Journal of Engineering Geology

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The previous studies underteaken in the region indicate that the Ekhtiarabad and Chah-Darya sinkholes have occurred as a result of dissolution of underground gypsum rocks. Hence, they represent the likelyhood of hidden and threatening caves in the region. The presence of gypsiferous formations having surficial karstic features attest to this supposition. So, in order to determine the possible dissolving sites which may contain caves, the electrical conductivity and evaporite dissolution index maps of Kerman-Baghin aquifier were prepared and matched with groundwater recharge and mobility conditions. Accordingly, four suspected hidden- cave sites were recognized which include a large area around Ekhtiarabad village (as the most suspected site), one spot at the northwest of Baghin Plain and two other areas (south of Baghin and south and southwest or Kabutarkhan). Based on the utilized hydrogeochemical criteria, these last two areas may contain hidden caves, but, due to unsuitable hydrodynamic conditions, the possibility seems weak.

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The world financial crisis has drastically raised the costs of hydrocarbon materials. This simply manifests the strategic significance of crude oil storage. Regarding the special rank of the oil in Iran’s economy, storage industry development can be one of the solutions to control such a crisis. Underground storage of crude oil in synthetic structures (rock caverns, salt caverns, and obsolete mines) and natural structures (depleted fields of oil and gas, underground water resources, and natural caves) is possible. Among these possibilities more adaptable to the environment is the most appropriate. Due to the existence of many caves in Iran, crude oils storage in natural caves is a proper option. It is clear that if natural caves are used instead of caverns, much can be saved. The present article intends to choose a proper cave for crude oil storage through studying the natural caves based on a combination of fuzzy analytical hierarchy process (FAHP) and technique for order performance by similarity to idea solution (TOPSIS). The likely option is chosen. Roudafshan Cave is considered appropriate for crude oil underground storage based on several qualitative and quantitative criteria including tourism and environment protection regulations, capacity, distance from both main pipes of crude oil transfer and country's major petroleum factories. It should be noted that these criteria are ranked by an experienced team. This cave is located in the north east of Tehran in Firoozkooh and has three passageways which are among the largest ones in the country. Generally, its capacity is estimated to be about 250,000 square meters

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The in-situ stress is one of the most important parameters in the design of underground structures. Conventional methods such as in-situ stress measurements using hydraulic fracturing method has two main disadvantages are time and cost of this methods. Acoustic emission is one of the indirect in-Situ stress measurement methods which is based on the theory of the Kaiser effect. When a rock is stressed, it release acoustic signals this phenomenon is called acoustic emission. Kaiser Effect is defined as lack of acoustic signals in the lower stress levels than the previous maximum stress level. In other words, as long as rock is not reached to the previous maximum stress level, do not show significant acoustic emission. Several factors affect on Kaiser Effect such as delay time, temperature, rock fabric, porosity, discontinuities, joints and geological structure. In this paper, effect of the delay time on Kaiser Effect has been presented. The time between coring operations and acoustic emission test is called delay time. The limestone rock is selected as main samples of test and after preloading, reloading and acoustic emission test were carried out with different delay times. The results showed that the felicity ratio is less than 1, when delay time is about 20 days and after three months has increased to be more than one.

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This research focuses on the identification and description of various features of pseudokarst in different parts of Alvand granitic batholith, Hamedan, west of Iran. In the literature, karst features have been presented as specific types of terrain or landscapes with particular characteristics suites of well-known surface and subsurface dissolutional forms. Whereas, pseudokarst refers to non-dissolutional surface or subsurface features and landforms created in different areas such as slopes, coastal lines crushed stone areas, lava tubes and permafrost regions. In this research, a comprehensive field investigation program has been carried out. During the field investigations, the most important features of pseudokarst in Alvand granitic batholith have been recognized and classified. Results show a wide range of pseudokarst features in the Alvand granitic rock masses. These landforms are created by erosion, weathering processes and some holes caused by rock block movements along the rock slopes. Some of the most important forms and features of the pseudokarst in the studied area are consist of tafoni, genama, pseudokarren, talus caves, caves associated with the residual blocks and erosional forms along joints and fractures within the granitic rock masses