Research On The Dynamic Characteristics Of The Solidified Lightweight Soil Of Alkali Waste Under The Rotation Of The Principal Stress Axis

During the production of soda ash by ammonia-alkali process,a large number of alkali dregs piled up,which occupies a large amount of land resources.The new solidifying agent and foaming agent developed by ourselves are used to cure the alkali slag for light weight,so that large quantities of waste alkali residue can be consumed quickly and safely.At the same time,the solidified lightweight soil has the requirements of high strength,low density and safety,which can be used for the roadbed of road engineering as filling material.Under the cyclic action of traffic load,the subgrade soil often produces the characteristics of accumulated deformation and strength attenuation,which leads to the disasters such as excessive deformation and instability.Therefore,it is of great social significance to carry out the experimental study on the dynamic characteristics of the solidified lightweight soil of alkali waste under the condition of rotation of the principal stress axis.Based on the basic physical and mechanical properties tests,the dynamic characteristics of the solidified lightweight soil of alkali waste under the condition of rotation of the principal stress axis are explored.The main results are as follows:（1）The solidified lightweight soil of alkali waste is prepared by means of light curing technology,then the optimal material ratio of solidified lightweight soil is obtained through orthogonal test.The density of solidified light soil is 1.24g/cm³under the optimum ratio.The curve of its axial stress-strain relation shows strain softening.After 28 days of curing,the unconfined compressive strength tends to be stable basically.The e-log p curve of solidified lightweight soil has obvious structural yield inflection point.And its permeability coefficients are between1.1×10^-4～1.8×10^-5 cm/s,which are much larger than soft dredger fill of Tianjin Binhai.（2）The traffic loading may cause the principal stress of solidified lightweight soil constantly rotation during the road operation period.By means of the GCTS Hollow cylindrical torsional apparatus,the feasibility of loading method of principal stress rotation under the condition of constant orientation angle of principal stress is verified,in order to simulate the stress path variation of subgrade soil element under traffic loading.（3）In the process of increasing the orientation angle of principal stressαfrom 0°to 90°,the axial strain of solidified lightweight soil underwent the test process from compression to tension,and the development rate of generalized shear strain is significantly accelerated.The characteristics of cumulative vertical strain and dynamic springback of the solidified lightweight soil under different cyclic stress ratios are deeply analyzed whenαequals to 0°and 90°,thus the relationship between the vertical springback modulus of the solidified lightweight soil and the cyclic vibration times is established.Under the same cyclic vibration times,the amplitude of generalized shear strain increases with the increase of orientation angle of principal stress,intermediate principal stress parameter and density,while decreases with the increase of vibration frequency.（4）The influence of the orientation angle of principal stress,the intermediate principal stress parameter,the vibration frequency and the density on the change rule of dynamic strength of solidified lightweight soil under the condition of rotation of the principal stress axis are emphatically studied.Through the single variable method,the functional relations between the dynamic strength of specific failure times and each factors are established respectively.（5）There is a critical yield strain in the cyclic coupled shear process of the solidified lightweight soil,and its range is not changed by the initial stress condition and the vibration frequency of cyclic loading.By analyzing the influence rule of the orientation angle of principal stress,the intermediate principal stress parameter,the vibration frequency and the density on tangential stiffness,the attenuation model of tangential stiffness of solidified lightweight soil is constructed.