Consolidation Characteristics and Bearing Behavior of Sand Pile Composite Foundation in Caisson Heightening

doi:10.16183/j.cnki.jsjtu.2020.058

Abstract

Abstract:

To study the influence of consolidation on the bearing capacity of the composite foundation in the process of caisson heightening, the consolidation characteristics of the sand pile composite foundation in the process of caisson heightening are discussed based on the sand pile composite foundation engineering of a large-scale onshore caisson foundation. The influence of loading duration and replacement rate of the sand pile are analyzed. Based on the area ratio method of pile-soil and the pile-soil stress ratio method, the formula of the ultimate bearing capacity of the sand pile composite foundation considering the consolidation effect is derived, which is compared with the measured value of the ultimate bearing capacity of the foundation. The results show that the time history curves of the bearing capacity of the composite foundation based on the two methods are close, and the initial bearing capacity is less than the measured value of bearing capacity, while the bearing capacity after consolidation is 68% and 80% higher than the natural strength of the composite foundation. This method considers the influence of consolidation on the bearing capacity of the foundation in the process of caisson heightening. It can avoid the problem of stagnant sinking of open caisson as it underestimates the actual bearing capacity of the foundation, and provides suggestions for calculation of ultimate bearing capacity of the composite foundation considering the influence of consolidation and formulating the reasonable construction scheme of open caisson.

Key words: sand pile, composite foundation, consolidation, bearing capacity, area ratio, stress ratio

CLC Number:

TD752.1

CHEN Peishuai, PAN Yazhou, LIANG Fayun, LI Dejie. Consolidation Characteristics and Bearing Behavior of Sand Pile Composite Foundation in Caisson Heightening[J]. Journal of Shanghai Jiao Tong University, 2021, 55(6): 707-715.

Figures/Tables 10

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References 27

[1]	朱建民, 龚维明, 穆保岗, 等. 超大型沉井首次下沉关键问题研究[J]. 公路, 2011, 56(4):13-18.
	ZHU Jianmin, GONG Weiming, MU Baogang, et al. Bottleneck problem study on first stage sinking of super-large caisson[J]. Highway, 2011, 56(4):13-18.
[2]	许增会. 高置换率挤密砂桩加固软土地基的承载力计算[J]. 水运工程, 2011(6):131-135.
	XU Zenghui. Calculation of composite foundation’s bearing capacity by high replacement ratio sand compacted pile in soft clay[J]. Port&Waterway Engineering, 2011(6):131-135.
[3]	穆保岗, 王岩, 朱建民, 等. 大型沉井实测下沉阻力分析[J]. 土木建筑与环境工程, 2012, 34(Sup.1):107-115.
	MU Baogang, WANG Yan, ZHU Jianmin, et al. Analysis of large caisson sinking measured resistance[J]. Journal of Civil, Architectural & Environmental Engineering, 2012, 34(Sup.1):107-115.
[4]	张玲, 赵明华. 散体材料桩复合地基承载力计算[J]. 湖南大学学报(自然科学版), 2007, 34(6):10-14.
	ZHANG Ling, ZHAO Minghua. Study on bearing capacity calculation method of discrete material pile composite foundation[J]. Journal of Hunan University (Natural Sciences) , 2007, 34(6):10-14.
[5]	闫澍旺, 李嘉, 林澍, 等. 考虑土体强度增长的黏性土地基承载力分析[J]. 岩土力学, 2016, 37(Sup.2):629-634.
	YAN Shuwang, LI Jia, LIN Shu, et al. Bearing capacity analysis of cohesive soil foundation considering the increase of soil strength[J]. Rock and Soil Mechanics, 2016, 37(Sup.2):629-634.
[6]	MUNFAKAH G A, SARKAR S K, CASTELLI R J. Performance of a test embankment founded on stone columns[C]// Proceedings of the International conference on advances in piles and ground treatment for foundations, London: Thomas Telford Limited, 1983, 259-265.
[7]	HAN J, YE S L. Settlement analysis of buildings on the soft clays stabilized by stone columns[C]// Proceedings of the International Conference on Soil Improvement and Piles Foundations, Nanjing, China: International Society for Soil Mechanics and Foundation Engineering, 1992, 446-451.
[8]	张鸿. 大跨度桥梁沉井基础研究与实践[M]. 北京: 人民交通出版社, 2016.
	ZHANG Hong. Research and practice of open cai-sson foundation of long span bridge[M]. Beijing: China Communications Press, 2016.
[9]	谢康和, 曾国熙. 等应变条件下的砂井地基固结解析理论[J]. 岩土工程学报, 1989, 11(2):3-17.
	XIE Kanghe, ZENG Guoxi. Consolidation theories for drain wells under equal strain condition[J]. Chinese Journal of Geotechnical Engineering, 1989, 11(2):3-17.
[10]	沈珠江, 易进栋. 海滩软土路基的固结变形分析[J]. 岩土工程学报, 1987, 6(6):39-45.
	SHEN Zhujiang, YI Jindong. Comparison of models in deformation analysis of beach soft ground under embankment[J]. Chinese Journal of Geotechnical Engineering, 1987, 6(6):39-45.
[11]	YOO W, KIM B I, CHO W. Model test study on the behavior of geotextile-encased sand pile in soft clay ground[J]. KSCE Journal of Civil Engineering, 2015, 19(3):592-601. doi: 10.1007/s12205-012-0473-4 URL
[12]	AMBILY A P, GANDHI S R. Behavior of stone co-lumns based on experimental and FEM analysis[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2007, 133(4):405-415. doi: 10.1061/(ASCE)1090-0241(2007)133:4(405) URL
[13]	BALAAM N P, BROWN P T. Settlement analysis of soft clay reinforced with granular piles[M]. Proceedings of the Fifth Southeast Asian Conference on Soil Engineering, Bangkok, 1977: 81-92.
[14]	中交第一公路勘察设计研究院有限公司. 公路软土地基路堤设计与施工技术规范: JTG/T D31-02-2013[S]. 北京: 人民交通出版社, 2013.
	CCCC First Highway Consultants Co., Ltd. Technical code for design and construction of embankment on Highway Soft Soil Foundation: JTG/T D31-02-2013[S]. Beijing: China Communications Press, 2013.
[15]	李建国, 白朝能. 路堤荷载下复合地基下卧层附加应力分布研究[J]. 铁道工程学报, 2017, 34(7):24-29.
	LI Jianguo, BAI Chaoneng. Study on the distribution of additional stress in the underlying layer of compo-site foundation under embankment load[J]. Journal of Railway Engineering Society, 2017, 34(7):24-29.
[16]	李雅婷, 毛卉, 李森林. 强夯碎石桩复合地基承载力的计算方法简析[J]. 港工技术, 2019, 56(Sup.1):138-141.
	LI Yating, MAO Hui, LI Senlin. Analysis of calculation method on the bearing capacity of dynamic replacement gravel pile composite foundation[J]. Port Engineering Technology, 2019, 56(Sup.1):138-141.
[17]	龚晓南. 复合地基理论及工程应用[M]. 北京: 中国建筑工业出版社, 2002.
	GONG Xiaonan. Theory and engineering application of composite foundation[M]. Beijing: China Architecture & Building Press, 2002.
[18]	朱小军, 孔伟阳, 李文帅. 高置换率挤密砂桩模型试验与承载力计算方法研究[J]. 公路, 2017, 62(8):1-7.
	ZHU Xiaojun, KONG Weiyang, LI Wenshuai. Study of model tests and calculation methods of bearing capacity on high replacement ratio sand compacted pile[J]. Highway, 2017, 62(8):1-7.
[19]	上海市政工程设计研究总院(集团)有限公司. 给水排水工程钢筋混凝土沉井结构设计规程, CECS 137: 2015[S]. 北京: 中国计划出版社, 2015.
	Shanghai Municipal Engineering Design Institute(Group) Co., Ltd. Specification for structural design of reinforced concrete sinking well of water supply and sewage engineering,CECS 137: 2015[S]. Beijing: China Planning Press, 2015.
[20]	上海市基础工程有限公司. 沉井与气压沉箱施工技术规程: J11875-2011[S]. 上海: 上海市城乡建设与交通委员会, 2011.
	Shanghai Foundation Engineering Co., Ltd. Specification for open caisson and pneumatic caisson: J11875-2011[S]. Shanghai: Shanghai Urban Rural Development and Transportation Commission, 2011.
[21]	中华人民共和国住房和城乡建设部. 复合地基技术规范: GB/T 50783-2012[S]. 北京: 中国计划出版社, 2012.
	Minister of Housing and Urban-rural Development of the People’s Republic of China. Technical code for composite foundation: GB/T 50783-2012[S]. Beijing: China Planning Press, 2012.
[22]	卢萌盟. 复杂条件下复合地基固结解析理论研究[D]. 杭州: 浙江大学, 2009.
	LU Mengmeng. Study on consolidation theory of composite foundation under complex conditions[D]. Hangzhou: Zhejiang University, 2009.
[23]	卢萌盟, 谢康和, 王坤. 考虑桩体内径向渗流的复合地基固结解[J]. 固体力学学报, 2009, 30(2):155-161.
	LU Mengmeng, XIE Kanghe, WANG Kun. Analytical solutions for for the consolidation of a compound foundation with consideration on the radial flow within the column[J]. Chinese Journal of Solid Mechanics, 2009, 30(2):155-161.
[24]	龚晓南. 广义复合地基理论及工程应用[J]. 岩土工程学报, 2007, 29(1):1-13.
	GONG Xiaonan. Generalized composite foundation theory and engineering application[J]. Chinese Journal of Geotechnical Engineering, 2007, 29(1):1-13.
[25]	龚晓南. 复合地基理论与实践[M]. 杭州: 浙江大学出版社, 1996.
	GONG Xiaonan. Theory and practice of composite foundation[M]. Hangzhou: Zhejiang University Press, 1996.
[26]	熊启东, 高大钊. 用汉森公式确定地基承载力的可靠度分析[J]. 岩土工程学报, 1998, 20(2):79-81.
	XIONG Qidong, GAO Dazhao. Reliability analysis of foundation bearing capacity determined by Hansen formula[J]. Chinese Journal of Geotechnical Engineering, 1998, 20(2):79-81.
[27]	沈珠江. 基于有效固结应力理论的黏土土压力公式[J]. 岩土工程学报, 2000, 22(3):353-356.
	SHEN Zhujiang. The equation of clay soil pressure based on the theory of the effective consolidation stress[J]. Chinese Journal of Geotechnical Engineering, 2000, 22(3):353-356.

编号	土层	h/m	c/kPa	φ/(°)	ρ/(g·cm^-3)	P/kPa
1	淤泥质黏土(砂桩加固)	9.32	8.8	3.3	1.74	402.2
2	淤泥质黏土夹粉砂(砂桩加固)	3.41	8.7	3.6	1.72	413.8
3	淤泥(砂桩加固)	15	7.4	2.5	1.64	354.2
4	淤泥质黏土(砂桩加固)	4.88	13.2	7.1	1.71	381.1
5	黏土	5.74	17.1	8.3	1.76	240
6	黏土夹粉砂	5.12	26.2	8.6	1.78	300

工况	x	P_T/kPa	P_B/kPa	t_c/d
1	1	57.7	19.1	26
2	2	110.7	36.6	52
3	3	142.3	47.1	78
4	4	181.8	60.1	104

工况	实测值	P₀/kPa		P_0.4/kPa				P_0.7/kPa				P₁/kPa
工况	实测值	面积比法	应力比法	面积比法		应力比法		面积比法		应力比法		面积比法		应力比法
1	402	140	225	203	251		272		304		357		383
2				244	274		364		375		517		528
3				261	288		406		417		596		615
4				275	305		446		471		675		724

m	实测值	P'₀/kPa		P'_0.4/kPa		P'_0.7/kPa		P'₁/kPa
m	实测值	面积比法	应力比法	面积比法	应力比法	面积比法	应力比法	面积比法	应力比法
10%	-	243	183	385	344	491	465	598	586
20%	-	266	200	404	375	508	508	612	640
36%	402	346	226	477	424	576	574	675	724
50%	-	416	250	541	466	635	630	730	794