局部渗漏地铁隧道地表长期沉降研究

Study on long-term surface settlement induced by partial leakage of subway tunnel

地铁隧道局部渗漏对地表长期沉降有较大影响。本文采用数值分析方法,将局部渗漏地铁隧道的衬砌等效为均质透水体,利用相对渗透性系数κ来反映其透水情况,对Abaqus软件进行二次开发,自编USDFLD子程序以实现相对渗透性系数κ随地铁运营时间的发展线性增大的条件,探究隧道局部渗漏程度随地铁运营时间的发展而加剧时,软土地区地铁隧道地表长期沉降发展的规律。结果表明,当κ由下限值随运营时间线性增加至上限值时,相应地表沉降值介于κ取上下限时的沉降值之间,且沉降值大小与κ取上限时的地表长期沉降值较为接近,相对渗透性系数κ越大时该特点越明显。沉降初始发展速率介于κ取上下限时的沉降初始发展速率之间,且地表最大沉降发展速率的衰减速度小于κ取上下限时的衰减速度。

Partial leakage of subway tunnel has a great influence on the long-term surface settlement.In this work,the numercial method is used to treat the lining of the subway tunnel with partial leakage as a homogeneous permeable body,and the relative permeability coefficient is used to reflect its water conductivity.The Abaqus software was redeveloped,and the USDFLD subroutine was used to achieve the condition that the relative permeability coefficient k increases linearly with the development of the subway operation time.As the partial leakage of the tunnel deteriorates with the increase of the subway operation time.The development of the long-term settlement of the subway tunnel in the soft soil area was studied.The results show that when k increases linearly from the lower limit to the upper limit with the increaseing operating time,the corresponding surface settlement is between the values when x takes the upper and lower limits,and the magnitude of the settlement is close to value obtained when x reaches upper limit.The larger the relative permeability coefficient x is,the more obvious is this characteristic.The initial rate of settlement is between the initial rate of settlement when takes the upper and lower limits,and the attenuation rate of the maximum rate of settlement is smaller than that when k takes the upper and lower limits.