Research On Frost Heave Distribution Of Seepage Ground During Horizontal Freezing Construction Of Subway Tunnel

As a special stratum reinforcement technology,artificial ground freezing method has been widely used in subway tunnel construction project.During the construction period of the subway tunnel level freeze,the freeze wall would delay or difficult to develop if the seepage stratum is encountered,which speed of flow is big.It follows that the groundwater seepage flow has great effect on the distribution of freezing temperature field,then creating influence greatly on the freezing of the ground during the construction periodTherefore,this study takes the Subway tunnel level freeze project as object,the numerical simulation method was adopted to research the ground,distributed laws of freezing temperature field and cold air displacement fields under the effect of groundwater seepage,the main conclusions of the research are as follows:(1)Three kinds of groundwater seepage flow velocity(Om/day?1m/day and 2m/day),frozen pipe spacing(0.8m?1.15m and 1.25m),frozen pipe Diameter(194mm?219mm and 245mm),and frozen pipe wall temperature(-23??-25? and-27?)were taken into consideration and the single-factor typical parameter method was used to design the numerical and simulate scheme.Taking advantage of the Comsol Multiphysics finite element software,the ground of freezing temperature field and distributed laws were studied based on the flow and temperature of the coupling mathematical models.The results show that the groundwater seepage flow velocity has great effect on the development speed of the freezing frontal area under the same condition,both within and outside the wall,while the influence is small on frozen pipe spacing?diameter and wall temperature.Meanwhile,under the action of seepage,the leakage current of the upstream wall of freezing the development speed is significantly smaller than the downstream freezing wall.(2)The Comsol finite element model was inducted into the Abaqus finite element software by the Hypermesh software,Five kinds of groundwater seepage flow velocity(Om/day?0.5m/day?1m/day?1.5m/day and 2m/day),three kinds of tunnel burying depth(11m?13m and 15m)were considered on the basis of water hot coupling by Comsol software.Then,considering the orthogonal anisotropic deformation characteristics of permafrost,the thermal coupling analysis method of sequence was used to research the distributed rule of cold air displacement fields based on the re-development technology of Abaqus finite element software.The results indicate that under the transfusion function,the stratum vertical heave bias field present the asymmetrical distribution along the tunnel middle line,upstream the surface vertical heave displacement is smaller than the downstream the surface vertical heave displacement;with tunnel burying depth growing,the surface vertical heave displacement is smaller,under the same seepage velocity,the tunnel burying depth can not affect the surface heave peak value the occurrence position.The research results of this paper have certain reference value and significance to the design and construction of the horizontal freezing project of the seepage ground subway tunnel.Figure 62 table 11 reference 55...