考虑渗流作用和围岩损伤的地铁隧道下穿古运河区段变形分析

Deformation Analysis of Tunnel Section Crossing under the Ancient Canal Considering Seepage and Surrounding Rock Damage

目的:青岛地铁13号线香江路站至井冈山路站区间隧道下穿古运河,为确保该区间典型富水松散地层的施工安全,需研究地铁隧道施工对古运河的影响。方法:阐述了该地铁区间的工程概况,分析了土体的初始含水率、粒径及饱和度3个参数对渗流系数影响。开展室内试验,对富水松散地层中的非饱和渗流特性进行研究。对FLAC3D软件中内置的饱和渗流-应力耦合计算模块进行修正,并考虑围岩损伤后强度变化情况,得到改进型的渗流-应力耦合计算模块。将实测值和计算值进行对比,以验证改进型计算模块的合理性与有效性。将改进型计算模块运用于实际计算中,分析地铁隧道开挖对于古运河的影响。结果及结论:经验证,该改进型计算模块合理、有效;下穿古运河的隧道区间的渗流-应力耦合作用不能忽视;土体的初始含水率越大,其渗透系数也越大;隧道施工使得古运河整体下沉和部分结构扭转,需采取相应的施工保护措施。

Objective:The tunnel section from Xiangjiang Road Station to Jinggangshan Road Station on Qingdao Metro Line 13 crosses under the ancient canal,in order to ensure the construction safety of the typical water-rich loose strata,it is necessary to study the impact of subway tunnel construction on the ancient canal.Method:The project overview of the subway section is described,and the influence of initial moisture content,particle size and saturation three parameters on seepage coefficient is analyzed.A laboratory test is carried out to study the characteristics of unsaturated seepage in water-rich loose formation.The saturated percolation-stress coupling calculation module built in FLAC3D software is modified,and an improved one is obtained considering the strength changes of surrounding rock after damage.The measured and calculated values are compared to verify the rationality and validity of the improved calculation module.The improved calculation module is applied to the actual calculation to analyze the influence of subway tunnel excavation on the ancient canal.Result&Conclusion:It is proved that the improved computing module is reasonable and effective.The coupling effect of seepage and stress in the tunnel section under the ancient canal cannot be ignored.The greater the initial moisture content of soil,the greater the permeability coefficient.The tunnel construction causes the overall sinking of the ancient canal and partial structure twist,so the construction protection measures need to be taken.