拉拔作用下土工合成材料在风化料-废弃轮胎橡胶颗粒轻质土中的变形行为研究

Deformation behaviour of geobelt in weathered rock material-tire shred lightweight soil under pullout condition

风化料-废弃轮胎橡胶颗粒轻质土密度小、透水性强,可以有效减小结构变形。然而筋材在此类轻质土中的变形规律尚不清楚。为此,考虑不同的橡胶颗粒质量比(10%、15%和30%)和不同的法向压力(30、50、100kPa),基于自主研发的传感型土工合成材料(SEGB),开展了SEGB筋材的拉拔试验。SEGB具有拉敏效应,可以通过测试电阻变化确定自身应变,实现分布式变形测量。基于单向拉伸试验和直剪试验结果,分别建立了筋材全应力-应变曲线的双线性本构模型和筋土界面作用的双曲线本构模型,并以此为基础推导了筋材在拉拔过程中的荷载传递方程。通过有限差分法求解该方程,得到了拉力、应变、位移和界面剪应力等指标在筋材上的分布情况。通过对比分析试验结果和数值计算结果,认为所建立的本构模型是有效的。橡胶颗粒质量比对筋土界面的摩擦特性有影响,且存在最优值。拉力、应变、位移和界面剪应力的最大值均出现在筋材的拉拔端,而后沿着筋材减小并逐步稳定。土体中筋材在较高法向应力下表现出黏塑性状态,且应变水平较高,但位移值较小。与高法向应力相比,低法向应力下筋材的界面剪应力分布更加均匀。

The weathered rock material-tire shred lightweight soil has advantages such as low density and high permeability,which could significantly reduce the structure deformations.However,the deformations of geosynthetics in this lightweight soil are still needed to be investigated.This paper presents a series of pullout tests on an innovative geosynthetics-sensor-enabled geobelts(SEGB).Different mass ratios of tire shreds(10%,15%and 30%)and normal pressures(30 kPa,50 kPa and 100 kPa)are also considered.With the reinforcement and self-measurement of SEGB,the distributed measurement on strain of SEGB could be realized via measurement of electric resistances.Based on the uniaxial tensile tests and direct shear tests,a bilinear model capturing the full stress-strain curves of SEGB and a hyperbolic model evaluating the geobelt-soil responses are developed,respectively.The two models are employed in the derivation of the load transfer equation of pullout process.Solved by finite difference method,the load transfer equation gives numerical results about the distributions of tensile force,strain,displacement and interfacial shear stress along the geobelt.The test results validate the numerical results,including the constitutive models and the solving method.There exists an optimal mass ratio of tire shreds for the best frictional characteristics of geobelt-soil interfaces.The values of tensile force,strain,displacement and interfacial shear stress reach the peak values at the front end of geobelts,then decrease along the geobelts and gradually remain stable.Under high normal pressures,the geobelts exhibit visco-plasticity with larger strain levels and smaller displacements.The interfacial shear stress shows a more even distribution under a low normal pressure.