نشریه زمین شناسی مهندسی ایران
سال هفدهم شماره 2 (تابستان 1403)

Due to the widespread problem of excavation in urban and non-urban constructions, the importance of stabilization of excavations and walls is felt more. One of the methods used in this matter is the use of steel sheet pile walls. When using steel sheet pile wall, the soil in and around the site may be of weak soil type for backfill, so it is necessary to strengthen this soil by using different methods. In this research, using the available information about the characteristics of the mixture of sandy soil and tire chips with volume ratios of 15 and 30%, the behavior of the sheet pile wall with different heights, under the effects of increasing the depth of the reinforced layer in the backfill, with The use of PLAXIS finite element software is investigated. The results show that the use of a mixture of sand and tire chips in the backfill part of the wall instead of full sand backfill leads to a reduction in the lateral displacement and the bending moment of the sheet pile. Also, the anchor force decreases. In this case, the settlement, increases to a small amount. Also, by increasing the depth of the reinforced layer, so that the entire backfill is reinforced with tire chips, the lateral displacement and bending moment of the sheet pile is reduced.

Earthquakes have the potential to cause widespread destruction, especially in urban areas with high infrastructure and population density. Understanding and analyzing urban earthquake vulnerability is crucial for reducing the impact of earthquakes. Earthquake hazard zoning plays a significant role in assessing urban earthquake vulnerability. By dividing a region into different zones based on earthquake hazard levels, authorities can prioritize resources and implement targeted mitigation measures. In this regard, the vulnerability assessment of different areas in the city of Shiraz has been studied. The present research is of a practical nature, and its investigation has been conducted using a descriptive-analytical method. In order to achieve the research objectives, the effective criteria for urban tissue vulnerability to earthquakes (physical and environmental factors, land morphology, access to emergency and medical centers, and proximity to hazardous facilities) were first identified. Then, using the Analytic Network Process (ANP) model and its software, the value and importance of each criterion were determined. In the next stage, the results of the network analysis process with 4 criteria and 21 sub-criteria were combined, and a map of the level of vulnerability of urban tissues in Shiraz was prepared. The research results indicate that among the influential criteria, physical and environmental factors received the highest score, and the central and southwestern urban areas have the highest vulnerability to earthquakes in the city of Shiraz.

In geotechnical engineering, using additives to improve soils is very important. This research aims to investigate the effects of Temperature and nano-magnetite on the physical and mechanical properties of clayey soil. The selected percentages for nano-magnetite as 0. 0.5, 1, 1.5, and 2% in standard curing conditions (1, 28, and 90 days) and under different temperatures (3 days at 20, 40, and 60oC) to evaluate the physical and mechanical characteristics of the samples, atterberg limits, standard compaction, unconfined compressive strength (UCS), direct shear test (DST), and ultrasonic pulse velocity (UPV) were used. The results of this research show that by adding 1% of nano-magnetite to clayey soil at a temperature of 60oC, the UCS of clayey soil increased by about 175%, and further, according to the DST, it can be seen that the parameters of cohesion and Internal friction angle have increased by 115% and 77% respectively. Also, the UPV was the highest due to the addition of 1% nano-magnetite, which can confirm the results obtained for mechanical tests.

Profitable production of decorative stone depends on the dimensions of the extractable block. Identifying, discontinuities modeling, their role in mining operation, instability and sliding of blocks are important parameters in mine design. The shape and volume of sub-blocks obtained from mine exploitation are challenging issues in mining operations, which are controlled by the three-dimensional model of the discontinuity. Failure to pay attention to this issue leads to many problems such as severe crushing of stone blocks and low extraction efficiency. In this research, an extraction optimization approach has been used for decorative stone mines. 3D block model was made for different directions of extraction working face. For each direction, the number and volume of sub-blocks were calculated. Blocks with a volume of less than 2 cubic meter were considered as waste and the percentage of recovery was calculated. Face alignment with azimuth of 15 degrees that led to the largest volume blocks production was suggested as the optimal face direction. Stability analysis of the face was done. There was no possibility of plane and toppling sliding, but there was a possibility of wedge sliding. The stability analysis showed that there is a possibility of wedge slide in other stretches as well, which was expected due to the jointing of the rock mass. Therefore, the face direction with the highest percentage of recovery, considering the safety of wedge failure, was suggested for the mine extraction plan.

Mashhad plain is affected by a series of active faults in the northern margin of the binalood and the kopehe-Dagh mountain ranges. The activity of these faults forms the morphology of the stepped bedrock of the plain. Besides, the faults activities in the Quaternary period are the main effective parameters in the aquifer thickness and depth of bedrock in Mashhad plain.The investigation of data from drilling wells in Mashhad plain shows that the thickness of alluvial aquifer at very low intervals has been also changed abruptly under the influence of hidden faults in the plain. In the present study, due to the gathered data from exploration wells reaching the bedrock and geoelectric studies, iso-alluvial thickness curves from southern parts of Mashhad plain (which are important in terms of discharge) have been provided. Also the location of hidden faults in the plain has been determined. The results of this research indicate that the main fault in southern parts of Mashhad plain (especially Souran and S.chenaran faults) have a major effect in sudden changes in depth and the kind of bedrock, alluvial thickness and the texture of alluvial particles in Mashhad plain.

Predicting the long-term durability of rock in the construction of breakwaters is crucial for their safe and economic operation, but remains challenging. Here, we report on the application of Machine Learning models to such prediction. We developed a database of physical and mechanical properties of rocks from 35 rubble mound breakwaters on the Caspian Sea, Oman Sea and Persian Gulf coastlines of Iran. Properties include uniaxial compressive strength, point load strength, Brazilian tensile strength, aggregate impact and aggregate crushing values, Los Angeles abrasion, porosity, ultrasonic wave velocity, density, sodium sulfate soundness and slake durability index, together with petrophysical data. These data were analysed using the four supervised machine learning (ML) models of random forest (RF), support vector (SV) machine, gradient boost (GB) and k nearest (KN) neighbor. Model performance was assessed using RMSE computed using predicted and measured values of slake durability, and R2 of the linear regression of the predicted and measured slake durability values. The results indicate that the random forest (RF) models perform best, especially for igneous rocks: for both saturated and oven dry igneous rocks the RF model produced prediction errors of under ±0.6%, and R2 was unity to five significant figures. We conclude that ML techniques are robust methods for predicting the slake durability resistance of rock material used in the construction of breakwaters.