Mechanical properties of waste tyre grid reinforced weathered sand based on large triaxial test
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摘要: 采用废旧轮胎格栅加筋粗粒料,可有效增加界面承载力,提高耐久性,避免施工损伤,在加筋路基方面具有重要的工程应用价值,但目前有关废旧轮胎格栅加筋土抗剪特性的研究较为缺乏。以废旧轮胎格栅加筋风化砂为研究对象,考虑不同围压、不同加筋率的变化,开展了大三轴室内试验,以揭示废旧轮胎格栅加筋风化砂三轴剪切特性,确定抗剪强度参数。结果表明:试件剪切破坏形态与加筋率和围压具有强相关性,相比纯砂破坏形态,废旧轮胎加筋土未发生贯穿性剪切面,试件中部呈现鼓胀破坏,且随加筋率及围压的提升,试件鼓胀变形减小;不同于纯砂的应变软化特征,加筋试件均表现出应变硬化特征;无论有无加筋,土体均表现出了剪胀性特征,且围压越大,体积膨胀越明显,加筋率的影响很小;废旧轮胎格栅加筋土的峰值强度与等效内摩擦角随加筋率增大而大幅提高,而内摩擦角与剪胀角增幅较小。Abstract: Waste tyre grid reinforced coarse granular material can effectively increase the interface bearing capacity, improve durability, avoid construction damage, and has important engineering application value for reinforced roadbed. However, there is a lack of in-depth study on the shear characteristics of waste tyre grid reinforced soil. Therefore, in order to reveal the triaxial shear characteristics of waste tyre grid reinforced weathered sand and determine the parameters of shear strength, taking into account the changes of different confining pressure and different reinforcement rate, a large triaxial indoor test was carried out. The results show that the shear damage pattern of the specimen has a strong correlation with the reinforcement rate and the confining pressure. Compared with the damage pattern of pure sand, the waste tyre reinforced soil did not have a penetrating shear surface, and the middle part of the specimen showed a bulging break. The bulging deformation of the specimen was reduced with the increase of the reinforcement rate and the confining pressure. At the same time, unlike the strain softening characteristics of pure sand, the reinforced specimens showed a strain hardening phenomenon. With or without reinforcement, they showed shear expansion characteristics, and the greater the confining pressure, the more obvious the volume expansion, but the effect of the reinforcement rate is very small. The peak strength and equivalent internal friction angle of the waste tyre grid reinforced soil increased the most with the increase of the reinforcement rate, while the increase of the internal friction angle and shear expansion angle was small.
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Key words:
- waste tyre grid /
- weathered sand /
- large triaxial test /
- stress−strain relationship /
- shear strength
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表 1 风化砂物理力学参数
Table 1. Physical and mechanical parameters of weathered sand
有效粒径
d10/mm中值粒径
d50/mm不均匀
系数曲率
系数土粒
比重最小
干密度/
($ \text{g}\cdot {\text{cm}}^{-3} $)最大
干密度/
($ \text{g}\cdot {\text{cm}}^{-3} $)0.361 1.671 6.6 0.73 2.65 1.522 1.805 表 2 试验工况设置
Table 2. Test condition settings
工况序号 围压/kPa 加筋层数 S-1 200 纯砂 S-2 300 S-3 400 I-1 200 1层轮胎格栅 I-2 300 I-3 400 II-1 200 2层轮胎格栅 II-2 300 II-3 400 III-1 200 3层轮胎格栅 III-2 300 III-3 400 表 3 不同加筋率条件下试件力学指标
Table 3. Mechanical indexes of specimens under different reinforcement rate conditions
工况 内摩擦角/(°) 黏聚力/kPa 剪胀角/(°) 未加筋 38.19 31.22 6.07 1层加筋 37.90 61.39 6.72 2层加筋 40.08 253.30 6.86 3层加筋 42.25 388.69 8.28 -
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