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The rock mass deformation modulus is an important parameter in numerical modeling for the stability analysis of tunnels and underground excavations. This parameter can be determined by direct and indirect methods. The direct method includes in-situ tests which are costly, timing consuming and the reliability of the result is also questionable. In indirect method different empirical models are used for estimation of rock mass deformation modulus. In this paper Rock Mass Rating (RMR), Geological Strength Index (GSI), Young Modulus of Elasticity and Uniaxial Compressive Strength (UCS) were used as input parameters in empirical models for determination of deformation modulus for rock mass. The Multi Liner Regression (MLR) and Artificial Neural Network (ANN) were used for assessment of the prediction performance of different established empirical models for estimation deformation modulus for rock mass. After analysis and comparison of results obtained from MLR and ANN, it was concluded that, the ANN based model predicting performance is better as compared to MLR model for all five data sets and the performance of both models is much better for those data sets which are collected from empirical equation containing three input variables. [ABSTRACT FROM AUTHOR]

Introduction. One of the main principles in designing modern ultra-high rockfill dams with reinforced concrete face is the principle of zoning rockfill of various quality in the dam body. It envisages that rockfill in the shell upper part should be compacted very carefully in order to minimize to the maximum the deflections of the reinforced concrete face. In the shell lower part it is allowed placing heterogeneous rockfill with less degree of compaction. Analysis of the results of field observations over settlements of the already constructed dams shows that this pattern of zoning may lead to considerable irregularity in distribution of rockfill deformation moduli between the upstream and the downstream parts of the dam. Numerical modeling of the existing Aguamilpa dam carried out by use arlier showed that this effect may be caused by unfavorable stress-strain state of the reinforced concrete face threatening with crack formation. Were come ended using dams of homogenous structure. However, this conclusion caused doubts of some experts. More detailed studies who see results are described in this article were conducted in order to confirm or disprove this conclusion. Materials and methods. The studies were conducted by finite element method on the example of 100 m high rockfill dam. Different alternatives of rockfill deformation properties in the shell upstream and downstream parts were considered. Results. Analysis of the results of studies confirmed the conclusions made earlier about the features of the rockfill dam reinforced concrete face stress-strain state. It was revealed that increase of rockfill deformation in the dam shell downstream part leads to appearance of additional tensile longitudinal force in the face. It increases the risk of appearance of through transversal cracks in the face. However, the heterogeneous structure of the dam shell may not have a decisive impact on stress values because the value of bending moment plays a great role. Conclusions. The results of the fulfilled study as well as modern dam construction practice show the necessity of modifying the traditional pattern of rockfill zoning in the dam body. It is necessary to provide decrease of differences in rockfill deformation of the upstream and downstream parts of the dam.

Obtaining reasonable and reliable mechanical parameters of rock mass in engineering is a challenge. These parameters are difficult to obtain from a large sum of field tests due to the restrictions of time and costs. In this paper, linear equations of estimating rock mass mechanical parameters based on the P wave modulus are proposed through dimensional analysis. The field tests data of the Xiangjiaba, Baihetan, and Jinping I dam foundations are discussed to verify the universality and applicability of these linear equations. In addition, a new equation for calculating the disturbance factor D based on the P wave modulus is presented to estimate the mechanical parameters of rock mass in the disturbed zones, and then the field test data of the Three Gorges Project (TGP) shiplock slope are studied to verify the equation. The results show that the linear equations based on the P wave modulus have higher correlation than other function equations based on the P wave velocity. Therefore, the empirical equations using P wave modulus are feasible for estimating the mechanical parameters of rock mass. [ABSTRACT FROM AUTHOR]

Triaxial compression tests were performed to determine the strength and deformability of small-scale rock mass models with multiple joint sets and frequencies under confining stresses up to 12 MPa. The cubical sandstone specimens (80 × 80 × 80 mm) with joint sets simulated by saw-cut surfaces were compressed to failure using a true triaxial load frame. The joint frequencies ranged from 26 to 76 joints per meter. The results indicate that the Hoek-Brown criterion with two material parameters ( m and s) can describe rock mass strengths as well as the three parameter criteria of Sheorey, Yudhbir and Ramamurthy-Arora. The parameter s notably decreases with increasing joint frequency, while parameter m is less sensitive to joint frequency. The confining stresses tend to enhance the effects of joint frequencies on rock mass compressive strengths. The deformation moduli in the direction normal to the joints tend to be lower than those parallel to the joints. They decrease with increasing joint frequency. Goodman's equation was modified here to allow calculation of the deformation moduli of the rock mass along the three principal directions. The modified equation can sufficiently describe the deformation moduli normal and parallel to the joints for one-joint set and three-joint set specimens under all confining stresses. [ABSTRACT FROM AUTHOR]

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Estimating the deformation modulus of gravelly soils is a challenging task. The estimate of deformation modulus of cohessionless soils in general relies on availability of correlation between in situ test parameters and deformation modulus back-calculated from field results of pressure settlement relationship based on plate load or footing load tests or observed settlement records. However, such a correlation is rare for gravelly soils. Even if it exists, the correlation is usually constrained with few limitations due to field testing problems associated with presence of gravel size particles. The aim of this paper is to develop a new correlation between deformation modulus of gravelly soils and results of dynamic cone penetration tests. The correlation relies on results of footing load tests carried out in a reclaimed site in Alexandria, Egypt, side by side to dynamic cone penetration tests. The developed correlation is reinforced by settlement records for structures on gravelly soils from literature.

This article summarises dynamic deformation modulus correlation with second reload of static plate load test results for an even thickness soil strata layer. An analysis of execution and result interpretation of both static deformation modulus and dynamic deformation modulus is provided also. Different correlations between the two modulus according to different authors are provided. Since dynamic plate load test is not regulated in Lithuania as a soil compaction contron method, a few dynamic plate load tests and static plate load tests were executed in order to compare compaction results. The additional experiments for dynamic plate load tests in different depths were executed which showed that deformation modulus is dependant on depth of test execution, thus it is worthwile to mention to be cautious on compaction results in trenches.

The paper describes the results of making the mathematical and physical models of the authors, by using analogous methods and materials. There is the mathematical rock mass deformability model as a base for foundation engineering a concrete arch dam and the physical rock slope model which was tested by loading until failure and the results were compared with the calculation procedure. In the first example the correlation is established between the static and the analogous dynamic in situ investigations for creating the mathematical rock mass deformability model. In the second example there is application of the analogous materials for the discontinuity shearing simulation on the physical slope model. The results of the geotechnical in situ investigations and laboratory testing carried out in the Institute for Development of Water Resources "Jaroslav Cerni" in Belgrade were used for making the models.

The surface protection of hydropower construction is directly related to the safety of the building itself and the security of energy supply. Epoxy mortar is widely used as protection material in the field of hydropower engineering, and its mechanical properties are greatly influenced by temperature and loading rate. Under the three tensile rates of 0.01 mm/min, 0.05 mm/min and 0.1 mm/min, and three test temperatures of 0 °C, –10 °C and -20 °C, the tensile strength, deformation modulus and ultimate tensile strain of epoxy mortar were obtained from tensile experiment. It was shown that the deformation modulus and tensile strength of epoxy mortar had little relationship to tensile rate, which is linear to temperature index, and the ultimate tensile strain had little relationship to both the tensile rate and temperature, which has laid a foundation for the study on low temperature stress and cracking mechanism of the surface protection material, and provides technical support for the application safety of hydropower energy. [ABSTRACT FROM AUTHOR]

In real conditions of the building and operation the loads on the ground bases are applied by stages at the moment of construction buildings or structures. Active load stages during the construction are replace to stages of long exposure under load. In this connection there is necessity to improve the settlement calculation methodology of foundations under the regime long static loadings. Were performed high-rise buildings foundation settlements numerical studies with using different computational models, including the modified model of Pasternak at the basis of analytical ground deformation diagrams under triaxial regime loading. The test building has a frame-wall system, which is made from reinforced concrete and has the following parameters: total height of 144.9 m (39 floors); number of underground floors – 4; depth of laying the foundation – 15.15 m; raft foundation square – 1377 m2. For description of ground stress-strain state changes under regime loading, were developed analytical diagram of ground deformation at the coordinates “deviator stress – linear deformation” in the conditions of triaxial compression. Were constructed initial ground deformation diagrams for short triaxial static loading and transformed diagrams for prolonged triaxial regime loading, taking into account the changes in the mechanical characteristics during these loadings. Performed numerical studies of high-rise building foundation groundbase settlement on the basis of the proposed model allowed to calculate results, which have a good agreement with monitoring data. Deviation estimated average settlement from the real was not more than 1%. [ABSTRACT FROM AUTHOR]

Deformability of rock masses influencing their behavior is an important geomechanical property for the rock structures design. Due to the problems in determining the deformability of jointed rock masses at the laboratory-scale, various in situ test methods such as plate loading tests, dilatometer etc. have been developed. Although these methods are currently the best techniques, they are expensive and time consuming, and present operational problems. Furthermore, the influence of the test volume on modulus of deformation depending on the technique used is also important. For these reasons, in this paper, the adaptive network-based fuzzy inference system (ANFIS) was used to build a prediction model for the indirect estimation of deformation modulus of a rock mass. Three ANFIS models were implemented by grid partitioning (GP), subtractive clustering method (SCM) and fuzzy c-means clustering method (FCM). The estimation abilities offered using three ANFIS models were presented by using field data of achieved from road and railway construction sites in Korea. In these models, rock mass rating (RMR), depth, uniaxial compressive strength of intact rock (UCS) and elastic modulus of intact rock (E) were utilized as the input parameters, while the deformation modulus of a rock mass was the output parameter. Various statistical performance indexes were utilized to compare the performance of those estimation models. The results achieved indicate that the ANFIS-SCM model has strong potential to indirect estimation of deformation modulus of a rock mass with high degree of accuracy and robustness. [ABSTRACT FROM AUTHOR]

Deformation modulus of a rock mass is one of the crucial parameters used in the design of surface and underground rock engineering structures. Determination of this parameter by testing cylindrical core samples is almost impossible due to the presence of discontinuities. Due to the problems in determining the deformability of jointed rock masses at the laboratory-scale, various in situ test methods such as plate loading tests, dilatometer etc. have been developed. Although these methods are currently the best techniques, they are expensive and time-consuming, and present operational problems. To overcome this difficulty, in this paper, presents the results of the application of hybrid support vector regression (SVR) with harmony search algorithm , differential evolution algorithm and particle swarm optimization algorithm (PSO). The optimized models were applied to available data given in open source literature and the performance of optimization algorithm was assessed by virtue of statistical criteria. In these models, rock mass rating (RMR), depth, uniaxial compressive strength of intact rock (UCS) and elastic modulus of intact rock ( E ) were utilized as the input parameters, while the deformation modulus of a rock mass was the output parameter. The comparative results revealed that hybrid of PSO and SVR yield robust model which outperform other models in term of higher squared correlation coefficient ( R ) and variance account for (VAF) and lower mean square error (MSE), root mean squared error (RMSE) and mean absolute percentage error (MAPE). [ABSTRACT FROM AUTHOR]

The mechanical properties (uniaxial compressive strength and deformation modulus) of frozen tailings are key parameters for the safety assessment of a tailing dam. However, the experimental data on such mechanical properties are limited. In this study, more than sixty tailings samples with four tailings (medium sand, fine sand, silty sand, and silt) were frozen at the temperature of − 16 °C, and then tested under uniaxial compression in order to investigate their mechanical properties. The effects of four parameters (average particle size, dry density, water content and strain rate) on the uniaxial compressive strength (UCS) and the deformation modulus of frozen tailings were investigated. The test results show that three failure patterns of samples were observed: inclined plane shear failure, lateral tensile failure, and composite failure involving both. Their uniaxial compressive strength is related logarithmically to average particle size, exponentially to dry density, linearly to moisture content, and parabolically to strain rate. On the other hand, their deformation modulus is related logarithmically to average particle size, parabolically to moisture content, exponentially to both dry density and strain rate. [ABSTRACT FROM AUTHOR]

The characterization of rock mass is an essential part of the preliminary engineering design in the field of civil and mining engineering. It is considered very beneficial when limited geological and geotechnical data of site is available. In the present research, the empirical methods i.e. Rock Mass Rating (RMR), Tunneling Quality Index (Q-System) and Geological Strength Index (GSI) classification systems for assessment and classification of rock mass along the axis of tunnel. These empirical methods were applied on the geological and geotechnical data collected along the axis of tunnel. The strength properties and intrinsic properties of rock samples, which are important for characterization, were determined in the laboratory. The rock mass along tunnel axis was characterized based on the empirical methods, intrinsic and strength properties of the rock mass. After characterization, the rock mass was divided into three geotechnical units i.e. GU-1, GU-2 and GU-3. Different support systems for each geotechnical unit were recommended to stabilize the tunnel. The conventional drilling and blasting technique was proposed for driving of the tunnel. [ABSTRACT FROM AUTHOR]

This article summarises dynamic deformation modulus correlation with second reload of static plate load test results for an even thickness soil strata layer. An analysis of execution and result interpretation of both static deformation modulus and dynamic deformation modulus is provided also. Different correlations between the two modulus according to different authors are provided. Since dynamic plate load test is not regulated in Lithuania as a soil compaction contron method, a few dynamic plate load tests and static plate load tests were executed in order to compare compaction results. The additional experiments for dynamic plate load tests in different depths were executed which showed that deformation modulus is dependant on depth of test execution, thus it is worthwile to mention to be cautious on compaction results in trenches. [ABSTRACT FROM AUTHOR]

This paper investigates a series of experimental results and numerical simulations employed to estimate the deformation modulus of a stratified rock mass. The deformation modulus of rock mass has a significant importance for some applications in engineering geology and geotechnical projects including foundation, slope, and tunnel designs. Deformation modulus of a rock mass can be determined using large scale in-situ tests. This large scale sophisticated in-situ testing equipments are sometimes difficult to install, plus time consuming to be employed in the field. Therefore, this study aims to estimate indirectly the deformation modulus values via empirical methods such as the neural network, neuro fuzzy and genetic programming approaches. A series of analyses have been developed for correlating various relationships between the deformation modulus of rock mass, rock mass rating, rock quality designation, uniaxial compressive strength, and elasticity modulus of intact rock parameters. The performance capacities of proposed models are assessed and found as quite satisfactory. At the completion of a comparative study on the accuracy of models, in the results, it is seen that overall genetic programming models yielded more precise results than neural network and neuro fuzzy models. [ABSTRACT FROM AUTHOR]