土工格室加筋路基振动压实行为及预应力效应

Vibration compaction behaviors and prestressing effect of geocell-reinforced subgrade

通过建立路基离散元模型和土工格室有限差分模型,开展了一系列有限差分法-离散元法(finite difference method-discrete element method,简称FDM-DEM)耦合数值计算,探明了土工格室加筋路基在振动荷载作用下的压实行为。进一步揭示了土工格室对路基压实后水平残余应力的贡献,并在此基础上,提出了土工格室加筋路基的预应力效应,以体现施工期格室填料在经历加载并卸载后引起的格室撑阔对加筋效果的提升。结合微观接触组构、配位数变化、压实过程的应力路径,探讨土工格室加筋路基预应力效应的形成机制。研究结果表明,相较于未加筋路基,土工格室可以提高加筋路基的回弹模量,增加压实路基的水平残余应力。在振动荷载作用下,土工格室呈现上开口的喇叭形,土工格室口袋被撑阔,格室壁的最大应变为0.17%~0.21%。接触力分布也表明,在振动压实作用后,力链由竖直向水平方向发展,这体现在水平残余应力的增加,而土工格室则进一步提升了颗粒的横向接触力。

This paper developed a subgrade discrete element model and a geocell finite difference model.A series of coupled finite difference method-discrete element method(FDM-DEM)numerical calculations was carried out to study the compaction behavior of geocell-reinforced subgrade under vibration loads.The contribution of geocells to the horizontal residual stresses after vibration compaction was further revealed.Additionally,the prestressing effect of the geocell-reinforced subgrade was proposed to reflect the reinforcement improvement due to the stretching of geocell pockets induced by the infill materials after loading and unloading during construction.The mechanism of the prestressing effect of geocell-reinforced subgrade was discussed by combining the microscopic particle contact,the changes in coordination,and the stress path during compaction process.The results suggest that geocells can improve the resilient modulus of reinforced subgrade and significantly increase the horizontal residual stress compared to the unreinforced subgrade.Under vibration loading,the geocell shows a flared shape with an upper opening.After compaction,the geocell pockets stretch wider,and the maximum tensile strain in the geocell walls ranges from 0.17%to 0.21%.The distribution of contact force also indicates that the force chain develops from a vertical to horizontal direction after vibration compaction,reflecting the increase of horizontal residual stresses.The geocell further enhances the development of lateral contact forces among particles.