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（1 中國建筑科學(xué)研究院地基基礎(chǔ)研究所， 北京  100013； 2 建筑安全與環(huán)境國家重點(diǎn)實(shí)驗(yàn)室，北京  100013； 3 北京市地基基礎(chǔ)與地下空間開發(fā)利用工程技術(shù)研究中心， 北京  100013）

［摘要］針對(duì)震害特征明顯、承受水平荷載不利的高承臺(tái)群樁基礎(chǔ)，以埋入式低承臺(tái)群樁基礎(chǔ)作為比較對(duì)象，開展砂質(zhì)粉土地基條件下高、低承臺(tái)群樁基礎(chǔ)模型體系的振動(dòng)臺(tái)試驗(yàn)，詳細(xì)分析試驗(yàn)體系的加速度響應(yīng)、樁身內(nèi)力、土-結(jié)構(gòu)接觸動(dòng)土壓力等響應(yīng)特征。試驗(yàn)結(jié)果表明：采用的均勻砂質(zhì)粉土地基主要起放大作用，地基土與樁身的加速度響應(yīng)自下而上被逐漸放大；高承臺(tái)樁體系由于承臺(tái)與樁身外露，使得輻射阻尼耗散能量的作用減弱，導(dǎo)致高承臺(tái)樁結(jié)構(gòu)體系的動(dòng)力響應(yīng)顯著，而低承臺(tái)樁基由于埋入式承臺(tái)結(jié)構(gòu)受到較強(qiáng)的土體約束作用，造成其加速度響應(yīng)較小；樁頂與承臺(tái)聯(lián)結(jié)的嵌固效應(yīng)、承臺(tái)與樁身自由段的外露（樁周側(cè)向無地基土約束），將會(huì)顯著改變樁身的內(nèi)力分布；同時(shí)也觀測到埋入式承臺(tái)結(jié)構(gòu)的正側(cè)面動(dòng)土壓力顯著發(fā)揮，反映了在承臺(tái)、基樁和地基土協(xié)同工作中承臺(tái)側(cè)面水平抗力的貢獻(xiàn)不容忽視。試驗(yàn)揭示了地震作用下高承臺(tái)樁基礎(chǔ)的動(dòng)力響應(yīng)規(guī)律，為樁基礎(chǔ)的抗震設(shè)計(jì)提供參考。

［關(guān)鍵詞］高承臺(tái)樁基礎(chǔ)； 振動(dòng)臺(tái)試驗(yàn)； 輻射阻尼； 土-結(jié)構(gòu)動(dòng)力相互作用

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)17-0120-10

Experimental study on seismic response of pile group foundation with high-cap by shaking table

Zhao Xiaoguang1,2,3， Gao Wensheng1,2,3

(1 Foundation Institute， China Academy of Building Research， Beijing 100013， China; 2 State Key Laboratory of Building Safety and Built Environment， Beijing 100013，  China;  3 Beijing Engineering Technology Research Center of Foundation and City Underground Space  Development and Utilization， Beijing 100013， China)

Abstract:In view of the high-cap group piles with obvious seismic damage characteristics and unfavorable bearing horizontal load, the shaking table test for the model system of high-cap and low-cap group piles foundation under sandy silt soil was carried out, and the response characteristics of the test system, such as acceleration response, internal force of pile body and soil-structure contact dynamic earth pressure, were analyzed in detail. The test results show that the uniform soil mainly plays an amplifying role, and the acceleration response of  soil and free section of  pile body is gradually enlarged from bottom to top; the radiation damping dissipation energy is weakened due to the exposure of pile cap and pile body in high-pile system, resulting in significant dynamic response of high-pile structural system, while the low-cap pile foundation is subjected to strong soil body due to the embedded cap. The embedding effect of the connection between pile top and pile cap, the exposure of   pile cap and free section of pile body (without foundation soil constraints in the lateral direction of pile), will significantly change the internal force distribution of pile body; at the same time, it is observed that the dynamic earth pressure on the front side of the embedded cap structure plays a significant role in the collaborative work of cap, foundation pile and foundation soil. The test reveals the law of dynamic response of pile foundation with high cap under earthquake action, which provides reference for seismic design of pile.

Keywords:high pile foundation; shaking table experiment; radiation damping effect; dynamic pile-soil interaction

*中國建筑科學(xué)研究院基礎(chǔ)研究課題項(xiàng)目-高承臺(tái)樁基礎(chǔ)的抗震性能研究（20161602330710022）。

作者簡介：趙曉光，博士，工程師，Email：zxgcabr@qq.com。