上覆土嵌岩扩底桩抗拔承载特性离心模型试验及计算方法研究
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摘要
随着我国西部输电线路工程的快速发展,杆塔基础抗拔问题日益突出,岩体的破坏模式、极限抗拔承载力的计算方法都是目前亟待解决的关键问题。根据离心模型试验结果,分析了岩体破坏模式、荷载-位移曲线、桩身轴力分布和桩侧摩阻力曲线。基于试验结果对岩体破坏形状进行无量纲化处理并拟合,得到了统一的函数描述形式。在此基础上,利用极限平衡法推导出上覆土嵌岩扩底桩极限抗拔承载力的计算方法,并对该计算方法作了简化分析,将积分计算值和简化计算值分别与离心模型试验结果进行对比。研究结果表明:上覆土嵌岩扩底桩的软质岩破坏模式为喇叭型曲面,可用统一的幂函数形式进行描述。简化计算方法的结果与离心模型试验结果吻合良好,提出的新方法对西部山区杆塔基础的抗拔设计具有参考和应用价值。
With the rapid development of the transmission line project in western China, the problems of the tower foundation uplift become prominent. It is necessary to solve the failure model of rock and the calculation method of ultimate uplift bearing capacity urgently. The centrifuge model test results are used to analyze the failure model of rock, load-displacement curve, axial force distribution and friction resistance curve of piles. According to the test results, after the failure shape of rock is non-dimensionally processed and fitted, a unified function description form is obtained. On this basis, the limit equilibrium method is used to derive the calculation method of ultimate uplift bearing capacity of the rock-socketed pedestal pile overburden soil, and the calculation method is simplified. The integral calculation value and the simplified calculation value are compared with the results of the centrifugal model test. The results show that the failure model of the soft rock is trumpet-shaped surface, which can be described by a unified power function. The results of the simplified calculation method are in good agreement with the results of the centrifugal model test. Therefore, the method proposed in this paper provides a reference for the uplift design of tower foundation in the western mountainous area.
With the rapid development of the transmission line project in western China, the problems of the tower foundation uplift become prominent. It is necessary to solve the failure model of rock and the calculation method of ultimate uplift bearing capacity urgently. The centrifuge model test results are used to analyze the failure model of rock, load-displacement curve, axial force distribution and friction resistance curve of piles. According to the test results, after the failure shape of rock is non-dimensionally processed and fitted, a unified function description form is obtained. On this basis, the limit equilibrium method is used to derive the calculation method of ultimate uplift bearing capacity of the rock-socketed pedestal pile overburden soil, and the calculation method is simplified. The integral calculation value and the simplified calculation value are compared with the results of the centrifugal model test. The results show that the failure model of the soft rock is trumpet-shaped surface, which can be described by a unified power function. The results of the simplified calculation method are in good agreement with the results of the centrifugal model test. Therefore, the method proposed in this paper provides a reference for the uplift design of tower foundation in the western mountainous area.
引文
[1]王卫东,吴江斌,许亮,等.软土地区扩底抗拔桩承载特性试验研究[J].岩土工程学报, 2007, 29(9):1418-1422.WANG Wei-dong, WU Jiang-bin, XU Liang, et al.Full-scale field tests on uplift behavior of piles with enlarged base[J]. Chinese Journal of Geotechnical Engineering, 2007, 29(9):1418-1422.
[2]张尚根,袁正如,孙传怀.扩底抗拔桩变形非线性分析[J].岩土工程学报, 2013, 35(增刊2):1091-1094.ZHANG Shang-gen, YUAN Zheng-ru, SUN Chuan-huai.Nonlinear analysis of deformation for belled tension piles under vertical loading[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(Suppl.2):1091-1422.
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[4] CLEMENCE S P, VEESAERT C J. Dynamic pullout resistance of anchors in sand[C]//Proceedings of International Symposium on Soil Structure Interaction.Roorkee:[s. n.], 1977:389-397.
[5] MURRAY E J, GEDDES J D. Uplift of anchor plates in sand[J]. Journal of Geotechnical Engineering Division,ASCE, 1987, 113:202-215.
[6] BALLA A. The resisitance to breaking-out of mushroom foundations for pylons[C]//Proceedings of the 5th International Conference on Soil Mechanics and Foundation Engineering. Paris:[s. n.], 1961, 1:569-576.
[7] MEYERHOF G G, ADAMS J I. The ultimate uplift capacity of foundations[J]. Canadian Geotechnical Journal, 1968, 5(4):225-244.
[8] MORS H. The behavior of mast foundations subjected to tensile forces[J]. Bautechnik, 1959, 10(3):67-78.
[9] DESHMUKH V B, DEWAIKAR D M, CHOUDHURY D.Computations of uplift capacity of pile anchors in cohesionless soil[J]. Acta Geotechnica, 2010, 5(2):87-94.
[10] SHELKE A, MISHRA S. Uplift capacity of single bent pile and pile group considering arching effects in sand[J].Geotechnical and Geological Engineering, 2010, 28(4):337-347.
[11]周治国,唐孟雄,董晓斌,等.嵌岩旋挖扩底抗拔桩工程应用研究[J].岩石力学与工程学报, 2009, 28(增刊2):3838-3843.ZHOU Zhi-guo, TANG Meng-xiong, DONG Xiao-bin,et al. Application to bearing capacity of rock-embedded under-reamed uplift piles[J]. Chinese Journal of Rock Mechanics and Engineering, 2009, 28(Suppl.2):3838-3843.
[12]何思明,张晓曦,王东坡.分层地基中抗拔桩破裂面的确定方法与极限抗拔承载力计算方法研究[J].岩土力学, 2012, 33(5):1433-1437.HE Si-ming, ZHANG Xiao-xi, WANG Dong-po. Study of computation methods of ultimate uplift capacity and determining position of failure surface of uplift piles in layered soil[J]. Rock and Soil Mechanics, 2012, 33(5):1433-1437.
[13]邵光辉,赵志峰,吴正余.托底抗拔桩承载特性的模型试验研究[J].岩土工程学报, 2016, 38(6):1140-1146.SHAO Guang-hui, ZHAO Zhi-feng, WU Zheng-yu. Model tests on shaft capacity properties of bottom uplift pile[J].Chinese Journal of Geotechnical Engineering, 2016,38(6):1140-1146.
[14]钱建固,陈宏伟,贾鹏,等.注浆成型螺纹桩接触面特性试验研究[J].岩石力学与工程学报, 2013, 32(9):1744-1749.QIAN Jian-gu, CHEN Hong-wei, JIA Peng, et al.Experimental study of mechanical behaviours of grouting-screw pile interface[J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32(9):1744-1749.
[15]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):1076-1083.HU Qi, LING Dao-sheng, KONG Ling-gang, et al. Effects of deep excavation on uplift capacity of piles by centrifuge tests[J]. Chinese Journal of Geotechnical Engineering,2013, 35(6):1076-1083.
[16]钱建固,马霄,李伟伟,等.桩侧注浆抗拔桩离心模型试验与原位测试分析[J].岩土力学, 2014, 35(5):1241-1247.QIAN Jian-gu, MA Xiao, LI Wei-wei, et al. Centrifuge model test and in-situ observation on behabiors of side-grounting uplift pile[J]. Rock and Soil Mechanics,2014, 35(5):1241-1247.
[17]袁文忠,于志强,谢涛.岩基强度对嵌岩抗拔桩承载力影响的试验研究[J].西南交通大学学报, 2003, 38(2):178-182.YUAN Wen-zhong, YU Zhi-qiang, XIE Tao. Vertical bearing capacity of rock-socketed piles influenced by batholith strength[J]. Journal of Southwest Jiaotong University, 2003, 38(2):178-182.
[18]张尚根,陈志龙,尹峰,等.等截面抗拔桩的变形分析[J].解放军理工大学学报(自然科学版), 2002, 3(5):71-73.ZHANG Shang-gen, CHEN Zhi-long, YIN Feng, et al.Analysis of deformation of tension piles[J]. Journal of PLA University of Science and Technology(Natural Science Edition), 2002, 3(5):71-73.
[19]周杨,肖世国,徐骏,等.变截面螺纹桩竖向承载特性试验研究[J].岩土力学, 2017, 38(3):101-109.ZHOU Yang, XIAO Shi-guo, XU Jun, et al. Model test on vertical bearing capacity of tapered concrete screw piles[J]. Rock and Soil Mechanics, 2017, 38(3):101-109.
[20]中华人民共和国行业标准编写组. JGJ 94―2008建筑桩基技术规范[S].北京:中国建筑工业出版社, 2008.The Professional Standards Compilation Group of People’s Republic of China. JGJ 94―2008 Technical code for building pile foundation[S]. Beijing:China Architecture and Building Press, 2008.
[21]邹健,张忠苗,刘俊伟,等.一种考虑桩侧土应变软化的荷载传递函数[J].岩土工程学报, 2010, 32(7):1109-1113.ZOU Jian, ZHANG Zhong-miao, LIU Jun-wei, et al. A load transfer model considering strain softening of soils[J].Chinese Journal of Geotechnical Engineering, 2010,32(7):1109-1113.
[22]郦建俊,黄茂松,木林隆,等.分层地基中扩底抗拔桩的计算方法研究[J].岩土力学, 2008, 29(7):1997-2003.LI Jian-jun, HUANG Mao-song, MU Lin-long, et al.Research on computation methods of uplift capacity of enlarged base pile in layered soils[J]. Rock and Soil Mechanics, 2008, 29(7):1997-2003.
[2]张尚根,袁正如,孙传怀.扩底抗拔桩变形非线性分析[J].岩土工程学报, 2013, 35(增刊2):1091-1094.ZHANG Shang-gen, YUAN Zheng-ru, SUN Chuan-huai.Nonlinear analysis of deformation for belled tension piles under vertical loading[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(Suppl.2):1091-1422.
[3] MAJER J. Zur Berechnung von Zugfundamenten[J].Ostereichische Bauzeitschrift, 1955, 10(5):85-90.MAJER J. For the calculation of access bases[J].Austrian Construction Magazine, 1955, 10(5):85-90.
[4] CLEMENCE S P, VEESAERT C J. Dynamic pullout resistance of anchors in sand[C]//Proceedings of International Symposium on Soil Structure Interaction.Roorkee:[s. n.], 1977:389-397.
[5] MURRAY E J, GEDDES J D. Uplift of anchor plates in sand[J]. Journal of Geotechnical Engineering Division,ASCE, 1987, 113:202-215.
[6] BALLA A. The resisitance to breaking-out of mushroom foundations for pylons[C]//Proceedings of the 5th International Conference on Soil Mechanics and Foundation Engineering. Paris:[s. n.], 1961, 1:569-576.
[7] MEYERHOF G G, ADAMS J I. The ultimate uplift capacity of foundations[J]. Canadian Geotechnical Journal, 1968, 5(4):225-244.
[8] MORS H. The behavior of mast foundations subjected to tensile forces[J]. Bautechnik, 1959, 10(3):67-78.
[9] DESHMUKH V B, DEWAIKAR D M, CHOUDHURY D.Computations of uplift capacity of pile anchors in cohesionless soil[J]. Acta Geotechnica, 2010, 5(2):87-94.
[10] SHELKE A, MISHRA S. Uplift capacity of single bent pile and pile group considering arching effects in sand[J].Geotechnical and Geological Engineering, 2010, 28(4):337-347.
[11]周治国,唐孟雄,董晓斌,等.嵌岩旋挖扩底抗拔桩工程应用研究[J].岩石力学与工程学报, 2009, 28(增刊2):3838-3843.ZHOU Zhi-guo, TANG Meng-xiong, DONG Xiao-bin,et al. Application to bearing capacity of rock-embedded under-reamed uplift piles[J]. Chinese Journal of Rock Mechanics and Engineering, 2009, 28(Suppl.2):3838-3843.
[12]何思明,张晓曦,王东坡.分层地基中抗拔桩破裂面的确定方法与极限抗拔承载力计算方法研究[J].岩土力学, 2012, 33(5):1433-1437.HE Si-ming, ZHANG Xiao-xi, WANG Dong-po. Study of computation methods of ultimate uplift capacity and determining position of failure surface of uplift piles in layered soil[J]. Rock and Soil Mechanics, 2012, 33(5):1433-1437.
[13]邵光辉,赵志峰,吴正余.托底抗拔桩承载特性的模型试验研究[J].岩土工程学报, 2016, 38(6):1140-1146.SHAO Guang-hui, ZHAO Zhi-feng, WU Zheng-yu. Model tests on shaft capacity properties of bottom uplift pile[J].Chinese Journal of Geotechnical Engineering, 2016,38(6):1140-1146.
[14]钱建固,陈宏伟,贾鹏,等.注浆成型螺纹桩接触面特性试验研究[J].岩石力学与工程学报, 2013, 32(9):1744-1749.QIAN Jian-gu, CHEN Hong-wei, JIA Peng, et al.Experimental study of mechanical behaviours of grouting-screw pile interface[J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32(9):1744-1749.
[15]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):1076-1083.HU Qi, LING Dao-sheng, KONG Ling-gang, et al. Effects of deep excavation on uplift capacity of piles by centrifuge tests[J]. Chinese Journal of Geotechnical Engineering,2013, 35(6):1076-1083.
[16]钱建固,马霄,李伟伟,等.桩侧注浆抗拔桩离心模型试验与原位测试分析[J].岩土力学, 2014, 35(5):1241-1247.QIAN Jian-gu, MA Xiao, LI Wei-wei, et al. Centrifuge model test and in-situ observation on behabiors of side-grounting uplift pile[J]. Rock and Soil Mechanics,2014, 35(5):1241-1247.
[17]袁文忠,于志强,谢涛.岩基强度对嵌岩抗拔桩承载力影响的试验研究[J].西南交通大学学报, 2003, 38(2):178-182.YUAN Wen-zhong, YU Zhi-qiang, XIE Tao. Vertical bearing capacity of rock-socketed piles influenced by batholith strength[J]. Journal of Southwest Jiaotong University, 2003, 38(2):178-182.
[18]张尚根,陈志龙,尹峰,等.等截面抗拔桩的变形分析[J].解放军理工大学学报(自然科学版), 2002, 3(5):71-73.ZHANG Shang-gen, CHEN Zhi-long, YIN Feng, et al.Analysis of deformation of tension piles[J]. Journal of PLA University of Science and Technology(Natural Science Edition), 2002, 3(5):71-73.
[19]周杨,肖世国,徐骏,等.变截面螺纹桩竖向承载特性试验研究[J].岩土力学, 2017, 38(3):101-109.ZHOU Yang, XIAO Shi-guo, XU Jun, et al. Model test on vertical bearing capacity of tapered concrete screw piles[J]. Rock and Soil Mechanics, 2017, 38(3):101-109.
[20]中华人民共和国行业标准编写组. JGJ 94―2008建筑桩基技术规范[S].北京:中国建筑工业出版社, 2008.The Professional Standards Compilation Group of People’s Republic of China. JGJ 94―2008 Technical code for building pile foundation[S]. Beijing:China Architecture and Building Press, 2008.
[21]邹健,张忠苗,刘俊伟,等.一种考虑桩侧土应变软化的荷载传递函数[J].岩土工程学报, 2010, 32(7):1109-1113.ZOU Jian, ZHANG Zhong-miao, LIU Jun-wei, et al. A load transfer model considering strain softening of soils[J].Chinese Journal of Geotechnical Engineering, 2010,32(7):1109-1113.
[22]郦建俊,黄茂松,木林隆,等.分层地基中扩底抗拔桩的计算方法研究[J].岩土力学, 2008, 29(7):1997-2003.LI Jian-jun, HUANG Mao-song, MU Lin-long, et al.Research on computation methods of uplift capacity of enlarged base pile in layered soils[J]. Rock and Soil Mechanics, 2008, 29(7):1997-2003.
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