Z. Jorkesh; R. Ajalloeian; A. H. Sadeghpour; M. J. Kalantar Hormozi
Abstract
In this research, the effect of salinity on engineering characteristics of sandstones is investigated. For this purpose, two sandstones from abutments and rock fill (Rip-Rap) of Vanyar dam (in Eastern Azerbaijan province) were selected in addition to three water samples (drinking water, semi-brine and ...
Read More
In this research, the effect of salinity on engineering characteristics of sandstones is investigated. For this purpose, two sandstones from abutments and rock fill (Rip-Rap) of Vanyar dam (in Eastern Azerbaijan province) were selected in addition to three water samples (drinking water, semi-brine and brine) to saturate these rock samples. Water content, uniaxial compressive, point load, thawing and freezing, sound velocity, and durability tests were carried out on dry and saturated samples at different time intervals. After 5 months of submerging type 1 and 2 sandstones in brine water, the uniaxial compressive strength values were decreased 13 and 4%, respectively, and after 10 months to 12 and 0.2%, respectively, compared to those of samples prepared using drinking water. By increasing the salinity of the water, the durability values after 10 cycles changed from 2.3 to 4.2% and from 1.8 to 3.2% for sandstones types 1 and 2, respectively. The sound velocity in a dry sample of sandstones types 1 and 2 was measured as 4450 and 4950 m/sec, respectively, while they reached 4699 and 5255 m/sec, respectively, by increasing salinity. The results show that brine water almost has no effect on thawing and freezing.
A Jamshidi; M.R Nikudel; M Khamehchiyan
Abstract
In cold regions, freeze-thaw cycles are one of the most important agents affecting on the mechanical properties of stones and consequently their durability. Uniaxial compressive strength, Brazilian tensile strength and P-Wave velocity are among important mechanical properties in assessing the durability ...
Read More
In cold regions, freeze-thaw cycles are one of the most important agents affecting on the mechanical properties of stones and consequently their durability. Uniaxial compressive strength, Brazilian tensile strength and P-Wave velocity are among important mechanical properties in assessing the durability of the stones used in cold regions. As regards of determination these properties during the freeze-thaw cycles experiment is very time consuming and cumbersome, statistical relationships can be used to estimate the mechanical properties. In this study, a multivariate statistical model is presented for 15 samples of travertine, which can estimate uniaxial compressive strength, Brazilian tensile strength and P-Wave velocity in each cycle of the freeze-thaw experiment. In this model, mechanical properties after freeze-thaw cycles were considered to be the dependent variable that dependent on the variables of the initial mechanical properties, water absorption and the number of freeze-thaw cycle. The statistical tests results and also data from other researchers show that model presented is reasonably accurate in estimating uniaxial compressive strength, Brazilian tensile strength, P-Wave velocity and consequently their durability of the travertines in each cycle of the freeze-thaw experiment.
M. Kianpour; M. Sayari; A. Oromiea
Abstract
The uniaxial compressive strength and modulus of deformability of intact rocks are highly important parameters for rock engineering and engineering geology projects. Because of the difficulty of measuring these parameters and the need for laboratory equipments for their prediction, indirect methods ...
Read More
The uniaxial compressive strength and modulus of deformability of intact rocks are highly important parameters for rock engineering and engineering geology projects. Because of the difficulty of measuring these parameters and the need for laboratory equipments for their prediction, indirect methods are often used. In this study, some predictive models using regression analysis and fuzzy inference system have been developed for the Shales cropping out in the Shemshak formation in Siahbishe area. For this purpose, a series of easy measurable parameters such as density, porosity and point load index were applied. Both multiple regression analyses and the fuzzy inference system exhibited good performance in prediction of the uniaxial compressive strength and modulus of deformability. The variation of regression coefficient (R2), performance indices (VAF) and root mean square error (RMSE) were calculated as for the uniaxial compressive strength and the modulus of deformability obtained from the multiple regression model and the fuzzy inference system revealed that the prediction performances and accuracy of the fuzzy model are higher than those of multiple regression equations in prediction of uniaxial compressive strength and modulus of deformability.
