Study On The Structural Characteristics Of The Ice Water Accumulation Body And Its Control On Deformation In Huanxi Village

A large number of Quaternary ice-water deposits are developed on both banks of the upper reaches of the Minjiang River,showing complex sedimentary structural characteristics.It is important to identify the structural characteristics of such kind of ice-water deposits and the control effect of the structure on the deformation of the deposits for the local geohazard prevention and project construction.By multiple on-site investigations and sampling of the ice-water deposits in Huanxi Village of Li County,identifying the macro-structural and deformation characteristics of the deposits,based on the window statistics,fractal theory,and image recognition technology,the quantitative analysis on the microstructure of the ice-water deposits in Huanxi Village was carried out in this paper.Moreover,By measuring the force strength of the deposits through the shearing tests and stimulating and verifying the relationship between the deposits deformation and deposits interface through Particle Flow Code(PFC2D),the results are as follows:(1)The ice-water deposits in Huanxi Village is mainly composed of silty clay,breccia and crushed stone soil.The content of fine particles in soil decreases with elevation decreasing,and the content of coarse particles increases with elevation decreasing.It can be divided into 5 large layers,(1)silty clay layer,(2)silty clay-crushed soil layer,(3)silty clay with breccia-crushed soil layer,(4)corner Gravel soil-block gravel soil layer,(5)block gravel soil layer,according to the order of elevation from high to low:(2)There are a large number of smooth sedimentary interfaces exposed on the surface of the deposit,where shows many obvious signs of deformation and destruction.The roughness,attitude,free space conditions of the sedimentary combination of the upper and lower layers of soil play a controlling role in the deformation of the ice-water deposits in Huanxi Village.(3)According to the fractal theory,it is concluded that there are many thick and fine alternating layers of ice water deposits in Huanxi Village;through windowing statisticscombined with image recognition technology,the contour shape of the particles increases firstly and then decreases as the particle size increases.The whole trend is long-strip shape and the roughness shows good self-similar characteristics.Considering the size effect,the rock content of ice-water deposits in Huanxi Village alternates between 16-24% and increases with the decreasement of elevation.The main arrangement direction of particles(Long axis direction)is 345-355°,which is arranged along the slope.(4)Through the medium-scale shear test,the shear strength of the soil at the sedimentary interface and non-sedimentary interface was obtained.The sedimentary interface is highly sensitive to water,comparing with the natural state,the cohesion of the two sedimentary interfaces in the saturated state is reduced by 56.91% and 40.68%,and the internal friction angle is reduced by 23.93% and 23.44%.The force is reduced by 32.34%,and the internal friction angle is reduced by 22.98%.(5)The generalized model of the accumulation body was analyzed by PFC2 D.The results showed that : the accumulation body did not undergo overall destabilization and destruction under the action of rainfall,plastic deformation occurred at the part of the sediment interface,and the whole was not penetrated;many deformation areas under the earthquake were basically Through,there is a phenomenon of sliding failure.(6)The control effect of the structure on the ice-water accumulation in Huanxi Village is mainly the sedimentary structure and its meso-structure characteristics.Sedimentary interface is the main controlling factor for the deformation of ice-water deposits.Its lower shear strength reduces the overall mechanical properties of ice-water deposits.In the meso-structure,the greater the difference in the relative content of the block stones in the upper and lower layers of soil,the deformation The more obvious,and the expansion has the phenomenon of rock-rolling.The direction of deformation expansion is controlled by the outline shape and orientation of the block stones.The more regular the particle shape and the more blocks along the slope,the easier the ice water deposits to deform.