| The research on the compressive strength and creep characteristics of frozen soil has always been an important research topic in the field of frozen soil.Because the mechanical properties of frozen soil are more sensitive to environmental temperature,water content,load state,soil type,freezing time and other factors,its strength characteristics and creep development law are more complex and changeable.The traditional constitutive model of molten soil can not consider the influence of temperature,moisture content and other factors.When the external environment changes,the model will no longer be applicable.Therefore,it is of great significance to study the strength characteristics and creep development law of frozen soil under different temperature,moisture content and other influencing factors,and to establish the corresponding constitutive model of frozen soil to guide the design and construction of projects in cold regions.The uniaxial compressive strength test and uniaxial compression creep test of frozen remolded clay under different temperatures(-5 ℃,-10 ℃,-15 ℃)and moisture content(12%,14%,16%,18%,20%)were carried out with Xi’an clay as the research object by combining indoor mechanical test,ultrasonic flaw detection test,numerical simulation and theoretical analysis,The evolution mechanism of crack growth during creep loading is analyzed,and the corresponding constitutive model is established.The main research contents and achievements are as follows:1)The influence of temperature and water content on the strength of frozen clay is analyzed.It is found that the strength of frozen remolded clay increases with the decrease of temperature,which is approximately linear;With the increase of water content,the strength first increases and then decreases,and the maximum strength is obtained under the condition of 16% water content,which is approximately a quadratic parabola;Finally,the theoretical formula of frozen clay strength is established by least square regression analysis.2)Based on the rock micro element strength theory of Weibull distribution,a damage constitutive model that can describe the full stress-strain curve of frozen remolded clay under uniaxial compression is established,and the model parameter change rule under different temperatures and water content is analyzed.A uniaxial damage model considering the effects of temperature and water content is established.The simulation results are verified by the test results,and it is found that the model simulation results are good.3)The factors influencing the creep behavior of frozen remolded clay were studied from three angles of temperature,moisture content and loading stress grade.Carry out uniaxial compression creep tests under three loading stress levels of 0.3,0.5 and 0.7,and analyze the influence of various factors on the creep development law of frozen remolded clay in combination with the test result curve.4)The empirical creep model proposed in Physical and Mechanical Properties Test of Artificial Frozen Soil is introduced.Based on the linear relationship between the logarithm of strain and time under various negative temperatures and different stress levels,a process of determining model parameters based on analytical method is proposed and verified by the creep test results.5)The accelerated creep development behavior of frozen clay is analyzed from the perspective of damage evolution,and ultrasonic flaw detection is carried out to explore the damage development law in the creep loading process of different load levels;According to the damage test results,the creep time dependent damage function is introduced into the model,and the creep damage model of frozen soil is established;Comparing the test value with the predicted value of the model,it is found that the model can better describe the accelerated creep behavior of frozen clay.Figure[29] Table[10] Reference[85]... |
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