长春泥岩地区AM桩抗压承载性能

Compressive Bearing Capacity of AM Pile in Mudstone Area of Changchun

目的研究泥岩地质条件下AM桩承载特性,确定泥岩地质条件下AM桩极限抗压承载力、端阻比、单位体积混凝土承载力,并分析扩底与否、扩底位置、地层特性对AM桩承载性能的影响.方法对泥岩地区AM桩进行自平衡试验,建立M IDAS-gts三维数值模拟模型,将试验数据与数值模拟结果对比分析,推出AM桩单桩极限承载力.考虑AM桩的横向尺寸效应,计算分析两类非泥岩地质条件下AM桩的端阻比、单位体积混凝土承载力并与泥岩地质条件下AM桩对应参数对比.结果数值模拟所得极限承载力比自平衡试验值大30%左右,泥岩地质条件下AM桩端阻比比非泥岩地质条件下AM桩端阻比高12. 5%,单位体积混凝土承载力也要比非泥岩地质条件下高140. 5 k N/m3.泥岩地质条件下通过扩底作用,AM桩极限承载力比同尺寸等直径桩提高35%,泥岩地质工程性质较好,更有利于AM桩发挥较高承载性能.结论扩底作用很好地发挥了端承效应,提高了AM桩的承载能力以及混凝土利用效率.改变扩底位置对承载力没有影响,但在桩基底部扩底更有利于桩基整体协调变形.承载性能较好的土体更能够发挥了AM桩的承载性能.

To determine the ultimate compressive bearing capacity,end resistance ratio and unit volume concrete bearing capacity of AMpiles under mudstone geological conditions,the bearing characteristics of AMpiles was studied,and the influence of bottom enlargement or not,the location of bottom enlargement and stratum characteristics on the bearing capacity of AMpiles were analyzed. MIDAS-gts three-dimensional numerical simulation model was built. The ultimate bearing capacity of AMpile was deduced by comparing test data with numerical simulation results.Considering the transverse size effect of AMpile,the end resistance ratio,unit volume concretebearing capacity of AMpile were calculated and analyzed under two kinds of non-mudstone geological conditions,which were compared with corresponding parameters of AMpile under mudstone geological conditions. Results showthat the ultimate bearing capacity of AMpiles obtained by numerical simulation is about 30% larger than that of self-balanced test,the end resistance ratio of AMpiles under mudstone geological conditions is 12. 5% higher than that under non-mudstone geological conditions,and the bearing capacity of concrete per unit volume is also 140. 5 kN/m3 higher than that under non-mudstone geological conditions. Under mudstone geological conditions,the ultimate bearing capacity of AMpile is 35% higher than that of the pile with the same size and diameter,and the mudstone geological engineering property is better,which is more conducive to the high bearing capacity of AMpile. Bottom enlargement plays a good role in the end-bearing effect and improves the bearing capacity and coagulation of AMpile. Soil utilization efficiency and changing the position of the bottom have no effect on the bearing capacity,but the bottom enlargement at the base of the pile is more conducive to the overall coordinated deformation of the pile foundation. The soil with better bearing capacity can give full play to the bearing capacity of AMpile.