Experimental Investigation of The Granite Subjected to Unloading Confining Pressure Creep Test

International Journal of Civil Engineering

© 2020 by SSRG - IJCE Journal

Volume 7 Issue 2

Year of Publication : 2020

Authors : Longyun Zhang, Shangyang Yang

10.14445/23488352/IJCE-V7I2P102

How to Cite?

Longyun Zhang, Shangyang Yang, "Experimental Investigation of The Granite Subjected to Unloading Confining Pressure Creep Test," SSRG International Journal of Civil Engineering, vol. 7,  no. 2, pp. 6-18, 2020. Crossref, https://doi.org/10.14445/23488352/IJCE-V7I2P102

Abstract:

Triaxial tests were performed on granite specimens from dam foundation of the Mengdigou hydropower station by using triaxial servo rheometer, and the basic mechanical characteristic parameters of the granite were obtained. After that, the triaxial unloading rheology tests of the granite specimens were developed. Based on the unloading rheological test results, the characteristics of granite unloading rheology stress-strain were analyzed, the rheological properties and the rheology regularity of granite specimens in terms of the axial, lateral and volume were discussed, and the macro and microscopic failure modes of granite specimens were analyzed. The test results demonstrated that the granite behaved remarkable rheological properties under long-term unloading, and existed a typical unloading rheology threshold effect. According to the volume change, the rheological curve was mainly divided into stages of volume compression, volume stability, volume expansion and the last failure stage after the peak. Throughout the whole process of unloading rheology tests, the deformation of the lateral was more observable than that of the axial, and the unloading rheological deformation was given priority to the lateral expansion. But the U-shape of the creep rate is constant with the process development. When the confining pressure of unloading at a low level, the failure mode is splitting failure, with the increase of confining pressure level, the failure mode gradually changes into shear failure, but when the confining pressure reached a high level, it would develop into a “V” shape failure surface on granite specimens. The tests and related analysis results provide reference for related high arch dam engineering.

Keywords:

high arch dam；unloading rheology；creep characteristic；granite；failure mode; long-term loading

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