Research On The Law Of Long Arm Horizontal Freezing And Natural Thawing In Soft Ground Ends

In the launching and receiving construction of the shield method, weak water-rich layer of shield end is often affected by the surrounding environment and formation conditions under complicated conditions. Conventional ground reinforcement scheme can not be implemented, the long arm of cup type horizontal freezing method can solve this problem very well, this reinforcement scheme can effectively prevent the inflow of water and sand phenomenon in shield launching and receiving process. The application of freezing method is more and more widely used in the reinforcement engineering of the shield originating and receiving end, by researching on freezing wall temperature field of cup type level, it can provide a theoretical basis for the key construction links of shield launching and receiving process; On the other hand, the long arm of cup type horizontal freezing due to freeze the larger range to improve the stability of soft soil stratum, a wide range of phenomena that occur thaw settlement would cause harm to the surrounding buildings and ground during the natural thawing period, this requires a more in-depth study of the spatial distribution of temperature field during the thaw period.The eastern end of the right line receiving engineering head shield adopted the long arm of cup type horizontal freezing scheme in Jimingsi subway station of Nanjing Metro line 4. The law of temperature field of long arm of cup type freezing wall have been got through the study of the field measured temperature, and used the finite element software to simulate the actual engineering of freezing temperature field. By comparing the measured temperature and the temperature of the simulation analysis, Verifying the rationality of the numerical calculation. Comparative analysis of natural thawing temperature spatial distribution of undisturbed soil in winter and summer, and natural thawing temperature of cement soil in summer to master the thawing rate and the completion time of the frozen soil under different conditions.Through the natural thawing research shows: For natural thawing temperature of undisturbed soil in winter and summer, and natural thawing temperature of cement soil in summer. In the direction perpendicular to the shield machine, The ratio of thawing time of 0.5 meters inside of the axial plane was 3:1.8:1, the ratio of thawing time of the axial plane was 2.4:1.7:1,the ratio of thawing time of 0.5 meters outside of the axial plane was 4.5:3.2:1. In the direction parallel to the shield machine, the ratio of thawing time of 0 meters away from the portal was 1.8:1.4:1, the ratio of thawing time of 3 meters away from the portal was 2.3:1.7:1, the ratio of thawing time of 6(9) meters away from the portal was 2:1.7:1, the ratio of thawing time of 12 meters away from the portal was 1.6:1.4:1.