土工材料力学性能对风积沙复合地基抗拔加固效果的影响

为促进土工合成材料在输电线路工程地基处理中的选型应用,加固改良铁塔基础风积沙地基抗拔性能,通过室内钢塑土工格栅、塑料双向土工格栅、土工布加筋复合地基基础抗拔性能模型试验,并结合沙漠风积沙常规地基与加筋复合地基基础原位载荷试验中抗拔失稳时地表裂缝分布特征,研究了土工材料改良风积沙地基抗拔性能的加固机理,分析了筋材抗拉强度、伸长率及其与风积沙间摩擦系数性能指标对风积沙地基抗拔性能改良效果的影响。结果表明：复合地基土工材料有利于将基础荷载作用传递扩散至更大范围,通过筋材对基础底板的下拉作用实现基础抗拔性能的提升；筋材拉伸强度对地基抗拔能力提升影响较小,较大的伸长率会弱化地基抗拔加固效果,筋材与风积沙间摩擦系数越大地基抗拔加固效果更优。因此风积沙地基抗拔性能加固处理的筋材选型主要考虑伸长率和摩擦系数,钢塑土工格栅和塑料双向土工格栅的抗拔加固效果优于土工布。

Effects of Mechanical Properties of Geomembrane Materials on Uplift Reinforcement Results of Aeolian Sand Reinforced Composite Ground

In order to promote the geosynthetics selection application of the ground treatment in the transmission line engineering, strengthen the uplift resistant performance of the aeolian sand composite ground, the laboratory model tests on uplift performance of the composite foundations reinforced with the steel-plastic geogrid, plastic two-way geogrid and geotextile were carried out. Combining the surface crack distribution characteristics during the in-situ uplift loading tests of the conventional aeolian sand foundation and the reinforced composite foundation under uplift failure, the reinforcement mechanism of improving the uplift resistance of aeolian sand ground with geotextile materials was studied. And the effects of tensile strength, elongation and friction coefficient of geosynthetics on the improvement of uplift resistance of aeolian sand foundation was analyzed. The results show that the geosynthetics in composite ground is beneficial to transfer and spread the foundation loading to a wider range, and the uplift performance of foundation is improved by the pull down effect of reinforced materials on the foundation slab, and the tensile strength of the geosynthetics has little influence on the improvement of the foundation uplift ability, and the larger elongation ratio can weaken the uplift reinforcement effect of the composite ground, and the greater the friction coefficient between the reinforced materials and aeolian sand is, the better the uplift reinforcement effect will be. Therefore, the elongation and friction coefficient should be taken into account in the selection of reinforcement materials for aeolian sand ground. And the reinforcement effect of the steel-plastic geogrid and the plastic two-way geogrid is better than the geotextile.