Evaluation Of Rock Mass Quality Research Articles

Advances in statistical mechanics of rock masses and its engineering applications

To efficiently link the continuum mechanics for rocks with the structural statistics of rock masses, a theoretical and methodological system called the statistical mechanics of rock masses (SMRM) was developed in the past three decades. In SMRM, equivalent continuum models of stress–strain relationship, strength and failure probability for jointed rock masses were established, which were based on the geometric probability models characterising the rock mass structure. This follows the statistical physics, the continuum mechanics, the fracture mechanics and the weakest link hypothesis. A general constitutive model and complete stress–strain models under compressive and shear conditions were also developed as the derivatives of the SMRM theory. An SMRM calculation system was then developed to provide fast and precise solutions for parameter estimations of rock masses, such as full-direction rock quality designation (RQD), elastic modulus, Coulomb compressive strength, rock mass quality rating, and Poisson’s ratio and shear strength. The constitutive equations involved in SMRM were integrated into a FLAC3D based numerical module to apply for engineering rock masses. It is also capable of analysing the complete deformation of rock masses and active reinforcement of engineering rock masses. Examples of engineering applications of SMRM were presented, including a rock mass at QBT hydropower station in northwestern China, a dam slope of Zongo II hydropower station in D.R. Congo, an open-pit mine in Dexing, China, an underground powerhouse of Jinping I hydropower station in southwestern China, and a typical circular tunnel in Lanzhou-Chongqing railway, China. These applications verified the reliability of the SMRM and demonstrated its applicability to broad engineering issues associated with jointed rock masses.

Joint Investigation and 3D Visual Evaluation of Rock Mass Quality

In order to realize the high efficiency quality classification and three-dimensional visualization of engineering rock mass and to solve the technical difficulties of the traditional rock mass quality evaluation method such as high labor intensity, long process time consumption, many intervention processes such as scale measurement and manual calculation, and nonintuitive classification results, this paper puts forward a 3D visual rock mass quality evaluation method and system based on close-range photography, which optimizes the traditional rock mass quality evaluation method, makes the rock mass classification three-dimensional and visible, and realizes the estimation of unrevealed rock mass quality evaluation index. The research results show the following: (1) The method of storing joint information by close-range photography and extracting joint information by human-computer interaction improves the working efficiency and the process is safe and controllable compared with the traditional method of collecting fracture parameters. (2) Based on the statistical analysis of 97 groups of roadway survey data, the comprehensive statistical regression formula between BQ value of Chinese national standard and RMR value is given, and there is a good correlation between BQ value and RMR value of rock mass quality index. (3) Based on the power-inverse ratio method, the three-dimensional model of rock mass classification of the mine was established, and the cutting model obtained the current distribution diagram of rock mass quality grade, providing scientific reference for drilling, blasting, support, and other production design optimizations.

Post-mining failure characteristics of rock surrounding coal seam roadway and evaluation of rock integrity: a case study

Accurate knowledge of the distribution characteristics of structural planes in rocks is beneficial in the evaluation of rock mass quality and roadway support decision-making. In this study, in situ monitoring results were used to analyse the deformations and failure characteristics of the rock surrounding the main haulage roadway in the Huahong coal mine to establish a deformation and failure model for the surrounding rock affected by mining. According to an analytic hierarchy process, a comprehensive evaluation index for the degree of fracturing in the rock surrounding the coal seam roadways was proposed. Additionally, a classification method based on the comprehensive widths of the structural planes (CWSPs) inside the complete rock mass was proposed to determine the quality of the surrounding rock. The structures of the rocks surrounding the main haulage roadway in the mine before and after coal mining were observed in situ at monitoring station no. 22. Borehole imaging technology was used to classify the surrounding rock quality using the CWSP-based evaluation method. The results indicated that the roof rock was mildly affected by mining; the corner rock had a large degree of fracturing in the central part of the borehole and a small degree of fracturing at both ends; the rib rock was highly fractured. These evaluation results were consistent with the macroscopic characteristics of the surrounding rocks, indicating the reliability of the deformation and failure model for characterizing the surrounding rocks affected by mining.

Rock Mass Quality Evaluation Based on Unascertained Measure and Intuitionistic Fuzzy Sets

Evaluation of rock mass quality is of great significance to the design and construction of geotechnical engineering. In order to evaluate the quality of engineering rock mass scientifically and deal with the fuzzy information in the rock mass quality evaluation reasonably, a model for evaluation of rock mass quality based on unascertained measure and intuitionistic fuzzy sets (UM-IFS) was proposed. First, the membership of rock mass quality evaluation index was determined by the single index measure function of unascertained measure (UM) theory. Based on the intuitionistic fuzzy sets (IFS) theory, the single index measure evaluation matrix based on IFS (IFS-single index measure evaluation matrix) was obtained. By synthesizing various subjective and objective weighting methods, the range of index weight was determined, and the index weight vector based on IFS (IFS-index weight vector) was constructed. Then, the IFS-single index measure evaluation matrix and the IFS-index weight vector were used to calculate the scores of rock mass samples and evaluate rock mass quality. Finally, fuzzy analysis was performed on the weight of rock mass quality evaluation index. The established model for evaluation of rock mass quality was applied to the underground engineering rock mass in Guangzhou pumped storage power plant, and the evaluation results were compared with the other 4 effective models for rock mass quality evaluation. The results show that rock mass quality evaluation based on UM-IFS is consistent with the actual situation, and the fuzziness of evaluation index weight has no obvious correlation with its value.

Parametric study of integrity on the mechanical properties of transversely isotropic rock mass using DEM

The evaluation of the mechanical properties of a transversely isotropic rock mass is a challenging task in practical engineering. This paper aims to study the relationships between the integrity parameters and mechanical properties of a transversely isotropic rock mass. The rock mass quality designation (RQD) is an important index and reference for rock mass quality evaluation that was introduced to establish the numerical models of a jointed rock mass with different integrities. The numerical models of a transversely isotropic rock mass were established using the bonded particle model (BPM) and smooth joint model (SJM) embedded into the Particle Flow Code software (PFC2D). After calibrating the microscopic parameters of the intact rock and structural planes, a series of compression tests of a transversely isotropic rock mass was carried out to determine compressive strength and deformation modulus, and main factors were considered including the RQD, inclined angle of structural planes, structural plane thickness, structural plane properties, intact rock properties, and confining pressure. The experimental results showed that the mechanical parameters and failure modes of a transversely isotropic rock mass were controlled by the integrity parameters. By comparing the value of σcm/σc (ratio of the compressive strength of rock mass to rock mass) and Em/Er (ratio of the deformation modulus of rock mass to rock mass) with field test results, the results obtained from the discrete element method were demonstrated to be reasonable.

Research on the application of dynamic weighting on the rock mass quality rating

Many rock mass classification systems have been proposed for rock masses by considering a particular rock structure and/or specific purposes. The traditional rock mass quality rating system ignores the impact of uncertainty, complexity, and ambiguity on the classification of tunnels surrounding rock masses. The calculation of the traditional weighted values only addresses the selection of the evaluation index rather than self-adjustment with changes to the total weight. To solve this issue, the dynamic weight and extension methodology are introduced to improve the evaluation of rock quality. The sample grade can be evaluated by calculating the variable eigenvalue of the object grade. This method can avoid disadvantages that occur during the calculation of the weight value. Additionally, it can fully reflect the impact of the rock mass when the same factor has different data for the evaluation, making the results more reasonable. Therefore, it can avoid the subjectivity of the evaluation process and make the evaluation results more reasonable. Finally, the results from studies of tunneling projects show that factors affecting the weight value have a dynamic property. Even if the evaluation factors are same, the weight value will alter the values of the factors.

Research on Rock Mass Quality Classification Based on An Improved Rough Set–Cloud Model

Rock mass grading is a basic problem in the construction industry and underground engineering research. Because the index parameters that affect the rock mass quality are ambiguous and random, rock mass quality classification is often uncertain. Based on this issue, this paper selects the rock quality index RQD , rock uniaxial saturated compressive strength Rw , rock mass integrity coefficient Kv , structural surface strength coefficient $K_{f}$ and groundwater seepage quantity $\omega $ as quantitative evaluation indicators to construct an evaluation system. Thirty sets of data collected in China are selected as learning samples. Through the related concepts and finite interval cloud model, the characteristic parameters of the measured data are obtained, and a cloud model is generated with a forward cloud generator to achieve the transformation between qualitative and quantitative concepts. Combined with the basic knowledge of rough set theory, the weight determination problem is transformed into an attribute importance problem. To avoid zero weights in the traditional rough set approach, this paper introduces a calculation method based on the conditional information entropy, and the weight calculation method is modified to obtain the comprehensive weights. According to the principle of the maximum membership degree, the classification of rock mass quality is performed, and the rock mass quality data are determined to have different levels of comprehensive membership. A rock mass quality evaluation method based on the coupled improved rough set–cloud model is established and successfully applied for a rock mass quality evaluation of the 0+000~0+560 test section of the second stage of underground engineering at the Guangdong Pump Storage Power Station. The results show that the model is reliable and practical and provides a new approach for uncertainty analysis and evaluation in rock engineering practice.

Surface Rock Mass Quality Evaluation for High-Level Radioactive Waste Disposal of Beishan Preselected Area and Its Application

Surface Rock Mass Quality Evaluation for High-Level Radioactive Waste Disposal of Beishan Preselected Area and Its Application

Some New Correlations of Q-Value with Rock Mechanics Parameters in Underground Oil Storage Caverns

Q-system is a preferred alternative method of rock mass classification for underground oil storage caverns where stable lithological rocks are widely distributed. In this paper, correspondences between important input rock mechanics parameters (friction angle, cohesion, tensile strength, Poisson’s ratio, deformation modulus) and Q values were investigated, thereby bringing convenient to rapidly obtain available parameters when it’s hard to collect measured field data in underground storage projects basically with similar lithology. The proposed correlations were verified through numerical simulation and on-site monitoring measurement. In addition, comparison of different criteria among Q-system and other codes for rock mass classification has been made to help for making a preliminary evaluation of rock mass quality in the practical engineering. Finally, the behaviours of surrounding rock deformations under different Q values were analysed by using FLAC3D code with the calculating parameters suggested in this paper, and the calculation results match well with measured values in situ. Above results will not only guide the construction but also could be relevant to other underground storage engineering under similar geological conditions.

Evaluation of Rock Mass Quality in Underground Section of Anguran Mine Using Geostatistical Analyst in GIS Environment

Evaluation of Rock Mass Quality in Underground Section of Anguran Mine Using Geostatistical Analyst in GIS Environment

Assessment of a Modified Rock Mass Classification System for Rock Slope Stability Analysis in the Q-system

<p>This paper explores the applicability of a modified Q classification system and its component parameters for analysis and conclusion of site investigation data to estimate rock slope stability. Based on the literature, Q classification system has high applicable potential for evaluation of rock mass quality. Therefore, in this study, it was used with RMR and SMR rock mass classification systems to assess stability or instability of different rock slopes along the Hamedan-Ganjnameh-Tuyserkan road, Hamedan province west of Iran. Furthermore, a modified rock mass classification system namely Slope Quality Rating (SQR) was proposed based on the correction of the Q classification parameters and calculating some new parameters such as dip and strike of discontinuities and the method of rock excavation or blasting. For this purpose, the SMR and RMR rock mass classifications were also needed. By measuring SQR for different rock slopes, it will be possible to measure Slope Mass Rating (SMR).</p><p> </p><p><strong>Evaluación del sistema Q modificado de clasificación del macizo rocoso para el análisis de estabilidad de pendiente de roca</strong></p><p> </p><p><strong>Resumen</strong></p>Este artículo explora la aplicabilidad del sistema de clasificación Q modificado y sus parámetros para analizar y determinar la información estimada de estabilidad de pendiente de roca en el sitio determinado de estudio. Según la literatura, el sistema de clasificación Q tiene un alto potencial de aplicabilidad paral a evaluación de la calidad del macizo rocoso. En este estudio además se utilizó el sistema Q junto con los sistemas Índice de Masa de Pendiente (SMR) y Clasificación Geomecánica de Bienawski (RMR) para evaluar la estabilidad e inestabilidad de diferentes pendientes rocosas en la carretera Hamedan-Ganjnameh-Tuyserkan, de la provincia de Hamedan, en el Oeste de Irán. Además, se propone el Índice de Calidad de Pendiente (SQR), un sistema de clasificación de macizo rocoso modificado, a partir de la corrección de los parámetros de clasificación Q y el cálculo de nuevos parámetros como pendiente y caída de las discontinuidades y el método de excavación o explosión de la roca. Para esta propuesta también se utilizaron las clasificaciones SMR y RMR. La medición SQR en diferentes pendientes hizo posible el cálculo del sistema SMR.</p>

Rock Mass Quality Rating (RMQR) for Rock Engineering

Rock Mass Quality Rating (RMQR) for Rock Engineering

EVALUATION OF ROCKMASS QUALITY BASED ON THE REVISED RMR METHOD IN COASTAL MINE DURING DEEP EXPLOITATION

Owing to its deficiency in considering influence factors of deep rock mass quality and determination of evaluation index values, the traditional RMR method has many limitations in the quality evaluation of deep mining rock mass. The marking indexes including uniaxial compressive strength of rock, rock quality designation, joint space and in-situ stress in traditional RMR method are firstly revised by calculation method of continuous thinning, regression curves and continuity equations between evaluation indexes and score values are obtained. Secondly, based on the analysis of bad geological factors and deep mining technology influence in rock mass quality, two new indexes including blasting vibration effect coefficient and stope exposed area are put forward; furthermore, M-IRMR evaluation system is established. Finally, the M-IRMR method is applied to the rock mass quality evaluation of Sanshandao gold mine which is a deep mining mine near coast. Achieved results will provide certain guiding significance to stability evaluation of rock engineering in deep mining mine.

Evaluation of rock mass improvement due to cement grouting by Q-system at Bakhtiary dam site

In this research, Q-logging system was developed based on the cores drilled at the grouting panels to investigate the influence of the cement grouting on the rock mass properties at the Bakhtiary dam site. In this way, rock masses in the different boreholes at the grouting panels were classified using the Q-system. Then, using the experimental equations, rock mass deformation modulus (Erm) was calculated for each borehole. In order to evaluate this method, value of the rock mass deformation modulus was also obtained by the dilatometer test results. The outcomes display that the Q-logging system can be used as a practical and undemanding method in evaluation of rock mass quality by the grouting treatment.

Acoustic Detection on Analysis of Rock Mass Integrality

This paper briefly described borehole wave velocity test and the principle and method of wave velocity test technique, by using acoustic measurement and control technology of tunnel rock mass test, integrality index of rock mass is obtained, ultimately, we evaluate the rock mass integrity. The actual application effect is good and provides an important basis for the engineering rock mass quality evaluation.

A New Rock Mass Quality Rating System: Rock Mass Quality Rating (RMQR) and Its Application to the Estimation of Geomechanical Characteristics of Rock Masses

The qualitative description of rock masses by means of classification systems and subsequent correlation to establish engineering quantities or design parameters has become one of the most challenging topics in rock engineering. Many rock mass classification systems have been proposed for rock masses with the consideration of a particular rock structure and/or specific purposes. Therefore, direct utilization of these systems, in their original form, for the characterization of complex rock mass conditions is not always possible. This is probably one of the reasons why rock engineers continue to develop new systems or modify and extend current ones. The recent tendency is to obtain rock mass properties from the utilization of properties of intact rock and rock classification indexes, which have some drawbacks. In this study, it is aimed to propose a new rock mass quality rating system designated as Rock Mass Quality Rating (RMQR). This new rock mass rating system is used to estimate the geomechanical properties of rock masses. In the first part of this paper, the input parameters of RMQR and their ratings are given and discussed. In the second part, the unified formula proposed by the first author is adopted for the new rock mass rating system for estimating the rock mass properties and compared with the results of the in situ tests carried out in Japan and those estimated from some empirical relationships developed by other investigators, and the outcomes of these studies are presented and discussed.

A Method of Investigation of Fracture Ratio of Rock Based on Digital Image Analysis

Fracture ratio is one of important parameters for evaluation of rock mass quality. The fracture ratio of rock is analyzed by digital image analysis with matlab. In this paper, the width of different place on fracture of rock is gotten, which is more important than average width of fracture for analysis characteristic of fracture. The area of fracture is directly gotten from the binary image of fracture and it can avoid the error of area of fracture due to average width of fracture. So the fracture ratio of area is more exacter. The practice shows that the method of digital image analysis is a good method for investigation of fracture ratio of rock.

Surrounding Rock Mass Quality Evaluation of Huangdao Water Sealed Underground Oil Tank

Huangdao water sealed underground oil tank, which lies in Qingdao, Shandong province, is one of strategic reservoir of oil in China. Targeting at a real pragmatic problem that sometimes the rock mass integrity index is more than 1 and taking Huangdao water sealed underground oil tank as an example, the rock sample wave velocity-stress relation tests are carried out. Then unloading index is put forward and formula of raock integrity index is modified so as to improve rock quality classification method. In the end, the improved rock quality classification method is applied to Huangdao water sealed underground oil tank engineering. The result shows that the quality of most rock masses here is level I or II.

Estimating the excavation disturbed zone in the permanent shiplock slopes of the Three Gorges Project, China

Abstract The stability and deformation of the permanent shiplock slopes are among the key issues in the design and construction of the Three Gorges Project. The permanent shiplock slopes, formed by deeply and steeply cutting into weathered and fresh granites, are 1607 m in length and 50–170 m in height. The disturbed zone in the permanent cut slopes induced by excavation is therefore one of the most important aspects in slope stability and deformation evaluation. A comprehensive investigation including non-linear finite element analysis, in-situ testing, instrumentation and monitoring, back analysis and rock mass quality rating has been carried out for the identification and evaluation of the excavation disturbed zone in the permanent cut slopes. The results of the investigation confirmed the existence of such an excavation disturbed zone in the permanent cut slopes. This zone is characterized by a considerable weakening in the mechanical properties of the rock mass. From the cut surface to the deeper region of the permanent cut slopes, the excavation disturbed zone can be further divided into a damaged zone, an affected zone and a slightly affected zone according to the extent of weakening in the rock mass. The damaged zone and the affected zone have thicknesses of 5–10 m and 10–20 m, respectively. The exact pattern of the excavation disturbed zone is variable in different parts of the permanent cut slopes and are generally similar to that of the plastic zones estimated by using the non-linear finite element analysis. The present investigation has provided both factual data and insights for the stability and deformation evaluation of the permanent shiplock slopes. The approach and methodology developed in the paper can be used to assess similar excavation disturbed zones in other large cut slopes.

Profile area method for statistical evaluation of rock mass quality : Bull Assoc Engng Geol V28, N4, Nov 1991, P351–357

Profile area method for statistical evaluation of rock mass quality : Bull Assoc Engng Geol V28, N4, Nov 1991, P351–357