Numerical Simulations of Pullout Characteristics and a Calculation Method for Ultimate Pullout Resistance of Denti-Geogrids
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摘要: 针对新型土工筋材——带齿格栅,采用数值模拟方法对其拉拔过程进行研究,对比考察了绕流滑动模型、Perterson-Anderson模型、Jewell模型、Chai模型、Rankine模型和数值分析模型在计算单齿格栅拉拔力时的准确性,研究了带齿格栅界面摩擦特性。在因素分析的基础上提出了多齿格栅极限拉拔力计算式。研究表明:1)对于单齿格栅极限拉拔力,由Jewell模型计算所得结果与数值模拟结果最为接近(平均误差约为5.35%),Rankine模型在筋材拉拔力计算中应用简便且误差较小。2)在相同的试验条件下,带齿格栅的拉拔力远高于普通土工格栅;相应地,带齿格栅的界面黏聚力和界面摩擦角、拉拔系数以及各级法向应力作用下的似摩擦系数均比普通格栅要大。3)对于多齿格栅,其极限拉拔力与齿筋数目、齿筋间距、法向应力分别呈指数、对数和线性关系。最后,采用构建的多齿格栅极限拉拔力算式计算了不同工况条件下的极限拉拔力,验证了其可靠性。Abstract: Aiming at a new geotechnical reinforcing material—denti-geogrids, pullout tests were simulated by numerical simulations. The accuracy for calculation results of the ultimate pullout resistance for denti-geogrids with a single transverse rib by the flow-around model, Peterson-Anderson model, Jewell model, Chai model and Rankine model, as well as the numerical analysis model were comparatively researched. And the friction characteristics of the interfaces were studied and the formula for the ultimate pullout resistance of denti-geogrids with multi-ribs was put forward on the basis of factor analysis. Researches showed that: 1) For denti-geogrid with a single transverse rib, the ultimate pullout resistance calculated by Jewell model was closest to the numerical simulation result (with an average error of 5.35%), the Rankine model was relatively simple and precise for engineering application. 2) In the same test conditions, the pullout resistance of denti-geogrids was much higher than that of common geogrids. Also, the interface cohesion, friction angles, pullout coefficients, and apparent friction coefficients of denti-geogrids at all levels of normal stress were larger. 3) For denti-geogrids with multi-ribs, the relations for the ultimate pullout resistance between the detni-geogrid rib quantities, spacing and normal stress were separately exponential, logarithmic and linear. The ultimate pullout resistance for denti-geogrids with multi-ribs in different working conditions was calculated by the suggested formula, and the reliability was verified.
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Key words:
- denti-geogrid /
- pull-out test /
- numerical simulation /
- ultimate resistance
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