Study On Mechanical Properties Of Seasonal Frozen Soil Based On A New Method Of Freezing And Thawing Water Supplement

Seasonally frozen area suffers from its special seasonal temperature changes.Subgrade soil undergoes periodic freezing and thawing cycles,causing some natural frost damage such as frost heave and thawing settlement of subgrade.Especially in the case of water supply,it will aggravate the degree of subgrade frost damage and weaken the soil.Intensity,the road produces uneven settlement,affects the safe driving and comfort of the road,and increases the investment in road maintenance and maintenance.However,the internal and external factors affecting the strength and mechanical properties of the subgrade soil in the seasonal freezing area are complex,and the interaction between the factors affects each other.Due to too many uncontrollable factors in the field test and low operability,the indoor simulation test is used to reflect the seasonal freezing Soil properties have become a universal method.The existing indoor seasonal frozen soil test is nothing more than a closed system and an open system.However,because the closed system has no external water supply or water discharge,the open system is directly connected to the external water source for replenishment,which often results in rapid saturation of the sample.Or oversaturated.In this paper,considering the actual freeze-thaw water replenishment method on site,it is found that the two replenishment methods are inconsistent with the freeze-thaw water replenishment method in the real natural environment.Therefore,a new method of seasonal freezing and thawing replenishment is proposed—one-way freeze-thaw natural replenishment method,and a test device is developed;an indoor seasonal frozen soil test is carried out based on the new freeze-thaw test method and the test device,and one-way freezing and thawing is analyzed.The characteristics of temperature changes during the natural replenishment test and the characteristics of water migration after freezing and thawing;and based on the triaxial UU test under the one-way freeze-thaw natural replenishment test method,the stress-strain of the sample after one-way freeze-thaw natural replenishment is given The characteristic changes of the curve,static strength and shear strength index;finally,the change characteristics of the stress-strain curve,static strength and shear strength index of the sample under different freezing and water supplement methods are compared and analyzed.The main research work is as follows:(1)Combining the shortcomings and deficiencies of the existing indoor simulated seasonal frozen soil test methods and devices,and considering the real freeze-thaw water replenishment methods in nature,a new method of freeze-thaw replenishment that is more in line with the actual on-site water replenishment method—one-way natural freeze-thaw replenishment method is proposed.In addition,the experimental device is developed,and the implementation of the new method and the composition and function of the device are given,which can more accurately simulate the actual freezing and thawing water supply conditions on site in the seasonal freezing area.(2)The indoor seasonal frozen soil test-one-way freeze-thaw natural replenishment test was carried out through the self-made test device,and the temperature change in the replenishing soil layer was monitored in real time by a temperature sensor,and the characteristics of the freeze-thaw temperature change were analyzed;the layered slicing method was used to compare the test.The water content of the soil layer at different heights of the sample and the water-filled soil layer is tested,and the characteristics of the water migration in the soil under the unidirectional freezing action are analyzed.(3)Based on the triaxial UU test under the one-way freeze-thaw natural replenishment test,the change characteristics of the sample stress-strain curve,static strength and shear strength index under different initial moisture contents and different confining pressures are given.(4)Considering different freeze-thaw replenishment methods: one-way freeze-thaw natural replenishment,one-way no replenishment freeze-thaw,three-way freeze-thaw,and the stress-strain curves,static strength and resistance of samples under different freeze-thaw replenishment methods are given.Shear strength index,comparative analysis of the influence characteristics of different freezing and water supplement methods on the mechanical properties of the sample.