顶管穿越大堤引起的土体沉降变形及稳定性研究  

Soil Deformation and Stability Caused by Pipe Jacking Crossing Levee

作　　者：吴跃东[1,2] 卞安琪 刘坚[1,2] 赵为豪 WU Yuedong;BIAN Anqi;LIU Jian;ZHAO Weihao(Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210098,China;Geotechnical Research Institute,Hohai University,Nanjing 210098,China;Wenzhou Dexin Oujing Real Estate Co.Ltd.,Wenzhou 325100,Zhejiang China)

机构地区：[1]河海大学岩土力学与堤坝工程教育部重点实验室,南京210098 [2]河海大学岩土工程科学研究所,南京210098 [3]温州德信瓯景置业有限公司,浙江温州325100

出　　处：《河南科学》2023年第2期217-224,共8页Henan Science

基　　金：中央高校基本科研业务费(B210202034)。

摘　　要：为研究顶管穿越大堤引起的土体沉降变形及稳定性变化规律,依托南京高淳渔歌-古柏π入淳西变220 kV电缆工程顶管项目,通过对比魏纲修正公式计算值、现场监测数据和MIDAS-GTS模拟结果,分析了横纵向地表及不同深度地层的沉降变形方式.结合瑞典条分法推导了大堤在天然工况、顶进未支护及推管注浆三个施工阶段的安全系数计算公式,与数值分析得到的模拟值进行对比,并分析其变化规律.研究表明:顶管施工过程中,距轴线约10倍洞宽范围内的横向地表均受不同程度影响,顶管轴线纵向地表呈现出逐渐隆起、匀速沉降、反复回弹沉降和沉降稳定的变形趋势.在地层隆起阶段,隆起量随埋深增大,深地层隆起时间较长;在地层沉降阶段,各地层沉降速率和沉降量随埋深增大,沉降速率约3.0~7.0 mm/d.条分法与数值模拟得到的大堤安全系数较为相近,它在开挖阶段有所降低,推管注浆后明显回升,其变化幅度随顶程增加而逐渐减小,隧道贯穿完成注浆后大幅度回升至略小于天然工况下初始值.In order to study the law of soil deformation and stability caused by pipe jacking crossing levee,we take the 220 kV line(cable part)pipe jacking project of Nanjing Gaochun Yuge-Gubai Substation as case study. The paper compares the calculated values of Wei Gang’s modified formula,actual monitoring results and MIDASGTS simulated results,to analyze the longitudinal,transverse surface settlement and deformation laws of different depths. The formulas of safety factor of levee are deduced in three different stages,which are original natural condition,excavation unsupported condition and grouting reinforced condition,then the change law of the safety factor is obtained by comparing the simulated values with theoretical results. The results reveal that during pipe jacking construction process,the main transverse disturbance range of soil is about 10 times of the tunnel width. The longitudinal surface of the pipe jacking axis shows a trend of gradual uplift,uniform settlement,repeated rebound settlement and stable settlement. During the uplift stage,the uplift volume increases with the buried depth,the deep soil layers maintain longer uplift period. During the settlement stage,the rate and amount of each layer increase with the buried depth,and the rate is about 3.0-7.0 mm/d. The safety factor of the levee is the smallest when digging the soil of the first pipe,it decreases during the excavation stage and rises obviously after pushing pipe and grouting,the amplitude of the change gradually decreases in jacking process. When construction is achieved,the safety factor rises significantly to slightly less than the value in original natural condition.

关 键 词：顶管穿越大堤 土体损失 沉降 变形 稳定性 数值模拟 

分 类 号：TU433[建筑科学—岩土工程]