| When building roads and railways on deep or soft and uneven foundations,the foundations are prone to slippage,instability and even collapse.In order to reduce the adverse effect of horizontal load on the road foundation at the foot of the slope,it is proposed to set inclined piles or inclined straight double-row piles at the foot of the slope to strengthen the road foundation.In this paper,indoor model tests were conducted to set up single piles at 0°,10° and 20° in the model sandy soil to derive the horizontal displacement,horizontal earth pressure and bending moment of the piles under lateral piling conditions for three different sets of angled piles,and the finite difference software Flac3D was used to compare the simulation with the test law for verification.On this basis,the horizontal displacement,horizontal earth pressure and bending moment of oblique straight double row piles under lateral piling load were investigated by Flac3D numerical simulation compared with other three common double-row piles.The results show that.(1)The bending moment of passive positive inclined pile increases first from top to bottom,then decreases and then slightly increases.The horizontal earth pressure at the loading side increases first,then decreases and then slightly increases along the pile from top to bottom,with the peak value located at 0.3 times the pile length.The soil resistance in front of the pile increases first and then decreases from top to bottom,and the peak value is 0.3 times of the pile length.Under the action of load,the straight pile mainly rotates with a little translation,while the positive inclined pile both rotates and rotates.p/pu-y/y50 curves can be fitted smoothly.(2)When the top of the lateral constraint pile at the foot of the subgrade is far away from the foot of the slope,the bending moment of the pile body,horizontal earth pressure at the pile side,soil resistance in front of the pile,and rotational momentum decrease,and the translation of the pile body increases,the pile itself becomes safer and safer,but the lateral constraint effect decreases and the subgrade settlement increases.In engineering,the lateral confining pile at slope foot should not be designed as positive inclined pile,and should be prevented from tilting outward from slope foot.(3)During the loading process,the peak horizontal displacement of the double-row pile with connecting beam is smaller than that of the double-row pile without connecting beam.The peak horizontal displacement of the outer pile is higher than that of the inner pile,and the horizontal displacement of the bottom of the pile is smaller.(4)The bending moment distribution of the inner piles of the four combined pile types is a single-peaked curve,the peak moment of the inner piles is in the middle and upper part,and the bottom moment is smaller.The bending moment distribution of the outer pile is a single-peaked curve,the peak moment of the outer pile is at the top of the pile and the bottom moment is smaller,the peak position is higher than that of the inner pile.The peak bending moment of the combination pile with connecting beam is smaller than that of the ordinary double-row pile without connecting beam.(5)In terms of peak bending moment and horizontal displacement,the oblique straight double row pile has the advantage of smaller horizontal displacement and smaller bending moment than other combination pile types,and the combination pile type with connecting beam is more effective in resisting horizontal load than the combination pile type without connecting beam. |
