为研究不同填充材料对废旧轮胎柱(scrap tire columns,STC)加筋体循环剪切性能的影响,利用自行研制的土工合成材料循环剪切试验机,分别得到河砂、碎石、壤土3种填充材料的STC加筋体在竖向压力100 k Pa、最大水平剪应变2%条件下的循环剪切滞回曲线。试验结果表明:河砂、碎石STC的等效动剪切模量和等效阻尼比在数值上基本接近,且均优于壤土STC的动力参数,考虑到减振消能效果以及填筑过程的便利性,河砂STC具有较好的实际应用优势。采用ABAQUS有限元程序,分别选用Mohr-Coulomb、Mooney-Rivlin和Rebar本构模型来模拟土石填筑料、橡胶超弹性材料和帘线钢丝材料,数值重现了3种填筑料STC加筋体的应力-应变滞回曲线,数值模拟结果与试验结果的规律基本一致。由模拟所得的循环剪切过程中STC加筋体能量变化曲线可知:填充材料主要起"消能"作用,轮胎则主要起"加筋"作用。
The cut-off wall in a clay-core rockfill dam built on a thick overburden layer is subjected to a large compressive pressure under the action of the loads such as the dead weight of both the dam and the overburden layer, the frictional force induced by the differential settlement between the cut-off wall and surrounding soils, and the water pressure. Thus, reduction of the stress of the cut-off wall has become one of the main problems for consideration in engineering design. In this paper, numerical analysis of a core rockfill dam built on a thick overburden layer was conducted and some factors influencing the stress-strain behaviors of the cut-off wall were investigated. The factors include the improvement of the overburden layer, the modeling approach for interfacial contact between the cut-off wall and surrounding soils, the modulus of the cut-off wall concrete, and the connected pattern between the cut-off wall and the clay core. The result shows that improving the overburden layer,selecting plastic concrete with a low modulus and high strength, and optimizing the connection between the cut-off wall and the clay core of the dam are effective measures of reducing the deformations and compressive stresses of the cut-off wall. In addition, both the Goodman element and the mud-layer element are suitable for simulating the interfacial contact between the cut-off wall and surrounding soils.
