- 摘 要
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（中煤科工集團重慶設計研究院有限公司， 重慶 400016）
［摘要］針對山區(qū)極軟巖上覆原生土很薄且新近填土較厚時，機械成孔樁即使按最大嵌巖深徑比計算單樁的豎向極限承載力仍無法滿足上部荷載要求的情況，利用現行規(guī)范推導出中風化極軟巖樁的極限端阻力標準值和極限側阻力標準值取值范圍，并結合巖基載荷試驗數據對取值范圍進行了修正。提出了嵌巖樁按經驗參數法計算單樁豎向極限承載力的思路，并結合工程實例中的樁載荷試驗數據驗證了此計算思路及中風化極軟巖樁的極限端阻力標準值和極限側阻力標準值取值范圍的安全合理性。研究結果表明：中風化極軟巖樁的極限端阻力標準值取值范圍為1 500～3 800kPa，極限側阻力標準值取值范圍為140～280kPa，按新計算思路獲得的單樁豎向承載力特征值比按嵌巖樁計算方法獲得的數值可最大提高約12%，且計算深度大于8倍的嵌巖深徑比。
［關鍵詞］樁基; 極限端阻力; 極限側阻力; 極軟巖
中圖分類號：TU473 文獻標識碼：A 文章編號：1002-848X(2014)08-0021-04
Research on ultimate tip resistance and ultimate shaft resistance of piles in middle weathered extremely soft rock
Zhan Kaiyu
(Chongqing Design and Research Institute Co., Ltd., China Coal Technology and Engineering Group, Chongqing 400016, China)
Abstract: According to machine drilling hole can not meeting the requirements of upper loads calculating by largest embedded depth-diameter ratio under the conditions of thin primary soil and thick recent filling overburden extremely soft rock in mountain area, the standard value range of ultimate tip resistance and shaft resistance of piles in middle weathered extremely soft rock was derived by utilization of current code and was revised by utilization of rock foundation loading test data. A modified method of calculating single pile vertical ultimate bearing capacity by empirical formula for rock-socketed pile was put forward, and the modified method and the standard value range of ultimate tip resistance and shaft resistance of piles in middle weathered extremely soft rock were validated by pile loading tests in a project. The results show that the standard value range of ultimate tip resistance of piles in middle weathered extremely soft rock is 1 500～3 800kPa, the standard value range of ultimate tip resistance is 140～280kPa. The characteristic value of vertical bearing capacity of single pile can increase 12% and the calculation depth can be more than 8 to embedded depth-diameter ratio by the modified method.
Keywords: pile foundation; tip resistance; shaft resistance; extremely soft rock
作者簡介：湛鎧瑜，碩士，工程師，Email: zhankaiyu@163.com。
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