组合格构式型钢水泥土搅拌桩抗弯承载力计算方法
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摘要
传统型钢水泥土搅拌桩(SMW工法桩)具有施工便捷、造价经济等优势,但其侧向刚度主要由型钢独立承担,故存在着侧向刚度不足、水平变形较大等缺陷。本文针对传统SMW工法的缺陷,提出改由直线型钢板桩和窄翼H型钢组合而成的方形格构作为水泥土搅拌桩的加筋体,将搅拌桩中大部分水泥土置于方形格构内部,使得水泥土由传统工法中置于型钢外侧的单向拉弯受力状态变为型钢外包约束的三向受压状态,充分发挥了水泥土抗压强度远大于抗拉、抗剪强度的特性,从而大幅提高承载中水泥土的侧向刚度贡献。本文首先提出了组合格构式型钢水泥土搅拌桩的型钢布置形式与施工方法。其次,在讨论不同型钢布置形式的简化计算模型的基础上,提出新型工法桩的抗弯承载力和抗弯刚度的计算方法。最后通过算例分析与讨论,验证了新型工法桩相对于传统工法桩的抗弯刚度与抗弯承载力均得到了大幅提高。
The traditional SMW pile has many advantages including convenient construction,economical cost,but the lateral stiffness is mainly assumed by the steel. There are some defects,such as weak lateral stiffness and large horizontal deformation. To improve the above defects of traditional SMW pile,a kind of combined and latticed SMW pile was proposed to replace the rectangular lattice composed of linear steel sheet pile and narrow-wing H-beam as the reinforcement of cement-soil mixing pile. Most of the cement soil in the mixing pile was placed inside the square lattice to make the stress state of cement-soil change from unidirectional tension-bending to three-dimensional compression state confined by section steel envelope in traditional construction method. This gave full play to the characteristics that the compressive strength of cement-soil was far greater than the tensile and shear strength with greatly improving the lateral stiffness contribution of cement-soil in bearing capacity. The layout of section steels and the construction method about this new pile was put forward,and the calculating method for the flexural bearing capacity and bending stiffness were brought forward for considering the different layout of section steels. A case study demonstrated that the new method had a great improvement in the flexural capacity of the pilecomparing the traditional SMW method.
The traditional SMW pile has many advantages including convenient construction,economical cost,but the lateral stiffness is mainly assumed by the steel. There are some defects,such as weak lateral stiffness and large horizontal deformation. To improve the above defects of traditional SMW pile,a kind of combined and latticed SMW pile was proposed to replace the rectangular lattice composed of linear steel sheet pile and narrow-wing H-beam as the reinforcement of cement-soil mixing pile. Most of the cement soil in the mixing pile was placed inside the square lattice to make the stress state of cement-soil change from unidirectional tension-bending to three-dimensional compression state confined by section steel envelope in traditional construction method. This gave full play to the characteristics that the compressive strength of cement-soil was far greater than the tensile and shear strength with greatly improving the lateral stiffness contribution of cement-soil in bearing capacity. The layout of section steels and the construction method about this new pile was put forward,and the calculating method for the flexural bearing capacity and bending stiffness were brought forward for considering the different layout of section steels. A case study demonstrated that the new method had a great improvement in the flexural capacity of the pilecomparing the traditional SMW method.
引文
[1]谷淡平. SMW工法桩土共同作用模型试验研究及数值模拟分析[D].衡阳:南华大学,2010.
[2]刘霞. SMW工法的设计理论与计算方法[D].南京:南京工业大学,2004.
[3]杨平,曹宝飞,尹鹏,等.小刚度劲性水泥土墙基坑支护的机理及模型试验[J].南京林业大学学报(自然科学版),2007(3):19.
[4]陈卫林. SMW工法中型钢、水泥土组合体系的模拟与分析[D].天津:天津城市建设学院,2008.
[5]谢秀栋,方建瑞,李志高.基于遗传算法的SMW围护结构水泥土刚度系数计算[J].岩土工程学报,2006(增刊1):1422.
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[7]陈辉. SMW工法中型钢-水泥土共同作用的研究[J].建筑科学,2007(7):78.
[8]孔德志. SMW工法土挡墙的性能分析及在南京地铁工程中的应用[D].上海:同济大学,2001.
[9]郑刚,张华.型钢水泥土复合梁中型钢-水泥土相互作用试验研究[J].岩土力学,2007(5):939.
[10]姚民乐,徐东方,高金良.矩形钢管混凝土受弯构件承载力的研究[J].浙江建筑,2006(4):18.
[11]卢方伟,杨卫星,王迅.非等壁厚矩形钢管混凝土结构抗弯承载性能研究[J].工业建筑,2010(10):122.
[12]同济大学,浙江杭萧钢构股份有限公司,中国工程建设标准化协会.矩形钢管混凝土结构技术规程[M].北京:中国计划出版社,2004.
[13]薛政群,周旅健. U型钢板桩断面模量与锁口联结度关系的试验研究[J].水运工程,1992(10):7.
[14]刘震宇. U型钢板桩锁口抗弯刚度折减效应研究[J].中国水运,2016(3):304.
[15]王硕,杨彦军,岳祖润.锁口钢管桩抗弯刚度折减行为及其影响因素分析[J].中南大学学报(自然科学版),2013(4):1551.
[2]刘霞. SMW工法的设计理论与计算方法[D].南京:南京工业大学,2004.
[3]杨平,曹宝飞,尹鹏,等.小刚度劲性水泥土墙基坑支护的机理及模型试验[J].南京林业大学学报(自然科学版),2007(3):19.
[4]陈卫林. SMW工法中型钢、水泥土组合体系的模拟与分析[D].天津:天津城市建设学院,2008.
[5]谢秀栋,方建瑞,李志高.基于遗传算法的SMW围护结构水泥土刚度系数计算[J].岩土工程学报,2006(增刊1):1422.
[6]王健. H型钢-水泥土组合结构试验研究及SMW工法的设计理论与计算方法[D].上海:同济大学,1998.
[7]陈辉. SMW工法中型钢-水泥土共同作用的研究[J].建筑科学,2007(7):78.
[8]孔德志. SMW工法土挡墙的性能分析及在南京地铁工程中的应用[D].上海:同济大学,2001.
[9]郑刚,张华.型钢水泥土复合梁中型钢-水泥土相互作用试验研究[J].岩土力学,2007(5):939.
[10]姚民乐,徐东方,高金良.矩形钢管混凝土受弯构件承载力的研究[J].浙江建筑,2006(4):18.
[11]卢方伟,杨卫星,王迅.非等壁厚矩形钢管混凝土结构抗弯承载性能研究[J].工业建筑,2010(10):122.
[12]同济大学,浙江杭萧钢构股份有限公司,中国工程建设标准化协会.矩形钢管混凝土结构技术规程[M].北京:中国计划出版社,2004.
[13]薛政群,周旅健. U型钢板桩断面模量与锁口联结度关系的试验研究[J].水运工程,1992(10):7.
[14]刘震宇. U型钢板桩锁口抗弯刚度折减效应研究[J].中国水运,2016(3):304.
[15]王硕,杨彦军,岳祖润.锁口钢管桩抗弯刚度折减行为及其影响因素分析[J].中南大学学报(自然科学版),2013(4):1551.