【作者】 段超杰；

【导师】 李兴高；

【作者基本信息】 北京交通大学 ， 桥梁与隧道工程， 2011， 硕士

【摘要】 近年来地铁施工中管线渗漏诱发的工程事故频繁出现。究其重要原因如下,给排水管线往往存在初始渗漏,管道内水外渗使地层饱和,弱化土层的力学性质；同时施工扰动加大饱和土层变形和管线渗漏；管线渗漏和扰动土层相互作用导致地层塌陷和管线破裂。本文采用理论分析、数值模拟、工程实例应用等手段相结合,研究地铁施工中管线渗漏对隧道周边地层变形的影响。研究主要采用两阶段分析法：第一阶段,研究管线渗漏周围地层中的渗流场分布规律,主要采用数值方法研究水土特性函数、给水压力、管线位置对管线周围渗流场分布的影响；第二阶段,研究存在管线渗漏情况下,地铁施工隧道周围地层的变形规律,主要分析了不同位置的管线渗漏情况对隧道开挖导致地层变形的影响。最后,结合天津地铁二号线工程实例,对地铁施工中管线渗漏影响隧道开挖和地层变形的结果进行了预测分析,并建议了相应控制措施。研究主要取得了以下成果：(1)土层饱和状态渗透系数Ksat影响管线渗漏范围,同时随着饱和渗透系数的增加渗流速率也增加,达到渗流稳定的时间缩短,文中给出了Ksat与管线渗漏影响范围的关系表。(2)管线渗漏情况下,渗漏水影响范围随着管线给水压力增加而增加,在水土特性函数确定的情况下,管线渗漏水压力与影响范围大致成指数关系。在排水管线中,渗漏范围不随管线渗流量变化而变化,渗流量的改变只会影响土层中渗漏达到渗流稳定的时间。(3)讨论了管线与隧道之间六种位置关系(管线与隧道平行时在隧道正上方3m、2m、1.25m、在隧道上方2m偏右2m、在隧道上方2m偏右4m,以及管线与隧道垂直在隧道上方3m),管线渗漏水对隧道开挖地层变形的影响；分析了相应情况下管线渗漏水对隧道周围地层变形和塑性区分布以及地表沉降的影响。总的看来,管线距离隧道愈近,对地层变形的影响愈大。管线位于隧道正上方为最不利位置。(4)根据天津地铁二号线盾构下穿管线工程实例模拟分析管线未渗漏和发生渗漏两种情况下隧道开挖导致的地层变形,得出了：在管线与隧道相距8.4m情况下,管线渗漏水对隧道开挖基本没有影响；但隧道施工会对管线造成较大的影响,分析表明盾构隧道开挖时,管线底部沉降可达0.49m。由于工程实际中管线未发生渗漏,数值模拟地表沉降曲线与工程实际的地表监测基本上相一致。如果工程施工时监测数据出现有明显的增大趋势,就有可能是管线渗漏导致的地层变形加大。数值模拟分析管线渗漏情况的地层变形就是为了预测管线渗漏会产生危害,以便制定工程的监测方案和对管线的保护措施。更多还原

【Abstract】 In recent years, accidents happened frequently induced by pipeline leakage in subway constructions. Many accidents are caused by the inside water leakage to make the strata saturated, and the mechanics properties of weaken reduced soil.At the same time, the construction disturbance enlarged the deformation of the saturated soil and pipeline leakage. Then they interact with each other to lead to stratum collapsed and pipeline rupture. Based on the methods of theoretical analysis, numerical simulation and engineering examples in subway construction, this text research the effort of the pipeline leakage in the strata distortion in the subway construction.The thesis mainly adopt two phase analysis method. At the first stage, study the pipeline leakage in the soil, apply the numerical simulation to study soil characteristics function,water pressure, the law of location of pipeline leakage to the its effort; At the second stage, study the deformation of soil in subway construction where was leakage of the pipeline, mainly analysis of the impact on the tunnel when the position of the pipeline is different. At last, combined with the example of Tian Jin metro line 2 engineering to make a forecasting analysis about the effort of pipeline leakage in subway construction, to associated the engineering practice with the effort of pipeline leakage in the construction.This paper mainly got the following results:(1)the Ksat decided influence scope of pipeline leakage,with the increase of saturated seepage coefficient,the penetration range increased、the rate of seepage flow increased and the time to reach stable seepage shortened.This text gives the table of the relation between the Ksat and the influence of the pipe leakage.(2)When the pipeline leakage, the extent of leakage of water pressure expand with the increase of the water supply pressure of pipelines.Their corresponding relation is not linear, but curvilinear. In flowing line, the range of leakage doesn’t change with the change of the seepage discharge in pipeline area. The change of the seepage discharge only can influence the time between leakage and steady seepage.(3) This text discusses the influence of pipeline leakage on ground deformation under six kinds of position relation between pipeline and tunnel(Pipeline parallel with the tunnel and 3m,2m,1.25m above the tunnel,2m above the tunnel and 2m right in the tunnel,2m above the tunnel and 4m right in the tunnel, vertical with the tunnel and 3m above the tunnel).It mainly analysis of tunnel excavation plastic zone、the change of the ground settlement under the condition of pipeline. The result shows that the closer between tunnel and pipeline, the greater impact on ground deformation. When pipeline located above the tunnel as the most disadvantageous position(4)Based on the simulation and monitoring data of the shield tunneling across pipeline of Tian Jin subway 2 line,it can be found that pipeline leakage will not have influence on tunnel working face under the condition that the pipeline are 8.4m apart from the tunnel; but tunnel construction will have serious influence on the pipeline that the soil beside the pipeline will distort seriously When the tunnel is excavated under the condition the pipeline leaks stably, the settlement of the bottom of pipeline can be 0.49m. In engineering program, pipeline leak did not occur, so the surface subsidence of numerical simulation was consistent with the monitoring. If the monitoring data increased obviously in the construction, it may be induced by the pipeline leakage. The numerical simulation of ground deformation caused by pipeline leakage was to forecast the possible dangers, so we can make the monitoring program in the project and protection of pipelines in advance.更多还原