Research On The Mathematical Model And Calculation Of The Artificial Frost-thawed Soil Foundation Of The Primary Well In Liuzhuang Coal Mine Of Huainan

With some advantages like enhancing soil strength, decreasing permeability and adapting various environmental cases, the artificial ground freezing has already been applied extensively in various kinds of the engineering which are difficult to practice with common construction ways. The Liuzhuang Coal Mine of Huainan, whose primary well adopted artificial ground freezing method to dig, and then to thaw the foundation artificially and to construct the pile foundation, therefore, after the process of frost and thaw, the physical and mechanical properties, thermal field and stress field of the foundation soil have changes a lot. This paper combined laboratory tests, site observation, theoretical analysis and the numerical simulation, to analyze systematically the changes of the temperature, the stress and the bearing capacity in the artificial frost-thawed soil. Conclusion can be drawn out as:(1) According to the laboratory tests, to analyze the differences of the physics and mechanics properties in the artificial frost-thawed soil.(2) With integrating the various kinds of the standard formulas, to calculate the bearing capacity of single pile and the pile group, the negative skin friction and the settlement of pile foundation, then to check the result and to evaluate the stability of the pile foundation.(3) Based on the equations of heat exchange, the thermal field mathematical model is set up of the artificial frost-thawed soil, and on FEM got the moment heat exchange model to do numerical simulation and the refrozen analysis.(4) Based on the theory of soil moisture and heat, the frost heave and thawing settlement mathematical model is set up of the artificial frost-thawed soil, and the regress equations of frost heave and thawing settlement is set up by using of the regress theory.(5) Based on the soil constitutive function and destroy rule, the stress field mathematical model of the artificial frost-thawed soil is set up, the mathematical model of vertical bearing capacity is set up basing on the load transfer principle of pile-soil-cushion, and on FDM got the model basing on the relation among pile-soil-cushion and to do numerical simulation.(6) To analyze the influence of the various kinds of soil parameter on the stress field and ultimate bearing capacity of the pile foundation, and to compare the results of the simulation and the calculation with the site observation, and then to testify the feasibility of the numerical simulation, and offer the reference to the similar engineering for the future.