Abstract
The service performance of subgrade depends on the dynamic resilient modulus (MR) of subgrade soils. Meanwhile, due to complicated conditions such as rainfall infiltration, high temperature evaporation, and groundwater level fluctuations, it can be safely said that the humidity state and repeated wetting‐drying (WD) cycles affect the MR of subgrade soils. The object of this study is to conduct a series of dynamic triaxial tests after WD cycles to investigate the characteristics of the MR under various factors. The main results are as follows: (i) the MR decreased with the increase of deviator stress and rose with the growth of confining pressure; (ii) the humidification effect caused by the increase in moisture content attenuated the MR; (iii) the accumulation of WD cycles damaged the MR; however the decline rate was gradually retarded until it was stable with WD cycles 5 times; (iv) the satisfactory prediction model for the MR of subgrade soils considering WD cycles was proposed and verified. It is expected that the findings can provide valuable contributions for road engineering.
Highlights
Researchers have carried out numerous studies on the influence of humidity changes on MR of subgrade soils. rough two-year on-site monitoring, Elliott et al [12] found that the actual moisture content of the subgrade soils progressively increased to 1.1 optimal moisture content (OMC)
Zhang et al [13] conducted soils humidity surveys on several expressways in southern China and reported that the moisture content of the subgrade soils continued to increase and stabilized at around 116% OMC. They prepared high plasticity clays specimens under the moisture content conditions of 0.9 OMC, OMC, 1.1 OMC, 1.2 OMC, and 1.3 OMC, respectively, and performed corresponding repeated loading triaxial (RLT) tests [14]. e results showed that, under the given stress and compaction
Zhang et al [18] used this level of moisture content to compact coarse grained fillers and organized RLT tests. e results captured the weakening effect of humidity growth on the MR, in agreement with the findings on unbonded granular materials reported by Gu et al [19] and recycled construction wastes reported by Azam et al [20]
Summary
Researchers have carried out numerous studies on the influence of humidity changes on MR of subgrade soils. rough two-year on-site monitoring, Elliott et al [12] found that the actual moisture content of the subgrade soils progressively increased to 1.1 OMC. Zhang et al [18], based on the laws obtained from the RLT tests of construction and demolition wastes, established the model that can consider the number of freeze-thaw cycles, compactness, humidity state, and stress state as shown in the following equation: MR
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