Abstract：In order to clarify the impact of basement-addition on existing pile foundations，a geotechnical centrifugal was carried out to simulate the basement-addition excavations in sandy strata. Considering existing working load at pile head in the geotechnical centrifugal，the effect of bearing characteristics of existing pile foundation during basement-addition excavations was studied. A reference for the assessment and redesign of the pile foundation for basement-addition construction of the existing building is provided. The results show that：(1) Considering the influence of the existing load，the load test is carried out after the load at pile head is held for about 9 days with 0.94 times the bearing capacity characteristic value at the prototype state. The bearing capacity of the test pile is about 6% higher than that of the test pile without considering the existing working load. In the redesign of existing pile foundations，duo to soil compaction at pile side and pile end caused by existing load at pile head，the improvement of bearing capacity can be properly considered. (2) For a friction pile with length of 20 m under the existing load，the bearing capacity loss rate is 11.5% and 37.9% when the excavation depth is 20% and 40% of the pile length，respectively. When the excavation depth is 40% of the pile length，the pile changes from friction end-bearing pile to friction end-bearing pile，and the axial force and the settlement of the pile increase greatly during the process. In practical engineering，the compressive strength of pile should be checked and the risk caused by the increase of settlement should be avoided. (3) When the excavation depth is 40% of the pile length，the side friction resistance decreases. This may be related to the softening of the side resistance，or the reduction of vertical soil stress around the pile caused by excavation. The specific reason needs further verification. In the estimation of bearing capacity of existing pile foundation，this effect should be considered.
张敬一1，马 兵2. 既有建筑地下增层改造桩基承载特性离心模型试验[J]. 岩石力学与工程学报, 2025, 44(S1): 219-229.
ZHANG Jingyi1，MA Bing2. Geotechnical centrifugal model test on bearing characteristics of existing building pile foundations under excavation conditions. , 2025, 44(S1): 219-229.
[1] 单华峰，夏唐代，俞 峰，等. 地下增层开挖托换桩的屈曲稳定临界荷载分析[J]. 浙江大学学报：工学版，2016，50(8)：1 425–1 430. (SHAN Huafeng，XIA Tangdai，YU Feng，et al. Bucking stability analysis on critical load of underpinning pile for excavation beneath existing building[J]. Journal of Zhejiang University：Engineering Science，2016，50(8)：1 425–1 430.(in Chinese))
[2] 贾 强，应惠清，张 鑫. 锚杆静压桩技术在既有建筑物增设地下空间中的应用[J]. 岩土力学，2009，30(7)：2 053–2 057.(JIA Qiang，YING Huiqing，ZHANG Xin. Construction of basement in existing buildings by static bolt-pile[J]. Rock and Soil Mechanics，2009，30(7)：2 053–2 057.(in Chinese))
[3] 汤永净. 蒙特利尔地下空间扩建中的古建筑保护技术[J]. 地下空间与工程学报，2010，6(4)：672–676.(TANG Yongjing. Montreal underground pedestrian network and protection of ancient church[J]. Chinese Journal of Underground Space and Engineering，2010，6(4)：672–676.(in Chinese))
[4] 文颖文，刘松玉，胡明亮，等. 地下增层工程中既有结构变形控制技术研究[J]. 岩土工程学报，2013，35(10)：1 914–1 921.(WEN Yingwen，LIU Songyu，HU Mingliang，et al. Deformation control techniques for existing buildings during construction process of basement[J]. Chinese Journal of Geotechnical Engineering，2013，35(10)：1 914–1 921.(in Chinese))
[5] 王术剑，冯若峰，张乾青，等. 既有建筑地下开挖工程中在役桩竖向承载特性分析[J]. 哈尔滨工业大学学报，2023，55(2)：117–124. (WANG Shujian，FENG Ruofeng，ZHANG Qianqing，et al. Vertical bearing characteristics of in-service pile in underground excavation engineering of existing building[J]. Journal of Harbin Institute of Technology，2023，55(2)：117–124.(in Chinese))
[6] 李 勇. 既有建筑增层改造时桩基础的再设计试验研究[硕士学位论文][D]. 北京：中国建筑科学研究院，2010.(LI Yong. Experimental study on redesign of pile foundation for increasing story on built building[M. S. Thesis][D]. Beijing：China Academy of Building Research，2010.(in Chinese))
[7] 黄茂松，郦建俊，王卫东，等. 开挖条件下抗拔桩的承载力损失比分析[J]. 岩土工程学报，2008，30(9)：1 291–1 297.(HUANG Maosong，LI Jianjun，WANG Weidong，et al. Loss ratio of bearing capacity of uplift piles under deep excavation[J]. Chinese Journal of Geotechnical Engineering，2008，30(9)：1 291–1 297.(in Chinese))
[8] 郦建俊，黄茂松，王卫东，等. 开挖条件下抗拔桩承载力的离心模型试验[J]. 岩土工程学报，2010，32(3)：388–396.(LI Jianjun，HUANG Maosong，WANG Weidong，et al. Centrifugal model tests on bearing capacity of uplift piles under deep excavation[J]. Chinese Journal of Geotechnical Engineering，32(3)：388–396.(in Chinese))
[9] 罗耀武，胡 琦，陈云敏，等. 基坑开挖对抗拔桩极限承载力影响的模型试验研究[J]. 岩土工程学报，2011，33(3)：427–432.(LUO Yaowu，HU Qi，CHEN Yunming，et al. Model tests on ultimate uplift capacity of piles under excavation[J]. Chinese Journal of Geotechnical Engineering，2011，33(3)：427–432.(in Chinese))
[10] 胡 琦，凌道盛，孔令刚，等. 超深开挖对抗拔桩承载力影响的离心机试验研究[J]. 岩土工程学报，2013，35(6)：1 076–1 083.(HU Qi，LING Daosheng，KONG Linggang，et al. Effects of deep excavation on uplift capacity of piles by centrifuge tests[J]. Chinese Journal of Geotechnical Engineering，2013，35(6)：1 076–1 083.(in Chinese))
[11] ZHENG G，PENG S Y，NG C W W，et al. Excavation effects on pile behaviour and capacity[J]. Canadian Geotechnical Journal，2012，49(12)：1 347–1 356.
[12] 龚晓南，伍程杰，俞 峰，等. 既有地下室增层开挖引起的桩基侧摩阻力损失分析[J]. 岩土工程学报，2013，35(11)：1 957–1 964. (GONG Xiaonan，WU Chengjie，YU Feng，et al. Shaft resistance loss of piles due to excavation beneath existing basements[J]. Chinese Journal of Geotechnical Engineering，2013，35(11)：1 957–1 964.(in Chinese))
[13] 伍程杰. 增层开挖对既有建筑桩基承载性状影响研究[硕士学位论文][D]. 杭州：浙江大学，2014.(WU Chengjie. Study on bearing behavior of piles for excavation beneath existing buildings[M. S. Thesis][D]. Hangzhou：Zhejiang University，2014.(in Chinese))
[14] 王忠帅. 既有建筑钢管桩基础开挖条件下承载特性试验研究[硕士学位论文][D]. 济南：山东建筑大学，2016.(WANG Zhongshuai. Experimental study on bearing characteristics of existing building pile foundation under excavation condition[M. S. Thesis][D]. Jinan：Shandong Jianzhu University，2016.(in Chinese))
[15] 徐前卫，马险峰，朱合华，等. 软土地基超深基坑开挖的离心模型试验研究[J]. 土木工程学报，2009，42(12)：154–161.(XU Qianwei，MA Xianfeng，ZHU Hehua，et al. Centrifugal model test on extra-deep foundation pit excavations in soft ground[J]. China Civil Engineering Journal，2009，42(12)：154–161.(in Chinese))
[16] 梁发云，褚 峰，宋 著，等. 深基坑变形特性的离心模型试验、数值计算与现场实测对比分析[J]. 长江科学院院报，2012，29(1)：74–78.(LIANG Fayun，ZHU Feng，SONG Zhu，et al. Comparison of deformation behavior of deep excavation among centrifuge model test，numerical analysis and in-situ monitoring[J]. Journal of Yangtze River Scientific Research Institute，2012，29(1)：74–78.(in Chinese))
[17] ROSCOE K H. Soils and model tests[J]. Journal of Strain Analysis for Engineering Design，1968，3(1)：57–64.
[18] 中华人民共和国行业标准编写组. JGJ106—2014 建筑基桩检测技术规范[S]. 北京：中国建筑工业出版，2014.(The Professional Standards Compilation Group of People?s Republic of China. JGJ106—2014 Technical code for testing of building foundation piles[S]. Beijing：China Architecture and Building Press，2014.(in Chinese))
[19] LEHANE B M，JARDINE R J，BOND A J，et al. Mechanisms of shaft friction in sand from instrumented pile tests[J]. Journal of Geotechnical Engineering，1993，119(1)：19–35.
[20] 张乾青. 软土地基桩基受力性状和沉降特性试验与理论研究[博士学位论文][D]. 杭州：浙江大学，2012.(ZHANG Qianqing. Test and theoretical study on bearing capacity behavior and settlement of pile in soft soils[Ph. D. Thesis][D]. Hangzhou：Zhejiang University，2012.(in Chinese))
[21] 单华峰. 地下增层条件下既有受荷基桩承载特性研究[博士学位论文][D]. 杭州：浙江大学，2017.(SHAN Huafeng. Some issues on the bearing behavior of existing loaded foundation piles subjected to creating underground storey[Ph. D. Thesis][D]. Hangzhou：Zhejiang University，2017.(in Chinese))
2025, Vol. 44 
