中文摘要：

为促进轻质土在岩土工程中的广泛应用,添加改性聚丙烯纤维改善其力学性能,通过无侧限抗压强度试验分析探讨了纤维聚苯乙烯泡沫（EPS）颗粒轻质土强度-变形特性、受压破坏模式和无侧限抗压强度的影响因素,并运用SEM从微观层次上分析了其力学机制。结果表明：不同EPS颗粒、纤维及水泥掺量时,纤维EPS颗粒轻质土的应力-应变曲线不同;EPS和水泥掺量是强度的主要影响因素,其次为纤维掺量;强度随EPS掺量的增大而显著降低,随水泥掺量增大而显著提高;未加纤维的EPS颗粒轻质土松散且易破碎,强度骤然丧失;添加纤维能提高轻质土的峰值强度、残余强度、整体性和韧性,改善其脆性破坏模式;但EPS掺量较高（大于干土质量的3%）时,纤维与水泥土粘结有限,EPS颗粒轻质土力学性能改善效果较弱;EPS颗粒为空心蜂巢结构,纤维表面布满针状的水泥水化物并形成空间网状结构。所得结论表明纤维改善了轻质土力学性能。

英文摘要：

In order to promote the wide application of lightweight soil in geotechnical engineering,modified polypropylene fiber was added to improve its mechanical properties,the influencing factors of strength-deformation characteristics,compressive failure mode and unconfined compressive strength of fiber expanded polystyrene（EPS）particles lightweight soil were analyzed and discussed by unconfined compressive strength test,and the mechanics mechanism of fiber EPS particle lightweight soil was analyzed from micro level by SEM.The results show that when the EPS particle,fiber and cement contents are different,the stress-strain curves of fiber EPS particle lightweight soil are different.EPS and cement contents are the main factors which influence strength,and fiber content is the second.The strength decreases sharply with the increase of EPS content,and increases sharply with the increase of cement content.The EPS particle lightweight soil without adding fiber becomes loose and broken easily,and loses strength suddenly.The addition of fiber can enhance the peak strength,residual strength,integrity and toughness of lightweight soil,and improve its brittle failure mode.However,when the EPS content is higher（more than 3%for the mass of dry soil）,the adhesion between fiber and cemented soil is limited,and the improvement performance for mechanical properties of EPS particle lightweight soil is weaker.EPS particle is hollow honeycomb structure,fiber is covered with the needle-like hydration of cement on the surfaces and forms space network structure.The conclusions obtained show that fiber improves the mechanical properties of lightweight soil.