JOURNAL OF ENGINEERING GEOLOGY
Year:2016 | Volume:9 | Issue:4|Papers Count:8

Ground- Penetrating Radar (GPR) is a non-destructive and high-resolution geophysical method that uses high frequency reflected EM waves to detect buried objects and manmade structures. In current study this method has been used to identify geometrical characteristics of buried cylindrical targets such as tunnel structures. This aim has been obtained through determination of relationships between physical and geometrical characteristics of cylindrical targets with the parameters of GPR hyperbolic response using two intelligent pattern recognition methods known as artificial neural network and template matching. To this goal GPR responses of synthetic cylindrical objects corresponding to common geotechnical targets (such as tunnels, canals, qanats and pipes) have been simulated using forward modeling by 2D Finite Difference and have been used as templates in the neural network and template matching algorithms. The structure of applied neural network was designed based on extracting discriminant and unique features (eigen values and the norm of eigen values in the horizontal and vertical directions) from the GPR images and predicting all geometrical parameters of the objects simultaneously. The template matching operation also carried out by two different similarity approaches named spatial domain convolution and normalized cross correlation in 2D wave number domain. Afterward it was delineated that the wave number domain approach is generally faster (more than 23 times) than the other approach.The results of the research show that both two employed intelligent methods having in situ, real-time, accurate and automatic application capabilities can be applied for real geotechnical applications, however in general the neural network method has led to less error and as a result higher estimation power for the geometrical parameters of the cylindrical targets than template matching method.

Landslide is one of the mass movement processes that occur in Iran and parts of the world every year. It causes huge human loss and economical damages. In order to check the stability of slopes in Kakasheraf basin, in the first step sliding areas were identified using the aerial photography and field surveys and then distribution map of landslide is provided. Impact of each of these factors which are included: dip, aspect, altitude, lithology, landuse and distance from the Road and Drainage is assessed in Arc GIS software environment merging the effective factors on landslide with the landslide distribution map. Then these factors were prioritized using AHP model. In this study, the fuzzy logic and density area method in order to landslide hazard zonation has been used in the kakasheraf watershed. The used for assessment and classification of models outputs in Empirical probability index of landslide risk. Results show that, the fuzzy logic, is an applicable method than Density area model for mapping the landslide risk in Kakasheraf watershed.

Mountains are usually formation origin of their neighbor land surface features such as hillsides and plains. In these situations and due to spectral fusion of different land attributes, remote sensing (RS) technique cannot separate lithology units of mountainous regions from their neighbor areas. Therefore, some problems and errors may occur in application of RS technique for generation of geology maps and in separation of these units from other similar units. These errors almost arise from carrying and propagation of primary clastic materials from mountain ranges to hillsides and their surrounding land surfaces. These regions almost have similar spectral signatures and therefore, as an example, identification of massive from debris lime stones through RS technique becomes a challenge. Main objective of this study is to integrate RS and geomorphology approaches for identification of different geomorphology units and finally separation of debris lime stones from massive lime stones in Bahadoran region, Yazd province. For this purpose, a Landsat ETM+ image was acquired together with band ratios, principal component analysis and factor analysis approaches to generate lime stone distribution map. Additionally a knowledge-based image interpretation approach was used for recognition of lithology units and generation of a new limestone distribution map. The first map then was compared with the second one by Kappa statistics. Results of this study show that the second approach (integration of RS and geomorphology sciences) can better generate the lime stone distribution map compared with the first one. Kappa statistics of the two approaches were 0.73 and 0.51, respectively.

one of the major problems associated with the clay soils is their swelling due to moisture attraction, which results in imposing high pressure on the super structures, and may cause failure or deformation of light structures. One of solutions to mitigate the swelling problem of clay soils is their stabilization using additives. This paper, describes the evaluation of three types of additives on the swelling of two types of clay soils, one with low plasticity index and the other with a high plasticity index. The additives used in this research include two traditional additives, namely cement and lime, and one type of nontraditional stabilizer, namely CBR PLUS nano polymer. These additives were added to the soils in different contents, and the Atterburg limits, and swelling of the soils at different times from 2 to 96 hours after addition of additives were measured. The results show that, the CBR PLUS is more effective in decreasing the swelling of the soil with high plasticity index, with a 15 times reduction in swelling, against 1o times for the lime and cement. For the soil with low plasticity index, he cement is found to be more effective than the lime and CBR PLUS in reducing the swelling. The addition of 7% of cement resulted in 14 times reduction in swelling, against 6 times reduction for the addition of the same content of lime. In addition, it is found that, the CBR PLUS and cement, are, respectively, more effective in reducing the plasticity index of the soil with high and plasticity index.

Reinforced soil structures are finding increasing applications in seismic active zones. This makes it important to study the dynamic behavior of these structures. Therefore, the present article is an attempt to study the seismic behavior of reinforced soil retaining walls with polymeric strips. The effects of the most important parameters including the length of reinforcement, reinforcement arrangements (zigzag vs. parallel), maximum base input acceleration, and wave frequency on the wall displacement were investigated for sensitivity analyses. The main drawback of dynamic analysis is that numerical methods are time consuming. Therefore, determination of equivalent coefficients is a suitable and simple approach to converge results of pseudo-static and dynamic methods. In this case, a relatively accurate design is achieved by using pseudo static method that requires far less time. To this end, the earthquake equivalent horizontal acceleration coefficient is proposed by considering horizontal displacement of the wall as the basis for comparison.

Stability and safety of the dam is one of the most important challenges during construction and performances. The aim of this study is to make accurate water table and piezometric heads through embankment and its foundation of the shahghasem dam which is located near Yasouj city. Applying geostatistical, Simple Kriging, Ordinary Kriging and Weighted Moving Average, interpolation was done using Gaussian, exponential and spherical models. For comprising the results, we use the statistical index including MAE, MBE, RMSE and GSD. Results indicated that Simple Kriging with Gaussian model is the best one, while Ordinary Kriging with Gaussian model and Ordinary Kriging with spherical model are in the next order. The Weighted Moving Average method with different exponents indicated a significant error comparing to other methods. As a result, the depicted maps show a hole through foundation near right abutment of the dam. Finally, being a hole in foundation could strength piping and internal erosion.

Heavy concrete is an excellent shielding material most widely used for radiation shielding of gamma rays. It is possible to use lead slag as a partial replacement of aggregates to increase the density of concrete shields. From an environmental point of view, substitution of natural aggregate with lead slag can saves our natural resources and land. Also, using lead slag resulted in an increase of the attenuation of gamma radiation.The main goal of the present work is to study the possibility of using lead slag extracted from recycling of the spent batteries as concrete aggregates. The mechanical properties and linear attenuation coefficients of concrete samples fabricated by using lead slag as 40 to 60 percent replacement of fine aggregates were experimentally examined. Also the effects of lead powder on setting time of cement pastes were investigated.Experimental results indicated that the partial replacement of sand by fine lead slag increases the mechanical strength of concrete. Radiation absorption tests showed also a superior absorption of gamma rays with the use of lead slag as concrete aggregate. But, Addition of lead powder significantly delays the setting time of the cement pastes.Consequently, Lead slag concrete could be preferred for construction of shields with lower cost and better capacity of radiation absorption.

Average of the shear wave velocity of the upper 30 meters despite the numerous weaknesses in accurate explanation of the site dynamic characteristics, is one of the reliable parameters in ground seismic classification in the view of different building codes, until now. This study evaluated the results of shear wave velocity in 79 points in Mashhad, and then empirical relationship between average of the shear wave velocity of the upper 30 meters and lower depths is obtained. Based on the velocity profiles information in 79 boreholes and resonance period data of the Mashhad, the proper depths for dynamic analysis of the site effect are recommended. Therefore the velocity profiles required for analysis of the deposits effects in Mashhad, except for the south and north elevations margin is more than 30 m. For central, eastern and northeastern areas which have resonance period more than 0.7 s, this depth is estimated as 80m. Therefore, investigation depth of 30 meters in Mashhad is only adequate for site classification based on the building codes and deeper studies are needed for the theoretical analysis.