Comparison of Cyclic Triaxial Behavior of Unbound Granular Material under Constant and Variable Confining Pressure
Comparison of Cyclic Triaxial Behavior of Unbound Granular Material under Constant and Variable Confining Pressure
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DOI：
10.1061/(asce)te.1943-5436.0000009
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发表时间：
2009-03
期刊：
影响因子：
--
通讯作者：
H. Rondón;T. Wichtmann;T. Triantafyllidis;A. Lizcano
中科院分区：
文献类型：
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作者：
H. Rondón;T. Wichtmann;T. Triantafyllidis;A. Lizcano
循环应力，由于通过车轮强加的积累永久应变层的松散粒料（UGM）的柔性路面。空心圆柱体三轴试验是模拟原地应力条件的最合适的试验，但由于UGM的最大粒度较大，因此很难进行。简单的轴对称循环三轴试验不考虑剪应力分量。它可以在恒定围压（CCP）或可变围压（VCP）下进行。CCP和VCP测试通常被认为提供类似的残余应变和弹性应变，只要平均应力相同。因此，在路面工程中大多采用较为简单的CCP试验。然而，这一假设是基于文献中有限的测试数据，可能不安全。本文对UGM的CCP和VCP试验进行了对比研究。本文主要研究永久变形。结果表明，只有在某些特殊的应力路径，两种类型的测试提供类似的永久轴向或体积应变。对于其他一些应力路径，CCP试验可能会低估永久轴向应变，与相应的VCP试验相比。
Cyclic stresses due to passing wheels impose an accumulation of permanent strains in layers of unbound granular materials (UGMs) of flexible pavements. The hollow cylinder triaxial test would be the most appropriate test to simulate the in situ stress conditions but it is difficult to perform on UGMs due to their large maximum grain size. The simpler axisymmetric cyclic triaxial test does not consider the shear stress components. It can be performed with a constant confining pressure (CCP) or a variable confining pressure (VCP). CCP and VCP tests are commonly assumed to deliver similar residual and resilient strains as long as the average stress is the same. Thus, the simpler CCP test is mostly used in pavement engineering. However, this assumption is based on limited test data in the literature and may not be on the safe side. The present paper documents a comparative study of CCP and VCP tests on UGM. The study is mainly dedicated to the permanent deformations. The results show that only for some special stress paths do both types of tests deliver similar permanent axial or volumetric strains. For some other stress paths the CCP tests may underestimate the permanent axial strain in comparison to the corresponding VCP test.