基于平面应变模型的岩溶区嵌岩桩桩端极限承载力计算
|
摘要
为了给出嵌岩桩作用在含不同溶洞地层上的桩端极限承载力计算方法,首先,根据岩溶区桩基承载特性建立了简化计算模型;其次,分析了岩溶区嵌岩桩桩端承载机理,并提出了岩溶区嵌岩桩桩端极限承载力计算模型;再次,利用复变函数的方法对岩溶区嵌岩桩桩端平均约束应力进行求解,进而求得岩溶区嵌岩桩桩端极限承载力;然后,对岩溶区嵌岩桩桩端极限承载力的影响因素进行了参数分析,结果表明:(1)溶洞半径越大,对桩端极限承载力的影响越大。(2)桩端到溶洞中心的距离越大,对桩端极限承载力的影响越小。(3)溶洞埋深越大,对桩端极限承载力的影响越大。最后,工程算例对比分析表明该方法能满足工程要求,能为岩溶区嵌岩桩工程实践提供一些参考价值。值得注意的是,由于假定条件的限制,本文计算结果仅适用于溶洞洞边与桩端距离大于3倍桩径时的情形。
To provide a calculation method for the ultimate bearing capacity at the tip of a single rock-socketed pile in different stratum with karst cave. Firstly,a simplified calculation model was establishedab on the basis of bearing characteristics of a rock-socketed pile in Karst area. Secondly,the bearing mechanism at the tip of a rock-socketed pile in Karst area was analyzed and the calculation model of ultimate bearing capacity was built as well. Thirdly,average constraint stress at the tip of a rock-socketed pile in Karst area was solved by using the method of complex variable function,and therefore,the ultimate baring capacity at the tip of a rock-socketed pile in Karst area was obtained. Then,the influencing factors of ultimate bearing capacity at the tip of a rock-socketed pile in Karst area were analyzed,and the analysis results show that increasing the cavity radius,increasing the cavity depth or decreasing the distance from the pile tip to the center of cavity may increase the impact on ultimate bearing capacity at the tip of a rock-socketed pile in Karst area. At last,theoretical results based on an engineering example disclose that the proposed method can meet the requirements of practical projects. It is noteworthy that due to the assumptions,the validity of calculation results in this work is only applicable to the case that the distance between the cave and pile tip is larger than 3 times the pile diameter.
To provide a calculation method for the ultimate bearing capacity at the tip of a single rock-socketed pile in different stratum with karst cave. Firstly,a simplified calculation model was establishedab on the basis of bearing characteristics of a rock-socketed pile in Karst area. Secondly,the bearing mechanism at the tip of a rock-socketed pile in Karst area was analyzed and the calculation model of ultimate bearing capacity was built as well. Thirdly,average constraint stress at the tip of a rock-socketed pile in Karst area was solved by using the method of complex variable function,and therefore,the ultimate baring capacity at the tip of a rock-socketed pile in Karst area was obtained. Then,the influencing factors of ultimate bearing capacity at the tip of a rock-socketed pile in Karst area were analyzed,and the analysis results show that increasing the cavity radius,increasing the cavity depth or decreasing the distance from the pile tip to the center of cavity may increase the impact on ultimate bearing capacity at the tip of a rock-socketed pile in Karst area. At last,theoretical results based on an engineering example disclose that the proposed method can meet the requirements of practical projects. It is noteworthy that due to the assumptions,the validity of calculation results in this work is only applicable to the case that the distance between the cave and pile tip is larger than 3 times the pile diameter.
引文
[1]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 Bin,Fan Qiuyan,Qin Fengrong,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))
[2]阳军生,张军,张起森,等.溶洞上方圆形基础地基极限承载力有限元分析[J].岩石力学与工程学报,2005,24(2):296-301(Yang Junsheng,Zhan Jun,Zhang Qisen,et al.Finite element analysis of ultimate bearing capacity of circular footing above karst cave[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(2):296-301(in Chinese))
[3]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 Yingxia,Wang Jin'an,Zhang Zhihao.Failure pattern study and stability analysis of pile foundation in karst area[J].Industrial Construction,2012,42(9):96-102(in Chinese))
[4]刘之葵,梁金城,朱寿增,等.岩溶区含溶洞岩石地基稳定性分析[J].岩土工程学报,2003,25(5):629-633(Liu Zhikui,Liang Jincheng,Zhu Shouzeng,et al.Stability analysis of rock foundation with cave in karst area[J].Chinese Journal of Geotechnical Engineering,2003,25(5):629-633(in Chinese))
[5]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,2003,18(4):41-45(Zhao Minghua,Chen Changfu,Cao Wengui,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,2003,18(4):41-45(in Chinese))
[6]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 Minghua,Cao Wengui,He Pengxiang,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))
[7]赵明华,张锐,胡柏学,等.岩溶区桩端下伏溶洞顶板稳定性分析研究[J].公路交通科技,2009,26(9):13-16(Zhao Minghua,Zhang Rui,Hu Boxue,et al.Analysis of stability of cave roof under pile tip in karst area[J].Journal of Highway and Transportation Research and Development,2009,26(9):13-16(in Chinese))
[8]赵明华,蒋冲,曹文贵.岩溶区嵌岩桩承载力及其下伏溶洞顶板安全厚度的研究[J].岩土工程学报,2007,29(11):1618-1622(Zhao Minghua,Jiang Chong,Cao Wengui.Study on bearing capacity of rock-socketed piles and safe thickness of cave roofs in karst region[J].Chinese Journal of Geotechnical Engineering,2007,29(11):1618-1622(in Chinese))
[9]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):48-74(Gong Xianbing,Zhao Minghua,Yang Minghui,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):48-74(in Chinese))
[10]赵明华,雷勇,张锐.岩溶区桩基冲切破坏模式及安全厚度研究[J].岩土力学,2012,33(2):209-215(Zhao Minghua,Lei Yong,Zhang Rui.Study of punching failure mode and safe thickness of pile foundation in karst region[J].Rock and Soil Mechanics,2012,33(2):209-215(in Chinese))
[11]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 Yong,Chen Qiunan,Ma Binghui.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))
[12]Jiang Chong,Liu Lang,Wu Junping.A new method determining safe thickness of karst cave roof under pile tip[J].Journal of Central South University,2014,21(3):1190-1196
[13]王革立.岩溶地基嵌岩桩桩基特性分析与试验研究[D].长沙:中南大学,2002(Wang Geli.Analysis of rock-socketed pile and experiment research in karst area[D].Changsha:Central South University,2002(in Chinese))
[14]刘铁雄.岩溶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(Liu Tiexiong.Mechanism analysis of karst pile with cave roof and experiment research[D].Changsha:Central South University,2003(in Chinese))
[15]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 Huile,Zhang Zhihao,Wang Shuhong,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))
[16]张慧乐,马凛,张智浩.岩溶区嵌岩桩承载特性影响因素试验研究[J].岩土力学,2013,34(1):92-100(Zhang Huile,Ma Lin,Zhang Zhihao.Test research of influcing factor of rock-socked pile bearing capacity in karst area[J].Rock and Soil Mechanics,2013,34(1):92-100(in Chinese))
[17]张智浩,张慧乐,马凛,等.岩溶区嵌岩桩的破坏模式与工程设计探讨[J].岩石力学与工程学报,2013,32(增2):4130-4138(Zhang Zhihao,Zhang Huile,Ma Lin,et al.Discussion on failure mode and engineering design of rock-socked pile in karst area[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(S2):4130-4138(in Chinese))
[18]Zhang L,Einstein H H.End bearing capacity of drilled shafts in rock[J].Journal of Geotechnical&Geoenvironmental Engineering,1999,125(12):574-584
[19]李倩倩,张顶立,房倩.含空洞地层初始破坏的复变函数解析研究[J].岩土工程学报,2014,36(11):2110-2117(Li Qianqian,Zhang Dingli,Fang Qian.Analytic solution to initial damage of cavern strata by complex function method[J].Chinese Journal of Geotechnical Engineering,2014,36(11):2110-2117(in Chinese))
[20]徐芝纶.弹性力学(上册)[M].北京:高等教育出版社,2006(Xu Zhilun.Elasticity(Book one)[M].Beijing:Higher Education Press,2006(in Chinese))
[2]阳军生,张军,张起森,等.溶洞上方圆形基础地基极限承载力有限元分析[J].岩石力学与工程学报,2005,24(2):296-301(Yang Junsheng,Zhan Jun,Zhang Qisen,et al.Finite element analysis of ultimate bearing capacity of circular footing above karst cave[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(2):296-301(in Chinese))
[3]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 Yingxia,Wang Jin'an,Zhang Zhihao.Failure pattern study and stability analysis of pile foundation in karst area[J].Industrial Construction,2012,42(9):96-102(in Chinese))
[4]刘之葵,梁金城,朱寿增,等.岩溶区含溶洞岩石地基稳定性分析[J].岩土工程学报,2003,25(5):629-633(Liu Zhikui,Liang Jincheng,Zhu Shouzeng,et al.Stability analysis of rock foundation with cave in karst area[J].Chinese Journal of Geotechnical Engineering,2003,25(5):629-633(in Chinese))
[5]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,2003,18(4):41-45(Zhao Minghua,Chen Changfu,Cao Wengui,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,2003,18(4):41-45(in Chinese))
[6]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 Minghua,Cao Wengui,He Pengxiang,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))
[7]赵明华,张锐,胡柏学,等.岩溶区桩端下伏溶洞顶板稳定性分析研究[J].公路交通科技,2009,26(9):13-16(Zhao Minghua,Zhang Rui,Hu Boxue,et al.Analysis of stability of cave roof under pile tip in karst area[J].Journal of Highway and Transportation Research and Development,2009,26(9):13-16(in Chinese))
[8]赵明华,蒋冲,曹文贵.岩溶区嵌岩桩承载力及其下伏溶洞顶板安全厚度的研究[J].岩土工程学报,2007,29(11):1618-1622(Zhao Minghua,Jiang Chong,Cao Wengui.Study on bearing capacity of rock-socketed piles and safe thickness of cave roofs in karst region[J].Chinese Journal of Geotechnical Engineering,2007,29(11):1618-1622(in Chinese))
[9]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):48-74(Gong Xianbing,Zhao Minghua,Yang Minghui,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):48-74(in Chinese))
[10]赵明华,雷勇,张锐.岩溶区桩基冲切破坏模式及安全厚度研究[J].岩土力学,2012,33(2):209-215(Zhao Minghua,Lei Yong,Zhang Rui.Study of punching failure mode and safe thickness of pile foundation in karst region[J].Rock and Soil Mechanics,2012,33(2):209-215(in Chinese))
[11]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 Yong,Chen Qiunan,Ma Binghui.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))
[12]Jiang Chong,Liu Lang,Wu Junping.A new method determining safe thickness of karst cave roof under pile tip[J].Journal of Central South University,2014,21(3):1190-1196
[13]王革立.岩溶地基嵌岩桩桩基特性分析与试验研究[D].长沙:中南大学,2002(Wang Geli.Analysis of rock-socketed pile and experiment research in karst area[D].Changsha:Central South University,2002(in Chinese))
[14]刘铁雄.岩溶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(Liu Tiexiong.Mechanism analysis of karst pile with cave roof and experiment research[D].Changsha:Central South University,2003(in Chinese))
[15]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 Huile,Zhang Zhihao,Wang Shuhong,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))
[16]张慧乐,马凛,张智浩.岩溶区嵌岩桩承载特性影响因素试验研究[J].岩土力学,2013,34(1):92-100(Zhang Huile,Ma Lin,Zhang Zhihao.Test research of influcing factor of rock-socked pile bearing capacity in karst area[J].Rock and Soil Mechanics,2013,34(1):92-100(in Chinese))
[17]张智浩,张慧乐,马凛,等.岩溶区嵌岩桩的破坏模式与工程设计探讨[J].岩石力学与工程学报,2013,32(增2):4130-4138(Zhang Zhihao,Zhang Huile,Ma Lin,et al.Discussion on failure mode and engineering design of rock-socked pile in karst area[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(S2):4130-4138(in Chinese))
[18]Zhang L,Einstein H H.End bearing capacity of drilled shafts in rock[J].Journal of Geotechnical&Geoenvironmental Engineering,1999,125(12):574-584
[19]李倩倩,张顶立,房倩.含空洞地层初始破坏的复变函数解析研究[J].岩土工程学报,2014,36(11):2110-2117(Li Qianqian,Zhang Dingli,Fang Qian.Analytic solution to initial damage of cavern strata by complex function method[J].Chinese Journal of Geotechnical Engineering,2014,36(11):2110-2117(in Chinese))
[20]徐芝纶.弹性力学(上册)[M].北京:高等教育出版社,2006(Xu Zhilun.Elasticity(Book one)[M].Beijing:Higher Education Press,2006(in Chinese))