碎石注浆桩在灾后道路快速修复中的应用研究
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摘要
我国是世界上地震灾害最严重的国家之一。地震产生的剧烈震动,会使道路、桥梁受到严重破坏。一旦公路系统遭受破坏,不仅会影响人们的正常生活和经济运行,造成严重的经济损失,而且将严重影响震后人员抢救、救援、疏散和物资供应工作,从而进一步加剧地震灾害。因此震后道路的快速修复,保证道路在地震后的安全和正常使用,对震后灾区的恢复重建工作有着十分重要的意义。
路基在地震力的作用下,大都呈现高压缩性、高灵敏度、高含水量、大孔隙比、低强度和低透水性等软土工程性质特点。震后道路快速修复技术属于应急抢险,为特殊工程,对勘察、设计以及施工提出了很高要求。本文在整理道路遭受地震破坏的典型特征基础上,将目前在浙江等沿海地区得到广泛应用的新型软基处理方法碎石注浆桩应用于震后道路的修复工程中。
本文主要做了以下几方面的工作：
(1)整理山岭地区和平原地区道路遭受地震破坏的典型特征；
(2)基于现有注浆桩复合地基加固技术的基础上,利用震后未完全破损的基层及面层作为注浆桩的刚性承压盖板,提出带刚性承压盖板注浆桩快速修复震后道路的施工工艺,并初步探讨该注浆桩复合地基的加固机理及承载特性；
(3)借助于有限元软件ANSYS数值模拟分析带刚性承压盖板碎石注浆桩复合地基的加固机理、承载特性,计算时考虑了注浆桩的成桩特点设置浆液扩散区单元,较为合理地从荷载、桩长、桩体置换率、浆液扩散区置换率、盖板置换率、桩土模量比、浆土模量比等角度分析了注浆桩复合地基的承载特性及其对沉降影响的程度和规律；
(4)运用弹塑性有限元强度折减法分析注浆桩加固路基的边坡稳定性问题；
(5)利用有限元法,通过增量加载的方式来追踪分析每一步加载后路基的沉降变形,通过自动荷载步长加载技术来分析对比路基加固前后的沉降稳定性。
通过以上研究,给出了可供工程设计借鉴的一些结论,同时对研究中有待解决的问题进行了讨论。
China is one of the nations that most seriously vulnerable to seism. The drastic shaking emerged by seism will devastate land-based structures such as roads and bridges. Once the road system has been ravaged, it will not only bring about negative effects on people's daily life, but also lead to a serious economic triment. What's more, it will at a large extent impede the post-earthquake salvage, rescue, dispersing as well as the material providing work, and all these above will ulteriorly exaggerate earthquake disaster. Therefore, fast repairing and ensuring the safe and regular usage of post-earthquake roads are crutially significant to the restoring and restructuring work in disaster area after seism.
Under the effect of seismic force, the roadbeds mostly performs some mollisol engineering properties, like high compressibility, high sensitivity, high water content, macrovoid ratio, low strength, low permeability, etc.. The fast post-earthquake repairing technique, which belongs to emergency salvage, calls for a high requirement for reconnaissance, design and construction of special engineering. Based on collating the typical characteristics of roads suffered seism, this paper applied the new soft soil treating method, i.e. crushed stone grouting pile, which is widely adopted in coastal areas like Zhe Jiang, into the post-earthquake road repairing.
Several jobs have been done as followed:
(1) Collating the typical characteristics of mountainterrain and flat area roads suffered seism;
(2) Based on the present grouting pile consolidating technique of composite foundation, this paper used the partially damaged roadbed as rigid roof bearing plate for grouting pile, proposed the constructural techniques of fast repairing roads after seism of grouting pile with rigid roof bearing plat, and primarily discussed the solidating mechanism and bearing behaviors of this grouting pile in composite foundation;
(3) The transmission pattern of load, the characteristics of settlement and the influence factor of composite foundation borne with crushed stone grouting pile with rigid roof bearing plate were analyzed by FEM program, while the rule and the degree of the effect of these factors-such as load, the length of pile, capping plate replacement ratio, diffusing zone replacement ratio, capping plate replacement ratio, pile-soil module ratio, serous-soil module ratio. In the course of calculation, the element of diffusing zone is added in consider the pile character.
(4) Using the elastic-plastic finite element strength reduction method to calculate the slope stability of embankment reinforcemented by the grouting pile.
(5) By using the finite element method through step loading, the deformations is trackingly analylized between unreinforced and reinforced roadbeds after each added load step, and analylized the roadbed's sedimentation stability properties after reforcing through auto load step loading technique.
At last gives the summarization of the work, it makes a conclusion about the study work, presents some summing-ups from the study work, and points out some unresolved questions for the further study.
路基在地震力的作用下,大都呈现高压缩性、高灵敏度、高含水量、大孔隙比、低强度和低透水性等软土工程性质特点。震后道路快速修复技术属于应急抢险,为特殊工程,对勘察、设计以及施工提出了很高要求。本文在整理道路遭受地震破坏的典型特征基础上,将目前在浙江等沿海地区得到广泛应用的新型软基处理方法碎石注浆桩应用于震后道路的修复工程中。
本文主要做了以下几方面的工作：
(1)整理山岭地区和平原地区道路遭受地震破坏的典型特征；
(2)基于现有注浆桩复合地基加固技术的基础上,利用震后未完全破损的基层及面层作为注浆桩的刚性承压盖板,提出带刚性承压盖板注浆桩快速修复震后道路的施工工艺,并初步探讨该注浆桩复合地基的加固机理及承载特性；
(3)借助于有限元软件ANSYS数值模拟分析带刚性承压盖板碎石注浆桩复合地基的加固机理、承载特性,计算时考虑了注浆桩的成桩特点设置浆液扩散区单元,较为合理地从荷载、桩长、桩体置换率、浆液扩散区置换率、盖板置换率、桩土模量比、浆土模量比等角度分析了注浆桩复合地基的承载特性及其对沉降影响的程度和规律；
(4)运用弹塑性有限元强度折减法分析注浆桩加固路基的边坡稳定性问题；
(5)利用有限元法,通过增量加载的方式来追踪分析每一步加载后路基的沉降变形,通过自动荷载步长加载技术来分析对比路基加固前后的沉降稳定性。
通过以上研究,给出了可供工程设计借鉴的一些结论,同时对研究中有待解决的问题进行了讨论。
China is one of the nations that most seriously vulnerable to seism. The drastic shaking emerged by seism will devastate land-based structures such as roads and bridges. Once the road system has been ravaged, it will not only bring about negative effects on people's daily life, but also lead to a serious economic triment. What's more, it will at a large extent impede the post-earthquake salvage, rescue, dispersing as well as the material providing work, and all these above will ulteriorly exaggerate earthquake disaster. Therefore, fast repairing and ensuring the safe and regular usage of post-earthquake roads are crutially significant to the restoring and restructuring work in disaster area after seism.
Under the effect of seismic force, the roadbeds mostly performs some mollisol engineering properties, like high compressibility, high sensitivity, high water content, macrovoid ratio, low strength, low permeability, etc.. The fast post-earthquake repairing technique, which belongs to emergency salvage, calls for a high requirement for reconnaissance, design and construction of special engineering. Based on collating the typical characteristics of roads suffered seism, this paper applied the new soft soil treating method, i.e. crushed stone grouting pile, which is widely adopted in coastal areas like Zhe Jiang, into the post-earthquake road repairing.
Several jobs have been done as followed:
(1) Collating the typical characteristics of mountainterrain and flat area roads suffered seism;
(2) Based on the present grouting pile consolidating technique of composite foundation, this paper used the partially damaged roadbed as rigid roof bearing plate for grouting pile, proposed the constructural techniques of fast repairing roads after seism of grouting pile with rigid roof bearing plat, and primarily discussed the solidating mechanism and bearing behaviors of this grouting pile in composite foundation;
(3) The transmission pattern of load, the characteristics of settlement and the influence factor of composite foundation borne with crushed stone grouting pile with rigid roof bearing plate were analyzed by FEM program, while the rule and the degree of the effect of these factors-such as load, the length of pile, capping plate replacement ratio, diffusing zone replacement ratio, capping plate replacement ratio, pile-soil module ratio, serous-soil module ratio. In the course of calculation, the element of diffusing zone is added in consider the pile character.
(4) Using the elastic-plastic finite element strength reduction method to calculate the slope stability of embankment reinforcemented by the grouting pile.
(5) By using the finite element method through step loading, the deformations is trackingly analylized between unreinforced and reinforced roadbeds after each added load step, and analylized the roadbed's sedimentation stability properties after reforcing through auto load step loading technique.
At last gives the summarization of the work, it makes a conclusion about the study work, presents some summing-ups from the study work, and points out some unresolved questions for the further study.
引文
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[3]肖焕杰.旋喷注浆技术评述[J].长沙矿山研究院院刊,1987,7(4).
[4]付日荣,周玉学.粉喷桩在软土路基处理中的应用[J].低温建筑技术第4期.
[5]龚晓南.复合地基理论及工程应用[M].北京：中国建筑工业出版社,2002：150-161.
[6]刘汉龙.碎石注浆桩技术及其应用[J].岩土工程界,2006,(7)：27-30.
[7]史二元,陈明,郭长印等.碎石注浆桩复合地基技术及承载力分析[J].河北工程大学学报(自然科学版),2008,25(1)：14-16.
[8]洪昌地.路堤下注浆桩复合地基加固机理及沉降计算方法研究[D].硕士学位论文.南京：河海大学,2006.
[9]J.B.Jung.T.Moriwaki,N.Sumioka,and O.Kusakabe.Numerical Analyses and Model Tests of Composite Ground Improved by Partly Penetrated Sand Compaction Piles.Proc of 2nd international Conference on ground improvement techniques Singapore,1998,213-220
[10]G.Schnitter.新型桩基Schweizerische-Bauzeitung.1961,(2):13-19.
[11]Krubasik K.Ma β nahmen zur Tragkrafterhohung an Gro β boharpfalen.Baumaschine Bautechnik,1985(7,8).
[12]熊野生,区桦,陈燕山等.投石压浆无砂混凝土小桩在京珠高速公路湖北段上的应用与推广[J].交通科技,2002,(1)：4-5.
[13]平树江,孙鹏程,王立勇.碎石注浆桩在高速公路软基加固中的工程实践[J].华东公路,2005(2).
[14]赵鹏飞,杨书民.投石压浆无砂砼小桩复合地基处理技术在杂填土地层的应用[J].探矿工程,2004,(1)32-33.
[15]程华龙.注浆微型桩加固软土路基的机理与设计计算[J].地质科技情报,1999,18(增刊)：54-56.
[16]何样,司海宝.注浆混凝土桩在杭千高速公路路基处理中的应用[J].北京工业职业技术学院,2004;4(3).
[17]刑恩达.注浆桩复合地基加固机理及承载特性研究[D].硕士学位论文.南京：河海大学,2005.
[18]顾长存,刘汉龙,邢恩达等.路堤荷载下具盖板的浆固碎石桩桩土应力比研究[J].岩土 力学,2006,27(10)：1719-1722.
[19]左威龙,刘汉龙,陈永辉等.浆固碎石桩成桩注浆影响范围现场试验研究[J].岩土力学,2008,29(12)：3329-3332.
[20]Poulos H G.Analysis of piles vintage soil undergoing lateral movement[J].JSMFD,ASCE,1973,99(SM5):391-406.
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