大型储罐下碎石桩复合地基工作性状研究
摘要
近年来,随着我国石油化工工业的快速发展,大型储罐的使用逐渐增多。新建储罐工程越来越多的遇到不良地基,对地基处理的要求也越来越广泛。如何在保证工程质量的情况下节省工程投资成为摆在众多岩土工作者面前的一个问题。复合地基因其能利用桩体和土体共同承载、造价低廉,在工程界得到广泛应用。本文以碎石桩复合地基为研究对象,对其承载特性及变形特性进行了较为深入的探讨。
论文首先回顾了目前柔性基础下复合地基和碎石桩复合地基已有的研究成果。对储罐常用的基础、储罐下地基的变形规律和控制标准以及常用的地基处理方式做了简单的阐述。
提出应用多目标模糊数学优选理论来评价和选择地基处理方案,给出了该方法的原理、模型及应用步骤,并结合工程实例进行验证。
通过实际工程进行的碎石桩单桩复合地基静载试验,桩体重型动力触探,标准贯入试验等,从处理前后地基的承载力、土层的物理力学性质指标等方面对碎石桩的处理效果进行了综合评价。
利用Flac-3D软件对大型储罐下的碎石桩复合地基进行了模拟。分析了桩体、土体、垫层的参数变化对复合地基的影响,并结合工程实例,进一步分析了柔性基础下碎石桩复合地基的工作性状。论文所得主要结论如下:
(1)在储罐这样的柔性基础下,垫层模量在80～200MPa比较合适,大于一般复合地基所选用的垫层模量;厚度宜在400～600mm。
(2)当桩长增长到一定程度,复合地基的应力场和位移场的分布逐渐稳定,所以不仅对承载力存在临界桩长问题,对于复合地基的变形来说在一定条件下也存在临界桩长。碎石桩复合地基中桩的作用主要是减小沉降。
(3)为了充分发挥桩、土的承载能力,在设计碎石桩桩径时,应选取一个合适的置换率。一味的增加置换率来加大加固层的刚度以达到减小沉降的方法是不可取的,设计中应根据工程地质条件和建筑的上部荷载大小选取最优置换率。
(4)当桩周土的变形模量大于8MPa后,采用碎石桩加固效果不明显。
With the development of petroleum industry, oil tanks are used more than before. At the same time, many bad groundwork are met during the course of construction. So many of them must be treated with. How can we solve the problem with the lowest price? It is the problem that we must face with. As a kind of way of solving the problem of bad groundwork, composite foundation has two merits. The first one is that it can make piles and soil work together, and the second is that it cost low. The subject it studied is gravel pile composite foundation, the bearing characteristics and deformation performation was studied.
At the beginning of the thesis, some conclusions on composite foundation under flexible base and gravel pile composite foundation are provided. There are also a short introduction on the foundation of tanks, such as kinds of foundation used under tanks, The deformation tracks of foundation and many ways of treating with bad groundwork.
Put forward application of Multi-Objective Fuzzy Optimum Theory to evaluate and choose the foundation treatment scheme. Raise the principle, model and its application procedure and test and verify it with engineering case.
Evaluate the effect of gravel pile treatment from bearing capacity and physical and mechanic index in pre-& post-processing through static load test of single pile, dynamic penetration test and the standard penetration test.
And then the gravel pile composite foundation are simulated using a software Flac-3D. From the results of simulation, combined with an engineering example, we get to know some rules about the composite foundation. Here are some results :
(1) The modulus of cushion under tank’s base is about 80～200 MPa, It is larger than that of under other kind of base. The thickness of cushion is about 400～600mm.
(2) There is a length for pile, the stress and displacement is stable gradually. So there is a length for bearing ability, and a length for displacement for foundation. The major role for gravel pile is to decrease settlement.
(3) A suitable replacement ratio should be choosed when design the diameter of pile for giving full play to pile and soil’s bearing ability. It is not advisable to increase the modulus of strengthen place to decrease the settlement by increase the replacement ratio all along. The best replacement ratio should be choosed according to geological condition of engineering and load of building when design it.
(4) The strengthen effect is not remarkable by using gravel pile when the modulus of soil around pile more then 8 MPa.
论文首先回顾了目前柔性基础下复合地基和碎石桩复合地基已有的研究成果。对储罐常用的基础、储罐下地基的变形规律和控制标准以及常用的地基处理方式做了简单的阐述。
提出应用多目标模糊数学优选理论来评价和选择地基处理方案,给出了该方法的原理、模型及应用步骤,并结合工程实例进行验证。
通过实际工程进行的碎石桩单桩复合地基静载试验,桩体重型动力触探,标准贯入试验等,从处理前后地基的承载力、土层的物理力学性质指标等方面对碎石桩的处理效果进行了综合评价。
利用Flac-3D软件对大型储罐下的碎石桩复合地基进行了模拟。分析了桩体、土体、垫层的参数变化对复合地基的影响,并结合工程实例,进一步分析了柔性基础下碎石桩复合地基的工作性状。论文所得主要结论如下:
(1)在储罐这样的柔性基础下,垫层模量在80～200MPa比较合适,大于一般复合地基所选用的垫层模量;厚度宜在400～600mm。
(2)当桩长增长到一定程度,复合地基的应力场和位移场的分布逐渐稳定,所以不仅对承载力存在临界桩长问题,对于复合地基的变形来说在一定条件下也存在临界桩长。碎石桩复合地基中桩的作用主要是减小沉降。
(3)为了充分发挥桩、土的承载能力,在设计碎石桩桩径时,应选取一个合适的置换率。一味的增加置换率来加大加固层的刚度以达到减小沉降的方法是不可取的,设计中应根据工程地质条件和建筑的上部荷载大小选取最优置换率。
(4)当桩周土的变形模量大于8MPa后,采用碎石桩加固效果不明显。
With the development of petroleum industry, oil tanks are used more than before. At the same time, many bad groundwork are met during the course of construction. So many of them must be treated with. How can we solve the problem with the lowest price? It is the problem that we must face with. As a kind of way of solving the problem of bad groundwork, composite foundation has two merits. The first one is that it can make piles and soil work together, and the second is that it cost low. The subject it studied is gravel pile composite foundation, the bearing characteristics and deformation performation was studied.
At the beginning of the thesis, some conclusions on composite foundation under flexible base and gravel pile composite foundation are provided. There are also a short introduction on the foundation of tanks, such as kinds of foundation used under tanks, The deformation tracks of foundation and many ways of treating with bad groundwork.
Put forward application of Multi-Objective Fuzzy Optimum Theory to evaluate and choose the foundation treatment scheme. Raise the principle, model and its application procedure and test and verify it with engineering case.
Evaluate the effect of gravel pile treatment from bearing capacity and physical and mechanic index in pre-& post-processing through static load test of single pile, dynamic penetration test and the standard penetration test.
And then the gravel pile composite foundation are simulated using a software Flac-3D. From the results of simulation, combined with an engineering example, we get to know some rules about the composite foundation. Here are some results :
(1) The modulus of cushion under tank’s base is about 80～200 MPa, It is larger than that of under other kind of base. The thickness of cushion is about 400～600mm.
(2) There is a length for pile, the stress and displacement is stable gradually. So there is a length for bearing ability, and a length for displacement for foundation. The major role for gravel pile is to decrease settlement.
(3) A suitable replacement ratio should be choosed when design the diameter of pile for giving full play to pile and soil’s bearing ability. It is not advisable to increase the modulus of strengthen place to decrease the settlement by increase the replacement ratio all along. The best replacement ratio should be choosed according to geological condition of engineering and load of building when design it.
(4) The strengthen effect is not remarkable by using gravel pile when the modulus of soil around pile more then 8 MPa.
引文
[1]翟振远.大型储罐地基基础设计方法研究[D].大庆石油学院,2007.
[2]杨晓刚.挤密砂石桩性状及大型油罐地基现场试验研究[D].浙江大学,2005.3:1.
[3]龚哓南.复合地基设计和施工指南[M].人民交通出版社,2003.9.
[4]白晓红,崔广仁.CFG桩与夯实水泥土桩复合地基承载力计算[J].河南科技大学学报,2003, 24(2):90-93.
[5]刘杰,赵明华.基于双剪统一强度理论的碎石单桩复合地基性状研究[J].岩土工程学报2005,27(6):707-711.
[6]赵明,赵明华,陈昌富.确定碎石桩复合地基桩土应力比的一种新方法[J].湖南大学学报(自然科学版),2002,29(2):112-116.
[7]赵平,赵明华,赵明,等.确定碎石桩复合地基桩土应力比的新方法[J].公路工程学报, 2003(3):38-41.
[8]贺会团.碎石桩复合地基承载力瞬态面波测试技术研究[D].河北工业大学硕士学位论文,2004.
[9]姚琪阳.碎石桩复合地基承载机理及优化设计研究[D].湖南大学硕士学位论文,2004.
[10]张定.碎石桩复合地基的作用机理分析及沉降计算[J].岩土力学,1999,20(2):81-86.
[11]刘杰,张可能.影响桩基承载力及沉降因素的灰关联分析[J].株洲工学院学报, 2002,16(6):95-96.
[12]邓修甫,王祥秋.干振碎石桩复合地基沉降计算方法探讨[J].水文地质工程地质, 2003(3):92-94.
[13]邢皓枫,龚晓南,杨晓军.碎石桩复合地基固结简化分析[J].岩土工程学报,2005, 27(5):521-524.
[14]孙微微.路堤荷载下碎石桩复合地基沉降计算方法研究[D].南京林业大学博士学位论文,2005.
[15]王保田,王盛源.碎石桩复合地基现场大型直剪试验设计[J].大坝观侧与土工测试, 1995,19(2):31-35.
[16]周建安.碎石桩模型三轴试验及其成果应用分析[J].地质灾害与环境保护,1997, 8(2):39-44.
[17]赵明.碎石桩复合地基理论分析与试验研究[D].湖南大学硕士学位论文,2002.
[18]刘义怀,朱志铎,刘松玉.碎石桩材料变形特征的试验研究[J].公路交通科技, 2003(5): 31-33.
[19]赵明华,姚琪阳,陈昌富.碎石桩复合地基模型试验[J].公路,2003(10):33-36.
[20] Juran, I,Riccobono,0.Reinforced soft soil with artificially cemented compacted-sandcolumns[J].Jounal of feotechnical Engineering.1991,117(7):1042-1060.
[21]朱志铎,姜竹生,刘松玉.徐宿高速公路挤密碎石桩处理液化地基试验研究[J].公路交通科技,2004(7):45-47.
[22]周建安,场淑碧.碎石桩复合地基承力性状有限元分析[J].地质灾害与环境保护, 1996,7(1):104-107.
[23]丁继辉,张庆宏,李宗惠等.大型油罐碎石桩复合地基沉降量的数值计算与分析[J].勘察科学技术,1999(6):32-35.
[24]何开明,王兰民,曾国熙.饱和黄土地基的液化数值分析[J].工业建筑,2001,1(7):29-31.
[25]刘义怀,朱志铎,刘松玉.路堤荷载下碎石桩复合地基的有限元分析[J].公路交通科技,2002,19(5):11-13.
[26]马学宁,杨有海,刘永红等.碎石桩复合地基有限元分析[J].兰州铁道学院学报(自然科学版),2002,21(1):60-63.
[27]田松花.碎石桩复合地基数值模拟分析[J].山西建筑,2003,29(11):34-35.
[28]吴军民.砂土-碎石桩复合地基抗液化分析数值模拟[J].建筑技术开发2004, 1(9):81- 84.
[29]张忠苗,陈洪,吴慧明,柔性承台下复合地基应力和沉降计算研究[J],岩土力学,2004, 25(3) : 451-454.
[30]王欣,俞亚南,高文明.路堤柔性荷载下的粉喷桩复合地基内的附加应力分析[J],中国市政工程,2003.3:1-2.
[31]尹尧国,全志利,周常青.软土地区桩体复合地基沉降变形与稳定性分析[J],天津城市建设学院学报,2001.7:252-258.
[32]吴慧明.不同刚度基础下复合地基性状研究.[D]杭州:浙江大学,2000.
[33]曾开华,俞建霖,龚晓南.路堤荷载下低强度混凝土桩复合地基性状分析[J],浙江大学学报,2004.2:185-190.
[34]方磊,谢永利.柔性基础下复合地基模型试验研究[J],土木工程学报,2005.5:67-71.
[35]龚晓南,褚航.基础刚度对复合地基性状的影响,工程力学,2003(04).
[36]徐超,叶观宝.水泥土搅拌桩复合地基的变形特性与承载力[J],岩土工程学报2005. 5:600-603.
[37]窦明远,戴为民,刘晓立,刘熙媛.柔性荷载作用下水泥土桩复合地基的承载力与沉降特性的研究[J],河北工业大学学报,2001.2:80-83.
[38]冯瑞玲,谢永利,方磊.柔性基础下复合地基的数值分析[J],中国公路学报,2003.1:40- 42.
[39]朱云升,胡幼常,丘作中,舒鄂南.柔性基础复合地基力学性状的有限元分析[J],岩土力学,2003.3:395-400.
[40]徐至钧,许朝铨,沈珠江.大型储罐基础设计与地基处理[M].北京:中国石化出版社, 1999.
[41]张继文.大型储罐软土地基处理的几个问题的探讨(待续)[J],石油建设2002.10:6-10.
[42]张继文.大型储罐软土地基处理的几个问题的探讨(续)[J],石油建设2002.12:12-15.
[43]贾庆山,大型储罐软土地基变形控制标准的研究[J],石油工程建设1996.4:17-20.
[44]龚晓南.复合地基设计和施工指南[M]北京:人民交通出版社,2003.
[45]丘长青.公路边坡土钉支护变形分析与研究[D],长沙理工大学.2004.
[46]彭文斌.FLAC 3D实用教程[M],机械工业出版社.2008.
[47]陈守煌,系统模糊决策理论与应用[M].大连:大连理工出版社,1994.
[48]左名麒,朱树森.强夯法地基加固.北京:中国铁道出版社,1990.
[49]王燕,李夕兵,蒋卫东.多目标系统模糊模型在强夯参数优选中的应用.岩土力学,2003, 24 (3):410-411.
[52]阎明礼,张东刚.CFG桩复合地基技术及工程实践[M].中国水利水电出版社,2001.
[53]吴慧明,龚晓南.刚性基础与柔性基础下复合地基模型试验对比研究[J].土木工程学报,2001,34(5):81-83.
[54]中国建筑科学研究院. JGJ79-2002建筑地基处理技术规范.
[55]段继伟,龚晓南,曾国熙.复合地基桩土应力比影响因素有限元分析[[J].第二届华东地区岩土力学学术讨论会论文集.杭州:浙江大学出版社.1992.43-47.
[56]刘杰,张可能.碎石桩复合地基若干问题的理论分析[J],铁道工程学报2003.6:28-32.
[2]杨晓刚.挤密砂石桩性状及大型油罐地基现场试验研究[D].浙江大学,2005.3:1.
[3]龚哓南.复合地基设计和施工指南[M].人民交通出版社,2003.9.
[4]白晓红,崔广仁.CFG桩与夯实水泥土桩复合地基承载力计算[J].河南科技大学学报,2003, 24(2):90-93.
[5]刘杰,赵明华.基于双剪统一强度理论的碎石单桩复合地基性状研究[J].岩土工程学报2005,27(6):707-711.
[6]赵明,赵明华,陈昌富.确定碎石桩复合地基桩土应力比的一种新方法[J].湖南大学学报(自然科学版),2002,29(2):112-116.
[7]赵平,赵明华,赵明,等.确定碎石桩复合地基桩土应力比的新方法[J].公路工程学报, 2003(3):38-41.
[8]贺会团.碎石桩复合地基承载力瞬态面波测试技术研究[D].河北工业大学硕士学位论文,2004.
[9]姚琪阳.碎石桩复合地基承载机理及优化设计研究[D].湖南大学硕士学位论文,2004.
[10]张定.碎石桩复合地基的作用机理分析及沉降计算[J].岩土力学,1999,20(2):81-86.
[11]刘杰,张可能.影响桩基承载力及沉降因素的灰关联分析[J].株洲工学院学报, 2002,16(6):95-96.
[12]邓修甫,王祥秋.干振碎石桩复合地基沉降计算方法探讨[J].水文地质工程地质, 2003(3):92-94.
[13]邢皓枫,龚晓南,杨晓军.碎石桩复合地基固结简化分析[J].岩土工程学报,2005, 27(5):521-524.
[14]孙微微.路堤荷载下碎石桩复合地基沉降计算方法研究[D].南京林业大学博士学位论文,2005.
[15]王保田,王盛源.碎石桩复合地基现场大型直剪试验设计[J].大坝观侧与土工测试, 1995,19(2):31-35.
[16]周建安.碎石桩模型三轴试验及其成果应用分析[J].地质灾害与环境保护,1997, 8(2):39-44.
[17]赵明.碎石桩复合地基理论分析与试验研究[D].湖南大学硕士学位论文,2002.
[18]刘义怀,朱志铎,刘松玉.碎石桩材料变形特征的试验研究[J].公路交通科技, 2003(5): 31-33.
[19]赵明华,姚琪阳,陈昌富.碎石桩复合地基模型试验[J].公路,2003(10):33-36.
[20] Juran, I,Riccobono,0.Reinforced soft soil with artificially cemented compacted-sandcolumns[J].Jounal of feotechnical Engineering.1991,117(7):1042-1060.
[21]朱志铎,姜竹生,刘松玉.徐宿高速公路挤密碎石桩处理液化地基试验研究[J].公路交通科技,2004(7):45-47.
[22]周建安,场淑碧.碎石桩复合地基承力性状有限元分析[J].地质灾害与环境保护, 1996,7(1):104-107.
[23]丁继辉,张庆宏,李宗惠等.大型油罐碎石桩复合地基沉降量的数值计算与分析[J].勘察科学技术,1999(6):32-35.
[24]何开明,王兰民,曾国熙.饱和黄土地基的液化数值分析[J].工业建筑,2001,1(7):29-31.
[25]刘义怀,朱志铎,刘松玉.路堤荷载下碎石桩复合地基的有限元分析[J].公路交通科技,2002,19(5):11-13.
[26]马学宁,杨有海,刘永红等.碎石桩复合地基有限元分析[J].兰州铁道学院学报(自然科学版),2002,21(1):60-63.
[27]田松花.碎石桩复合地基数值模拟分析[J].山西建筑,2003,29(11):34-35.
[28]吴军民.砂土-碎石桩复合地基抗液化分析数值模拟[J].建筑技术开发2004, 1(9):81- 84.
[29]张忠苗,陈洪,吴慧明,柔性承台下复合地基应力和沉降计算研究[J],岩土力学,2004, 25(3) : 451-454.
[30]王欣,俞亚南,高文明.路堤柔性荷载下的粉喷桩复合地基内的附加应力分析[J],中国市政工程,2003.3:1-2.
[31]尹尧国,全志利,周常青.软土地区桩体复合地基沉降变形与稳定性分析[J],天津城市建设学院学报,2001.7:252-258.
[32]吴慧明.不同刚度基础下复合地基性状研究.[D]杭州:浙江大学,2000.
[33]曾开华,俞建霖,龚晓南.路堤荷载下低强度混凝土桩复合地基性状分析[J],浙江大学学报,2004.2:185-190.
[34]方磊,谢永利.柔性基础下复合地基模型试验研究[J],土木工程学报,2005.5:67-71.
[35]龚晓南,褚航.基础刚度对复合地基性状的影响,工程力学,2003(04).
[36]徐超,叶观宝.水泥土搅拌桩复合地基的变形特性与承载力[J],岩土工程学报2005. 5:600-603.
[37]窦明远,戴为民,刘晓立,刘熙媛.柔性荷载作用下水泥土桩复合地基的承载力与沉降特性的研究[J],河北工业大学学报,2001.2:80-83.
[38]冯瑞玲,谢永利,方磊.柔性基础下复合地基的数值分析[J],中国公路学报,2003.1:40- 42.
[39]朱云升,胡幼常,丘作中,舒鄂南.柔性基础复合地基力学性状的有限元分析[J],岩土力学,2003.3:395-400.
[40]徐至钧,许朝铨,沈珠江.大型储罐基础设计与地基处理[M].北京:中国石化出版社, 1999.
[41]张继文.大型储罐软土地基处理的几个问题的探讨(待续)[J],石油建设2002.10:6-10.
[42]张继文.大型储罐软土地基处理的几个问题的探讨(续)[J],石油建设2002.12:12-15.
[43]贾庆山,大型储罐软土地基变形控制标准的研究[J],石油工程建设1996.4:17-20.
[44]龚晓南.复合地基设计和施工指南[M]北京:人民交通出版社,2003.
[45]丘长青.公路边坡土钉支护变形分析与研究[D],长沙理工大学.2004.
[46]彭文斌.FLAC 3D实用教程[M],机械工业出版社.2008.
[47]陈守煌,系统模糊决策理论与应用[M].大连:大连理工出版社,1994.
[48]左名麒,朱树森.强夯法地基加固.北京:中国铁道出版社,1990.
[49]王燕,李夕兵,蒋卫东.多目标系统模糊模型在强夯参数优选中的应用.岩土力学,2003, 24 (3):410-411.
[52]阎明礼,张东刚.CFG桩复合地基技术及工程实践[M].中国水利水电出版社,2001.
[53]吴慧明,龚晓南.刚性基础与柔性基础下复合地基模型试验对比研究[J].土木工程学报,2001,34(5):81-83.
[54]中国建筑科学研究院. JGJ79-2002建筑地基处理技术规范.
[55]段继伟,龚晓南,曾国熙.复合地基桩土应力比影响因素有限元分析[[J].第二届华东地区岩土力学学术讨论会论文集.杭州:浙江大学出版社.1992.43-47.
[56]刘杰,张可能.碎石桩复合地基若干问题的理论分析[J],铁道工程学报2003.6:28-32.