the field prediction of the static bearing capacity of pile foundations for well over 180 years. On account of the immense number of different formulas that have been amassed during this time frame, a review of published literature was performed to identify the most common dynamic pile driving formulas utilized in the United States and their documented reliability. The results of this review indicated that no one dynamic pile driving formula is consistently better than all the rest; however, the Hiley, Janbu, Pacific Coast Uniform Building Code (PCUBC), and Gates formulas were shown to provide, on average, the best predictions of ultimate pile capacity. In contrast, the Engineering News Record (ENR) formula, which has been probably the most widely used dynamic formula within the United States, was shown to be among the worst predictors of pile capacity.For well over 100 years, the Working Stress Design (WSD) approach has been the traditional basis for geotechnical design with regard to settlements or failure conditions. However, considerable effort has been put forth over the past couple of decades in relation to the adoption of the Load and Resistance Factor Design (LRFD) approach into geotechnical design. With the goal of producing engineered designs with consistent levels of reliability, the Federal Highway Administration (FHWA) issued a policy memorandum on June 28, 2000, requiring all new bridges initiated after October 1, 2007, to be designed according to the LRFD approach. Likewise, regionally calibrated LRFD resistance factors have been permitted by the American Association of State Highway Officials (AASHTO) to improve the economy of bridge foundation elements. Thus, the bulk of this study focused on the development of regionally calibrated LRFD resistance factors for the construction control of driven pile foundations via a suitable dynamic pile driving formula.Using data from pile load tests performed in the State of Iowa, which was analyzed for reliability and placed in a newly designed relational database management system termed PILOT-IA, the efficiency of seven dynamic pile driving formulas (i.e., the Gates, FHWA Gates, ENR, Iowa Department of Transportation (DOT) Modified ENR, Janbu, PCUBC, and Washington DOT (WSDOT) formulas) was investigated. In addition to verifying the poor performance of the ENR formula, it was demonstrated that the efficiency of the Iowa DOT Modified ENR formula, which is presently specified in the Iowa DOT\u27s Standard Specifications for Highway and Bridge Construction manual, is sufficient to allow for its recommended use with steel H-shaped and timber pile foundations driven in any soil type; these two driven pile foundation types were found to be the most commonly used in Iowa via the results of both a state- and county-level survey. More specifically, LRFD resistance factors were calibrated and verified on a pile and soil type basis for the Iowa DOT Modified ENR formula using the first-order, second-moment (FOSM) reliability approach and the findings obtained from nine full-scale field load tests performed throughout the State of Iowa on steel H-shaped piles. For a target probability of failure of 1%, LRFD resistance factors of 0.49, 0.62, and 0.50 have been recommended for use with steel H-shaped piles driven in sand, clay, and mixed soil profiles, respectively, with a factor of 0.35 having been cautiously recommended for use with timber piles driven in any soil type.Finally, a displacement-based signal matching technique was recommended for use with PDA measured data to arrive at prediction correlations for soil quake values, Smith damping factors, and the degree-of-degradation of such parameters with respect to pile penetration depth. Although an insufficient amount of data was analyzed to even begin to develop such correlations, the accuracy, uniqueness, and theoretical basis of the displacement-based signal matching approach over the more commonly employed Case Pile Wave Analysis Program (CAPWAP) approach was demonstrated. Provided the future establishment of such prediction correlations from the increased use of this proposed technique, it was suggested that a one-dimensional pile-soil model could be used in conjunction with a dynamic pile driving formula to design driven pile foundations.
機譯：在超過180年的時間里，動態(tài)樁驅動公式已可用于樁基礎靜態(tài)承載力的現(xiàn)場預測。由于在此時間段內已積累了大量不同的公式，因此對已發(fā)表的文獻進行了回顧，以確定在美國使用的最常見的動態(tài)打樁公式及其記錄的可靠性。這項審查的結果表明，沒有一個動態(tài)的打樁公式始終比其他所有公式更好。但是，平均而言，Hiley，Janbu，太平洋海岸統(tǒng)一建筑規(guī)范（PCUBC）和Gates公式顯示出了對最大樁身承載力的最佳預測。相比之下，工程新聞記錄（ENR）公式可能是美國使用最廣泛的動態(tài)公式，被認為是樁容量最差的預測指標之一.100多年來，工作應力設計（在沉降或破壞條件方面，WSD方法一直是巖土工程設計的傳統(tǒng)基礎。然而，在過去的幾十年中，在巖土工程設計中采用了載荷和阻力因子設計（LRFD）方法方面已經做出了相當大的努力。為了生產出具有一致可靠性水平的工程設計，美國聯(lián)邦公路管理局（FHWA）于2000年6月28日發(fā)布了一項政策備忘錄，要求根據LRFD方法設計2007年10月1日以后啟動的所有新橋梁。同樣，美國國家公路官員協(xié)會（AASHTO）允許對區(qū)域校準的LRFD抗力因子進行改進，以改善橋梁基礎構件的經濟性。因此，本研究的大部分重點是通過適當的動態(tài)打樁公式來開發(fā)用于驅動樁基礎施工控制的區(qū)域校準LRFD阻力因子。使用在愛荷華州進行的樁載試驗數據，可靠性并放置在新設計的關系數據庫管理系統(tǒng)PILOT-IA中，它具有七個動態(tài)打樁公式的效率（即，蓋茨，F(xiàn)HWA蓋茨，ENR，愛荷華州交通部（DOT）修改的ENR，Janbu，PCUBC和華盛頓DOT（WSDOT）公式）進行了調查。除了驗證ENR公式的性能不佳之外，還證明了愛荷華州DOT修改的ENR公式的效率（目前已在愛荷華州DOT \ u27s公路和橋梁施工標準規(guī)范手冊中指定）足以滿足以下要求：建議與任何土壤類型打入的H型鋼和木樁基礎一起使用；通過州和縣級調查的結果，發(fā)現(xiàn)這兩種打樁基礎類型是愛荷華州最常用的。更具體地說，針對愛荷華州DOT修正的ENR公式，使用一階，第二階矩（FOSM）可靠性方法以及從九個全面現(xiàn)場載荷測試中獲得的結果，在樁和土壤類型的基礎上對LRFD阻力因子進行了校準和驗證。在整個愛荷華州進行的H型鋼樁表演。對于1％的目標破壞概率，建議將LFD阻力系數分別為0.49、0.62和0.50分別用于在沙子，粘土和混合土壤剖面中打入的H型鋼樁，其0.35的系數為最后，建議將基于位移的信號匹配技術與PDA測量數據一起使用，以得出關于土震值，史密斯阻尼系數和震級的預測相關性。這些參數相對于樁穿透深度的降低。盡管分析的數據量不足，甚至沒有開始發(fā)展這種相關性，但仍證明了基于位移的信號匹配方法相對于更常用的“案例樁波分析程序”（CAPWAP）方法的準確性，唯一性和理論基礎。通過增加使用該擬議技術可以提供這種預測相關性的未來建立，建議將一維樁土模型與動態(tài)樁驅動公式結合使用，以設計驅動樁基礎。

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  • 作者

    Roling, Matthew John;

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  • 年度 2010
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