東非地區(qū)黑棉土工程特性和樁基病害處理*
張大峰1，楊軍1,2，李連友3，沈兆普3
- 摘 要
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(1 清華大學(xué)土木工程系，北京 100084；2 清華大學(xué)土木工程安全與耐久教育部重點(diǎn)實(shí)驗(yàn)室，北京 100084；3 中國路橋工程有限責(zé)任公司，北京 100011)［摘要］東非地區(qū)黑棉土是一種強(qiáng)膨脹性土，它的脹縮變形易導(dǎo)致建筑物地基、道路路基、邊坡、樁基礎(chǔ)等結(jié)構(gòu)受到嚴(yán)重破壞，工程問題突出。結(jié)合文獻(xiàn)調(diào)研，對膨脹土尤其是黑棉土的研究歷史、分類標(biāo)準(zhǔn)、工程特性進(jìn)行了綜合介紹。根據(jù)國家標(biāo)準(zhǔn)《膨脹土地區(qū)建筑技術(shù)規(guī)范》(GB 50112—2013)對東非地區(qū)黑棉土的自由膨脹率進(jìn)行了測試，并采用掃描電子顯微鏡對其微觀結(jié)構(gòu)進(jìn)行了觀測。結(jié)果表明，東非地區(qū)黑棉土的自由膨脹率可達(dá)205%，干濕循環(huán)后黑棉土的膨脹性能下降；黑棉土微觀結(jié)構(gòu)使其具有更強(qiáng)的膨脹性，屬于強(qiáng)膨脹土。另外，也調(diào)研并分析了黑棉土對樁基的不利影響，提出了相應(yīng)的工程處理措施。［關(guān)鍵詞］黑棉土; 工程特性; 電鏡掃描; 樁基; 工程措施中圖分類號：TU473.1 文獻(xiàn)標(biāo)識碼：A 文章編號：1002-848X(2015)01-0072-05Engineering properties of black cotton soil in East Africa and pile foundation disease treatmentZhang Dafeng1, Yang Jun1,2, Li Lianyou3, Shen Zhaopu3(1 Department of Civil Engineering, Tsinghua University, Beijing 100084, China; 2 Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry, Beijing 100084, China; 3 China Road and Bridge Corporation, Beijing 100011, China)Abstract: Black cotton soil in East Africa is one kind of strong expansive soil. Its swelling and shrinkage deformation can damage building foundations, road embankment, slope, pile foundation and other structures easily.The engineering problems are very prominent. Combining literature study, the research history, classification criteria, engineering properties of expansive soil expecially black cotton soil were introduced in detail. Referring to national standard of Technical specifications for construction ground in expanding soil areas (GB 50112—2013), the free expansion ratio of black cotton soil in East Africa is tested, and its microstructure is observed by scanning electron microscopy. The result shows that the free expansion ratio of black cotton soil in East Africa can reach 205% and the expansion capability decreases after dry-wet cycle. The special microstructure of black cotton soil contributes to strong expansion characteristic. Black cotton belongs to the strong expansive soil. In addition, the adverse impacts on pile foundation were analyzed and corresponding treatment measures were given.Keywords: black cotton soil; engineering property; electron microscope scanning; pile foundation; treatment measure*國家重點(diǎn)基礎(chǔ)研究發(fā)展計劃（2014CB047004）。通迅作者：楊軍，博士，副研究員，博導(dǎo)，Email:junyang@mail.tsinghua.edu.cn。參考文獻(xiàn)［1］ORIOLA F，MOSES G. Groundnut shell ash stabilization of black cotton soil［J］. Electronic Journal of Geotechnical Engineering, 2010, 15(D): 415-428.［2］FREDLUND D G，RAHARDJO H. Soil mechanics for unsaturated soils［M］. New York: John Wiley & Sons, Inc., 1993: 1-19.［3］JONES D, HOLTZ J. Expansive soils: hidden disaster ［J］. Civil Engineering, 1973, 43(8):54.［4］FREDLUND D G, RAHARDJO H. 非飽和土力學(xué)［M］. 陳仲頤,張在明，陳愈炯，等譯. 北京:中國建筑工業(yè)出版社, 1997: 15-18.［5］GB 50112—2013膨脹土地區(qū)建筑技術(shù)規(guī)范［S］. 北京:中國建筑工業(yè)出版社, 2013.［6］Earth Manual［M］. Denver: United States Bureau of Reclamation, 1973.［7］Indian Standard classification and identification of soils for general engineering purposes［S］. New Delhi: Bereau of Indian Standards, 1970.［8］WILLIAMS A B, DONALDSON G W. Building on expansive soils in South Africa［C］//Proceedings of 4th International Conference on Expansive Soils. Denver: ASCE, 1980.［9］張愛軍，哈岸英，駱亞生. 壓實(shí)膨脹土的膨脹變形規(guī)律與計算模式［J］. 巖石力學(xué)與工程學(xué)報, 2005, 24(7): 1236-1241.［10］鄭健龍, 楊和平. 公路膨脹土工程 ［M］. 北京: 人民交通出版社, 2009.［11］郭愛國，劉觀仕，孔令偉，等. 高速公路建設(shè)中膨脹土特性的試驗(yàn)研究［J］. 巖土力學(xué), 2005, 26(3): 397-403.［12］楊宏偉,趙鵬程,吳超,等. 掃描電子顯微鏡在摩擦學(xué)研究中的應(yīng)用［J］. 合成潤滑材料, 2011, 38(2): 23-27.［13］李生林, 施斌, 杜延軍.中國膨脹土工程地質(zhì)研究［J］.自然雜志, 1997, 19(2): 82-86.［14］王年香，顧榮偉，章為民，等. 膨脹土中單樁性狀的模型試驗(yàn)研究［J］. 巖土工程學(xué)報, 2008, 30(1): 56-60.［15］(蘇) 索洛昌 E A (Сорочан Е А). 膨脹土上建筑物的設(shè)計與施工［M］. 徐祖森,等譯. 北京: 中國建筑工業(yè)出版社, 1982.［16］陳善雄, 李伏保, 孔令偉. 弱膨脹土工程特性及路基處治對策［J］. 巖土力學(xué), 2006, 27(3): 353-359.［17］YADU L, TRIPATHI R K, SINGH D. Comparison of fly ash and rice husk ash stabilized black cotton soil［J］. International Journal of Earth Sciences and Engineering, 2011, 4(6): 42-45.［18］OSINUBI K J, OYELAKIN M A, EBEREMU A O. Improvement of black cotton soil with ordinary portland cement-locust bean waste ash blend［J］. Electronic Journal of Geotechical Engineering, 2011, 16(E): 619-627.［19］MILLER D J. Expansive soils: problems and practice in foundation and pavement engineering［M］. New York: John Wiley & Sons, Inc., 1997
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