Assessment of the swelling potential of Baghmisheh marls in Tabriz, Iran

Abstract

Tabriz is a large Iranian city and the capital of the East Azerbaijan province. The bed rock of this city is mainly consisted of marl layers. Marl layers have some outcrops in the northern and eastern parts of city that mainly belong to the Baghmisheh formation. Based on their colors, these marls are classified into three types: yellow, green, and gray marls. The city is developing toward its eastern side wherein various civil projects are under construction including tunnels, underground excavation, and high-rise building. In this regard, the swelling behavior assessment of these marls is of critical importance. Also, in lightweight structures with foundation pressure less than swelling pressure, several problems such as walls cracking and jamming of door and windows may occur. In the present study, physical properties and swelling behavior of Baghmisheh marls are investigated. According to the X-ray diffractometer (XRD) results, the marls are mainly composed of Illite, Kaolinite, Montmorillonite, and Chloride minerals. Type and content of clay minerals and initial void ratio have a decisive role in swelling behavior of these marls. The swelling potential of these marls was investigated using one-dimensional odometer apparatus under stress level up to 10 kPa. The results showed that yellow marls have high swelling potential and expansibility compared to the other marls. In addition, green and gray marls showed intermediate and low swelling potential and swelling pressure, respectively.