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, Gholam Lashkaripour, M Akbari,
Volume 5, Issue 2 (4-2012)

Tunnel boring machines (TBM) are widely used in excavating urban tunnels. These kinds of machines have different types based on supporting faces and tunnel walls. One type of these machines, is the Earth Pressure Balance (EPB) type that was used in excavating the Line 1 Tunnel of Tabriz Metro. Different parameters such as geological conditions, rock mass properties, dip and machine specifications affect the efficiency of the machine. One method of predicting the efficiency of these machines is to estimate their penetration rates. In this study the value of TBM penetration rates are predicted by an artificial neural network. Predicting of this parameter is so effective for conducting in high risk regions by understanding the time of facing to these regions. The main result of this study is to forecast the penetration rate with an acceptable accuracy and to determine the effective parameters through sensitivity analysis measured by an artificial neural network.
Delara Oshnaviyeh, Rouzbeh Dabiri2,
Volume 12, Issue 2 (10-2018)

When loose sand is subjected to seismic shaking, it tends to volume reduction and settlement. The density of the under layers is revealed in the settlement of the ground surface that causes the destruction of the structures located on ground surface. In dry sand layer, settlement in severe shakings occurs under a constant and effective stress condition and very rapid stress. In this regard, the sand deposit settlement is completed before the end of an earthquake, but if the sandy soil layer is saturated and drainage is limited the condition is prepared of fixed volume situation and the major effect of the seismic shocks is generation of exceed pore water pressure. Therefore, the deposit settlement of saturated sand requires a longer time, varying from a few minutes to a few days, depending on the permeability and compressibility of the soil and the length of the drainage path. The main purpose of the present study is to evaluate liquefaction hazards along Tabriz Metro Line 2 with using Standard Penetration test (SPT) and shear wave velocity (Vs) methods. Also, the probable rate of settlement in the soil layers in study area and correlation with liquefaction potential index (LPI) according to both procedure have been determined and discussed in the following paragraphs.
Material and Methods
In order to evaluate the liquefaction potential of soils using two field methods, geotechnical information of 54 boreholes in Tabriz Metro Line 2 were collected. The types of soil and geotechnical properties can affect the liquefaction potential. In this study, the gravely sand, silty sand, silty and sandy soils were studied. Ground water level is one of the main parameters in in soil liquefaction potential evaluation of soils. Variation of water level in boreholes is 2 to 30 meters. The peak ground acceleration (PGA) is necessary for the analysis of boreholes to evaluate liquefaction potential of soils. PGA values were selected in each boreholes position according to the Iranian Code of Practice for Seismic Resistant Design of Buildings (Code-2800-ver.4) equal to 0.35g (for return period 475 years and design life 50 years). Liquefaction potential of soil layers based on SPT results with appliying Idriss and Boulanger (2010) method has been assessed. Andrus, Stokoe and Jung (2004) procedure was used in shear wave velocity (Vs) method (with assuming cementation and un cementation condition in soils). Liquefaction potential index (LPI) of soil layers was calculated for both field tests results. Then, probable rate of settlement due to liquefaction in saturate soil layers was determined. Tokimatsu and Seed (1978) method applied for SPT results, Yoshimine (1992), Yoshimine et al. (2006) and Yi (2009) procedures have been used in Vs test. Finally, correlation between rate of settlement and LPI results were determined.
Results and discussions
Outcomes of this study can be explained in below:
1. Results obtained from comparison of both methods in liquefaction potential evaluation have been showed, agreement between two methods have been happened rarely. Specially, with assuming cementation condition in soils, LPI obtained from Vs method is more than SPT. Although, different factors can be affected at uncertainties in SPT results such as type of drilling machine, energy efficiency and accuracy of test performing. Also, in shear wave velocity method, maximum velocity for occurring liquefaction in soil layers () related to fines content percentage. It is possible that boundary values in procedure not compatible with geotechnical properties in study area.
2. Evaluation of probable rate of settlements in soil layer in study area have been showed that settlement values obtained from Vs is more than SPT. This condition is compatible with LPI amounts.
In sum up, settlement due to liquefaction in saturate soil layers is one of the important phenomena in geotechnical earthquake engineering. Maximum rate of settlement in soil layers in study area is equal 0.45m based on SPT method and 0.9m according to Vs procedure which should be considered. Accordingly, serious damages can be inflicted to buildings, underground structures and life lines in study area.  Therefore, it is suggested in future researches with using empirical and numerical (or soft computing) methods based on field and experimental tests results a detailed assessment conducted and influence of various parameters on settlement of soil layers be determined and the items listed below should be considered:
- Cementation parameter (C) values of soils in shear wave velocity method maybe not compatible with geotechnical properties in study area. It should be evaluated exactly. 
- In this research, peak ground acceleration (PGA) value was selected based on code 2800-ver.5. As regard to Tabriz Metro Line 2 is beside to Tabriz North Fault, PGA value according to historical earthquake catalogue and seismic risk analysis should be evaluated and seismic hazard have to determine with accuracy. 
Alireza Alizadeh Majdi, Rouzbeh Dabiri,
Volume 13, Issue 3 (11-2019)

The standard penetration test (SPT) is one of the most common tests in geotechnical investigations. The results of this test are known as a simple, inexpensive, and tangible criterion in geological and geotechnical engineering. Many computational methods and engineering judgments depend on the results of this test. In this research, estimation of physical and engineering properties of clay soils was carried out using statistical methods based on standard penetration test results. The scope of this case study is related to a variety of clayey soils in Tabriz (the northwest of Iran). The existing relationships were confirmed based on database of this study. After statistical analysis of the database, eight relationships including single and two-variable associations have been proposed to estimate the physical and engineering properties with better performance using nonlinear regression.
Material and Methods
Different types of clayey silt and marl layers spread in Tabriz were included for the purpose of this study. The geological age of these layers dates back to the Miocene and Pliocene era. This research was conducted in two sections of the field and analysis. Two machine boreholes were drilled, and, based on ASTM, a standard penetration test with other laboratory tests were performed on the soil specimens in order to determine the physical and plasticity properties. According to the results of this study and the existing data, a total of 107 series were prepared. Based on the soil properties, 11 variables were selected including the fine grain percentage (FGP), liquid limit (LL), plastic limit (PL), percentage of clay particles (C), plastic index (PI), consistency index (CI), activity (A), dry unit weight (γd), natural moisture content (wn), initial void ratio (eo), and effective vertical stress (σ'v). The standard penetration tests were run for each meter in drilled boreholes. The results of this test were corrected according to NCEER method. The correlation between the variables and corrected standardized penetration test results (N60) were studied by Spearman ranking coefficient. Verifications of the existing eight experimental relationships between  standard penetration and other soil properties, proposed by Kayabasi (2015) and Hoshmand et al., (2012), were checked out using the findings and data of the present study. The linear, exponential, logarithmic, and exponential regressions between each variable and N60 were investigated using SPSS software, version 16. The best regression with the highest R2 for each variable was selected. Eight new relationships were proposed. Performance of the suggested relationships was compared with the existing relationships.
Results and Discussion
The findings of the current study could be summarized as:
1. The clay soils of the studied area in Tabriz were classified into four categories including CH, MH, CL, and ML according to USCS classification. The range of changes in plastic index and liquid limits of the samples were 9.19 ~ 45% and 29 ~ 77%, respectively. The corrected standard penetration test results (N60) changed from 9 to 28 showing that soil compression was low to high.
2. The highest positive and negative Spearman correlation coefficients were related to the consistency index (+0.772) and moisture content (-0.759), respectively.
3. The existing empirical relationships, based on the database of this study, were found to have better statistical coefficients in terms of consistency index, activity, moisture percentage, and fine grained percentage. In term of sample depth, the experimental relationship, showed the lowest statistical coefficient.
4. Four single-variable and two-variable relationships were proposed by nonlinear regression analysis. Using these relationships, clay soil properties including activity, moisture content, fine grain percentage, and consistency index were estimated based on N60. In addition, two relations were proposed between sample depth (D) and vertical effective stress (σ'v) with N60. The statistical coefficients of the suggested relationships were better than the existing empirical relationships. The proposed relationship of estimating the consistency index with coefficient (R2) of 0.673 and regression line slope of about 1 had the best performance.
In general, the main objective of this study was to investigate the correlation between physical and plasticity properties of clay soils and N60 on Tabriz clayey soils. Clay soils of the present study included various silty and marl layers. Sufficient correlation was observed between the physical and engineering properties of clay soils and N60. The validation of the existing experimental relationships based on A, wn, FGP, and D resulted in weak statistical coefficients (R2 <5) employing the database of the current study. Six new experimental relationships were proposed to estimate A, FGP, wn, and CI as well as two correlations of N60 with effective stress and sample depth. Generally, the results have been revealed that the statistical coefficients of the proposed relationships were improved compared with the existing relationships. The most suitable relationship was the estimation of soil consistency index (R2~70) and root mean square error (RMSE=129). Finally, due to the novelty of this research topic, verification and development of the proposed relationships for the soils has been recommended in other areas.
Amirhasan Rezaei Farei, Masoud Mostafaei, Kazem Razavi,
Volume 13, Issue 4 (1-2020)

Urban development and rapid extension of cities have been accompanied by a considerable growth in mechanized tunneling. The abrasivity of rock and even soil is a factor with considerable influence on the wear of tools. Soil abrasion and the resulting tool wear has a major impact on machine operation, utilization, and tunneling costs and time. One of the problematic aspects of working in abrasive grounds is the frequent need for the replacement of cutting tools, especially in pressurized face tunnel boring machines (TBMs). The effect of worn and damaged TBM cutter heads has been documented for numerous tunnel projects around the world. However, the lack of a standard or universally accepted test for soil abrasivity in geotechnical investigations has made the prediction of tool wear a difficult task.
Material and methods
A reliable prognosis of the abrasiveness of soils on a project would be of great benefit for designers, clients, and contractors. Many abrasion tests exist for rocks, and some have been proposed for soils; however, there is no universally accepted or international standard test for soil abrasivity testing. One of the most important and available tests in this field is LCPC abrasivity test which was developed by the Laboratoire Central des Ponts et Chaussées in the 1980’s. The LCPC Abrasivity Coefficient (ABR or LAC) can be used as a measure for both the abrasivity of the soil material and the influence of the grain size. The  abrasivity  testing  of  rock  is  controlled  by well-known parameters, whereas in soils many factors are influencing the abrasivity such as in-situ soil conditions, sedimentary petrology and technical   properties.
Tabriz metro line 2 Project about 22 km in length that will connect eastern part of the Tabriz city to its western part, considered as a case study. The project comprises a single tunnel which has been constructed using two earth pressure balance EPB-TBM with a cutting-wheel diameter of 9.49 m. In this study, based on geological and geotechnical properties, the tunnel route was divided into four parts and the abrasion and brittleness coefficients of alluviums determined by LCPC test. Besides that, the influences of some factors such as moisture content, mineralogy, grain size and shape, type and amount of foam have been studied.
Results and discussion
Based on more than 130 LCPC test results, in general, the Tabriz Metro’s line-2 route alluviums have the abrasion in the range of low to very high and the brittleness in the range of high to very high. In order to measure the effect of moisture content on abrasion and brittleness coefficient, the LCPC test was done on some samples related to the tunnel route in dried and moistened modes (5%, 0%, 15%, 20%, 25%, and 30%). Three types of sandstone, andesite, and conglomerate of the route were used to test the effect of moisture and petrology on abrasion. In a moisture range of 0 to 5%, in all types of materials, abrasion was increased. In a moisture range of 5 to 10%, abrasion was decreased in all three types, and this shows that a moisture level of 10% is a normal moisture content to create minimum abrasion. The behavior of sandstone and conglomerate is similar at higher moisture contents, and an increase in moisture content to 30% can increase abrasion of materials in both types. In conglomerate, abrasion at higher moisture levels is significantly more than in other modes. In andesite, an increase in moisture content to 20% can increase abrasion, although the abrasion is decreased with a moisture content of over 20%. In most samples, increase in moisture content led to decrease in brittleness of materials. In general, the highest abrasion level was related to conglomerate and the lowest level was related to sandstone. Moreover, andesite was at a lower level than conglomerate and a higher level than sandstone in terms of abrasion. Also, the results show that increased grain size led to increased abrasion, and the changes in andesite were greater than in sandstone.
In order to test the effectiveness of foam on abrasion, the foam used in workshops (A 168) made by Komeil Company Kashan was used for four types of petrography: conglomerate, andesite, sandstone, and silica. This test was conducted in the range of dried to 100 ml foam. In all types, decreased abrasion is observed from 0 to 20 ml and increased abrasion is observed from 20 to 100 ml.
The following conclusions are drawn from this research.
- With regard to the effect of grain size, increased size of grains could lead to more abrasion and less brittleness
- In terms of the effect of mineralogy, the conglomerate had the most effect on abrasion. In terms of brittleness, andesite was the most brittle.
- When the foam is moisturized in the sample, minimum abrasion is observed and above this level, the abrasion is increased.
Mr. Mohammad Alizadeh Mansouri, Dr. Rouzbeh Dabiri,
Volume 16, Issue 1 (10-2022)

In this study, it is attempted to analyze sensitivity and reliability in order to evaluate the liquefaction potential in soil layers in Tabriz. 62 boreholes that had possible conditions for liquefaction were selected. Seismic mapping was simulated using finite fault method and then the effect of soil layers on PGA was estimated. In continue, the liquefaction potential index was estimated and the zoning map of liquefaction risk was presented. In final, through sensitivity and reliability analysis of the Monte Carlo method, the rate of density function against safety factor of the soil layers versus to liquefaction was determined.

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