CFG芯水泥土环组合桩复合地基动力特性试验研究
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摘要
基于优化桩型的观点,将工法成熟的水泥粉煤灰碎石桩(简称CFGP)和夯实水泥土桩(简称RCSP)进行组合,设计CFG芯桩-水泥土环桩(简称CFGCP-RCSLP)组合桩复合地基,通过现场试验研究CFGCP-RCSLP组合桩复合地基的静力特性和动力特性。现场载荷试验表明,当土性、桩长、桩间距相同的情况下,CFGCP-RCSLP组合桩复合地基的荷载沉降曲线具有明显的线性关系,复合地基承载力比CFGP复合地基降低19.1%,比RCSP桩复合地基降低23.8%,比天然地基增加了102%。现场爆破试验表明,在爆炸能量、爆炸点位置相同条件下,复合地基的动力特性主要取决于土性、桩体刚度分布和堆载的大小。爆炸点的位置直接影响CFGCP-RCSLP组合桩复合地基中峰值加速度沿桩体的分布规律,堆载的增加使得各测点的峰值加速度明显降低。
For optimized pile foundation design, the concepts of cement-flyash-gravel pile(CFGP) and rammed cement-soil pile(RCSP) were combined in this study to form the rammed cement-soil loop pile with CFG cores(CFGCP-RCSLP). The static and dynamic characteristics of the CFGCP-RCSLP composite foundation were studied using in-situ tests. Test results show that with identical soil properties, pile length and pile spacing, the load-settlement curve of the CFGCP-RCSLP composite foundation demonstrates a clear linear relationship. The bearing capacity of the CFGCP-RCSLP composite foundation is 19.1% lower than the CFGP composite foundation, 23.8% lower than that of the RCSP pile composite foundation, and 102% higher than a natural foundation. The blasting tests show that under same explosion energy and the arrangement of blast points, the dynamic characteristics of composite foundations are primarily related to soil properties, pile rigidity distribution and pilling load. The blast point location arrangement directly influences the distribution of peak acceleration along the pile body of CFGCP-RCSLP composite foundations, and the peak acceleration decreases significantly as the pilling load increases.
For optimized pile foundation design, the concepts of cement-flyash-gravel pile(CFGP) and rammed cement-soil pile(RCSP) were combined in this study to form the rammed cement-soil loop pile with CFG cores(CFGCP-RCSLP). The static and dynamic characteristics of the CFGCP-RCSLP composite foundation were studied using in-situ tests. Test results show that with identical soil properties, pile length and pile spacing, the load-settlement curve of the CFGCP-RCSLP composite foundation demonstrates a clear linear relationship. The bearing capacity of the CFGCP-RCSLP composite foundation is 19.1% lower than the CFGP composite foundation, 23.8% lower than that of the RCSP pile composite foundation, and 102% higher than a natural foundation. The blasting tests show that under same explosion energy and the arrangement of blast points, the dynamic characteristics of composite foundations are primarily related to soil properties, pile rigidity distribution and pilling load. The blast point location arrangement directly influences the distribution of peak acceleration along the pile body of CFGCP-RCSLP composite foundations, and the peak acceleration decreases significantly as the pilling load increases.
引文
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[2]闫明礼,王明山,闫雪峰,张东刚.多桩型复合地基设计计算方法探讨[J].岩土工程学报,2003,25(3):352―355.Yan Mingli,Wang Mingshan,Yan Xuefeng,Zhang Donggang.Study on the calculation method of multi-type-pile composite foundation[J].Chinese Journal of Geotechnical Engineering,2003,25(3):352―355.(in Chinese)
[3]李正,丁继辉,王维玉,等.现浇刚性芯复合桩承载力试验研究[J].勘察科学技术,2006(1):37―39.Li Zheng,Ding Jihui,Wang Weiyu,et al.Experimental Study on composite pile with cast-in-place core[J].Site Investigation Science and Technology,2006(1):37―39.(in Chinese)
[4]丁继辉,孟艳杰,王维玉,等.刚性芯夯实水泥土桩复合地基非线性数值分析[J].工程力学,2010,27(增刊):136―140.Ding Jihui,Meng Yanjie,Wang Weiyu,et al.Non-linear numerical simulation on the composite foundation of rammed soil-cement piles with rigid core[J].Engineering Mechanics,2010,27(Supp1):136―140.(in Chinese)
[5]袁满,丁继辉,冯俊辉,等.同一场地上不同桩型复合地基的静力特性试验[J].工程力学,2014,31(增刊):46―50.Yuan Man,Ding Jihui,Feng Junhui,et al.Static characteristics test on composite foundation of different typed-piles on an identical site[J].Engineering Mechanics,2014,31(Suppl):46―50.(in Chinese)
[6]Yuan Man,Ding Jihui,Zhang Panxing,et al.The settlement computation of composite foundation of different typed-pile based on the load test[J].Applied and mechanics and materials,2014,490/491:1706―1711.
[7]王维玉,赵拓,孟艳杰.爆破地震作用下CFG桩复合地基动力特性的数值分析[J].工程力学,2012,29(增刊):150―155.Wang Weiyu,Zhao Tuo,Meng Yanjie.The numerical analysis on bearing capacity of CFG pile composite foundation under blasting[J].Engineering Mechanics,2012,29(Supp1):150―155.(in Chinese)
[8]王维玉,赵拓,丁继辉.夯实水泥土桩复合地基动力特性和时程响应影响因素分析[J].工程力学,2011,28(2):187―191.Wang Weiyu,Zhao Tuo,Ding Jihui.Effects on dynamic characteristics and response of rammed soil-cement pile composite foundation[J].Engineering Mechanics,2011,28(2):187―191.(in Chinese)
[9]Ding Jihui,Cao Yanliang,Zhao Tuo et al.Experimental study of dynamic characteristics on composite foundation with CFG long pile and rammed cement-soil short pile[J].Open Journal of Civil Engineering,2014,4:1―12.
[10]Jihui Ding,Weiyu Wang,Tuo Zhao et al.The dynamic characteristic experimental method on the composite foundation with rigid-flexible compound piles[J].Open Journal of Civil Engineering,2013,3:94―98.
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