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(湖南大學(xué)巖土工程研究所， 長(zhǎng)沙 410082)

［摘要］為分析PHC管樁沉樁過程中土塞效應(yīng)對(duì)擠土徑向位移的影響，首先從土塞的形成過程和作用機(jī)理出發(fā)，建立了土塞單元體的受力平衡方程，得出了垂直向總荷載的表達(dá)式；其次，將土塞視為“樁中樁”，基于Gibson提出的不排水條件下黏性土樁端極限承載力模型，得出“樁中樁”樁端極限承載力的表達(dá)式，從而導(dǎo)得PHC管樁在沉樁過程中土塞高度的表達(dá)式；再次，應(yīng)用圓柱孔擴(kuò)張理論對(duì)PHC管樁樁周土體進(jìn)行彈塑性分析，獲得塑性區(qū)半徑、土體徑向位移等解析表達(dá)式；最后，將理論計(jì)算結(jié)果與工程實(shí)例進(jìn)行對(duì)比分析，并進(jìn)一步分析了徑厚比、剛度比對(duì)靜壓PHC管樁樁周土體徑向位移的影響，驗(yàn)證了所提出的解析表達(dá)式的合理性。所提出的解析表達(dá)式對(duì)PHC管樁沉樁過程中擠土徑向位移的計(jì)算具有一定的參考價(jià)值。

［關(guān)鍵詞］PHC管樁； 土塞效應(yīng)； 土塞高度； 圓柱孔擴(kuò)張理論； 土體徑向位移

中圖分類號(hào)：TU473.1文獻(xiàn)標(biāo)識(shí)碼：A文章編號(hào)：1002-848X(2019)16-0133-07

Study on calculation method of radial displacement caused by squeezing effect of PHC pipe pile considering plugging effect

Zhao Minghua, Xiao Rong, Yang Chaowei, Xiao Yao

(Institute of Geotechnical Engineering, Hunan University, Changsha 410082, China)

Abstract:In order to analyze the influence of plugging effect on the radial displacement due to soil squeezing effect in the process of driving PHC pipe piles, the force balance equation of plug element was established based on the formation process and mechanism of plugging, and the expression of vertical total load was obtained firstly. Secondly, the soil plug was regarded as a “pile in pile” and the ultimate bearing capacity model of clay pile tip under undrained condition proposed by Gibson was derived to obtain the formula of ultimate bearing capacity at the end of “pile in pile”. Then the formula for soil plug height of PHC pipe pile was obtained during pile driving. Thirdly, the elastic-plastic analysis of soil around PHC pipe pile was carried out by using cylindrical cavity expansion theory, and the analytical formulas of radius of plastic zone and radial displacement of soil were obtained. Finally, the theoretical calculation results were compared with engineering examples. The influence of diameter-thickness ratio and stiffness ratio on the radial displacement of soil around static pressure PHC pipe pile was  further analyzed, and the rationality of the analytical expression was verified. The analytical expression presented  has certain reference value for calculating the radial displacement of soil compaction during pile driving of PHC pipe piles.

Keywords:PHC pipe pile; plugging effect; height of soil plug; cylindrical cavity expansion theory; radial displacement of soil

*國家自然科學(xué)基金項(xiàng)目(51478178)。

作者簡(jiǎn)介：趙明華，博士，教授，博士生導(dǎo)師，Email:mhzhaohd@21cn.com。