砂土中能量桩单桩水平承载特性模型试验研究

MODEL TESTS ON LATERAL BEARING BEHAVIOR OF SINGLE ENERGY PILE IN SAND

为探究能量桩单桩水平承载特性,针对砂土中能量桩在水平荷载下的承载特性进行研究,基于模型试验,分析了水平荷载作用下能量桩在制冷和加热过程中的桩顶位移、桩前土压力以及桩身弯矩等的变化规律。研究结果表明:制冷会引起能量桩桩顶水平位移略微增大,增量为0.48%D(D为桩体直径),而加热会引起较大的桩顶水平位移,达到了2.38%D;制冷和加热在初始阶段会引起桩前土压力增大,初始增长阶段结束后,土压力变化较小,多为缓慢增长或基本不变。相较于初始土压力,制冷和加热结束时的土压力基本呈增长趋势,仅个别埋深处土压力减小。制冷过程中,埋深0%L~40%L(L为有效桩长)范围内的弯矩增大,埋深40%L~100%L位置处的弯矩变化较小;加热过程中,埋深0%L~60%L范围内的弯矩均有所增大,0%L~40%L位置处的弯矩增大最为明显。制冷和加热过程中均在20%L处产生了最大弯矩,最大弯矩的增加量分别为9.93%和10.32%。进一步基于圆孔扩张理论提出了弯矩计算的理论解,并与试验结果进行对比分析,理论计算值与实测值较为吻合。

In order to explore the lateral bearing characteristic of single energy piles,the bearing behavior of energy piles subjected to lateral load in sand is studied.Based on model tests,the pile top displacement,the soil pressure in front of the pile,and the bending moment during cooling and heating of the energy pile subjected to lateral load are analyzed.The results show that cooling process will slightly increase the pile top lateral displacement by 0.48%D(D is the pile diameter).The heating process will also significantly increase the pile top lateral displacement,and the increment reaches 2.38%D.In the initial stage cooling and heating,the soil pressure in front of the pile will increase,and after the initial stage,the change of pressure is small with slow or no increment.The horizontal soil pressure increases generally after cooling and heating,and the pressure decrease is observed only at a few points.After cooling,the pile bending moment at the depth of 0%L~40%L(L is the effective pile length)will increase,while the bending moment at the depth of 40%L~100%L will have less change.During heating,the bending moment at the depth of 0%L~60%L will increase significantly,and the bending moment at the depth of 0%L~40%L has the most obvious increase.The maximum bending moments during heating and cooling are both produced at the depth of 20%L,and the increment reaches 9.93%and 10.32%respectively.Based on the cavity expansion theory,the theoretical solution of the bending moment is proposed.Compared with the experimental results,the calculated values are in good agreement with the measured values.