A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Summary Although the known evaporite minerals amount to more than 25, anhydrite and gypsum are the most conspicuous from the engineering geological point of view. They present considerable difficulties in the construction of tunnels, dams and other structures because of their solubility and swelling when treated with water. Swelling phenomena observed in anhydrites have been exaggerated before the 1960's. During those years anhydrite has been thought to be solely responsible for all kinds of harmful swelling effects. The results of observations and investigations made after 1960, showed that besides anhydrite, clay minerals such as corrensite and montmorillonite have the property of swelling and that of stress releasing owing to gravitational and tectonic stresses and also preconsolidation properties which are responsible for deformation. The investigations and measurements made during the last 20 years, have shown that the pressures in conversion of anhydrite to gypsum under normal conditions vary between 2–38 kg/$ cm^{2} $ whereas the most commonly observed values remain confined to between 8–13 kg/$ cm^{2} $. When gypsum deposits come into contact with water solution channels and caves tend to form with time. If gypsum occurs as the cementing agent it presents most dangerous conditions for engineering purposes. Vast areas in Central Eastern Turkey are mainly covered with Neogene clastic deposits which consist of clays and gypsum with mudstones, siltstones and others. In the Upper Zizilirmak Basin a total of about 180 m of gypsum layers has been measured in about 1250 m of Oligo-Miocene deposits. Typical karst features are seen around the Sivas area, because of solution of thick gypsum layers. Some of the karstic dolinas are more than 100 m deep. In the Dicle (Tigris) River Basin, a total of 30 dam sites were chosen. On the 8 preferred sites chosen from the above, layers and lenses of gypsum and anhydrite were observed. By means of detailed field and laboratory experiments, numerical values on the swelling and solution behaviour of evaporitic formations have been obtained.
Summary Although the known evaporite minerals amount to more than 25, anhydrite and gypsum are the most conspicuous from the engineering geological point of view. They present considerable difficulties in the construction of tunnels, dams and other structures because of their solubility and swelling when treated with water. Swelling phenomena observed in anhydrites have been exaggerated before the 1960's. During those years anhydrite has been thought to be solely responsible for all kinds of harmful swelling effects. The results of observations and investigations made after 1960, showed that besides anhydrite, clay minerals such as corrensite and montmorillonite have the property of swelling and that of stress releasing owing to gravitational and tectonic stresses and also preconsolidation properties which are responsible for deformation. The investigations and measurements made during the last 20 years, have shown that the pressures in conversion of anhydrite to gypsum under normal conditions vary between 2–38 kg/$ cm^{2} $ whereas the most commonly observed values remain confined to between 8–13 kg/$ cm^{2} $. When gypsum deposits come into contact with water solution channels and caves tend to form with time. If gypsum occurs as the cementing agent it presents most dangerous conditions for engineering purposes. Vast areas in Central Eastern Turkey are mainly covered with Neogene clastic deposits which consist of clays and gypsum with mudstones, siltstones and others. In the Upper Zizilirmak Basin a total of about 180 m of gypsum layers has been measured in about 1250 m of Oligo-Miocene deposits. Typical karst features are seen around the Sivas area, because of solution of thick gypsum layers. Some of the karstic dolinas are more than 100 m deep. In the Dicle (Tigris) River Basin, a total of 30 dam sites were chosen. On the 8 preferred sites chosen from the above, layers and lenses of gypsum and anhydrite were observed. By means of detailed field and laboratory experiments, numerical values on the swelling and solution behaviour of evaporitic formations have been obtained.
Engineering properties of evaporites and evaporitic formations of Turkey
Yuzer, E. (author)
1982
Article (Journal)
English
Engineering properties of evaporites and evaporitic formations of Turkey
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