Study On The Horizontal Resistance Of The Soil Before The Pile Foundation Of The Sloped Gravel Soil

The horizontally loaded piles in the slope foundation compress the soil and cause soil resistance.Soil resistance is related to soil type and its physical and mechanical properties,and is also affected by pile foundation and terrain conditions.Soil resistance is the performance of bearing capacity under the influence of soil,pile foundation and topographic conditions as well as other comprehensive factors.Especially under the condition of slope topography,the existence of the slope reduces the stability of the pile-soil system,reduces the resistance of the soil,and the structure is unstable or even destroyed under the load to threaten the safety of life and property.Therefore,it is of great significance to study the horizontal resistance of the soil in the slope with the stress-strain response of the pile-soil system along the pile depth.It can guide the stability of the pile foundation in the slope soil.In this paper,the physical model test and numerical simulation method are used to take the transmission tower pole in the most common gravel soil foundation in the southwest slope mountain area as the pile foundation prototype.The horizontal resistance of slope soils with different stiffness gravel soils and slopes with different slopes is studied along the pile depth.The distribution model of horizontal resistance of the soil in the gravel soil slope is obtained,and the ultimate horizontal soil resistance is studied,the main conclusions are as follows:(1)Through the development of load-displacement curve and displacement gradient curve and pre-pile crack,the deformation response of pile-soil under horizontal static load is divided into three stages: The first stage is a linear stage,and the pile soil is in the stage of elastic deformation.If the external load is cancelled,the pile soil can be restored to the undeformed state;the second stage is a nonlinear stage.In this stage,the rotational speed of the top table of the pile increases,the stabilization time increases,the crack starts to sprout,and the pile soil is mainly plastic deformation,resulting in irreversible deformation;the third stage is the acceleration stage.In the acceleration stage,the deformation of the pile and the crack development of the soil are significant.The surface of the slope has soil sliding and the shallow soil reaches its horizontal resistance limit state.(2)According to the law of resistance-displacement curve,when the soil does not enter the plastic stage,the resistance increases with the displacement of the pile body.After entering the acceleration stage,the soil resistance does not increase with the increase of the displacement,it means soil resistance reaching it’s level of ultimate.The degree of soil resistance is related to the pile-soil stress deformation response.(3)According to the different stages of the stress-deformation response of the pile-soil system,the change of the resistance of the soil before the pile with the depth is studied: Due to the small displacement,both the soil and the loaded pile at the top of the pile are elastically deformed.The most deformed part is at the top of the pile.At the top of the pile,there is soil resistance first and decreases along the pile body;when the pile-soil is in the stage of elastoplastic stage,the soil begins to crack,and the resistance of the soil from the shallow depth of the pile to the middle layer is increased;in the plastic deformation stage,the soil resistance of the shallow depth of the pile is not increased with the displacement of the pile foundation.reaching its level of ultimate soil resistance.(4)The increase of slope slope reduces the effective exertion of soil resistance.The horizontal ultimate soil resistance of the shallow soil in the slope is relatively reduced by the fixed value related to the slope.(5)The increase of soil strength can increase the horizontal ultimate bearing capacity of the soil and improve the bearing capacity of the pile foundation.(6)The horizontal ultimate soil resistance of the soil is linearly positively correlated with the soil stiffness at the same depth,and the soil resistance increases with the increase of the depth.