| The "Belt and Road" initiative has benefited the northwest and has driven the economic development of the region to a large extent.However,in the loess area of the northwest,there are usually a large number of ravines,and high-fill projects came into being.At present,the research on high fill mainly focuses on the main consolidation settlement.However,this type of the project has a long service life,and its post-construction settlement is often one of the important factors affecting the safety of the upper building.Research.At present,the relevant theories are mostly based on one-dimensional consolidation creep tests,and the triaxial creep characteristics and theoretical studies under high stress conditions in loess areas are relatively scarce.In this paper,taking the high-fill soil of an airport in Gansu as the research object,the law of soil creep under different conditions is studied by the combination of triaxial creep test and theory.The specific contents are as follows:(1)Setting a certain degree of compaction and gradient of confining pressure,the influence of different factors on the soil strength was studied by carrying out triaxial compression tests on remodeled soil samples under different conditions.Effectively enhances the soil strength;in the stress-strain curve,the greater the confining pressure,the more obvious the degree of hardening,when the compaction degree is 0.90,and the confining pressure is from 500 kPa to 1000 kPa,the peak stress increases the most;the deviatoric stress rises stress rapidly in the axial direction.To the first 5%of the strain,and then the soil strength increases slowly until it is stable;the smaller the compaction degree,the more obvious the effect of confining pressure on the soil strength.(2)In order to study the influence of different factors on the creep characteristics of remodeled loess,triaxial creep tests were carried out under different compaction degrees and confining pressure conditions.Large deformation occurs rapidly in time,that is,instantaneous deformation;with the increase of confining pressure or the decrease of compaction degree,the instantaneous deformation will gradually increase,and the total amount of creep deformation will also gradually increase;when the soil sample compaction degree when the confining pressure is 0.96 and the confining pressure is 1000 kPa,the instantaneous deformation of the soil sample under the first-level load is about 0.8%;when the confining pressure is 1500 kPa,the instantaneous deformation corresponding to the first-level load is about 2.2%;when the confining pressure increases When it is large,the creep deformation stabilization time gradually increases;when the compaction degree increases,the total creep deformation decreases gradually,and the creep stabilization time gradually shortens,but the change range is small.(3)Combining the Singn-Mitchell creep model and the Mesri creep model,the functions representing the stress-strain and strain-time relationships in the two creep models are modified to obtain a self-built empirical model suitable for Gansu high fill engineering;Based on the Burgers creep model,the model parameters are identified according to the test data,and the creep model considering the soil pressure compaction degree under different confining pressure conditions is established.The two models were verified by data that did not participate in the model establishment,and the applicability of different models was obtained.(4)Taking the actual high-fill project as the background,divide the project site into regions,carry out the creep deformation calculation for different regions,and obtain the time required for the final creep deformation amount and deformation rate to reach the stable standard in each region;orthogonal analysis of the influencing factors is carried out to determine the important factors and secondary factors,and based on this,the corresponding construction suggestions in the filling project are given. |
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