双层加筋长度对GESC承载性能影响的研究

The effect of length of double reinforcement on GESC bearing capacity

为研究双层加筋包裹长度对土工格栅加筋包裹碎石桩(geosynthetic-encased stone column,GESC)承载性能的影响,基于已建立的离散-连续耦合数值模型进行了多组不同加筋包裹长度的GESC静载数值试验,对不同加筋包裹长度下桩体荷载-沉降规律、应力传递规律、孔隙率变化和接触力分布的差异进行分析。试验结果表明:相较于单层加筋包裹,双层加筋包裹不影响桩体极限承载力,但桩顶最终沉降明显减小,加筋长度取1.0D(D为桩径)时单位加筋长度减少的沉降为单层加筋时的19.38%,此时可以兼顾加筋效果、承载性能和经济效益;桩体轴向应力传递规律不受加筋长度的影响,但加筋长度的增加增强了筋土作用,使得桩体上部轴向应力快速衰减;在细观方面,随着双层加筋长度的增加,桩体孔隙率降低了5.19%,强接触力分布峰度增加了117.22%,这表明加筋长度的增加提升了桩周约束条件,使得桩体内部受力结构更加密实。

To study the effect of length of double reinforcement on GESC bearing capacity,based on the established discrete-continuous coupled numerical model,several sets of GESC static loading numerical tests with different reinforced package lengths were carried out,and the differences of pile load settlement,stress transfer,porosity change and contact force distribution under different reinforced package lengths were analyzed.The results show that compared with single-layer reinforced stone column,double-layer reinforced stone column does not affect the ultimate bearing capacity of pile body,but the ultimate settlement of pile top decreases obviously.When the reinforcement length is 1.0D,the settlement of per reinforcement length is 19.38%of that of single layer reinforcement,which can balance the bearing capacity and economic benefits of reinforcement.The axial stress transfer law of pile is not affected by the reinforcement length,but the increase of the reinforcement length intensifies the effect of reinforcement and soil,which makes the axial stress on the top of pile decay rapidly.In terms of microstructure,with the increase of double reinforcement length,the porosity of pile decreases by 5.19%,and the kurtosis of strong contact force distribution increases by 117.22%,which indicates that the increase of reinforcement length improves the circumferential constraints of pile and makes the internal stress structure of pile more compact.