Rock Engineering Systems Research Articles

Development of the Landslide Susceptibility Map of Attica Region, Greece, Based on the Method of Rock Engineering System

The triggering of slope failures can cause a significant impact on human settlements and infrastructure in cities, coasts, islands and mountains. Therefore, a reliable evaluation of the landslide hazard would help mitigate the effects of such landslides and decrease the relevant risk. The goal of this paper is to develop, for the first time on a regional scale (1:100,000), a landslide susceptibility map for the entire area of the Attica region in Greece. In order to achieve this, a database of slope failures triggered in the Attica Region from 1961 to 2020 was developed and a semi-quantitative heuristic methodology called Rock Engineering System (RES) was applied through an interaction matrix, where ten parameters, selected as controlling factors for the landslide occurrence, were statistically correlated with the spatial distribution of slope failures. The generated model was validated by using historical landslide data, field-verified slope failures and a methodology developed by the Oregon Department of Geology and Mineral Industries, showing a satisfactory correlation between the expected and existing landslide susceptibility level. Having compiled the landslide susceptibility map, studies focusing on landslide risk assessment can be realized in the Attica Region.

Application of fuzzy comprehensive assessment and rock engineering system to assess cavability in block caving mining and establishment of its regionalized model

The assessment of rock mass cavability is a key research topic when mines intend to adopt block caving mining during the feasibility stages. However, cavability assessment is a multi-index and non-linear complex process in system engineering, and uncertainty exists in the assessment process. In this situation, it is important for cavability assessments to minimize the subjectivity of human judgements and consider the factors that influence cavability and their interrelationships. In this study, we introduce a new approach that combines fuzzy comprehensive assessment (FCA) with rock engineering system (RES). First, the FCA was applied to establish an assessment model based on a conversion function, membership function, and fuzzy assessment matrix. Second, the RES was used to determine the weights of influential factors by applying an interaction matrix. Third, rock mass cavability was analysed based on the assessment model and the factor weights. The results of the cavability assessment were for a partial rock mass due to the discontinuity of the cavability assessment index value in space. Therefore, geostatistics and block models were adopted to establish a regionalized model of rock mass cavability, and the spatial distribution of cavability was obtained. Based on the Luoboling copper-molybdenum mine as a case study, FCA and the RES were applied, and a regionalized model of cavability was established. The results can provide a basis for studies of block caving mining and mine design.

Prediction of penetration rate of drilling by using rock engineering system approach case study: a well in Azadegan oilfield

One of the criteria in the operational efficiency of drilling is the rate of penetration of the drill bit. Numerous factors affect the rate of penetration. Identification of the effective factors on rate of penetration may lead to a more accurate assessment of drilling time, and as a result, the controlling of operational costs. The concurrent effect of the entire influential factors as well as the differing significance of each of them on the rate of penetration makes the study and optimization of drilling operations much more complicated and difficult. Using the rock engineering systems (RES), the impact of effective operational and geomechanical factors on the rate of penetration has been assessed in this article and a model has been proposed for the prediction of the rate of penetration. Data from one of the wells within the Azadegan oilfield have been used in order to study the impact of effective factors on the rate of penetration. To this end, the effective factors on rate of penetration are initially identified and then an index called “the rate of penetration index (ROPi)” is proposed through the application of the rock engineering systems approach. This index has been calculated at four different depths along the aforementioned well. The results suggested the compliance of penetration rate predictions with field observations. Moreover, porosity and uniaxial compressive strength are the most effective factors on the rate of penetration whereas the weight of drilling fluid has the smallest impact. Finally, a classification for the penetration rate index is presented.

Relationships between shear strength parameters and microstructure of alkaline-contaminated red clay.

The leachate (pH = 14) from alumina production changes the mechanical properties of red clay, and the shear strength parameters of the system vary due to the multiple-dimensional interactions of the microscopic parameters. In this paper, the alumina production liquid and the concentrations of the NaOH solution were designed to contaminate the red clay during 80days. The cohesion and friction angle of the alkaline-contaminated red clay were obtained from direct shear tests. Through qualitative and quantitative analyses using scanning electron microscopy (SEM), the microstructure was observed. Based on the rock engineering systems (RES) theory, interactions among microscopic parameters were analysed, and the relationships between shear strength parameters and microscopic parameters of alkaline-contaminated red clay were established. Results show that both of the cohesion and friction angle of alkaline-contaminated red clay are increased in general; the adsorption in alumina production liquid and dispersing effect of 0.7% NaOH concentration are noticeable, and the interactions of the microscopic parameters are intense; the ratio of the intra-aggregate pore number, the probability distribution index and the number of particles can significantly influence cohesion; the particle morphology fractal dimension, aspect and probability entropy have a severe effect on friction angle. This work is expected to serve as a reference for future research on the relationship between macroscopic properties and microcosmic structure of soil.

Systems Engineering Approach to Slope Stability Monitoring in the Digital Mine

Slope stability monitoring in open cut mining is increasingly based on the use of a variety of different sensors and associated analytics, each capable of providing part of the understanding required to manage complex geotechnical environments. Designing an integrated monitoring system that is both attainable and fit for purpose can therefore be particularly challenging. In this paper, a systems engineering approach based on a novel methodology is presented to design the slope monitoring system. The methodology uses the rock engineering systems (RES) approach to system decomposition for geotechnical engineering problems, to determine the critical rock mass behaviours requiring monitoring. It follows this with the application of the system theoretic process analysis (STPA) approach, to design the control system for the monitoring system and identify and mitigate sub-optimal configurations. We demonstrate that the approach is practical to implement and supports transparent and defensible decision making for designing and implementing slope monitor systems. We apply the method to the design of a monitoring system for an Australian coal mine and demonstrate how the approach can facilitate the identification and design of new sensing modalities.

Evaluation model of surrounding rock stability based on fuzzy rock engineering systems (RES)-connection cloud

The factors affecting the stability of surrounding rock have fuzzy randomness, and their evaluation indicators not only show boundary ambiguity and interval discreteness but also have complex interactions. In order to reflect the distribution characteristics and interaction relationship of the indicators, and improve the accuracy of surrounding rock stability evaluation, a stability evaluation model of surrounding rock based on a fuzzy Rock Engineering Systems (RES)-connection cloud is proposed. The research showed that the introduction of linguistic hesitant fuzzy sets improves RES, resulting in experts’ compilation completely retained. Through cloud theory transformation, the subjectivity can be further weakened, and the credibility of indicator weight can be effectively improved. The two-dimensional cloud cause-effect map can reflect the indicator interaction relationship more intuitively and accurately. The joint state is found to be the most dominant parameter, and groundwater seepage is found to be the least dominant parameter. Furthermore, the connection cloud can overcome the defects of traditional cloud model which assumes the indictor follow normal distribution. Comparing the engineering application results with the matter-element extension method and the fuzzy set method, the feasibility of the present model is verified.

A Fuzzy Rule-Based Approach to Address Uncertainty in Risk Assessment and Prediction of Blast-Induced Flyrock in a Quarry

Strict control of the environmental impacts of blasting operations needs to be completely in line with the regulatory limits. In such operations, flyrock control is of high importance especially due to safety issues and the damages it may cause to infrastructures, properties as well as the people who live within and around the blasting site. Such control causes flyrock to be limited, hence significantly reducing the risk of damage. This paper serves two main objectives: risk assessment and prediction of flyrock. For these objectives, a fuzzy rock engineering system (FRES) framework was developed in this study. The proposed FRES was able to efficiently evaluate the parameters that affect flyrock, which facilitate decisions to be made under uncertainties. In this study, the risk level of flyrock was determined using 11 independent parameters, and the proposed FRES was capable of calculating the interactions among these parameters. According to the results, the overall risk of flyrock in the studied case (Ulu Tiram quarry, located in Malaysia) was medium to high. Hence, the use of controlled blasting method can be recommended in the site. In the next step, three optimization algorithms, namely genetic algorithm (GA), imperialist competitive algorithm (ICA) and particle swarm optimization (PSO), were used to predict flyrock, and it was found that the GA-based model was more accurate than the ICA- and PSO-based models. Accordingly, it is concluded that FRES is a very useful for both risk assessment and prediction of flyrock.

Developing a new uncertain rule-based fuzzy approach for evaluating the blast-induced backbreak

This study proposes a new uncertain rule-based fuzzy approach for the evaluation of blast-induced backbreak. The proposed approach is based on rock engineering systems (RES) updated by the fuzzy system. Additionally, a genetic algorithm (GA) and imperialist competitive algorithm (ICA) were employed for the prediction aim. The most key step in modeling of fuzzy RES is the coding of the interaction matrix. This matrix is responsible for analyzing the interrelationships among the parameters influencing the rock engineering activities. The codes of the interaction matrix are not unique; thus, probabilistic coding can be done non-deterministically, which allows the uncertainties to be considered in the RES analysis. To achieve the objective of this research, 62 blasts in Shur River dam region, located in south of Iran, were investigated and the required datasets were measured. The performance of the proposed models was then evaluated in accordance with the statistical criteria such as coefficient of determination (R2). The results signify the effectiveness of the proposed GA- and ICA-based models in the simulating process. R2 of 0.963 and 0.934 obtained from ICA- and GA-based models, respectively, revealed that both models were capable of predicting the backbreak. Further, the fuzzy RES was introduced as a powerful uncertain approach to evaluate and predict the backbreak.

A NEW MODEL FOR PREDICTING THE ADVANCE RATE OF A TUNNEL BORING MACHINE (TBM) IN HARD ROCK CONDITIONS

The prediction of the advance rate of a Tunnel Boring Machine (TBM) in hard rock conditions is one of the most impor- tant concerns for estimating the time and costs of a tunnel project. In this paper, in the first step, a model based on Rock Engineering Systems (RES) is proposed to predict geotechnical risks (representing media characteristics) in rock TBM tunnelling. Fifteen main parameters that influence the geotechnical hazards were used in the modelling. In establishing an interaction matrix and also a parameter rating, the views of five experts were taken into account. The Vulnerability Index (VI) (geotechnical risk levels) for 2058 datasets out of 2168 sets of data from 53 geological zones in 11 km of the Zagros long tunnel was obtained. In the second step, based on the machine operating parameters such as torque, cutter head rotation per minute, cutter normal force and media characteristics (represented by VIs), which were used as input parameters and advance rate was used as an output parameter, while using 2058 datasets, linear and non-linear multiple regression analyses were carried out. 110 datasets (out of 2168 datasets), which were not used in the modelling, were ap- plied to evaluate the performance of regression models and other models in literature and the results were compared. The obtained results showed that the new linear model proposed with R2=0.83 and RMSE=0.12 has a better performance than the other models.

RISK ANALYSIS OF ROOF FALL AND PREDICTION OF DAMAGED REGIONS AT RETREAT LONGWALL COAL MINING FACE

This study presents a model based on rock engineering systems (RES) to evaluate the risk of roof falls and determine damaged regions, using recorded roof falls, prior to mining with a retreat from a longwall face. In this regard, a case study was considered to examine the model. The results showed that the level of determined risk has an acceptable correlation with the special roof fall (SRF), with R-squared value (R2) equal to 0.792 for all estimated vulnerability indexes (VIs) in considered longwall panels. By investigating and comparing the evaluated values of VI in considered panels and their corresponding recorded roof falls, damaged regions were distinguished from undamaged regions. Based on these investigations, four classes including safe, moderate, danger, and critical regions were determined to identify the safe and damaged regions prior to mining operations. The results of the research showed that the identification of damaged regions is feasible to provide a detailed operation plan to control roof falls in longwall mining faces through the developed approach. The RES-based model could be used for the same conditions and the presented methodology could be applied to other parts in underground coal mines.

Applying Rock Engineering Systems Approach for Prediction of Overbreak Produced in Tunnels Driven in Hard Rock

Drilling and blasting is the predominant excavation method of the tunnels driven in hard rock. Overbreak is an undesirable outcome of blasting operation that has a profound effect on the safety and cost of tunnels. Determination of overbreak and the corresponding risk is of vital importance. The main aim of this research has therefore been to assess the risk associated with overbreak as well as its prediction. To do this, a rock engineering system (RES) based model has been proposed. The research data in this study was drawn from four tunnels located in Bakhtiari dam project, Iran. For 54 blasting operations carried out in the investigated tunnels, the values of 14 causative factors in overbreak were carefully measured. The result of this study shows that the developed RES based model with a high value of coefficient of determination (R2 = 0.91) is a reliable technique to predict overbreak. Furthermore, the evidence from this study suggests that the Tunneling Rock Quality Index, perimeter specific charge and burden to spacing ratio play a large part in the values of overbreak. From the risk assessment conducted for the investigated tunnels, no blast operation was found to be highly problematic. Also, the overall risk level posed by overbreak was in medium range where the overbreak might be slightly problematic, and need to be monitored. The newly suggested RES model is also evaluated using 8 blasting operations, showing high level of performance.

Evaluating short-term rock burst damage in underground mines using a systems approach

ABSTRACT A new rock burst damage scale index (RDSI) based on the Rock Engineering Systems paradigm and on a BP-ANN is proposed. Seven parameters that are likely to affect rock burst damage are considered to construct the ANN and to objectively code the interaction matrix. A probabilistic analysis is employed to associate damage categories to RDSI values. The methodology is validated using 24 case histories that had not been employed during the training of network. Results suggest that the RDSI can probabilistically predict the damage scale with an accuracy that could be acceptable in engineering, hence simplifying the prediction for real applications.

Combining fuzzy RES with GA for predicting wear performance of circular diamond saw in hard rock cutting process

Predicting the wear performance of circular diamond saw in the process of sawing hard dimensional stone is an important step in reducing production costs in the stone sawing industry. In the present research work, the effective parameters on circular diamond saw wear are defined, and then the weight of each parameter is determined through adopting a fuzzy rock engineering system (Fuzzy RES) based on defining an accurate Gaussian pattern in fuzzy logic with analogous weighting. After this step, genetic algorithm (GA) is used to determine the levels of the four major variables and the amounts of the saw wear (output parameter) in the classification operation based on the fixed, dissimilar, and logarithmic spanning methods. Finally, a mathematical relationship is suggested for evaluation of the accuracy of the proposed models. The main contribution of our method is the novelty of combination of these methods in fuzzy RES. Before this work, all Fuzzy RESs only use simple membership functions and uniform spanning. Using GA for spanning and normal distribution as membership function based upon our latest work is the first work in fuzzy RES. To verify the selected proposed model, rock mechanics tests are conducted on nine hard stone samples, and the diamond saw wear is measured and compared with the proposed model. According to the results obtained, the proposed model exhibits acceptable capabilities in predicting the circular diamond saw wear.

An Application of Rock Engineering System for Assessment of the Rock Mass Fragmentation: A Hybrid Approach and Case Study

Rock mass fragmentation process plays a major role in the design of the block cave mining. To assess rock mass fragmentation, identification and determination of influencing parameters are crucial. In most case studies, the cross-impact or indirect interaction of influencing parameters has not been considered in the assessment of rock mass fragmentation. The aim of this paper is to present a hybrid approach to consider the direct and indirect effects of influencing parameters on rock mass fragmentation by use of classic rock engineering system (RES) and matrices impact cross multiplication applied to classification method (MICMAC). The most important effective parameters in the system were identified and ranked based on both RES and hybrid approach. Thereafter, the indirect fragmentation index was calculated for RENO and Diablo Regimente mines in Chile and Kemess mine in Canada. An appropriate consistency was found between the results of the hybrid approach and available fragmentation data of the respective mines. The result of the analysis showed that the interaction of the geometrical and operational parameters has increased while the interaction of the geomechanical parameters, due to being less susceptible to change of the other parameters, has decreased in the hybrid approach compared to the RES. The geomechanical parameters showed the highest impact on the system and the lowest share of interaction in the system. The geometrical and operational parameters showed a high level of interaction, in the system, which the system had low influence on them.

Prediction of face advance rate and determination of the operation efficiency in retreat longwall mining panel using rock engineering system

A new approach for prediction of face advance rete (FAR) prior to mining operation and determination of the operation efficiency after mining operation in retreat longwall mining panel is presented based upon the concepts of rock engineering system (RES). For this purpose, six longwall panels considered in Parvadeh-I coal mine. Seven major effective parameters on FAR was selected including coal mine roof rating, gas propagation, safety factor of longwall face, ratio of joint spacing to cutting depth at longwall face, longwall face inclination, panel width, floor rock mass rating. To performance evaluation of the presented model, the relationship between the average vulnerability indexes of advance operation with FAR was determined in considered panels with coefficient of determination (R2) equal to 0.884 that indicate relatively acceptable correlation and compatibility. Investigations of the research indicated that it is possible to determine the actual operation efficiency under fair conditions by a RES-based model. The inevitable reduction of FAR for each longwall panel was determined by presented model that the difference amount between the maximum possible practical face advance rate (FARmpp) and recorded actual face advance rate (FARa) indicate the operation efficiency. Applied approach in this paper can be used to prediction of FAR in retreat longwall mining panel for same conditions that can have many benefits, including better and more accurate planning for the sales market and mine operation. Also, presented method in this paper can be applied as a useful tool to determination of actual operation efficiency for other sections and extraction methods in coal mines.

Improved Rock Engineering System (RES)- Multidimensional Cloud Evaluation Model and Its Application to the Rock Mass Blastability

Improved Rock Engineering System (RES)- Multidimensional Cloud Evaluation Model and Its Application to the Rock Mass Blastability

DEVELOPMENT OF A NEW INDEX FOR METHANE DRAINAGEABILITY OF A COAL SEAM USING THE FUZZY ROCK ENGINEERING SYSTEM

Coal seam gas is one of the most significant energy resources in unconventional gas fields. The identification of influenc- ing parameters and methane drainage assessment are, thus, a prime geotechnical focus for all potential methane drain- age projects. In methane drainage operations of coal seams, many factors, such as natural factors and operational factors affect the drainage efficiency. In this paper, a new coal seam methane drainageability index (CMDI) is introduced for pre-drainage techniques in a working mine. In this approach, seventeen parameters are considered as the main factors affecting the methane drainage form coal seam, and the interaction matrix based on the fuzzy rock engineering system (FRES), which analyzes the interrelationship between the parameters affecting methane drainage activities, are used to study coal seam methane drainageability. Since the value of interaction in the RES method is not unique, the fuzzy sys- tem is used to minimize subjectivity of the weights which are computed in the RES method. The Tabas coal mine (Iran) was selected as a case study and the proposed index was used to rank the C1 seam in this mine. It was observed that the methane drainageability index could suitably predict the potential of the methane drainage of coal seam. The newly proposed index can be used as a basis for decision-making when uncertainties about the evaluation of the parameters affect the methane drainage of a coal seam and reduce the risk of methane drainage projects.

Integrating Rock Engineering Systems device and Artificial Neural Networks to predict stability conditions in an open pit

Stability performance of newly open pit slopes are is affected by many factors, namely, overall complex geological environment, water flow, in situ and induced rock stresses, continuous blasting effects and construction methods. It is therefore important to identify the critical parameters affecting slope stability, as well as their interactions, in order to reduce the associated uncertainty and risk. In this paper, we extend a worldwide open pit slope stability database further and build on the use of an open pit mine slope stability index to predict the stability conditions, coupling Rock Engineering Systems (RES) and artificial neural networks, namely, Back Propagation and Self Organising Maps. The Open Pit Mine Slope Stability Index (OPMSSI) can be computed as a simple weighted sum of ratings for all parameters involved in the RES. The basic device used in the Rock Engineering Systems approach is the Generic Interaction Matrix (GIM). By coding the GIM cause-effect coordinates, relevant cause-effect plots are generated indicating interaction intensity and dominance. We propose the coding of the GIM using scatter plots produced by an unsupervised, trained, self-organising map and a comparison with GIM coding through connection weights resulting from a trained back propagation neural network. Depending on the resulting OPMSSI, the approach informs on low, medium and high susceptibility levels associated with stable status, failure at set of benches or overall slope failure, respectively. Verification of results suggests that OPMSSI, resulting from self-organising maps, appears to be superior to a back propagation algorithm in prediction capacity and that the SOM proves to be an informative knowledge extraction tool.

Estimation model of sandy soil liquefaction based on RES model

In order to evaluate sandy soil liquefaction, Rock Engineering Systems (RES) was utilized to establish the estimation model of sandy soil liquefaction. Aiming at unascertained factors in the analysis of sandy soil liquefaction evaluation, earthquake magnitude, maximum ground acceleration, the value of standard penetration test, specific penetration resistance, relative density, mean particle size, and water table were selected as influencing factors of sandy soil liquefaction. The interaction matrix was utilized to describe the interaction among the factors. Expert semi-quantitative (ESQ) method was employed to code the interaction matrix. The interaction strength and dominance were analyzed by cause and effect diagram. Finally, the estimation model-based RES was proposed, and the results were in line with actual situation well. In addition, the improved estimation model-based RES was also presented and discussed, which was more convenient with the same prediction accuracy rate.

Determination and assessment of coal bed methane potential using rock engineering systems

The presence of methane in coal mines is one of the major problems in underground coal mines. Every year, in underground coal mines, a lot of casualties due to outbursts and explosions of methane gas is occurring. Existence of this gas in the mines not only creates a difficult and dangerous situation for work but also makes it more expensive. The release of this gas to the air causes a further pollution of the atmosphere and increases the greenhouse gases in the air. Thus Coal Bed Methane (CBM) drainage before, during, and after coal mining is necessary. Accordingly, the CBM drainage can reduce the risks involved in these mines. In the past decade, CBM has offered a significant potential to meet the ever-growing energy demand and can decrease the disastrous events. In this research work, the CBM potential in Eastern Kelariz, Western Razmja, Bornaky, Bozorg, Razzi, and Takht coal mines of Eastern Alborz coal mines company is investigated using the rock engineering systems (RES) based on the intrinsic and geological parameters. Nine main parameters are considered for modeling CBM, and the interactions between these parameters are calculated by a proposed system. Based on the RES method, the parameters that are dominant (depth of cover) or subordinate (gas content) and also the parameters that are interactive are introduced. The proposed approach could be a simple but efficient tool in the evaluation of the parameters affecting CBM, and hence be useful in decision-making. The results obtained show that Razzi coal mine has a good potential to perform CBM drainage.