Analysis Of Behaviour And Influencing Factors Of Laterally-loaded Single Pile On Sloping Loess Ground

Many power transmission poles and towers in the northwest region must be built on the loess slope and supported by piles to form the pile foundation of the loess slope.In addition to the vertical load of the upper pole and tower structure,the loess slope pile foundation also bears the horizontal load from the tension of the transmission line,wind load and seismic load.In this paper,relying on the project "Influencing factors and evaluation of horizontal load-bearing performance of single-slope piles",and based on the horizontal load test of single-slope piles on loess slopes,the FLAC3D numerical analysis model is established,numerical simulation and theoretical calculations are carried out,and orthogonal experiments are used.And the factor-by-factor analysis method is used to study the influence of slope slope,pile outcrop buried depth ratio,pile diameter buried depth ratio and slope front and slope back distance ratio on the horizontal bearing performance of single pile in loess slope.Appropriate amendments have been made to the application of the m method given in "Technical Specifications for Building Pile Foundations" on loess slopes.The main research conclusions are as follows:(1)The orthogonal test method was used to determine the sensitivity of the factors affecting the horizontal bearing capacity of a single pile foundation on a loess slope.The descending order is:slope angle,pile diameter buried depth ratio,slope front and slope back spacing ratio,pile outcrop The buried depth ratio,slope gradient and pile diameter buried depth ratio have a significant impact on the horizontal bearing capacity of the loess slope pile foundation,while the pile outcrop buried depth ratio and the slope front slope back distance ratio have no significant effect on the loess slope pile foundation horizontal bearing capacity influences.(2)Based on the numerical analysis method,the influence of various factors on the horizontal bearing capacity of a loess slope is studied:1)Slope:As the slope of the loess slope increases,the horizontal bearing capacity of a loess slope gradually decreases.When the slope is 0～20°,the horizontal bearing capacity of a single pile will decrease by 7%～15%for every increase of 5°.When the slope is 20°～30°,for every 5° increase in the slope angle,the horizontal bearing capacity of the pile foundation will decrease by about 22%～54%;2)Pile diameter buried depth ratio:the horizontal bearing capacity of a single pile on loess slopes increases linearly with the increase of the pile diameter buried depth ratio.For every increase of 0.04 in the pile diameter buried depth ratio,the ultimate horizontal bearing capacity of a single pile is approximately Increase 35kN;3)Pile outcrop depth ratio:As the pile outcrop depth ratio increases,the horizontal bearing capacity of a single pile gradually decreases.Every time the pile outcrop depth ratio increases by 0.05,the single pile’s horizontal ultimate bearing capacity decreases by about 5kN;4)The ratio of the distance between the front and the back of the slope:The ratio of the distance between the front and the back of the slope has less influence on the horizontal bearing capacity of a single pile on a loess slope.(3)According to the simulation test results,the change law of the pile-soil stress and strain during the loading process was analyzed,the distribution mode of the soil resistance around the pile was determined,and the parameter correction was made for the application of the standard m method on the loess slope,and the correction formula for:b’0=0.9(d+1)-0.73tanθ-1.12tan2θ(d≥ 1.0m)b’0=0.9(1.5d+ 0.5)-0.73tanθ-1.12tan2θ(d<1.0m)。...