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| Coefficient of earth pressure at rest of sand considering density effect |
| CAI Zhengyin，ZHU Xun，DAI Zhiyu |
| (Department of Geotechnical Engineering，Nanjing Hydraulic Research Institute，Nanjing，Jiangsu 210024，China) |
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Abstract The coefficient of earth pressure at rest is one of the important parameters in the design and analysis of bracing structures，and its value determines the magnitude of the initial horizontal earth pressure acting on the structures. Taking the Fujian standard sand as the object，the centrifugal model tests and the triaxial consolidated drained tests are performed to investigate the variation rules of both the coefficient of earth pressure at rest and the peak strength of the sand with the initial relative density. Based on the above test results，a NHRI equation，which can truly reflect the relationship between the earth pressure at rest and the peak friction angle of sand，is proposed. To validate the correctness of the NHRI equation，a conceptualized model for microstructure of particles to depict the mesoscopic stress characteristics is put forward. The relationships between the coefficient of earth pressure at rest of sand with the contact angle and the deviation angle of particles are obtained through derivation of the NHRI equation. The effect of the initial relative density on the internal stress transfer mechanism of sand is preliminarily discussed. It is pointed out that with increasing the relative density of sand，there exists the possibility for the microstructure of particles to transform from the high-order circular unit structure to the low-order steady unit structure，while that the dual-bracing action of the low-order steady unit structure will promote the vertical stress of particles to laterally transfer. The research results are of a certain reference value to improve the earth pressure theories of sand.
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2021, Vol. 40 
