作者：张茂刚^1,2, 畑中重光³, 吴东岳⁴

作者单位：1. 无锡环境科学与工程研究中心，江苏 无锡 214153;
2. 无锡城市职业技术学院建筑与环境工程学院，江苏 无锡 214153;
3. 三重大学工学研究科，日本 三重县 514-8570;
4. 江苏科技大学土木工程与建筑学院，江苏 镇江 212005

关键词：侧阻力;钢管桩;软弱岩层;端阻力;波动方程

摘要：

巴拿马邮轮码头项目主码头采用打入钢管桩基础。对于软弱岩层中的打入桩，目前尚无公认的设计方法。该文开展7组桩基动力测试，采用波动方程分析方法获取桩侧阻力与端阻力，研究地层中桩侧阻力分布规律，岩层中桩端阻力系数与岩石质量特性的关系，得出如下结论：侧阻力分布曲线均呈抛物线形式，据此可以明显区分出软粘土、粉质砂土和粉砂岩3个地层，提出确定钢管桩嵌岩深度的判定方法，判定7个试验桩均满足设计最小嵌岩深度5 m的要求；对于软岩中打入钢管桩，单轴抗压强度无法反映桩端岩体的受力状态，需要采用嵌岩深径比与岩体破碎程度进行修正；考虑深径比的影响，计算得到端阻力系数N_k在4.3~6.5之间，均大于国内规范桩端阻力系数；提出采用岩芯回收率Re及岩石质量指标RQD反映岩体破碎程度对桩端阻力影响的研究方法，验证该方法的合理性。

Research on PDA testing and end resistance coefficient of steel pipe pile in weak rock
ZHANG Maogang^1,2, HATANAKA Shigemitsu³, WU Dongyue⁴
1. Wuxi Research Center for Environmental Science and Engineering, Wuxi 214153, China;
2. College of Architectural and Environmental Engineering, Wuxi City College of Vocational Technology, Wuxi 214153, China;
3. Graduate School of Engineering, Mie University, Mie Prefecture 514-8570, Japan;
4. School of Civil Engineering and Architecture, Jiangsu University of Science and Technology, Zhenjiang 212005, China
Abstract: The main terminal of Panama cruise terminal project is rock socketed steel pipe pile foundation. At present, there is no accepted design method for driven pile in soft rock. Seven groups of dynamic tests of pile foundation are carried out, and wave equation analysis method is used to obtain the pile side resistance and end resistance. The distribution law of pile side resistance in the stratum and the relationship between resistance coefficient of pile tip and rock quality characteristics in the stratum are studied. The conclusions are as follows: the distribution curve of side resistance is in parabola form, which can be clearly distinguish soft clay, silty sand and siltstone. It is proposed to determine the steel pipe pile embedment. According to the determination method of rock depth, it is determined that all the seven test piles meet the requirements of the minimum rock socketed depth of 5 m. For the steel pipe pile driven in soft rock, the uniaxial compressive strength can’t reflect the stress state of the rock mass at the end of the pile, which needs to be corrected by the rock socketed depth to diameter ratio and the degree of rock fragmentation. Considering the influence of the depth diameter ratio, the end resistance coefficient, N_k, is calculated to be between 4.3-6.5, which is greater than the end resistance coefficient of the domestic standard pile. The research method of core recovery Re and rock quality index RQD reflecting the influence of rock fragmentation degree on pile end resistance is put forward, which verifies the rationality of the method.
Keywords: side resistance;steel pipe pile;weak rock;end resistance;wave equation
2021, 47(8):1-5,30  收稿日期: 2020-10-12;收到修改稿日期: 2020-11-24
基金项目: 国家青年自然科学基金（51708260）；无锡城市职业技术学院科研创新团队项目（KYCXTD201801）
作者简介: 张茂刚(1973-),男,江苏句容市人,副教授,博士,研究方向为建筑工程
参考文献
[1] IRVINE J, TERENTE V, LEE L T, et al. Driven pile design in weak rock[C]//Proc. Int. Symp. on Frontiers in Offshore Geotechnics III. 2015: 569-574.
[2] 徐熙明. 沿海复杂地质区嵌岩桩施工工艺[J]. 水运工程, 2017, 37(25): 53-56
[3] 曾华彬, 桑登峰, 苏世定, 等. 风化岩层中开口钢管桩沉桩性状[J]. 水运工程, 2019, 39(4): 193-199
[4] 黄卫明, 方州恩. 大榭45万t原油码头锚岩桩施工技术[J]. 水运工程, 2012, 32(9): 186-189
[5] 时闽生, 孙言茂, 黎双邵, 等. 海上风电大型钢管嵌岩桩基础施工和试验研究[J]. 中国港湾建设, 2016, 17(1): 32-36
[6] 黄炳南. 海上风电基础大直径嵌岩桩施工技术[J]. 中国港湾建设, 2015, 16(8): 57-60
[7] 陈旭, 黄质宏, 陈旺, 等. 加载过程中嵌岩桩承载特性数值模拟分析[J]. 中国水运, 2019, 39(12): 113-116
[8] NISHIDA Y, SEKIGUCHI H, MATSUMOTO T. Drivability of steel pipe piles into diatomaceous mudstone in the construction of Notojima bridge[C]//Proc. Int. Symp. Penetrability and Drivability of Piles, 1985.
[9] HOEK E, MARINOS V. The geological strength index: applications and limitations[J]. Bull Eng Geol Environ, 2005(64): 55-65
[10] 公路桥涵地基与基础设计规范: JTG 3363—2019[S]. 北京: 人民交通出版社, 2007.
[11] 建筑桩基技术规范: JGJ 94—2008[S]. 北京: 人民交通出版社, 2008.
[12] REHNMAN S E, BROMS B B. Bearing capacity of piles driven in rock[J]. Canadian Geotechnical Journal, 1971, 8(2): 151-162
[13] WILLIAMS A F, JOHNSTON I W, DONALD I B. The design of socketed piles in weak rock[C]//Proc. Int. Conf. on Structural Foundations on Rock, 1980.
[14] FLEMING W G K, WELTMAN A J, RANDOLPH M F, et al. Piling engineering[M]. US: CRC Press, 1992.
[15] RODWAY R L, ROWE R K. The uplift capacity of steel piles driven into hawkesbury sandstone[C]//Proceedings of 3rd Australian and New Zealand Conference on Geomechanics, 1980.
[16] CFEM. Canadian foundation engineering manual[M]. 4th Edition. Canadian Geotechnical Society, Altona, MB, 2006.
[17] DEERE D U, DEERE D W. The rock quality designation (RQD) index in practice: ASTM STP 984[S].Rock Classification Systems for Engineering Purposes, Louis Ed., American Society for Testing and Materials, 1988(7): 91-101.
[18] PRIEST S D, HUDSON J A. Discontinuity spacing in rock[J]. International Journal of Rock Mechanics and Mining Sciences, 1976, 13(5): 135-148