摘 要

   随着深基坑工程的增多，隔离桩被广泛应用于深基坑围护结构中，用以隔离土压力的传递，减少基坑施工过程中对周边建筑物的影响。但在实际工程中，往往只注意到隔离桩对土体侧向压力的隔离，忽视了隔离桩施工过程中对土体的扰动，以及引起的周边建筑物沉降和后续施工影响。因此，工程施工中需要量化隔离桩施工对周边土体的扰动影响程度。

   本文首先对隔离桩施工引起土体扰动的机理进行阐述，介绍当前几种桩施工引起土体扰动的预估理论和计算方法；接着，从桩入土深度和土的性质等角度探讨隔离桩施工中引起土体扰动程度的影响因素，选取武汉轨道交通二号线一期工程循礼门站和武汉轻轨为研究对象，结合经验法和圆孔扩张理论，分析隔离桩施工引起轻轨桥墩沉降的影响因素；在此基础上，对隔离桩施工引起轻轨桥墩沉降的监测数据进行分析；最后，结合监测数据，通过有限元数值计算，模拟扰动过程，并对影响因素进行敏感性分析，论证特殊情况下基坑施工设置隔离桩合理性，并根据隔离桩施工的扰动影响提出相应的解决措施，降低因隔离桩施工所带来安全风险机率，确保项目的正常运行。

   本文总结了减少隔离桩施工对土体扰动的控制方法，具有较强的实用性，为隔离桩的设计和施工控制提供参考。

关键词：隔离桩  土体扰动  轻轨桥墩  仿真模拟  建筑物沉降  深基坑  地铁

Abstract

       Following  the  increase  of  deep  excavation  engineering,  partition  piles  were  widelyapplied to the buildingenvelope of deep foundation pit, to isolate the soil pressure and toreduce  the  influence  of  foundation  pit  to  surrounding  buildings  in  the  process  ofconstruction.  In  practical  projects,  however,  attention  is  only  payed  to  segregating  thelateral pressure of soil from partition piles, ignoring the influence of partition piles duringconstruction  processto  the  disturbance  of  soil  which  causes  the  displacement  ofsurrounding  buildings  and  the  subsequent  effects  of  constuction.  Under  suchcircumstances, project construction should be quantified the degree of disturbing influence of the partition piles to the peripheral soil in construction process.  

   Firstly,  this  thesis  elaborates  the  mechanics  of  soil  disturbance  caused  by  partitionpiles  in  the  process ofconstruction,  introducing  several  estimation  theories  andcomputational methods with regard to this problem currently. Then, the thesis explores theinfluencing  factors  of  soil  disturbing  degree  caused  by  partition  piles  in  the  process  ofconstruction from the angles of the depth of piles in soil and the properties of soil. Wuhanlight  rail  and  XunLiMen  station  of  the  firststage  project  of  the  line  two  of  Wuhan  railtranspotation  have  been  selected  as  research  objects.  With  the  combination  of  empiricalmethod and expansion theory of cylinder pore, the influencing factorsof the settlement ofbridges and light rails triggered by partition piles in construction process are analyzed infull explanation. On this basis, the monitoring data of the settlement of bridges and lightrails triggered by partition piles in construction process is analyzed. Lastly, the thesis setup a simulation model accordingly by combining the monitoring data as well as throughthe  calculation  of  finite  elements  numbers.  Additionally,  the  thesis  also  conducts  thesensitivity analysis  to  influencing  factors  and  demonstrates  the  rationality  of  settingpartition piles in foundation pits in constuction process in special situations. According tothe disturbance effects of partition piles in construction, a set of solutions are put forward to decrease safety and risk probability so as to ensure normal operation of the project.  

   The thesis has summarized the control method to reduce the degree of disturbance ofsoil impacted by partition piles under construction. The work I’ve done is of practicabilitywhich  could  offer  reference  to  the  design  of  partition  piles and  to  the  control  of construction.

Keywords: partition pile   soil disturbance   piers of light rails   simulation   building displacement   deep foundation pit   metro