Study On Influence Of Inclination Of Inclined Pile Under Lateral Load On Engineering Characteristics Of Inclined-straight Double Row Piles

When building embankment or square on soft foundation with deep or uneven thickness,vertical pile composite foundation is often used for reinforcement,and 3-4 rows or more piles are set outside the foot of slope,while the slip and collapse of the filling soil cannot be avoided.In order to ensure the stability of filling soil,the composite foundation scheme of inclined-straight double row piles at the foot of slope is proposed.Model test was carried out to investigate the horizontal soil pressure,lateral displacement and bending moment variation of four kinds of inclinations of inclined-straight double row piles in loose sand under lateral load,and the failure form was analyzed to provide experimental basis for the design and application of composite foundation of inclined-straight double row piles.The results show that:(1)When the inclination of the outside inclined pile increases,the horizontal soil pressure and bending moment of the inside straight pile increase,the horizontal soil pressure,lateral displacement and bending moment of the outside inclined pile decrease.The horizontal soil pressure of the inside straight pile is higher than that of the outside inclined pile(2)The displacement mode of the inclined-straight double row pile before the failure is"translation+rotation",and the failure mode is bending failure.The middle of the inside straight pile and the top of the outside inclined pile are dangerous sections,while the inside straight pile is more likely to break than the outside inclined pile.(3)Numerical analysis shows that the bending moment at the top of straight pile is negative and the bottom is positive when the load is small before and after loading.In the middle and later stage of loading,the pile top and pile bottom are negative bending moment,and the pile top has a large negative bending moment,and the section at the junction of straight pile and connecting beam in loose sand is also prone to bending failure.(4)The inside straight piles of inclined-straight double row pile always bears the active horizontal soil pressure,while the lateral inclined pile mainly bears the passive horizontal soil pressure except the pile bottom,while the pile bottom bears the active soil pressure.The rotation of the lateral inclined pile is the reason for the change of the soil pressure direction.The zero of the total soil pressure is the center of rotation,which is located at the bottom of the outside inclined pile.(5)Under the same load,the horizontal displacements of four kinds of double-row piles from small to large are as follows:inclined-straight double-row piles,double-row piles,straight inclined piles,double-row single piles.(6)In engineering,increasing the inclination of the outside inclined pile and strengthening the bending stiffness of the middle of the inside straight pile and the joint between the top of inside and outside piles and connecting beam will greatly improve the stability of the inclined-straight double row pile and effectively control the transverse deformation of the composite foundation.The inclination of inclined pile is determined by the construction equipment.