岩土锚固工程的若干力学概念问题
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摘要
我国当前某些岩土锚固工程存在力学概念模糊、设计施工方法不当,导致锚杆失效、工程失稳现象频频出现,工程坍塌破坏等事故也时有发生。通过对岩土锚固的典型工程及事故工程调查、理论分析和试验研究,研究显著影响锚固工程的稳定性与健康发展的若干力学概念问题,旨在为提高锚固工程的设计施工水平,改善锚固工程的安全性与经济性提供依据。主要研究结果为:(1)预应力锚杆(索)具有提供主动抗力、能将结构的拉力传至深部稳定地层等力学特征,凡抵抗倾倒、竖向位移、沿基础底面、地层剪切面破坏和洞室坍塌的结构锚固均应采用此类锚杆。(2)适应张拉控制应力要求的锚杆筋体截面,足够的自由段长度和能充分调动地层抗剪强度的锚固体形式是提高锚杆受拉承载力的基本要素。(3)压力分散型锚固体系显著改善了锚杆的荷载传递机制与防腐保护性能,具有良好的力学与化学稳定性。(4)施锚时机滞后是影响锚固工程稳定性的主要因素之一。及时施作低预应力(张拉)锚杆和发展预制的钢筋混凝土块件作锚杆的传力结构,可有效控制和避免施锚时机滞后现象。(5)为改善高应力低强度岩层中的大型洞室的稳定性,应全面采用低预应力锚杆作初期支护,严格控制高预应力锚杆施作滞后,提高锚杆拉力设计值与初始预应力值和加强围岩变形–锚杆抗力(刚度)相互作用失衡的调控力度。
The misconception in soil and rock mechanics,the irrational methods of design and construction for anchored structures in ground exist in China,which frequently lead to accidents such as anchor failure,instability and even collapse of engineering structures. According to geotechnical investigations of typical engineering and engineering accidents,theoretical analysis and experimental studies,some mechanical conceptual problems which significantly affect the stability of ground anchorage were studied. The prestressed anchor has the advantages of providing the active resistance and transferring the tensile stress of structures to the deep stable strata and can be widely used to resist dumping,vertical displacement,shear failure along the foundation base and openings collapse. The section of anchor meeting the requirements of tensile stress,the length of free end of the anchor being long enough and the anchoring formations being able to fully mobilize the ground shear strength are basic elements for raising the tensile bearing capacity of anchors. The pressure-dispersive anchor significantly improve the load transfer effect and the anti-corrosion protection performance and has excellent mechanical and chemical stability. The time delay in anchor installation can be effectively controlled and avoided after excavation in the slopes and openings by timely applying tensile anchors and prefabricated reinforced concrete blocks as the high bearing capacity transfer structures. In order to improve the stability of large openings in high stress and low-strength rock,it is necessary to adopt the low prestressed anchors as the initial support,to strictly control the time delay of the installation of high prestressed anchor,to raise the initial prestressed value in design and to strengthen the control of the interaction between the surrounding rock deformation and anchorage resistance(stiffness).
The misconception in soil and rock mechanics,the irrational methods of design and construction for anchored structures in ground exist in China,which frequently lead to accidents such as anchor failure,instability and even collapse of engineering structures. According to geotechnical investigations of typical engineering and engineering accidents,theoretical analysis and experimental studies,some mechanical conceptual problems which significantly affect the stability of ground anchorage were studied. The prestressed anchor has the advantages of providing the active resistance and transferring the tensile stress of structures to the deep stable strata and can be widely used to resist dumping,vertical displacement,shear failure along the foundation base and openings collapse. The section of anchor meeting the requirements of tensile stress,the length of free end of the anchor being long enough and the anchoring formations being able to fully mobilize the ground shear strength are basic elements for raising the tensile bearing capacity of anchors. The pressure-dispersive anchor significantly improve the load transfer effect and the anti-corrosion protection performance and has excellent mechanical and chemical stability. The time delay in anchor installation can be effectively controlled and avoided after excavation in the slopes and openings by timely applying tensile anchors and prefabricated reinforced concrete blocks as the high bearing capacity transfer structures. In order to improve the stability of large openings in high stress and low-strength rock,it is necessary to adopt the low prestressed anchors as the initial support,to strictly control the time delay of the installation of high prestressed anchor,to raise the initial prestressed value in design and to strengthen the control of the interaction between the surrounding rock deformation and anchorage resistance(stiffness).
引文
[1]程良奎,李象范.岩土锚固·土钉·喷射混凝土——原理、设计与应用[M].北京:中国建筑工业出版社,2008:41–89.(CHENG Liangkui,LI Xiangfan.The theory,design and application of ground anchorage,soil nail and shotcrete[M].Beijing:China Architecture and Building Press,2008:41–89.(in Chinese))
[2]HANNA T H.锚固技术在岩土工程中的应用[M].北京:中国建筑工业出版社,1981:127–154,193–204.(HANNA T H.The application of anchorage technology in geotechnical engineering[M].Beijing:China Architecture and Building Press,1981:127–154,193–204.(in Chinese))
[3]HOBST L,ZAJIC J.Anchoring in rock and soil[M].New York:Elsevier Scientific Publishing Company,1983:52–67.(in Chinese))
[4]BARLEY A D.Theory and practice of the single bore multiple anchor system[C]//Proceedings of International Symposium on Anchors in Theory and Practice.Salzburg,Austria:[s.n.],1995:293–301.
[5]程良奎.单孔复合锚固法的机制与实践[M].北京:中国科学技术出版社,2000:867–870.(CHENG Liangkui.Theory and application of single multiple anchors system[M].Beijing:Chinese Science and Technology Press,2000:867–870.(in Chinese))
[6]朱维申,何满潮.复杂条件下围岩稳定性与岩体动态施工力学[M].北京:科学出版社,1995:122–140.(ZHU Weishen,HE Manchao.Stability of surrounding on the complex condition and the dynamic construction mechanics of rock mass[M].Beijing:Science Press,1995:122–140.(in Chinese))
[7]黄福德,吕祖珩.预应力群锚高边坡增稳机制研究[C]//中国岩土锚固协会编.岩土锚固新技术.北京:人民交通出版社,1998:90–94.(HUANG Fude,LU Zuheng.Research on prestressed group anchorage mechanism of increasing stability of high slopes[C]//Chinese geotechnical anchoring Association ed.New Technology of Ground Anchorage.Beijing:China Communications Press,1998:90–94.(in Chinese))
[8]康洪普,林建,吴拥政.全断面高预应力强力锚索支护技术及其在动压巷道中的应用[J].煤炭学报,2009,34(9):1 153–1 159.(KANG Hongpu,LIN Jian,WU Yongzheng.High pretensioned stress and in tensive cable bolting technology set in full section and application in entry affected by dynamic pressure[J].Journal of China Coal Society,2009,34(9):1 153–1 159.(in Chinese))
[9]MIKE S,ZHANG M L.The PC frame anchorage technique[C]//Proceedings of the International Symposium on Application and Development of Rock-Soil Anchoring Technology.Beijing:International Academic Publishers,1998:76–80.
[10]中华人民共和国行业标准编写组.CECS22:2005岩土锚杆(索)技术规程[S].北京:计划出版社,2005.(The Professional Standards Compilation Group of People's Republic of China.CECS22:2005The technical specifications for ground anchor[S].Beijing:China Planning Press,2005.(in Chinese))
[11]British Standard Institution.BS8081 British standard code of practice for ground anchorages[S].[S.l.]:[s.n.],1989.
[12]Post-tensioning Institution.PTI recommendations for pressing rock and soil anchours[S].[S.l.]:[s.n.],1996.
[13]地盘工学会.JGS 4101–2000グラウンドアンカー设计施工基准[S].[S.l.]:[s.n.],2000.(in Japanese)
[14]程良奎,张作瑂,杨志银.岩土加固实用技术[M].北京:地震出版社,1994:18–62.(CHENG Liangkui,ZHANG Zuomei,YANG Zhiyin.Practical technology of strengthening ground[M].Beijing:Earthquake Press,1994:18–62.(in Chinese))
[15]周德培,刘世雄,刘鸿.压力分散型锚索设计中应考虑的几个问题[J].岩石力学与工程学报,2013,32(8):1 513–1 519.(ZHOU Depei,LIU Shixiong,LIU Hong.Some problems to be considered in design for compression dispersion type anchors[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(8):1 513–1 519.(in Chinese))
[16]SABATINI P J,PASS D G,BACHUS R C.Ground anchors and anchored systems[M].Honolala Hauaii:University Press of the Pacific,2006:46–78.
[17]WOODS R I,BARKHORDARI K.The influence of bond stress distribution on ground anchor design[C]//Proceedings of the Internayional Symposium on Ground Anchorages and Anchored Structures.London:Themas Telford,1997:55–64.
[18]程良奎.岩土锚固研究与新进展[J].岩石力学与工程学报,2005,24(21):3 803–3 810.(CHENG Liangkui.Research and new progress in ground anchorage[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(21):3 803–3 810.(in Chinese))
[19]程良奎.深基坑锚杆支护的新进展[C]//中国岩土锚固工程协会编.岩土锚固新技术.北京:人民交通出版,1998:1–15.(CHENG Liangkui.New development of anchor-supporting for deep excavations[C]//New Technology of Ground Anchorage ed.Beijing:China Communications Press,1998:1–15.(in Chinese))
[20]程良奎,于来喜,范景伦,等.高压灌浆预应力锚杆及其在饱和淤泥质土地层中的应用[J].工业建筑,1988,(4):1–6.(CHENG Lingkui,YU Laixi,FAN Jinglun,et al.High pressure grouting prestressed anchor and its application in saturated silt soil[J].Industrial Construction,1988,(4):1–6.(in Chinese))
[21]石家庄道桥建设总公司,石家庄道桥管理处.高承载力压力分散型锚固体系及其在新建坝体中的应用研究[R].石家庄:[s.n.],2006.(Shijiazhuang Road and Bridge Construction Company,Shijiazhuang Road Management Office.The application research for high bearing capacity pressure-dispersive anchorage system in new building dam[R].Shijiazhuang:[s.n.],2006.(in Chinese))
[22]刘玉堂,袁培中,白彦光.压力分散型锚索不宜作为永久性锚索[J].预应力技术,2008,(3):19–21.(LIU Yutang,YUAN Peizhong,BAI Yanguang.Inappropriate to use pressure-dispersion anchors as permanent anchors[J].Prestressed Technology,2008,(3):19–21.(in Chinese))
[23]杨秀山,刘宗仁,郑谅臣.黄河小浪底水利枢纽岩石力学研究与工程实践[C]//中国岩石力学与工程–世纪成就.南京:河海大学出版社,2004:829–860.(YANG Xiushan,LIU Zongren,ZHENG Liangchen.The Yellow Rivexiaolangdi key water control dam project rock mechanics and engineering practice[C]//Chinese Rock Mechanics and Engineering-century Achievements.Nanjing:Hohai University Press,2004:829–860.(in Chinese))
[24]锦屏建设管理局安全监测中心.锦屏一级电站地下厂房洞室群安全监测综合分析报告[R].[S.l.]:[s.n.],2009.(Jinping Construction Bureau Safety Monitoring Center,The underground caverns safety monitoring and analysis report of Jinping first stage hydropower station[R].[S.l.]:[s.n.],2009.(in Chinese))
[25]PETROS P.XANTHAKO S.Ground anchors and anchored structures[M].New York:John wiley and Sons,Inc.,1991:494–501.
[2]HANNA T H.锚固技术在岩土工程中的应用[M].北京:中国建筑工业出版社,1981:127–154,193–204.(HANNA T H.The application of anchorage technology in geotechnical engineering[M].Beijing:China Architecture and Building Press,1981:127–154,193–204.(in Chinese))
[3]HOBST L,ZAJIC J.Anchoring in rock and soil[M].New York:Elsevier Scientific Publishing Company,1983:52–67.(in Chinese))
[4]BARLEY A D.Theory and practice of the single bore multiple anchor system[C]//Proceedings of International Symposium on Anchors in Theory and Practice.Salzburg,Austria:[s.n.],1995:293–301.
[5]程良奎.单孔复合锚固法的机制与实践[M].北京:中国科学技术出版社,2000:867–870.(CHENG Liangkui.Theory and application of single multiple anchors system[M].Beijing:Chinese Science and Technology Press,2000:867–870.(in Chinese))
[6]朱维申,何满潮.复杂条件下围岩稳定性与岩体动态施工力学[M].北京:科学出版社,1995:122–140.(ZHU Weishen,HE Manchao.Stability of surrounding on the complex condition and the dynamic construction mechanics of rock mass[M].Beijing:Science Press,1995:122–140.(in Chinese))
[7]黄福德,吕祖珩.预应力群锚高边坡增稳机制研究[C]//中国岩土锚固协会编.岩土锚固新技术.北京:人民交通出版社,1998:90–94.(HUANG Fude,LU Zuheng.Research on prestressed group anchorage mechanism of increasing stability of high slopes[C]//Chinese geotechnical anchoring Association ed.New Technology of Ground Anchorage.Beijing:China Communications Press,1998:90–94.(in Chinese))
[8]康洪普,林建,吴拥政.全断面高预应力强力锚索支护技术及其在动压巷道中的应用[J].煤炭学报,2009,34(9):1 153–1 159.(KANG Hongpu,LIN Jian,WU Yongzheng.High pretensioned stress and in tensive cable bolting technology set in full section and application in entry affected by dynamic pressure[J].Journal of China Coal Society,2009,34(9):1 153–1 159.(in Chinese))
[9]MIKE S,ZHANG M L.The PC frame anchorage technique[C]//Proceedings of the International Symposium on Application and Development of Rock-Soil Anchoring Technology.Beijing:International Academic Publishers,1998:76–80.
[10]中华人民共和国行业标准编写组.CECS22:2005岩土锚杆(索)技术规程[S].北京:计划出版社,2005.(The Professional Standards Compilation Group of People's Republic of China.CECS22:2005The technical specifications for ground anchor[S].Beijing:China Planning Press,2005.(in Chinese))
[11]British Standard Institution.BS8081 British standard code of practice for ground anchorages[S].[S.l.]:[s.n.],1989.
[12]Post-tensioning Institution.PTI recommendations for pressing rock and soil anchours[S].[S.l.]:[s.n.],1996.
[13]地盘工学会.JGS 4101–2000グラウンドアンカー设计施工基准[S].[S.l.]:[s.n.],2000.(in Japanese)
[14]程良奎,张作瑂,杨志银.岩土加固实用技术[M].北京:地震出版社,1994:18–62.(CHENG Liangkui,ZHANG Zuomei,YANG Zhiyin.Practical technology of strengthening ground[M].Beijing:Earthquake Press,1994:18–62.(in Chinese))
[15]周德培,刘世雄,刘鸿.压力分散型锚索设计中应考虑的几个问题[J].岩石力学与工程学报,2013,32(8):1 513–1 519.(ZHOU Depei,LIU Shixiong,LIU Hong.Some problems to be considered in design for compression dispersion type anchors[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(8):1 513–1 519.(in Chinese))
[16]SABATINI P J,PASS D G,BACHUS R C.Ground anchors and anchored systems[M].Honolala Hauaii:University Press of the Pacific,2006:46–78.
[17]WOODS R I,BARKHORDARI K.The influence of bond stress distribution on ground anchor design[C]//Proceedings of the Internayional Symposium on Ground Anchorages and Anchored Structures.London:Themas Telford,1997:55–64.
[18]程良奎.岩土锚固研究与新进展[J].岩石力学与工程学报,2005,24(21):3 803–3 810.(CHENG Liangkui.Research and new progress in ground anchorage[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(21):3 803–3 810.(in Chinese))
[19]程良奎.深基坑锚杆支护的新进展[C]//中国岩土锚固工程协会编.岩土锚固新技术.北京:人民交通出版,1998:1–15.(CHENG Liangkui.New development of anchor-supporting for deep excavations[C]//New Technology of Ground Anchorage ed.Beijing:China Communications Press,1998:1–15.(in Chinese))
[20]程良奎,于来喜,范景伦,等.高压灌浆预应力锚杆及其在饱和淤泥质土地层中的应用[J].工业建筑,1988,(4):1–6.(CHENG Lingkui,YU Laixi,FAN Jinglun,et al.High pressure grouting prestressed anchor and its application in saturated silt soil[J].Industrial Construction,1988,(4):1–6.(in Chinese))
[21]石家庄道桥建设总公司,石家庄道桥管理处.高承载力压力分散型锚固体系及其在新建坝体中的应用研究[R].石家庄:[s.n.],2006.(Shijiazhuang Road and Bridge Construction Company,Shijiazhuang Road Management Office.The application research for high bearing capacity pressure-dispersive anchorage system in new building dam[R].Shijiazhuang:[s.n.],2006.(in Chinese))
[22]刘玉堂,袁培中,白彦光.压力分散型锚索不宜作为永久性锚索[J].预应力技术,2008,(3):19–21.(LIU Yutang,YUAN Peizhong,BAI Yanguang.Inappropriate to use pressure-dispersion anchors as permanent anchors[J].Prestressed Technology,2008,(3):19–21.(in Chinese))
[23]杨秀山,刘宗仁,郑谅臣.黄河小浪底水利枢纽岩石力学研究与工程实践[C]//中国岩石力学与工程–世纪成就.南京:河海大学出版社,2004:829–860.(YANG Xiushan,LIU Zongren,ZHENG Liangchen.The Yellow Rivexiaolangdi key water control dam project rock mechanics and engineering practice[C]//Chinese Rock Mechanics and Engineering-century Achievements.Nanjing:Hohai University Press,2004:829–860.(in Chinese))
[24]锦屏建设管理局安全监测中心.锦屏一级电站地下厂房洞室群安全监测综合分析报告[R].[S.l.]:[s.n.],2009.(Jinping Construction Bureau Safety Monitoring Center,The underground caverns safety monitoring and analysis report of Jinping first stage hydropower station[R].[S.l.]:[s.n.],2009.(in Chinese))
[25]PETROS P.XANTHAKO S.Ground anchors and anchored structures[M].New York:John wiley and Sons,Inc.,1991:494–501.
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