Damage And Dissipated Energy Of Cement Modified Subgrade Filling In Cold Area

When the local soil quality cannot meet the strength requirements of the subgrade filling,choosing cement to stabilize the subgrade filling is an economical and effective solution.However,in seasonally frozen soil areas,subgrade soil not only has to withstand repeated vehicle loads,but also withstand frost heave and thawing erosion in early spring and winter.Therefore,the positive-negative temperature damage and load damage of subgrade fillings improved with cement Is very important.This paper carries out compaction test,positive-negative temperature alternate test,uniaxial compression test after positive-negative temperature,triaxial compressive test after positive-negative temperature,and stress-type alternate loading and unloading tests on cement stabilized roadbed fillers.,Discussed the positive-negative temperature damage characteristics of cement stabilized roadbed fillers,analyzed the law of energy evolution,and established a positive-negative temperature damage model.The specific content is as follows:Firstly,The cement stabilized roadbed filler under different curing time,cement stabilizer content and cooling negative temperature was subjected to uniaxial compression test after positive-negative temperature and triaxial compression test after positive-negative temperature.From the phenomena observed in the experiment,it can be seen that the changes in the number of positive-negative temperature cycles,the compressive strength under various ambient pressures and various health-preserving periods all show a trend of first decreasing and then increasing.experiencing a positive-negative temperature alternation.The decrease in the ability of resisting pressure of the sample is the most obvious.The curing time,cement stabilizer mixing amount and negative cooling temperature within a certain range do not interfere with the influence trend of positive-negative temperature alternation on the maximum stress that the test block can withstand,but change the degree of influence that interferes with positive-negative temperature alternation.Then,alternate loading and unloading tests were carried out on stabilized soil samples under different ambient pressures and alternating times of positive-negative temperature,and the failure process and dissipation energy of cement stabilized roadbed filler under the interaction of positive-negative temperature damage and load damage were explored.The evolution process.The experimental study found that:under the same deviator stress conditions,compared with the samples that have not undergone the positive-negative temperature alternation,the stabilized soil samples that have experienced the positive-negative temperature alternation have greater dissipation energy,and with the positive-negative temperature alternation The number of negative temperatures increases with the increase.The change of dissipated energy can well reflect the damage evolution law of cement stabilized subgrade filling and subgrade filling during the destruction process;and when the cyclic load is 10%-30%of the damage load,it is very important to consider the influence of positive-negative temperature alternation.necessary.Based on the above research on the positive-negative temperature damage characteristics and energy dissipation of cement stabilized roadbed fillers,a positive-negative temperature fatigue damage model of cement stabilized roadbed fillers is established on the basis of continuum damage mechanics.The establishment of the model is mainly based on the observation of the mechanical properties of cement stabilized roadbed fillers under positive-negative temperature alternating conditions,the energy evolution in the failure process of the stabilized soil,and the use of damage variables to construct the positive-negative temperature fatigue evolution equation of cement stabilized roadbed fillers.Finally,the established model is verified through indoor experimental data and previous experimental data.It has been verified that the damage model can well reflect the fatigue damage propagation law of cement stabilized subgrade and filling subgrade under the alternating action of positive and negative temperature.In addition,a formula for predicting,provides a favorable reference for the evaluation of the service performance of cement stabilized subgrade fillers in seasonal freezing areas.