两种不同长度竖向排水体在真空预压法中应用的研究
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摘要
在我国沿海及各大江大河的入海三角洲冲积平原地区广泛分布着海相沉积、湖相沉积和河相沉积的软弱粘土层,这种土具有含水量高、渗透性差、压缩性大和强度低等特点。近年来,随着经济社会的发展,工程建设用地日益紧张,越来越多的建筑物将建造在这种软土地基上,促进了软基处理理论研究和工程实践的发展,其中真空排水预压法是比较成熟的软土地基处理方法,取得了良好的经济效益和社会效益。位于天津滨海新区的天津港陆域系吹填而成,是典型的软土地区,给港口各种建筑物的设计、施工都带来了不利的影响。国家已经明确把天津滨海新区开发开放纳入总体发展战略布局,天津港是滨海新区的重要组成部分,滨海新区的开发开放为天津港创造了难得的历史机遇。如何优化现有软土地基处理加固方法,为港口建设缩短工期、节约成本成为值得关注的重要研究课题。本文在总结回顾真空预压技术的发展历史和研究现状基础上,结合天津市重点工程“天津东疆保税港区保税库第二战役200万㎡软基处理工程”开展真空预压竖向排水体打设深度方面的研究工作,为今后软土地基加固方案的优化设计和施工提供指导性建议。主要内容如下:
(1)简要叙述天津滨海地区地质条件及适用的地基处理方法,回顾了真空预压法在大面积深厚软土地基中的发展历史及研究现状。
(2)介绍了真空预压施工的基本工艺,以及现场监测的基本要点,依据使用期对承载力和变形要求确定竖向排水体最佳打设深度,并在实际工程中设置两种不同的竖向排水体打设深度,对比竖向排水体打设深度不同情况下各层土体沉降、孔隙水压力消散等情况,对加固前后土体进行室内及现场试验,对比其物理力学性质的变化以确定竖向排水体最佳打设深度。
(3)介绍了地基沉降计算的基本方法,提出利用实测沉降曲线来推算最终沉降量更具有现实意义,并分别利用三点法、双曲线法和指数法推算了土体最终沉降量,提出在真空预压法处理软土地基中用双曲线法来推算更加合适。
(4)强调了控制土体工后沉降的重要意义,并从控制工后沉降的角度讨论了现有真空预压法加固卸载标准的合理性,提出了建议。
The soft clay layer is widely distributed in our country’s coastline and estuaries delta plain, sharing such features as the high water content, poor permeability, big compressibility and low strength. In recent years, with the economic and social development, project construction land increasingly tense, more and more buildings will be built on this soft ground, which promoting the theoretical research and development of the engineering practice for the soft soil treatment. Vacuum preloading is a relatively mature soft soil treatment method and achieves good economic and social benefits. Tianjin Port, located in Tianjin Binhai New Area, is a man-made port heaped up by silt. Tianjin Port land is a typical soft clay ground, brings adverse effects to the engineering design and construction in the port. Now the country has clearly brought the development and opening of Tianjin Binhai New Area into the overall development strategy. As an important part of the Tianjin Binhai New Area, Tianjin Port gets a rare historical opportunity for rapid development. How to optimize the existing Soft Soil reinforcement method, shorten construct time, reduce project costs for port construction has become a hot topic in research field recently. In this paper, on the review of the vacuum preloading method’s historical development and analysis its the current situation, combination of the key projects“Tianjin Dongjiang free trade port zone second battle of 2 million square meters of soft clay foundation treatment”in Tianjin City, carrying out the research work about the length of PVDs in vacuum preloading soft clay treatment to give guidance suggestions for future optimal design and construction. The main contents are as following:
(1) Give a brief description of the geology condition in Tianjin Binhai area and applicable foundation treatment method, reviewed the history and current progress of vacuum preloading method in a large area over soft soil reinforced.
(2) Describes the basic construction technology of vacuum preloading, and basic elements of on-site monitoring. In practical engineering, installing two different PVDs depths, contrast settlement, pore water pressure dissipation, etc. under the two different circumstances. Before and after foundation reinforcement, by means of the indoor and field tests result, comparing the changes in their physical and mechanical properties to determine the best depth of PVDs.
(3) Describes the basic method of calculating settlement, proposed using settlement curve to calculate the final settlement has more practical significance. And used three points, hyperbolic method and the index respectively to calculate the final settlement, thinking the hyperbolic method is more suitable.
(4) Emphasized the importance of soil settlements control, discussed rationality of unload standard for the vacuum preloading method in terms of the settlement after construction and give suggestions.
(1)简要叙述天津滨海地区地质条件及适用的地基处理方法,回顾了真空预压法在大面积深厚软土地基中的发展历史及研究现状。
(2)介绍了真空预压施工的基本工艺,以及现场监测的基本要点,依据使用期对承载力和变形要求确定竖向排水体最佳打设深度,并在实际工程中设置两种不同的竖向排水体打设深度,对比竖向排水体打设深度不同情况下各层土体沉降、孔隙水压力消散等情况,对加固前后土体进行室内及现场试验,对比其物理力学性质的变化以确定竖向排水体最佳打设深度。
(3)介绍了地基沉降计算的基本方法,提出利用实测沉降曲线来推算最终沉降量更具有现实意义,并分别利用三点法、双曲线法和指数法推算了土体最终沉降量,提出在真空预压法处理软土地基中用双曲线法来推算更加合适。
(4)强调了控制土体工后沉降的重要意义,并从控制工后沉降的角度讨论了现有真空预压法加固卸载标准的合理性,提出了建议。
The soft clay layer is widely distributed in our country’s coastline and estuaries delta plain, sharing such features as the high water content, poor permeability, big compressibility and low strength. In recent years, with the economic and social development, project construction land increasingly tense, more and more buildings will be built on this soft ground, which promoting the theoretical research and development of the engineering practice for the soft soil treatment. Vacuum preloading is a relatively mature soft soil treatment method and achieves good economic and social benefits. Tianjin Port, located in Tianjin Binhai New Area, is a man-made port heaped up by silt. Tianjin Port land is a typical soft clay ground, brings adverse effects to the engineering design and construction in the port. Now the country has clearly brought the development and opening of Tianjin Binhai New Area into the overall development strategy. As an important part of the Tianjin Binhai New Area, Tianjin Port gets a rare historical opportunity for rapid development. How to optimize the existing Soft Soil reinforcement method, shorten construct time, reduce project costs for port construction has become a hot topic in research field recently. In this paper, on the review of the vacuum preloading method’s historical development and analysis its the current situation, combination of the key projects“Tianjin Dongjiang free trade port zone second battle of 2 million square meters of soft clay foundation treatment”in Tianjin City, carrying out the research work about the length of PVDs in vacuum preloading soft clay treatment to give guidance suggestions for future optimal design and construction. The main contents are as following:
(1) Give a brief description of the geology condition in Tianjin Binhai area and applicable foundation treatment method, reviewed the history and current progress of vacuum preloading method in a large area over soft soil reinforced.
(2) Describes the basic construction technology of vacuum preloading, and basic elements of on-site monitoring. In practical engineering, installing two different PVDs depths, contrast settlement, pore water pressure dissipation, etc. under the two different circumstances. Before and after foundation reinforcement, by means of the indoor and field tests result, comparing the changes in their physical and mechanical properties to determine the best depth of PVDs.
(3) Describes the basic method of calculating settlement, proposed using settlement curve to calculate the final settlement has more practical significance. And used three points, hyperbolic method and the index respectively to calculate the final settlement, thinking the hyperbolic method is more suitable.
(4) Emphasized the importance of soil settlements control, discussed rationality of unload standard for the vacuum preloading method in terms of the settlement after construction and give suggestions.
引文
[1]徐至钧,软土地基和预压法地基处理,北京:机械工业出版社,2005
[2]郝占刚,真空预压法在天津港软基加固中的应用研究,硕士学位论文,天津大学,2009.7
[3]钱征,天津新港软土的一些工程特性,侯钊,天津软土地基,天津:天津科学技术出版社,1987:33-44
[4]申伯熙,塘沽和新港地区工程地质条件特征,侯钊,天津软土地基,天津:天津科学技术出版社,1987:47-55
[5]叶柏荣,综述真空预压法在我国的发展,地基处理,2000,11(3):49-57
[6]龚晓南,岑仰润,李昌宁,真空排水预压加固软土地基的研究现状及展望,第七届全国地基处理学术讨论会论文集,兰州,2002:3-7
[7] G.R.Halton,R.W.Loughney,E.Winter,Vacuum Stabilization of Subsoil beneath Runway Extension at Philadelphia International Airport, Proc.of IV ICSMFE,1965,61-65
[8] F.Masse,C.A.Spaulding, Pr.Ihm Chol Wong,Vacuum consolidation:a review of 12 years of successful development,Prepared for Distribution to Attendees at Geo-Odyssey-ASCE/Virginia Tech—Blacksburg,VA USA,2001,6:9-13
[9] M.Mikasa,Soil Improvement by Dewatering Osaka South Proc,Geotechnical Aspects of Coastal Reclamation Projects in Japan,19-81
[10]娄炎,负压条件下软土地基的孔隙水压力,水利学报,1998,(10):48-52
[11]陈环,真空预压法机理研究十年,港口工程,1991,(4):17-26
[12] Yan Shuwang,Feng Xiaowei,Chu Jian,Mechanism of Using preloading Method in Improving Soft Clay layers,US-China Workshop on Ground Improvement Technologies,308-317
[13]董良志,真空及真空联合堆载预压法加固软土地基的机理与理论研究,水运工程,2005,(9):83-91
[14]龚晓南,岑仰润,真空预压加固软土地基机理探讨,哈尔滨建筑大学学报,2002,35(2):7-10
[15]许胜,王媛,真空预压法加固软土地基理论研究现状及展望,岩土力学, 2006,27(supp):943-947
[16]孙立强,超软吹填土地基真空预压理论及模型试验的研究,博士学位论文,天津大学,2010,3
[17]娄炎,真空排水预压法加固软土技术,北京:人民交通出版社,2002
[18]杨进良,土力学(第4版),北京:中国水利水电出版社,2009
[19]刘慧敏,黄腾,竖向排水体长度对真空联合预压法处理软基效果的影响,公路,2006,8:267-269
[20]沈珠江,陆瞬英,软土地基真空排水预压的固结变形分析,岩土工程学报,1986,8(3):8-16
[21]赵维炳,唐彤芝,高长胜等,控制工后沉降处理深厚软土地基,北京:人民交通出版社,2006
[22]张效俭,硬壳层的成因及基岩工程评价,电力勘测,1997,3:14-17
[23]李善波,软土地基表层硬壳层的利用与工程实践,建筑技术,2000,31(3):166-167
[24]董剑,郑晓国,软土地基上硬壳层效应分析及工程应用,路基工程,2006,4:7-9
[25]刘成宇,土力学(第二版),北京:中国铁道出版社,2005
[26]钱家欢,殷宗泽,土工原理与计算(第二版),北京:中国水利水电出版社,2006
[27]闫澍旺,朱平,刘润,真空预压加固软土地基的效果观测分析,水利学报,2004,3:267-269
[28]刘润,闫澍旺,武玉裴等,真空预压后塑料排水板对地基承载力及沉降的影响,水利学报,2009,40(7):885-991
[29]麦月梅,最终沉降量的推算和软基的监测,公路测设简讯,1993,4:23-25
[30]岑仰润,真空预压加固地基的试验及理论研究,博士学位论文,浙江大学,2003,5
[31]中华人民共和国交通部,JTJ250-98,港口工程地基规范,北京:人民交通出版社,1998
[32]中华人民共和国交通运输部,JTS 147-2-2009,真空预压加固软土地基技术规程,北京:人民交通出版社,2009
[33]娄炎,杨守华,高华胜,对真空预压加固中沉降稳定标准的探讨,中国港湾建设,2004,128(1):23-25,31
[2]郝占刚,真空预压法在天津港软基加固中的应用研究,硕士学位论文,天津大学,2009.7
[3]钱征,天津新港软土的一些工程特性,侯钊,天津软土地基,天津:天津科学技术出版社,1987:33-44
[4]申伯熙,塘沽和新港地区工程地质条件特征,侯钊,天津软土地基,天津:天津科学技术出版社,1987:47-55
[5]叶柏荣,综述真空预压法在我国的发展,地基处理,2000,11(3):49-57
[6]龚晓南,岑仰润,李昌宁,真空排水预压加固软土地基的研究现状及展望,第七届全国地基处理学术讨论会论文集,兰州,2002:3-7
[7] G.R.Halton,R.W.Loughney,E.Winter,Vacuum Stabilization of Subsoil beneath Runway Extension at Philadelphia International Airport, Proc.of IV ICSMFE,1965,61-65
[8] F.Masse,C.A.Spaulding, Pr.Ihm Chol Wong,Vacuum consolidation:a review of 12 years of successful development,Prepared for Distribution to Attendees at Geo-Odyssey-ASCE/Virginia Tech—Blacksburg,VA USA,2001,6:9-13
[9] M.Mikasa,Soil Improvement by Dewatering Osaka South Proc,Geotechnical Aspects of Coastal Reclamation Projects in Japan,19-81
[10]娄炎,负压条件下软土地基的孔隙水压力,水利学报,1998,(10):48-52
[11]陈环,真空预压法机理研究十年,港口工程,1991,(4):17-26
[12] Yan Shuwang,Feng Xiaowei,Chu Jian,Mechanism of Using preloading Method in Improving Soft Clay layers,US-China Workshop on Ground Improvement Technologies,308-317
[13]董良志,真空及真空联合堆载预压法加固软土地基的机理与理论研究,水运工程,2005,(9):83-91
[14]龚晓南,岑仰润,真空预压加固软土地基机理探讨,哈尔滨建筑大学学报,2002,35(2):7-10
[15]许胜,王媛,真空预压法加固软土地基理论研究现状及展望,岩土力学, 2006,27(supp):943-947
[16]孙立强,超软吹填土地基真空预压理论及模型试验的研究,博士学位论文,天津大学,2010,3
[17]娄炎,真空排水预压法加固软土技术,北京:人民交通出版社,2002
[18]杨进良,土力学(第4版),北京:中国水利水电出版社,2009
[19]刘慧敏,黄腾,竖向排水体长度对真空联合预压法处理软基效果的影响,公路,2006,8:267-269
[20]沈珠江,陆瞬英,软土地基真空排水预压的固结变形分析,岩土工程学报,1986,8(3):8-16
[21]赵维炳,唐彤芝,高长胜等,控制工后沉降处理深厚软土地基,北京:人民交通出版社,2006
[22]张效俭,硬壳层的成因及基岩工程评价,电力勘测,1997,3:14-17
[23]李善波,软土地基表层硬壳层的利用与工程实践,建筑技术,2000,31(3):166-167
[24]董剑,郑晓国,软土地基上硬壳层效应分析及工程应用,路基工程,2006,4:7-9
[25]刘成宇,土力学(第二版),北京:中国铁道出版社,2005
[26]钱家欢,殷宗泽,土工原理与计算(第二版),北京:中国水利水电出版社,2006
[27]闫澍旺,朱平,刘润,真空预压加固软土地基的效果观测分析,水利学报,2004,3:267-269
[28]刘润,闫澍旺,武玉裴等,真空预压后塑料排水板对地基承载力及沉降的影响,水利学报,2009,40(7):885-991
[29]麦月梅,最终沉降量的推算和软基的监测,公路测设简讯,1993,4:23-25
[30]岑仰润,真空预压加固地基的试验及理论研究,博士学位论文,浙江大学,2003,5
[31]中华人民共和国交通部,JTJ250-98,港口工程地基规范,北京:人民交通出版社,1998
[32]中华人民共和国交通运输部,JTS 147-2-2009,真空预压加固软土地基技术规程,北京:人民交通出版社,2009
[33]娄炎,杨守华,高华胜,对真空预压加固中沉降稳定标准的探讨,中国港湾建设,2004,128(1):23-25,31