Study On Creep Characteristics Of Residual Slope Soil With Different Rock Content

In this paper,a residual slope soil in Western Henan Province is taken as the research object.The residual slope soil occurs in the loose material of Quaternary system and is formed by the erosion and transportation of rainwater.The stone content in different parts of the landslide is uneven because of the natural weathering of rainwater erosion.Creep failure of residual soil is not easy to attract the attention of engineers.It is a process of increasing deformation of landslide body with the increase of time.It has great destructive force,so we must pay attention to it.In order to better study the creep deformation mechanism of residual slope soil,it is necessary to study the creep characteristics of residual slope soil with different stone content.In this paper,laboratory tests are mainly used to study the effect of rock content on creep deformation in combination with field geological survey.Four groups of strain-time creep curves with different stone content were studied by direct shear creep tests under the same consolidation pressure,and creep curves were fitted by component creep model and empirical creep model respectively.Creep models of residual soil with different stone content were established.Long-term strength of four groups of samples with different stone content was solved by solving method of long-term strength.The influence of stone content on the long-term strength of residual soil is analyzed.The main contents of this paper are as follows:(1)Sampling the residual soil on site and taking it back to the laboratory for basic tests to obtain the corresponding performance parameters.Four groups of different stone content(10%,30%,50%,70%)were allocated in the laboratory to carry out direct shear tests.Three kinds of direct shear tests under different consolidation pressures are adopted.The experimental results show that the instantaneous shear strength increases with the increase of consolidation pressure,which indicates that the consolidation pressure increases and the confinement force on the specimen increases,and ultimately leads to the increase of the shear strength.During the shear process,the movement of particles is mainly horizontal slip,accompanied by vertical dilatancy deformation.(2)Direct shear creep tests of four groups of specimens with different stone content under the same consolidation pressure were carried out,and the creep curves of specimens with different stone content under graded loading were obtained.According to Chen's loading theory,the corresponding creep curves were constructed.According to the creep curve of the specimens,it can be known that the residual slope soil undergoes four creep processes: initial creep,attenuation creep,constant velocity creep and accelerated creep.The creep deformationof the initial creep reaches more than 60%,and the creep deformation of the specimens varies with the change of stress.The stress-strain isochronal curves of the specimens show a tendency of coincidence before gradual dispersion.(3)The component creep model and empirical creep model are used to fit the creep curve of the specimen,and the corresponding model parameters are solved.Singh-Mitchell model is used to fit the creep curves of specimens with different stone content.The results show that the Singh-Mitchell model is effective in fitting the creep curves under low stress,and vice versa.At the same time,Burgers creep model has also achieved good fitting results.(4)The creep rates of four groups of specimens with different stone content are calculated and the corresponding creep rate-stress isochronal curves are established.According to the theory of long-term failure criterion of residual slope soil,four groups of long-term strength with different stone content are determined.According to the results,it is known that the stone content of the sample has an important influence on its long-term strength.When the stone content increases,the long-term strength of the sample is also increasing.