The second lot of Tehran-Shomal freeway with approximately length of 22 km is on the development ... more The second lot of Tehran-Shomal freeway with approximately length of 22 km is on the development phase to select the suitable rout in central part of Alborz Mountain, northern Iran. There are three main proposed routs for construction of this freeway. According to the geological condition of the area, landslide hazard assessment is one of the main effective factors in rout selecting. So, in this paper we want to prepare an applicable landslide susceptibility map for the study area. For this purpose, at first, nine factors of slope angle, aspect, altitude, lithology, roads proximity, fault proximity, vegetation cover, precipitation and drainage density were recognized as major factors in occurrence of landslide in the study area. Then, the analytical hierarchy process (AHP), the frequency ratio (FR) and weight of evidence (WOE) methods were applied for landslide susceptibility mapping. A landslide inventory map applied to operation of two FR and WOE methods as well as validation of created landslide susceptibility maps. Finally, three landslide susceptibility maps were created using three mentioned method in the GIS environment. These maps were evaluated and validated using the landslide index (Li) and success rate carve (SRC). Results show that the two methods of FR and WOE, with the same SRC value of 80%, present a slightly better model fitting compared to the AHP method with the success rate of 77.2%.
Bulletin of Engineering Geology and the Environment
Water inflow caused by tunneling can have severe impacts on the springs’ discharge rate. If these... more Water inflow caused by tunneling can have severe impacts on the springs’ discharge rate. If these impacts have not been predicted beforehand, technical, economic, and environmental challenges could occur. While there are a few methods for evaluating the risk of water drawdown, their shortcomings create the need to develop a new one. First, in this research, five main tunneling projects in Iran were studied for evaluating the influence of tunneling on spring’s discharge, and a comprehensive database that contains information on 111 springs located in the vicinity of these tunneling projects was developed. Then, by learning from previously developed methods’ shortcomings and using an appropriate decision analysis method (Analytic Hierarchy Process or AHP), a new model was proposed for evaluating the risk of discharge reduction in springs located in the vicinity of tunneling projects. This new model, named TIS (Tunneling Impacts on Springs), was developed based on four important parameters of a) volume of water inflow toward the tunnel, b) distance between spring and tunnel, c) hydraulic connectivity, and d) aquifer recharge potential. In the next step, using data recorded in the database, TIS values were calculated for each spring, and using suitable statistical methods, the obtained TIS values were classified based on the actual behavior of springs. For using this model in practice, all springs must be checked using a screening process. In this process, according to some limitation criteria (including distance from the tunnel, groundwater condition in tunnel, spring origin), unimportant springs are excluded from the list and only springs with possible influence from tunneling are considered for further assessments. This helps to investigate the in-risk springs more effectively.
The Chamshir water conveyance tunnel (CWCT) with a length of 7.4 km and boring diameter of 5.3 m ... more The Chamshir water conveyance tunnel (CWCT) with a length of 7.4 km and boring diameter of 5.3 m is excavated using a refurbished single shield TBM, initially designed to work in hard rock formations. This study focuses on engineering geological issues, which are important for checking the suitability of this machine and proposing required modifications for improving its performance in soft rock. The main objective of the investigation was to predict geological problems and risks associated with TBM tunneling in the given ground conditions and to examine the ability of the selected TBM to overcome the anticipated challenges. Geotechnical parameters that could affect TBM operation are described in this paper. These parameters include the engineering geological and hydrogeological properties of the rock units, rock mass boreability and abrasivity, and assessment of geological problems (clogging potential, swelling, abrasive ground, unstable tunnel face and water inflow). Estimated too...
DOI:10.22044/jme.2021.10425.1993 Mechanized tunneling in rocks is based on fracture propagation a... more DOI:10.22044/jme.2021.10425.1993 Mechanized tunneling in rocks is based on fracture propagation and rock fragmentation under disc cutters. Rock chipping is an efficient kind of fragmentation process, while the grinding process may occur under special conditions. The cutterhead penetration is an appropriate parameter involved in order to distinguish between the chipping and grinding processes in rock cutting. In this work, the grinding and chipping processes are investigated in the Uma-Oya water conveyance tunnel in Sri Lanka. The Uma-Oya project is a water transfer, hydropower, and irrigation system in the SE part of the central highland region of Sri-Lanka. From a geological viewpoint, most parts of the tunnel route in the studied section consist of very strong and abrasive metamorphic rocks that potentially are susceptible to grinding occurrence during the boring process under disc cutters. In this work, firstly, data processing is performed in order to identify the boundary betwe...
In the academic and industrial environments of Iran, there is little understanding of the relatio... more In the academic and industrial environments of Iran, there is little understanding of the relationship between geological science and technical branches (mechanics, electronics, etc.). Such concepts are not explained in Iran's higher education curriculum, and almost no source of research has been published in persian. The history of collaborative studies between mechanical engineers and geoscientists can be considered at the onset of the topics of the Terramechanics. But one of the common industrial areas between mechanical engineers and geologists in our country is mechanized tunneling technology. The design and construction of TBMs is based on the geological data of the projects. Many mechanical and electronic technical defects occur on the TBM in the face of unfavorable geological conditions on the excavation path. The performance of the various parts of the machine and even the amount of their consumables (oils, greases, etc.) are directly related to changes in the geologica...
Bulletin of Engineering Geology and the Environment
The chipping and grinding processes are the basis for understanding rock cutting during TBM excav... more The chipping and grinding processes are the basis for understanding rock cutting during TBM excavation in hard rock conditions. The chips are produced when tensile fractures created by adjacent cutters propagate parallel to the tunnel face and coalesce whereas grinding occurs when fractures do not fully propagate through the rock and only fines are generated. Chipping is the normal and efficient boring process using machines equipped with disc cutters. Consequently, almost all of the models proposed for predicting the TBM penetration have been developed by the assumption that chipping is the dominant mode. It is obvious that these models are unable to predict correctly TBM performance when grinding is dominated in the rock cutting process. In this study, the relationships between engineering geological properties of the rock units (Cretaceous limestones) and operating and performance parameters of a refurbished EPB-TBM, employed for completion of SEL6 (the Southern Extension of Line 6, Tehran Metro) tunnel, were evaluated and analyzed. In this project due to limitations in the load capacity of the employed cutters and insufficient initial penetration in rock, the excavation was mostly carried out on grinding-dominated mode. So, the suitable data for establishing a special database and consequent analyses were provided. The established database composed of actual operating and performance parameters of the machine (i.e., cutterhead penetration and RPM and cutter load) and also engineering geological properties (i.e., UCS, alpha angle, GSI, and RQD) of limestone strata. Finally, by statistical analyses performed on collected and screened data (41 data sets), some simple, site-specific, empirical equations were developed to predict the TBM performance on grinding mode. In addition, according to the multivariate regression method, a significant relationship between the cutterhead penetration (PRev), the cutter load (Fn), intact rock strength (UCS), and geological strength index (GSI) was established, statistically. The obtained results demonstrate that this engineering geological-based model could provide a new applicable equation for accurately predicting TBM performance for similar geological conditions where grinding is dominant.
Earth pressure balance (EPB) TBMs are commonly used for soft ground tunneling in urban areas. In ... more Earth pressure balance (EPB) TBMs are commonly used for soft ground tunneling in urban areas. In metro tunnels’ excavation, designing a comprehensive monitoring system to control surface settlement is essential to prevent damage to surface structures. The present study aims to develop new prediction models to estimate the ground surface settlement using two soft computing techniques, SVM and ANN-MLP, and a multiple variable regression model to develop the new empirical formulas. The TBM operational parameters collected from the Tehran metro line 6, South extension (TML6-SE) project have been applied to confirm the provided models. In the data analysis process, the relationships between various parameters (torque index, thrust index, and earth pressure) and the ground surface settlement are investigated. Moreover, several statistical evaluation criteria are implemented to evaluate the performance of the developed models. The results show that the predicted values are in good agreement with the real data. The results can be used for similar ground and TBM tunneling conditions.
Geotechnical and geological parameters have the greatest impact on the performance of hard rock t... more Geotechnical and geological parameters have the greatest impact on the performance of hard rock tunnel boring machines (TBMs). This includes the rock and rock mass properties that affect the rate of penetration (ROP) as well as the machine utilization that is heavily dependent on ground support type and related machine downtime and delays. However, despite the widespread use of TBMs and established track records, accurate estimation of machine performance is still a challenge, especially in complex geological conditions. The past studies have tried to use rock mass classification systems for improving the accuracy of the machine performance prediction. Rock mass classifications has been primarily developed for design of ground support, and as such, have not offered a good fit for estimation of TBM performance. This paper will review performance of a hard rock TBM in a 12.24 km long tunnel and offers analysis of field performance data to evaluate the relationship between various lithological units and TBM operation. The results of statistical analysis of the initial 5.83 km long tunnel indicate strong relationships between geomechanical parameters and TBM performance parameters. Site specific models, including Non-linear regression analysis (NLRA), Classification and regression tree (CART), and Genetic Programming (GP) have been used for analysis of a TBM performance relative to the ground condition data. The current study has looked at the possibility of developing a new rock mass classification system for TBM application by using the above noted analysis. Preliminary results indicate that CART can be used for offering a proper rating scheme for a rock mass classification system that can be used for TBM applications.
Bulletin of Engineering Geology and the Environment
The southern section of the Zagros zone in southwestern Iran, a well-known sedimentary basin, was... more The southern section of the Zagros zone in southwestern Iran, a well-known sedimentary basin, was investigated to address two key questions: (1) whether it would be feasible to construct large unlined rock caverns (URCs) in moderate-quality sedimentary rocks of this area for the storage of crude oil, and (2) which parts of this wide area were most suitable for constructing such huge underground structures. To answer these questions, first, the geological, hydrogeological and engineering geological properties of typical rock units in the area were investigated, and preliminary analyses were performed to check the stability, permeability and water circulation conditions of typical rock masses at depth. Next, geographical information system (GIS) techniques were applied to select the best regions for constructing the URCs. Parameters including geological characteristics, governmental restrictions, and proximity to facilities were selected as important factors for area zonation and for preparing a suitability map for constructing URCs for storing crude oil. The results of the study indicated that limestone units of the Asmari and Sarvak Formations at a moderate depth (200–300 m) were the most appropriate rock units for construction of URCs with a cross-section area of around 500 m2. In addition, the suitability map showed that two small regions in the central and northern parts of the study area were best suited for URC construction. The key advantages of these regions include a wide distribution of surface exposures of good-quality stratigraphic units (Asmari and Sarvak Formations), limited distribution of active tectonic structures such as salt domes and faults, and proximity to crude oil facilities.
The second lot of Tehran-Shomal freeway with approximately length of 22 km is on the development ... more The second lot of Tehran-Shomal freeway with approximately length of 22 km is on the development phase to select the suitable rout in central part of Alborz Mountain, northern Iran. There are three main proposed routs for construction of this freeway. According to the geological condition of the area, landslide hazard assessment is one of the main effective factors in rout selecting. So, in this paper we want to prepare an applicable landslide susceptibility map for the study area. For this purpose, at first, nine factors of slope angle, aspect, altitude, lithology, roads proximity, fault proximity, vegetation cover, precipitation and drainage density were recognized as major factors in occurrence of landslide in the study area. Then, the analytical hierarchy process (AHP), the frequency ratio (FR) and weight of evidence (WOE) methods were applied for landslide susceptibility mapping. A landslide inventory map applied to operation of two FR and WOE methods as well as validation of created landslide susceptibility maps. Finally, three landslide susceptibility maps were created using three mentioned method in the GIS environment. These maps were evaluated and validated using the landslide index (Li) and success rate carve (SRC). Results show that the two methods of FR and WOE, with the same SRC value of 80%, present a slightly better model fitting compared to the AHP method with the success rate of 77.2%.
Bulletin of Engineering Geology and the Environment
Water inflow caused by tunneling can have severe impacts on the springs’ discharge rate. If these... more Water inflow caused by tunneling can have severe impacts on the springs’ discharge rate. If these impacts have not been predicted beforehand, technical, economic, and environmental challenges could occur. While there are a few methods for evaluating the risk of water drawdown, their shortcomings create the need to develop a new one. First, in this research, five main tunneling projects in Iran were studied for evaluating the influence of tunneling on spring’s discharge, and a comprehensive database that contains information on 111 springs located in the vicinity of these tunneling projects was developed. Then, by learning from previously developed methods’ shortcomings and using an appropriate decision analysis method (Analytic Hierarchy Process or AHP), a new model was proposed for evaluating the risk of discharge reduction in springs located in the vicinity of tunneling projects. This new model, named TIS (Tunneling Impacts on Springs), was developed based on four important parameters of a) volume of water inflow toward the tunnel, b) distance between spring and tunnel, c) hydraulic connectivity, and d) aquifer recharge potential. In the next step, using data recorded in the database, TIS values were calculated for each spring, and using suitable statistical methods, the obtained TIS values were classified based on the actual behavior of springs. For using this model in practice, all springs must be checked using a screening process. In this process, according to some limitation criteria (including distance from the tunnel, groundwater condition in tunnel, spring origin), unimportant springs are excluded from the list and only springs with possible influence from tunneling are considered for further assessments. This helps to investigate the in-risk springs more effectively.
The Chamshir water conveyance tunnel (CWCT) with a length of 7.4 km and boring diameter of 5.3 m ... more The Chamshir water conveyance tunnel (CWCT) with a length of 7.4 km and boring diameter of 5.3 m is excavated using a refurbished single shield TBM, initially designed to work in hard rock formations. This study focuses on engineering geological issues, which are important for checking the suitability of this machine and proposing required modifications for improving its performance in soft rock. The main objective of the investigation was to predict geological problems and risks associated with TBM tunneling in the given ground conditions and to examine the ability of the selected TBM to overcome the anticipated challenges. Geotechnical parameters that could affect TBM operation are described in this paper. These parameters include the engineering geological and hydrogeological properties of the rock units, rock mass boreability and abrasivity, and assessment of geological problems (clogging potential, swelling, abrasive ground, unstable tunnel face and water inflow). Estimated too...
DOI:10.22044/jme.2021.10425.1993 Mechanized tunneling in rocks is based on fracture propagation a... more DOI:10.22044/jme.2021.10425.1993 Mechanized tunneling in rocks is based on fracture propagation and rock fragmentation under disc cutters. Rock chipping is an efficient kind of fragmentation process, while the grinding process may occur under special conditions. The cutterhead penetration is an appropriate parameter involved in order to distinguish between the chipping and grinding processes in rock cutting. In this work, the grinding and chipping processes are investigated in the Uma-Oya water conveyance tunnel in Sri Lanka. The Uma-Oya project is a water transfer, hydropower, and irrigation system in the SE part of the central highland region of Sri-Lanka. From a geological viewpoint, most parts of the tunnel route in the studied section consist of very strong and abrasive metamorphic rocks that potentially are susceptible to grinding occurrence during the boring process under disc cutters. In this work, firstly, data processing is performed in order to identify the boundary betwe...
In the academic and industrial environments of Iran, there is little understanding of the relatio... more In the academic and industrial environments of Iran, there is little understanding of the relationship between geological science and technical branches (mechanics, electronics, etc.). Such concepts are not explained in Iran's higher education curriculum, and almost no source of research has been published in persian. The history of collaborative studies between mechanical engineers and geoscientists can be considered at the onset of the topics of the Terramechanics. But one of the common industrial areas between mechanical engineers and geologists in our country is mechanized tunneling technology. The design and construction of TBMs is based on the geological data of the projects. Many mechanical and electronic technical defects occur on the TBM in the face of unfavorable geological conditions on the excavation path. The performance of the various parts of the machine and even the amount of their consumables (oils, greases, etc.) are directly related to changes in the geologica...
Bulletin of Engineering Geology and the Environment
The chipping and grinding processes are the basis for understanding rock cutting during TBM excav... more The chipping and grinding processes are the basis for understanding rock cutting during TBM excavation in hard rock conditions. The chips are produced when tensile fractures created by adjacent cutters propagate parallel to the tunnel face and coalesce whereas grinding occurs when fractures do not fully propagate through the rock and only fines are generated. Chipping is the normal and efficient boring process using machines equipped with disc cutters. Consequently, almost all of the models proposed for predicting the TBM penetration have been developed by the assumption that chipping is the dominant mode. It is obvious that these models are unable to predict correctly TBM performance when grinding is dominated in the rock cutting process. In this study, the relationships between engineering geological properties of the rock units (Cretaceous limestones) and operating and performance parameters of a refurbished EPB-TBM, employed for completion of SEL6 (the Southern Extension of Line 6, Tehran Metro) tunnel, were evaluated and analyzed. In this project due to limitations in the load capacity of the employed cutters and insufficient initial penetration in rock, the excavation was mostly carried out on grinding-dominated mode. So, the suitable data for establishing a special database and consequent analyses were provided. The established database composed of actual operating and performance parameters of the machine (i.e., cutterhead penetration and RPM and cutter load) and also engineering geological properties (i.e., UCS, alpha angle, GSI, and RQD) of limestone strata. Finally, by statistical analyses performed on collected and screened data (41 data sets), some simple, site-specific, empirical equations were developed to predict the TBM performance on grinding mode. In addition, according to the multivariate regression method, a significant relationship between the cutterhead penetration (PRev), the cutter load (Fn), intact rock strength (UCS), and geological strength index (GSI) was established, statistically. The obtained results demonstrate that this engineering geological-based model could provide a new applicable equation for accurately predicting TBM performance for similar geological conditions where grinding is dominant.
Earth pressure balance (EPB) TBMs are commonly used for soft ground tunneling in urban areas. In ... more Earth pressure balance (EPB) TBMs are commonly used for soft ground tunneling in urban areas. In metro tunnels’ excavation, designing a comprehensive monitoring system to control surface settlement is essential to prevent damage to surface structures. The present study aims to develop new prediction models to estimate the ground surface settlement using two soft computing techniques, SVM and ANN-MLP, and a multiple variable regression model to develop the new empirical formulas. The TBM operational parameters collected from the Tehran metro line 6, South extension (TML6-SE) project have been applied to confirm the provided models. In the data analysis process, the relationships between various parameters (torque index, thrust index, and earth pressure) and the ground surface settlement are investigated. Moreover, several statistical evaluation criteria are implemented to evaluate the performance of the developed models. The results show that the predicted values are in good agreement with the real data. The results can be used for similar ground and TBM tunneling conditions.
Geotechnical and geological parameters have the greatest impact on the performance of hard rock t... more Geotechnical and geological parameters have the greatest impact on the performance of hard rock tunnel boring machines (TBMs). This includes the rock and rock mass properties that affect the rate of penetration (ROP) as well as the machine utilization that is heavily dependent on ground support type and related machine downtime and delays. However, despite the widespread use of TBMs and established track records, accurate estimation of machine performance is still a challenge, especially in complex geological conditions. The past studies have tried to use rock mass classification systems for improving the accuracy of the machine performance prediction. Rock mass classifications has been primarily developed for design of ground support, and as such, have not offered a good fit for estimation of TBM performance. This paper will review performance of a hard rock TBM in a 12.24 km long tunnel and offers analysis of field performance data to evaluate the relationship between various lithological units and TBM operation. The results of statistical analysis of the initial 5.83 km long tunnel indicate strong relationships between geomechanical parameters and TBM performance parameters. Site specific models, including Non-linear regression analysis (NLRA), Classification and regression tree (CART), and Genetic Programming (GP) have been used for analysis of a TBM performance relative to the ground condition data. The current study has looked at the possibility of developing a new rock mass classification system for TBM application by using the above noted analysis. Preliminary results indicate that CART can be used for offering a proper rating scheme for a rock mass classification system that can be used for TBM applications.
Bulletin of Engineering Geology and the Environment
The southern section of the Zagros zone in southwestern Iran, a well-known sedimentary basin, was... more The southern section of the Zagros zone in southwestern Iran, a well-known sedimentary basin, was investigated to address two key questions: (1) whether it would be feasible to construct large unlined rock caverns (URCs) in moderate-quality sedimentary rocks of this area for the storage of crude oil, and (2) which parts of this wide area were most suitable for constructing such huge underground structures. To answer these questions, first, the geological, hydrogeological and engineering geological properties of typical rock units in the area were investigated, and preliminary analyses were performed to check the stability, permeability and water circulation conditions of typical rock masses at depth. Next, geographical information system (GIS) techniques were applied to select the best regions for constructing the URCs. Parameters including geological characteristics, governmental restrictions, and proximity to facilities were selected as important factors for area zonation and for preparing a suitability map for constructing URCs for storing crude oil. The results of the study indicated that limestone units of the Asmari and Sarvak Formations at a moderate depth (200–300 m) were the most appropriate rock units for construction of URCs with a cross-section area of around 500 m2. In addition, the suitability map showed that two small regions in the central and northern parts of the study area were best suited for URC construction. The key advantages of these regions include a wide distribution of surface exposures of good-quality stratigraphic units (Asmari and Sarvak Formations), limited distribution of active tectonic structures such as salt domes and faults, and proximity to crude oil facilities.
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