Study On Bearing Behavior Of Rigid Pile Composite Foundation With Adjacent Retaining Wall Rotating Around The Bottom

The excavation process will inevitably cause unloading of the surrounding soil,when excavating adjacent composite foundation,soil unloading will inevitably reduce the bearing capacity of composite foundation.If reasonable measures are not taken,there is a high probability of engineering accidents.The theoretical derivation calculation results,test results and finite element simulation results are verified mutually,which lays a foundation for the research on the bearing capacity of the composite foundation adjacent excavated,and provides guidance and suggestions for the construction safety under this condition.First of all,through experiments,the bearing behavior of single long pile composite foundation and single short pile composite foundation under the condition of retaining wall rotating around the bottom is studied.In the rotation stage of retaining wall,the unloading amount of soil between piles of long pile composite foundation is less,the pile length increases by 110%,and the unloading amount of soil between piles decreases by 25.00%-27.78%.The unloading speed of soil between piles of short pile composite foundation is obviously faster than that of long pile composite foundation,and the unloading speed of short pile composite foundation will increase sharply when the top rotation of retaining wall exceeds0.0025 H.Subsequently,Through the simulation,the settlement of bearing plate,axial force of pile body,friction of pile side and distribution of sliding surface of single pile composite foundation and single pile under the condition of retaining wall rotating around the bottom are compared and analyzed.At the same time,the influence of the upper load,the horizontal distance between the edge of the bearing plate and the retaining wall,the replacement rate of the composite foundation and the change of the pile length on the bearing behavior of the single pile composite foundation under the condition of the retaining wall rotating around the bottom is analyzed.The results show that with the increase of load,the increment ratio of pile axial force and cap plate settlement increases.With the increase of the horizontal distance between the cap plate and the retaining wall,the axial force increment of the pile body and the settlement of the bearing plate of the composite foundation show a decreasing trend.When the horizontal distance between the cap plate and the retaining wall exceeds 21 d,the influence of the retaining wall rotation on the bearing characteristics of the composite foundation can be ignored.With the increase of replacement rate of composite foundation,the range of negative friction zone and the maximum value of negative friction decrease.The greater the replacement rate of composite foundation,the more full play of positive side friction of pile.When the replacement rate increases to 0.20,the negative friction zone of pile almost disappears.When the pile length is 0.5 H ～ 1.05 H,the depth range of the sliding surface of the composite foundation is 0.44 H ～ 0.78 H.When the pile bottom depth is within the range of the sliding surface,the overall stability of the composite foundation is weak.When the pile bottom depth exceeds the range of the sliding surface,the overall stability of the composite foundation is obviously improved.Finally,through theoretical calculation,the theoretical calculation model reflecting the bearing behavior of composite foundation under the condition of retaining wall rotating around the bottom is established,and verified by numerical simulation and theoretical calculation.