不同厚度溶洞顶板与基桩作用机理室内模型试验研究
Laboratory model tests on punching properties of karst cave roof under pile tip considering various thickness-span ratios
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摘要: 根据相似理论,设计了3组不同厚度条件下溶洞顶板破坏模式的大比例模型试验,得到了顶板和基桩的荷载-位移曲线、顶板底部的极限应变曲线和不同厚度条件下溶洞顶板的破坏特性。试验结果表明:当溶洞顶板厚度为1d,2d时,发生冲切破坏,冲切体为圆台;当溶洞顶板厚度为3d时,顶板则以弯拉破坏为主,无冲切体产生。在荷载-位移曲线中,线性阶段转变为非线性阶段的临界点约为极限承载力的一半。最后通过理论计算的方法,获得溶洞顶板最小安全厚度计算公式,分析结果与试验结果吻合较好,能满足工程计算精度要求。本文试验成果是基于工程最不利情况得出的,可供岩溶区基桩初步设计参考。Abstract: According to the similarity theory, punching properties of cave roof under pile tip are investigated through three series of large-scale laboratory model tests with different thickness. The load-displacement curves of pile foundation and roof, the ultimate strain curves of roof bottom and the failure characteristic of cave roof with different thickness are obtained. The test results show that the punching failure occurs within the circle table punching body when the thickness of the cave roof equals to 1d or 2d; however, the bending failure rather than the punching failure occurs when the thickness of the cave roof equals to 3d. The turning point of the elastic stage is transformed into the plastic stage in half the position of the ultimate bearing capacity according to the load-displacement curves, indicating that the plastic ultimate bearing capacity is two times the elastic ultimate bearing capacity. At last, the calculation formula of the minimum safety thickness is induced based on the theories of bending for thin plates and punching failure. The theoretical calculation results are in good agreement with the test results, which can meet the requirements of engineering calculation accuracy. The test results in this paper are based on critical situation, and they can provide reference for the preliminary design of piles in Karst areas.
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Keywords:
- roof failure mode /
- karst cave /
- model test /
- safety thickness
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[1] [1]赵明华,陈昌富,曹文贵,等.嵌岩桩桩端岩层抗冲切安全厚度研究[J]. 湘潭矿业学院学报,2004,18(4): 41-45. [ZHAO M H, CHEN C F, CAO W G, et al. Analysis for the safe terrane thickness of punching-shear resistance at the end of rock-socketed piles[J]. Journal of Xiangtan Mining Institute, 2004, 18(4): 41-45 (in Chinese)]
[2] [2]赵明华,曹文贵,何鹏祥, 等. 岩溶及采空区桥梁桩基桩端岩层安全厚度研究[J]. 岩土力学,2004,25(1):64-68. [ZHAO M H,CAO W G,HE P X,et al. Study on safe thickness of rock mass at end of bridge foundations pile in karst and worked-out mine area[J]. Rock and Soil Mechanics,2004,25(1):64-68 (in Chinese))
[3] [3]雷勇,陈秋南,马缤辉.基于极限分析的桩端岩层冲切分析[J]. 岩石力学与工程学报, 2014, 33(3): 631-638. [LEI Y, CHEN Q N, MA B H. Punching analysis of rock at pile tip base on limit analysis[J]. Chinese Journal of Rock Mechanics and Engineering,2014,33(3): 631-638 (in Chinese))
[4] [4]龚先兵,赵明华,杨明辉,等. 岩溶区桥梁基桩极限承载力的突变求解方法[J]. 公路交通科技, 2012, 29(11): 53-57. [GONG X B, ZHAO M H, YANG M H, et al. Determination of ultimate bearing capacity of pile in karst region based on catastrophe theory[J]. Journal of Highway and Transportation Research and Development, 2012, 29(11): 53-57 (in Chinese)]
[5] [5]JIANG Chong, LIU Lang, WU Jun-ping. A new method determining safe thickness of karst cave roof under pile tip[J]. Journal of Central South University, 2014, 21(3): 1190-1196.
[6] [6]黎斌,范秋雁,秦凤荣.岩溶地区溶洞顶板稳定性分析[J]. 岩石力学与工程学报, 2002, 21(4): 532-536. [LI B, FAN Q Y, QIN F R. Analysis on roof stability of karst cave in karst areas[J]. Chinese Journal of Rock Mechanics and Engineering, 2002, 21(4): 532-536 (in Chinese)]
[7] [7]孙映霞,王金安,张智浩. 岩溶区桩基破坏模式研究及稳定性分析[J]. 工业建筑, 2012, 42(9): 96-102. [SUN Y X,WANG J A, ZHANG Z H. Failure pattern study and stability analysis of pile foundation in karst area[J]. Industrial Construction,2012,42(9): 96-102 (in Chinese))
[8] [8]尹凯丽,郝世龙. 武汉地区岩溶对桩基承载力影响数值模拟研究[J]. 水文地质工程地质,2015,42(6):96-102. [YIN K L, HAO S L. A study of the effect of karst on the bearing capacity of pile foundation in Wuhan district based on numerical simulation[J]. Hydrogeology & Engineering Geology,2015,42(6):96-102 (in Chinese)]
[9] [9]MENETREY P. Synthesis of punching failure in rein-forced concrete[J]. Cement & Concrete Composites, 2002(24): 497-507
[10] [10]刘铁雄.溶洞顶板与桩基作用机理分析与模拟试验研究[D].长沙:中南大学,2003:70-90. [LIU T X. Mechanism analysis and simulation test of karst cave roof and pile foundation[D].Changsha: Central South University, 2003:70-90 (in Chinese)]
[11] [11]刘铁雄,彭振斌.溶洞顶板模拟试验研究[J].探矿工程,2002(6):1-4. [LIU T X, PENG Z B. Simulation test study of karst cave roof[J]. Prospecting Engineering, 2002(6):1-4 (in Chinese)]
[12] [12]张慧乐,张智浩,王述红,等.岩溶区嵌岩桩的试验研究与分析[J].土木工程学报, 2013, 46(1): 92-103. [ZHANG H L, ZHANG Z H, WANG S H, et al. Experimental study and analysis of rock-socketed pile in karst area[J]. China Civil Engineering Journal, 2013, 46(1): 92-103 (in Chinese)]
[13] [13]张慧乐,马凛,张智浩,等.岩溶区嵌岩桩承载特性影响因素的试验研究与分析[J]. 岩土力学,2013,34(1):92-101. [ZHANG H L,MA L,ZHANG Z H,et al. Test Research and analysis of influencing factors of rock-socketed pile bearing capacity in karst area[J]. Rock and Soil Mechanics,2013,34(1):92-101 (in Chinese)]
[14] [14]徐挺.相似理论与模型试验[M]. 北京:中国农业机械出版社, 1982. [XU T. Similarity theory and model test[M]. Beijing: Chinese Agricultural Machine Press, 1982 (in Chinese)]
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