水中沉井下沉期侧壁摩阻力分布试验研究
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摘要
以沪通长江大桥主墩沉井为背景,开展深水大截面沉井模拟下沉试验。通过对整个动态下沉过程的分析,确定了侧壁有效应力受下沉速率、压力松弛、倾斜、翻砂突沉等因素影响。停止吸泥后,侧壁有效应力由动态的分布形式转为准静态,整体呈减小趋势,表现为极值点的减小和压力松弛区的恢复。沉井侧壁台阶的设置可减小沉井侧壁总摩阻力,其减小主要来自沉井直壁段。发现阶梯式沉井侧壁受力分为线性区、台阶影响区、过度区和压力松弛区,建立了基于台阶影响的沉井竖直状态下侧壁摩阻力计算模型,并结合沪通大桥#29沉井现场监测试验加以验证。沉井倾斜会引起侧壁有效应力分布的改变,挤土产生的增大土压力可达对应侧主动土压力的3～4倍。
A sinking simulation experiment on a deep and large caisson is carried out based on the main caisson of Shanghai-Nomtong Bridge. Through the analysis of the whole dynamic sinking, it is determined that the effective stress on the sidewall is affected by various factors such as sinking rate, pressure relaxation, inclination, sand-casting and sudden sinking.After stopping sand suction, the effective stress of the sidewall changes from a dynamic distribution to a quasi-static one, the overall trend is decreasing and shows the reduction of extreme points and recovery of pressure relaxation zone. The arrangement of the step can reduce the total side friction of the caisson, and the reduction mainly comes from the vertical section of the caisson. It is found that the sidewall of stepped caisson can be divided into linear zone, step zone, excess zone and pressure relaxation zone. A model for calculating the side friction of the caisson in vertical state is established based on the influences of the step and verified by the on-site monitoring tests on No. 29 caisson of Shanghai-Nantong Bridge. The inclination the of caisson causes a change in the effective stress distribution of the sidewall, and the increased earth pressure generated by the compaction is 3～4 times the active earth pressure of the corresponding side.
A sinking simulation experiment on a deep and large caisson is carried out based on the main caisson of Shanghai-Nomtong Bridge. Through the analysis of the whole dynamic sinking, it is determined that the effective stress on the sidewall is affected by various factors such as sinking rate, pressure relaxation, inclination, sand-casting and sudden sinking.After stopping sand suction, the effective stress of the sidewall changes from a dynamic distribution to a quasi-static one, the overall trend is decreasing and shows the reduction of extreme points and recovery of pressure relaxation zone. The arrangement of the step can reduce the total side friction of the caisson, and the reduction mainly comes from the vertical section of the caisson. It is found that the sidewall of stepped caisson can be divided into linear zone, step zone, excess zone and pressure relaxation zone. A model for calculating the side friction of the caisson in vertical state is established based on the influences of the step and verified by the on-site monitoring tests on No. 29 caisson of Shanghai-Nantong Bridge. The inclination the of caisson causes a change in the effective stress distribution of the sidewall, and the increased earth pressure generated by the compaction is 3～4 times the active earth pressure of the corresponding side.
引文
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[13]穆保岗,朱建民,牛亚洲.南京长江四桥北锚碇沉井监控方案及成果分析[J].岩土工程学报,2011,33(2):269-274.(MU Bao-gang,ZHU Jian-min,NIU Ya-zhou.Monitoring and analysis of north anchorage caisson of Fourth Nanjing Yangtze River Bridge[J].Chinese Journal of Geotechnical Engineering,2011,33(2):269-274.(in Chinese))
[14]蒋炳楠.沪通大桥超深大沉井下沉阻力及突沉现场监测研究[D].成都:西南交通大学,2016.(JIANG Bing-nan.Resistance and suddenly sinking monitor research of deep and large open caisson of Hutong bridge[D].Chengdu:Southwest Jiaotong University,2016.(in Chinese))
[15]高宗余.沪通长江大桥主桥技术特点[J].桥梁建设,2014,44(2):1-5.(GAO Zong-yu,Technical characteristics of main bridge of hutong changjiang river bridge[J].Bridge Construction,2014,44(2):1-5.(in Chinese))
[16]徐力,高宗余,梅新咏.沪通长江大桥公铁合建斜拉桥桥塔基础设计[J].桥梁建设,2015,45(3):7-12.(XU Li,GAO Zong-yu,MEI Xin-yong.Design of pylon foundations for rail-cum-road cable-stayed bridge of Hutong Changjiang River Bridge[J].Bridge Construction,2015,45(3):7-12.(in Chinese))
[17]李军堂.沪通长江大桥主航道桥沉井施工关键技术[J].桥梁建设,2015,45(6):12-17.(LI Jun-tang.Key techniques for construction of open caissons of main ship channel bridge of hutong changjiang river bridge[J].Bridge Construction,2015,45(6):12-17.(in Chinese))
[18]CECS 137:2015给水排水工程钢筋混凝土沉井结构设计规程[S].2015.(CECS 137:2015 Specification for structural design of reinforced concrete sinking well of water supply and sewage engineering[S].2015.(in Chinese))
[2]叶政青,李珍烈,张觉生.沉井[M].北京:中国建筑工业出版社,1983.(YE Zheng-qing,LI Zhen-lie,ZHANGJue-sheng.Caissons[M].Beijing:China Architecture and Building Press,1983.(in Chinese))
[3]段良策,殷奇.沉井设计与施工[M].上海:同济大学出版社,2006.(DUAN Liang-ce,YIN Qi.Design and construction of caissons[M].Shanghai:Tongji University Press,2006.(in Chinese))
[4]张凤祥.沉井沉箱设计、施工及实例[M].北京:中国建筑工业出版社,2010.(ZHANG Feng-xiang,Design,construction and examples of caissons and open caissons[M].Beijing:China Architecture and Building Press,2010.(in Chinese))
[5]张勋,黄茂松.砂土中沉井加桩复合基础水平静力及循环模型试验[J].岩土工程学报,2015,37(增刊2):121-124.(ZHANG Xun,HUANG Mao-song.Model tests on a caisson-pile composite foundation in sand subjected to lateral static and cyclic loadings[J].Chinese Journal of Geotechnical Engineering,2015,37(S2):121-124.(in Chinese))
[6]张鸿,刘鹏,肖文福.泰州大桥中塔深水超深巨型沉井施工技术[J].岩土工程学报,2008,30(增刊1):559-563.(ZHANG Hong,LIU Peng,XIAO Wen-fu.Construction technology of super-large deepwater caisson of middle tower of Taizhou Bridge[J].Chinese Journal of Geotechnical Engineering,2008,30(S1):559-563.(in Chinese))
[7]王岩.大型沉井荷载分布模式研究[D].南京:东南大学,2011.(WANG Yan.Study on load distribution pattern of large caisson[D].Nanjing:Southeast University,2011.(in Chinese))
[8]冯广胜,盛华,罗瑞华.城市桥梁超大沉井关键施工技术[J].桥梁建设,2015,45(4):107-112.(FENGGuang-sheng,SHENG Hua,LUO Rui-hua.Key construction techniques for very huge caisson of a city bridge[J].Bridge Construction,2015,45(4):107-112.(in Chinese))
[9]王建,刘杨,张煜.沉井侧壁摩阻力室内试验研究[J].岩土力学,2013,34(3):659-666.(WANG Jian,LIUYang,ZHANG Yu.Model test on sidewall friction of open caisson[J].Rock and Soil Mechanics,2013,34(3):659-666.(in Chinese))
[10]穆保岗,别倩,赵学亮,等.沉井下沉期荷载分布特征的细观试验[J].中国公路学报,2014,27(9):49-56.(MUBao-gang,BIE Qian,ZHAO Xue-liang,et al.Meso-experiment on caisson load distribution characteristics during sinking[J].China Journal of Highway and Transport,2014,27(9):49-56.(in Chinese))
[11]刘青.沉井结构侧壁土压力分布研究[D].西安:西安建筑科技大学,2010.(LIU Qing.Study for the lateral earth pressure of open caisson structure[D].Xi'an:Xi'an University of Architecture and Technology,2010.(in Chinese))
[12]陈晓平,茜平一,张志勇.沉井基础下沉阻力分布特征研究[J].岩土工程学报,2005,27(2):148-152.(CHENXiao-ping,QIAN Ping-yi,ZHANG Zhi-yong.Study on penetration resistance distribution characteristic of sunk shaft foundation[J].Chinese Journal of Geotechnical Engineering,2005,27(2):148-152.(in Chinese))
[13]穆保岗,朱建民,牛亚洲.南京长江四桥北锚碇沉井监控方案及成果分析[J].岩土工程学报,2011,33(2):269-274.(MU Bao-gang,ZHU Jian-min,NIU Ya-zhou.Monitoring and analysis of north anchorage caisson of Fourth Nanjing Yangtze River Bridge[J].Chinese Journal of Geotechnical Engineering,2011,33(2):269-274.(in Chinese))
[14]蒋炳楠.沪通大桥超深大沉井下沉阻力及突沉现场监测研究[D].成都:西南交通大学,2016.(JIANG Bing-nan.Resistance and suddenly sinking monitor research of deep and large open caisson of Hutong bridge[D].Chengdu:Southwest Jiaotong University,2016.(in Chinese))
[15]高宗余.沪通长江大桥主桥技术特点[J].桥梁建设,2014,44(2):1-5.(GAO Zong-yu,Technical characteristics of main bridge of hutong changjiang river bridge[J].Bridge Construction,2014,44(2):1-5.(in Chinese))
[16]徐力,高宗余,梅新咏.沪通长江大桥公铁合建斜拉桥桥塔基础设计[J].桥梁建设,2015,45(3):7-12.(XU Li,GAO Zong-yu,MEI Xin-yong.Design of pylon foundations for rail-cum-road cable-stayed bridge of Hutong Changjiang River Bridge[J].Bridge Construction,2015,45(3):7-12.(in Chinese))
[17]李军堂.沪通长江大桥主航道桥沉井施工关键技术[J].桥梁建设,2015,45(6):12-17.(LI Jun-tang.Key techniques for construction of open caissons of main ship channel bridge of hutong changjiang river bridge[J].Bridge Construction,2015,45(6):12-17.(in Chinese))
[18]CECS 137:2015给水排水工程钢筋混凝土沉井结构设计规程[S].2015.(CECS 137:2015 Specification for structural design of reinforced concrete sinking well of water supply and sewage engineering[S].2015.(in Chinese))