Model Experiment On Horizontal Frost Heave Force Of Underground Continuous Wall At Seasonal Frozen Soil Area

A large number of deep foundation pit projects in China's deep-season permafrost areas face serious threats of frost heave and thawing.However,there are few research results on the problem of 2D frost heaving.The lack of effective technical solutions to the effect of the frost heaving of the underground continuous wall support system in the deep season frozen soil area in the 2D freezing process has led to some overwintering deep foundation pits.The specification requirements were met,but the support system still experienced serious frost heave deformation problems.At this stage,there is an urgent need to conduct a corresponding experimental study on the horizontal frost heave force of the underground continuous wall in the deep-season frozen ground area.In this paper,with the support system of underground continuous wall in deep-season frozen soil area as the research object,the two-dimensional frost heave model test system was independently developed by means of similar physical simulation test.The frost heave deformation of the soil caused by frost heave during the wintering of the underground continuous wall foundation pit and its interaction with the support system were completed.The evolution law of the soil temperature and moisture fields during the freezing process was measured.The support system The comprehensive test parameters such as the stress and deformation of the concrete are analyzed by taking the frozen soil and the supporting structure as the interaction as a whole,and the following main conclusions are obtained:(1)The lower the freezing temperature,the greater the temperature gradient,the faster the corresponding freezing front advances,and the greater the freezing depth at the end of freezing.Under the same freezing temperature condition,the test with water replenishment condition ends when the freezing depth is less than the test without water replenishment condition.(2)The lower the freezing temperature and the condition of water supply,the faster the horizontal frost heave force increases and the greater the final horizontal frost heave force value.The maximum horizontal frost heave force measured by the test is far greater than the standard design value.(3)The lower the freezing temperature,the earlier the initial frost heave and the faster the growth rate of frost heave,but the smaller the final horizontal frost heave.For the test with water replenishment conditions,the final frost heave amount is greater than the test without water replenishment under the same conditions.(4)The unfrozen water content is directly related to the development of frozen depth.When the freezing front advances to the influence range of this position,the unfrozen water content starts to change drastically,and a steep drop occurs;with the increase of freezing time,the rate of decrease of unfrozen water content gradually slows down,and the unfrozen water content slowly enters a stable stage,And the time to reach the stable stage is earlier than the temperature field.