Sharif Digital Repository

Oil contamination can affect the mechanical and physical properties of soil, making its reuse a challenge. In the present study, the effect of kerosene contamination on two types of poorly graded sand (S1 and S2) was investigated. Geotechnical tests for compaction, direct shear and constant head permeability were conducted. The compaction test revealed that dry density increased at a 3% and 6% kerosene content for S1 and S2 soil, respectively. A further increase in kerosene content caused the dry density to decrease for both S1 and S2. The optimum moisture content of kerosene-contaminated soil samples decreased. The direct shear test showed that kerosene contamination increased cohesion and... 

In this paper, the effect of joint separation on the shear behavior of planar non-persistent joints under high normal load has been investigated using PFC2D. Initially calibration of PFC was undertaken with respect to the data obtained from experimental laboratory tests to ensure the conformity of the simulated numerical models response. Furthermore, validation of the simulated models were cross checked with the results of direct shear tests performed on non-persistent jointed physical models. Through numerical direct shear tests, the failure process was visually observed, and the failure patterns were found reasonably similar to the experimentally observed trends. The discrete element... 

Usage of masonry system in many regions of the world like the Eastern Mediterranean, the Middle East, India, and China is still significantly high, despite their highly energy and intensive emission. Most of the failures in this system are caused by low ductility of cement mortars. This type of failure could be seen in masonry structures in areas in east Iran after Kermanshah earthquake in 2017. The present study investigates the shear bond characteristics of structures constructed by masonry using green materials. “Taftan” natural pozzolan and two types of rice husk ash (RHA) were used in mix design of used mortars as green materials. In this investigation, a modified direct shear test... 

This paper presents an experimental study on the interfacial characteristics of rammed earth materials stabilized with the combination of cement and alkali-activated fly ash (AAFA), an eco-friendly alternative for cement. Several direct shear tests were conducted to obtain cohesion and friction angle to do so. Moreover, pulse velocity and unconfined compression tests were exploited to assess other physical and mechanical properties of this material. Through the methodology used in this work, it is shown that the replacement of cement with AAFA dramatically improved cohesion, compressive strength, and pulse velocity. However, no general correlation was observed for the friction angle. © 2021,... 

The mechanism of crack propagation in concrete specimens containing cracks under shear loading conditions is studied. The shear box test of pre-cracked (double edge cracks) concrete specimens is carried out under laboratory conditions. The higher order displacement discontinuity formulation and the special crack tip elements for the treatment of crack ends is used to numerically simulate the crack propagation mechanism of brittle solids under direct shear loading. A special modeling technique is also proposed to take into account the effect of crack overlapping on the fracturing process of the bridge area in between the two parallel cracks. In this study, the wing cracks are produced at the... 

Sliding friction between a pavement and tire is an important concern in traffic safety. The British pendulum test has been used worldwide to evaluate friction characteristics of pavement surfaces. However, because of considerable differences in apparatus, procedures, and operation, significant variability can occur for evaluations of British pendulum number (BPN). In this investigation, a direct shear test (DST) device is modified and proposed to determine the sliding friction coefficient between tire and pavement surface under dry and wet conditions. Dissipated energy values obtained from DST were compared with evaluations of BPN, and a high correlation was obtained. Tests were done using... 

Asphaltic concrete has been used as waterproofing core in embankment dams, since 1948. In this application, the asphaltic core is surrounded by granular filter materials. The interaction of the asphaltic concrete and the granular materials has not been sufficiently investigated. In this paper the mechanical behavior of the interface between a natural smooth sand filter and asphaltic concrete at different levels of normal stresses and a constant shear strain rate has been studied. Small scale direct shear test has been conducted in this study, in which the shear surface is considered as the interface. Asphalt concrete specimens used in the shear test were cut in square shape (10×10×2.5 cm)...