大型沉井终沉前底部土体回弹变形特性试验分析  

Test Analysis on Resilience Deformation of Soil before Final Sinkage of Large Caisson

作　　者：穆保岗[1] 龚丛强 龚维明[1] 

机构地区：[1]东南大学土木工程学院,南京210096 [2]中航勘察设计研究院有限公司,北京100098

出　　处：《特种结构》2014年第3期48-54,共7页Special Structures

基　　金：江苏省自然科学基金资助项目(BK2011614);"十二五"交通运输重大科技专项(2011318494160)

摘　　要：为了准确描述大型沉井下沉到位前的回弹变形特征,对马鞍山长江大桥南锚沉井底部土体进行了6组压缩回弹的室内试验。借助于K_0试验仪,针对其卸载回弹再压缩的受力特征,分别对静止侧压力系数、回弹比率、回弹率、回弹模量与卸荷比R之间的关系进行回归分析,并与工程实测结果相对比。结果表明,当卸荷比大于极限卸荷比时,K_0值随卸荷比显著增大;当卸荷比大于0.8时,发生的回弹量约占总回弹变形量的60%;在相同卸荷比下,前期固结压力越大的土样,其对应的回弹率越大;随着卸荷比的增加,回弹模量则逐渐减小。对比结果显示,沉井内隔墙明显限制井底的回弹变形,沉井底部断面土体不能视作自由回弹。In order to describe the feature of resilience deformation before final sinkage of the caisson, six laboratory tests of compression resilience have been carried out on the soil from the bottom of south anchor of Ma ＇anshan Yangtze River Bridge. Regression analysis on the relationships between the coefficients of lateral earth pressure, rebound ratio, rebound rate, modulus of rebound and unloading ratio R have been performed and compared with in-situ data. The results indicate when unloading ratio is larger than limit unloading ratio, Ko will increase significantly. If unloading ratio is larger than 0.8, resilient modulus accounts for about 60% of total resilient modulus. Rebound rate is larger with larger consolidation pressure. And resilience modulus decreases with increase of the unloading ratio. The comparison results show： caisson within the partition significantly restrict the rebound deformation of the bottom soil, the caisson bottom soil can not be regarded as free rebound.

关 键 词：大型沉井 回弹量 卸荷比 终沉 

分 类 号：U443.131[建筑科学—桥梁与隧道工程]