| The permafrost in the high latitude and cold island permafrost area of Northeast China has high ice content,thick permafrost layer,high ground temperature,obvious degradation and poor thermal stability,which is disturbed and sensitive by engineering construction,so it is difficult to construct.Although some measures have been taken in many highways,such as composite foundation,thermal insulation,hot rod cooling and so on,some effects have been achieved,but different diseases still appear due to the complexity of island frozen soil in this area.Therefore,it is very important to study the engineering performance and control measures of frozen soil in this area.In this paper,taking the permafrost of Zhangling Xilinji section of Jingmo highway as the research object,the engineering performance and control scheme of high latitude and high cold island permafrost are studied.First of all,through on-site investigation and investigation,the main unfavorable geological types,frozen soil environment and distribution of frozen soil in this area are analyzed.It is concluded that the frozen soil foundation site in this test section is unstable and the suitability of road construction is poor,so the road can not be built directly.Secondly,through the indoor test of the frozen soil samples,the category of frozen soil is defined.Combined with the outdoor observation data,the frost heave and thaw settlement analysis is given for different soil layers.It is concluded that the engineering performance of the foundation soil in this test section is poor,and other engineering measures need to be removed or taken.Then through the embedded temperature sensor before the construction,the temperature change rule of the undisturbed frozen soil before the construction of the frozen soil foundation and the frozen soil after covering the sand gravel layer is analyzed,and the influence rule of the surface temperature on the temperature distribution of the undisturbed frozen soil is obtained,which provides the basis for the direct burial and replacement of the frozen soil treatment scheme.Finally,combined with the engineering performance of frozen soil in this test section,the comparison and selection of three treatment schemes.namely,direct filling,replacement of gravel and pile raft,are carried out,and the pile raft is more suitable for this test section.The feasibility of the pile raft is analyzed and the bearing capacity of the foundation pile is verified by the finite element method,which provides a reference for the treatment of foundation diseases in the high latitude and cold island frozen soil area. |
