Study On Creep Behavior Of Coarse Grained Soil And Its Application In Stability Analysis Of Slope With Gravity-type Anchorage Used In Dadu-river Suspension Bridge At Luding In Yaan-kangding Expressway Engineering

The coarse grained soil slope is common in road engineering in mountainous area.The engineering properties of coarse grained soil directly determine the stability of the slope.This paper relies on slope with gravity-type anchorage used in Dadu-river suspension bridge at Luding in Yaan-Kangding expressway engineering,through direct shear test and direct shear creep test on mechanical properties of coarse grained soil,analyzed the impact of particle size and moisture content on the creep properties,and then through the Flac3D numerical simulation this paper analyzed the long-term stability of gravity anchorage slope bridge.The main research work and results are as follows:(1)Conduct on-site sampling for coarse grained soil bridge anchor slope,based on the original soil samples prepared on 3 different gradation of coarse grained soil samples,using direct shear test and direct shear creep test reform of the mechanical properties of different test samples with different water content under the get the sample,the long-term shear strength about shear strength 0.7?0.8 times,the friction angle decreases about 2 degrees.(2)With the increase of the content of P5 particle diameter was greater than 5mm,the sample long-term cohesion c? value decreased gradually,the long-term internal friction angle ?? value increased gradually with the similar change of shear strength indexes of the ordinary direct shear test.Soil moisture content decreased from 10%to 5%,?? value increased by about 2 degrees,c? value increased by about 30%.(3)Using the Matlab program to test the soil sample creep curve fitting,accord with the basic characteristics of Burgers model.The samples of Maxwell and Kelvin unit shear modulus and viscosity coefficient calculation and analysis,the influence of stress of the specimen under the action of P5 on the initial shear modulus Gi,shear modulus G2,viscosity coefficient ?1 and the coefficient of viscosity of ?2 under different vertical pressure and shear.With the increase of Ps,G1 was almost unchanged,but G2,?1 and ?2 gradually decreased.(4)Based on the creep characteristics of soil,the Flac3D numerical simulation method is used to analyze the long-term stability of gravity anchor slope.The results show that the stability of gravity anchor slope of Dadu River Bridge in 5 years is good,and the value of the displacement of the anchor to the Dadu River is 13.59cm,which is in the working state.Comparing the 3 kinds of soil samples,the minimum value of the displacement of the anchor towards the Dadu River is obtained when the soil particle size is P5=20.7%.In this paper,the creep characteristics of the gravity anchor slope and the slope stability analysis of the bridge are analyzed.