上海地区静钻根植桩承载特性现场试验研究
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摘要
静钻根植桩是一种绿色环保的新型桩基,具有低噪声、无挤土、少排泥等优势,可应用于高层建筑、桥梁等工程中。基于现场抗压和抗拔静载试验及桩身内力测试,分析了上海地区静钻根植桩的竖向承载变形特性以及桩身轴力和侧摩阻力分布。研究结果表明:静钻根植桩在上海典型地层条件下具有较好的适用性,抗压试桩和抗拔试桩的承载力均大于规范估算值,采用目前的承载力计算方法有一定的安全储备;抗压试桩在加载初期,桩身轴力可以直接传递到桩端,在极限荷载下桩端(扩大头)承载力约占总荷载的25%;静钻根植桩极限侧摩阻力主要与土的特性和埋深有关,上部土层(埋深30 m以上)接近规范建议的预制桩侧摩阻力上限值,下部土层(埋深30 m以下)较规范建议的预制桩侧阻上限高约14%～28%。
The pre-bored precast pile with enlarged base(PPEB pile) is an innovative type of environmentally friendly pile foundation. It has the advantages of low noise, no squeezing of the soil, less mud discharge and so on. It is used in high-rise buildings, bridges and other engineering fields. Based on the compression tests, uplift static load tests and pile internal force tests, the vertical load-deformation characteristics, distributions of axial force and shaft resistance of PPEB piles in Shanghai area were analysed. The test results show that the PPEB pile has good applicability in typical stratum of Shanghai. The bearing capacities of the piles from the compression tests and the uplift tests are both higher than the estimated values based on the technical code, so the calculation methods of bearing capacities of PPEB piles in the current design code provide sufficient safety reserve. The axial force in the piles can be directly transmitted to the pile toe at the initial stage of compression tests, and the toe resistance is about 25% of the total load(under the ultimate conditions). The ultimate shaft resistance of PPEB piles is mainly affected by the soil properties and burying depth. The ultimate shaft resistance in the upper soil layers(buried depth is above 30 m) is close to the upper limit value of shaft resistance of precast piles, while the shaft resistance in the lower soil layers(buried depth is below 30 m) is about 14%-28% higher than the upper limit of precast piles recommended in the technical code.
The pre-bored precast pile with enlarged base(PPEB pile) is an innovative type of environmentally friendly pile foundation. It has the advantages of low noise, no squeezing of the soil, less mud discharge and so on. It is used in high-rise buildings, bridges and other engineering fields. Based on the compression tests, uplift static load tests and pile internal force tests, the vertical load-deformation characteristics, distributions of axial force and shaft resistance of PPEB piles in Shanghai area were analysed. The test results show that the PPEB pile has good applicability in typical stratum of Shanghai. The bearing capacities of the piles from the compression tests and the uplift tests are both higher than the estimated values based on the technical code, so the calculation methods of bearing capacities of PPEB piles in the current design code provide sufficient safety reserve. The axial force in the piles can be directly transmitted to the pile toe at the initial stage of compression tests, and the toe resistance is about 25% of the total load(under the ultimate conditions). The ultimate shaft resistance of PPEB piles is mainly affected by the soil properties and burying depth. The ultimate shaft resistance in the upper soil layers(buried depth is above 30 m) is close to the upper limit value of shaft resistance of precast piles, while the shaft resistance in the lower soil layers(buried depth is below 30 m) is about 14%-28% higher than the upper limit of precast piles recommended in the technical code.
引文
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[5] 周佳锦, 龚晓南, 王奎华, 等. 静钻根植竹节桩荷载传递机理模型试验[J]. 浙江大学学报(工学版), 2015,49(3):531-537. (ZHOU Jiajin, GONG Xiaonan, WANG Kuihua, et al. Model test on load transfer mechanism of a static drill rooted nodular pile[J]. Journal of Zhejiang University (Engineering Science), 2015, 49(3): 531-537. (in Chinese))
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[8] 徐礼阁, 王奎华, 张鹏, 等. 层状地基中考虑桩侧水泥土与土的静钻根植桩单桩沉降计算[J]. 中南大学学报(自然科学版), 2016,47(3):868-874. (XU Lige, WANG Kuihua, ZHANG Peng, et al. Calculation method for settlement of single static drill rooted pile considering cemented soil and soil around pile in layered soil[J]. Journal of Central South University (Science and Technology), 2016, 47(3): 868-874. (in Chinese))
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[11] ZHOU J J, GONG X N, WANG K H, et al. A field study on the behavior of static drill rooted nodular piles with caps under compression[J]. Journal of Zhejiang University (Science A), 2015,16(12):951-963.
[12] 静钻根植桩基础技术规程:DB33/T 1134—2017[S]. 北京:中国计划出版社, 2017. (Technical specification for pre-bored precast concrete pile foundation: DB33/T 1134—2017[S]. Beijing: China Planning Press, 2017. (in Chinese))
[13] 王卫东, 李永辉, 吴江斌. 上海中心大厦大直径超长灌注桩现场试验研究[J]. 岩土工程学报, 2011, 33(12): 1817-1826. (WANG Weidong, LI Yonghui, WU Jiangbin. Field loading tests on large-diameter and super-long bored piles of Shanghai Center Tower[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(12): 1817-1826. (in Chinese))
[14] 王卫东, 吴江斌, 聂书博. 武汉中心大厦超长软岩嵌岩桩承载特性试验研究[J]. 建筑结构学报, 2016, 37(6): 196-203. (WANG Weidong, WU Jiangbin, NIE Shubo. Field loading tests on large-diameter super-long rock-socketed bored piles of the Wuhan Center Tower[J]. Journal of Building Structures, 2016, 37(6): 196-203. (in Chinese))
[15] 胡庆红, 谢新宇. 深长大直径扩底灌注桩承载性能试验研究[J]. 建筑结构学报, 2009, 30(4): 151-157. (HU Qinghong, XIE Xinyu. Experimental study on bearing capacity behavior of deep large diameter cast-in-place belled pile[J]. Journal of Building Structures, 2009, 30(4): 151-157. (in Chinese))
[16] 地基基础设计规范: DGJ 08-11—2010[S]. 上海: 上海市建筑建材业市场管理总站, 2010. (Foundation design code of Shanghai: DGJ 08-11—2010[S]. Shanghai: Shanghai Construction and Building Materials Industry Market Management Station, 2010. (in Chinese))
[2] 张日红,吴磊磊,孔清华. 静钻根植桩基础研究与实践[J]. 岩土工程学报, 2013, 35(增刊2): 1200-1203. (ZHANG Rihong, WU Leilei, KONG Qinghua. Research and practice of JZGZ pile foundation[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(Suppl.2): 1200-1203. (in Chinese))
[3] KOBAYASHI K, OGURA H. Vertical bearing capacity of bored pre-cast pile with enlarged base considering diameter of the enlarged excavation around pile toe[C]// Advances in Deep Foundations: International Workshop on Recent Advances of Deep Foundations. Yokosuka, Japan:Taylor & Francis, 2007: 277-283.
[4] KUSAKABE O, KAKURAI M, UENO K, et al. Structural capacity of precast piles with grouted base[J]. Journal of Geotechnical Engineering, 1994,120(8):1289-1306.
[5] 周佳锦, 龚晓南, 王奎华, 等. 静钻根植竹节桩荷载传递机理模型试验[J]. 浙江大学学报(工学版), 2015,49(3):531-537. (ZHOU Jiajin, GONG Xiaonan, WANG Kuihua, et al. Model test on load transfer mechanism of a static drill rooted nodular pile[J]. Journal of Zhejiang University (Engineering Science), 2015, 49(3): 531-537. (in Chinese))
[6] ZHOU J J, GONG X N, WANG K H, et al. Testing and modeling the behavior of pre-bored grouting planted piles under compression and tension[J]. Acta Geotechnica, 2017,12(5): 1061-1075.
[7] 钱铮, 王奎华. 静钻根植桩水平承载性能试验研究[J]. 岩土力学, 2015, 36(增刊2): 588-594. (QIAN Zheng, WANG Kuihua. Experimental study of lateral capacity of static drill rooted pile[J]. Rock and Soil Mechanics, 2015, 36(Suppl.2): 588-594. (in Chinese))
[8] 徐礼阁, 王奎华, 张鹏, 等. 层状地基中考虑桩侧水泥土与土的静钻根植桩单桩沉降计算[J]. 中南大学学报(自然科学版), 2016,47(3):868-874. (XU Lige, WANG Kuihua, ZHANG Peng, et al. Calculation method for settlement of single static drill rooted pile considering cemented soil and soil around pile in layered soil[J]. Journal of Central South University (Science and Technology), 2016, 47(3): 868-874. (in Chinese))
[9] 建筑基桩检测技术规范: JGJ 106—2014[S]. 北京: 中国建筑工业出版社, 2014. (Technical code for testing of building foundation piles:JGJ 106—2014[S]. Beijing: China Architecture & Building Press, 2014. (in Chinese))
[10] LAM C, JEFFERIS S A. Critical assessment of pile modulus determination methods[J]. Canadian Geotechnical Journal, 2011, 48(10): 1433-1448.
[11] ZHOU J J, GONG X N, WANG K H, et al. A field study on the behavior of static drill rooted nodular piles with caps under compression[J]. Journal of Zhejiang University (Science A), 2015,16(12):951-963.
[12] 静钻根植桩基础技术规程:DB33/T 1134—2017[S]. 北京:中国计划出版社, 2017. (Technical specification for pre-bored precast concrete pile foundation: DB33/T 1134—2017[S]. Beijing: China Planning Press, 2017. (in Chinese))
[13] 王卫东, 李永辉, 吴江斌. 上海中心大厦大直径超长灌注桩现场试验研究[J]. 岩土工程学报, 2011, 33(12): 1817-1826. (WANG Weidong, LI Yonghui, WU Jiangbin. Field loading tests on large-diameter and super-long bored piles of Shanghai Center Tower[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(12): 1817-1826. (in Chinese))
[14] 王卫东, 吴江斌, 聂书博. 武汉中心大厦超长软岩嵌岩桩承载特性试验研究[J]. 建筑结构学报, 2016, 37(6): 196-203. (WANG Weidong, WU Jiangbin, NIE Shubo. Field loading tests on large-diameter super-long rock-socketed bored piles of the Wuhan Center Tower[J]. Journal of Building Structures, 2016, 37(6): 196-203. (in Chinese))
[15] 胡庆红, 谢新宇. 深长大直径扩底灌注桩承载性能试验研究[J]. 建筑结构学报, 2009, 30(4): 151-157. (HU Qinghong, XIE Xinyu. Experimental study on bearing capacity behavior of deep large diameter cast-in-place belled pile[J]. Journal of Building Structures, 2009, 30(4): 151-157. (in Chinese))
[16] 地基基础设计规范: DGJ 08-11—2010[S]. 上海: 上海市建筑建材业市场管理总站, 2010. (Foundation design code of Shanghai: DGJ 08-11—2010[S]. Shanghai: Shanghai Construction and Building Materials Industry Market Management Station, 2010. (in Chinese))
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