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石名磊 鄧學(xué)鈞 劉松玉
（東南大學(xué)交通學(xué)院 南京 210096）[提要] 根據(jù)試樁靜載荷試驗及樁身應(yīng)力測試結(jié)果和對樁側(cè)極限摩阻力預(yù)測技術(shù)系統(tǒng)的分析，研究了粘性土中大直徑鉆孔灌注樁(LDBPs)的樁側(cè)極限摩阻力的預(yù)測方法和指標確定。針對硬粘土或超固結(jié)土，提出了不排水強度指數(shù)的概念，綜合了粘性土不排水條件下的內(nèi)摩擦角和粘聚力?；谶@一概念，對傳統(tǒng)的“a法”進行了擴展，使之成功地應(yīng)用于粘性土中LDBPs樁側(cè)摩阻力的預(yù)測。同時還對用SPT錘擊數(shù)N預(yù)測粘性土中LDBPs的樁側(cè)摩阻力進行了統(tǒng)計分析，并對粘土和亞粘土分別提出了相應(yīng)的回歸公式。
[關(guān)鍵詞] 大直徑鉆孔灌注樁 樁側(cè)摩阻力 標準貫入擊數(shù)Based on results of static loaded tests and pile shaft stress tests of instrumented piles, the approaches of predicting pile shaft skin ultimate friction and determination of the parameters are researched in the result from the analyses of the methodology of predicting pile shaft skin ultimate friction in a systematic way. The concept of the index of undrained shear strength of cohesive soils is brought forward in allusion to hard clay or over consolidation one, and that combines the friction angle and the cohesion of clay in undrained condition in effect. The representativeHd method" is modified to predict the ultimate friction of LDBPs triumphantly. The approach of count N of SPT used to predict the ultimate friction is analyzed, and the calculating formulae are established for clay and silt-clay respectively.
Keywords: large diameter bored piles; pile shaft skin friction; standard penetration test
