降水及等效堆载对桩侧摩阻力影响的对比研究
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摘要
解析降水及桩侧地面等效堆载作用下,桩周不同区域土体有效应力增量分布的异同,用规范提供的解析式和数值方法研究降水与等效堆载时单桩侧摩阻力特性的差异,结果表明规范给出的负摩阻力解析式属极限分析法,在桩土相对位移较小时结果偏大,依照解析法进行桩基设计偏于安全。数值法得到的侧摩阻力曲线呈明显的三段式,而解析法得到的侧摩阻力曲线存在突变,中性点处侧摩阻力不为0,与实际显然不符。
The differences and similarities of soil effective stress increment distribution in different regions around pile is analyzed theoretically, which is respectively under the action of dewatering and pile-side equivalent surcharge loading. Then through the analytical formulas provided by specification and numerical method, the skin friction characteristics separately subjected to dewatering and pile-side surcharge loading are comparatively studied. Since the negative skin friction analytical formula given by specification belongs to limit analysis essentially, when the pile-soil relative displacement is smaller, the calculation result will be too large, and the pile foundation design directly according to analytical method seems somewhat safe. The curve of skin friction by numerical method appears a three-stage form, but there exists a sudden change in the curve obtained through analytical method; moreover the side friction at neutral point is not zero, which is obviously not match with the actual.
The differences and similarities of soil effective stress increment distribution in different regions around pile is analyzed theoretically, which is respectively under the action of dewatering and pile-side equivalent surcharge loading. Then through the analytical formulas provided by specification and numerical method, the skin friction characteristics separately subjected to dewatering and pile-side surcharge loading are comparatively studied. Since the negative skin friction analytical formula given by specification belongs to limit analysis essentially, when the pile-soil relative displacement is smaller, the calculation result will be too large, and the pile foundation design directly according to analytical method seems somewhat safe. The curve of skin friction by numerical method appears a three-stage form, but there exists a sudden change in the curve obtained through analytical method; moreover the side friction at neutral point is not zero, which is obviously not match with the actual.
引文
[1]Proceedings 7th International Conference on Soil Mechanics and Foundation Engineering[C].Mexico City,1969.
[2]Proceedings of the Tenth International Conference on Soil Mechanics and Foundation Engineering,Stockholm[C].1981.
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[4]贾煜,宋福贵,王炳龙,等.基于改进荷载传递法计算降水引起的基桩沉降[J].岩土力学,2015,36(1):68-82.
[5]夏力农,苗云东,廖常斌.地基土沉降对复合地基影响的三维数值模拟[J].岩土力学,2012,33(4):1217-1222.
[6]高昂,宋二祥.地面堆载引起桩基负摩擦力的分布特性分析[J].建筑技术,2014,45(9):824-828.
[7]付贵海,魏丽敏,邓宗伟,等.桩顶荷载对负摩阻力性状影响的三维数值分析[J].地下空间与工程学报,2015,11(2):456-461.
[8]建筑桩基技术规范:JGJ 94-2008[S].
[9]张荫,刘国强,孙淮.基坑降水引起地面沉降分析[J].建筑技术,2017,48(3):239-242.
[10]吴汉斌.钻孔桩施工中泥皮的分析及措施[J].建筑技术,2014,45(S1):75-77.
[11]刘前进,邱峡,梁锋,等.后压浆超长桩试验桩侧负摩阻力机理分析[J].建筑技术,2009,40(9):840-842.
[2]Proceedings of the Tenth International Conference on Soil Mechanics and Foundation Engineering,Stockholm[C].1981.
[3]王小燕,何立军,王敏.降水沉降对竖向受荷单桩的影响[J].重庆交通大学学报(自然科学版),2011,30(S1):629-708.
[4]贾煜,宋福贵,王炳龙,等.基于改进荷载传递法计算降水引起的基桩沉降[J].岩土力学,2015,36(1):68-82.
[5]夏力农,苗云东,廖常斌.地基土沉降对复合地基影响的三维数值模拟[J].岩土力学,2012,33(4):1217-1222.
[6]高昂,宋二祥.地面堆载引起桩基负摩擦力的分布特性分析[J].建筑技术,2014,45(9):824-828.
[7]付贵海,魏丽敏,邓宗伟,等.桩顶荷载对负摩阻力性状影响的三维数值分析[J].地下空间与工程学报,2015,11(2):456-461.
[8]建筑桩基技术规范:JGJ 94-2008[S].
[9]张荫,刘国强,孙淮.基坑降水引起地面沉降分析[J].建筑技术,2017,48(3):239-242.
[10]吴汉斌.钻孔桩施工中泥皮的分析及措施[J].建筑技术,2014,45(S1):75-77.
[11]刘前进,邱峡,梁锋,等.后压浆超长桩试验桩侧负摩阻力机理分析[J].建筑技术,2009,40(9):840-842.