碎石粒径对GESC承载性能影响的数值耦合分析

Numerical Coupling Analysis on the Influence of Gravel Particle Size on Bearing Performance of GESC

为研究碎石粒径对加筋包裹碎石桩(GESC)承载性能的影响,基于室内试验结果建立离散-连续耦合模型并进行了8组不同粒径组成的单桩静载数值试验,分析了不同粒径条件下加筋包裹碎石桩宏细观参数变化规律。研究结果表明:GESC承载性能随碎石平均粒径d_(50)的增加先提高后降低,桩顶极限承载力在d_(50)=40.84 mm时达到峰值726.00 kPa,与d_(50)=15.26 mm时相比增幅达66.35%;d_(50)的变化是以优化桩体传力结构、降低径向应力比的方式使得桩端持力层承担更多外荷载,从而提高GESC的承载性能。在试验中,径向应力比最多降低了66.33%,到达桩端持力层的外荷载最大提升了166.67%;桩体传力结构优化的细观指标是桩体内强接触力沿埋深分布的标准差系数,该系数随碎石平均粒径先降后升,在d_(50)=40.84 mm时达到最低值0.497,表明此时桩体内强接触力沿埋深分布最为均匀。

To study the influence of gravel particle size on the bearing performance of geosynthetic encased stone column,a discrete-continuous coupling model is established based on the laboratory test results,and nine groups of static load numerical tests of single pile with different particle sizes are carried out to analyze the variation rules of macro and meso parameters of reinforced gravel pile with different particle sizes.The results show that the load carrying capacity of GESC increases first and then decreases with the increase of d_(50),and the ultimate bearing capacity reaches the peak value of 726.00 kPa when d_(50)=40.84 mm,with an increase of 66.35%compared with d_(50)=15.26 mm.The change of d_(50)is to improve the bearing performance of GESC by optimizing the pile load transmission structure and making the pile tip bearing layer bear more external load.In this test,the maximum external load of the pile tip bearing layer is increased by 166.67%.The mesoscale performance of pile force transfer structure optimization is that the standard deviation coefficient of the buried depth distribution of strong contact force in pile decreases first and then increases with the particle size,reaching the lowest value of 0.497 when d_(50)=40.84 mm,indicating that the buried depth distribution of strong contact force is the most uniform.