Analysis of the Behavior of the Veveyse Bridge Under Impact of Massive Rockslides: a Practical Case Study

The Main Spillway and Diversion Tunnel at Manikin Dam is one of the dams under construction in the Kupang City area, where several soil or rock investigations have been carried out around it. However, the field investigations are not accompanied by a surface geological investigation or evaluation of subsurface geological conditions based on core drill results. Therefore, the purpose of this paper is to evaluate the engineering geological condition in tunnel construction by displaying surface and subsurface geological mapping with a scale of 1:10,000 and evaluate samples of core drilling using the Rock Mass Rating method in order to have more accurate stand-up time assumptions. The result of engineering geological mapping shows that the research area has three lithologies, namely a basalt unit, a carbonaceous sandstone unit, and a scaly claystone with a chaotic rock unit. The core-drill evaluation indicates that the research area is classified into three quality rock masses, namely Good Rock with an RMR Rating of 64, Fair Rock with an RMR Rating of 46, and Poor Rock with an RMR Rating of 36. The stand-up time value for each rock mass quality category is obtained from the quality rock mass results. The stand-up time value for the Good Rock category is 2200 hours, the Fair Rock category is 30 hours and the Poor Rock category is 1.2 - 1.7 hours. Based on the low stand-up time values in the Fair Rock and Poor Rock categories, it is expected that a support system will be installed immediately after tunnel excavation.

Interpretation of displacement monitoring data for tunnels in heterogeneous rock masses

Simulations of fracture and fragmentation of geologic materials using combined FEM/DEM analysis

On the influence of rock mass quality on the quality of blasting work in tunnel driving

To mitigate unforeseen incidents, such as key block failure or tunnel collapse during excavation, an appropriate support pattern that correlates with the geological conditions of the rock mass at the tunnel face should be designed. Rock mass evaluations should be conducted through geological face mapping during the construction phase, alongside predictions based on field investigations during the design phase. When marked discrepancies are identified, it is customary to convene an on-site evaluation involving a committee of experts. This study develops a digital tunnel face mapping system that utilises mobile devices to facilitate online evaluations during the construction phase. This system effectively replaces the traditional on-site field evaluation method. Tunnel face mapping can be promptly accomplished using images captured at the excavation face, enabling rapid analysis. In conjunction with the mapping capabilities, the developed system was designed to digitally store geological information, which includes parameters such as rock strength distribution, the spacing and length of discontinuities observed during the mapping process, as well as data pertaining to weathering and the groundwater conditions of those discontinuities. This information was then correlated with the rock mass rating sheet to automate the determination of ratings for each parameter, ultimately leading to a conclusive classification of the rock mass quality. By employing this system for tunnel face mapping and rock quality evaluation, we significantly reduced the discrepancies in the evaluation results that often arise due to the subjective judgement of geologists, as well as human errors that can occur throughout the rating process.

The documentation of excavation method and support design based on rock mass classification systems i.e. rock mass rating (RMR), Q-system and New Austrian tunneling method (NATM) for adit-7 tunnel being constructed in Garhwal Himalaya, India is discussed in this paper. The New Austrian tunneling method classes of rock units have been developed by using correlations with the RMR and Q systems, according to the ONORM B 2203. NATM principles were used because the geological conditions were continually changing. The study indicated that the RMR-based rock mass estimation was overstated, but the qualitative assessment was right. The NATM technique is more adaptable for Garhwal Himalayan rocks having various uncertainties in rock mass evaluation. The current adit investigations indicate that there are numerous unanswered concerns, concerning rock mass quality evaluation, tunnel behavior during construction and usability. Results of the analysis are considered to be useful for the design of the new tunnels constructed in the similar type of the terrain.

The relevance of the work is due to the existence of a large number of empirical methods for predicting the condition of a rock mass and the need to apply them at the design and operational stage of mining enterprises to minimize costs during construction and future maintenance. Research objective is to analyze and compare existing empirical methods for determining the strength and deformation properties of rock mass. Methods of research include the analysis, systematization and synthesis of existing empirical methods of rock mass condition assessment and their applicability to real-world sites. Recommendations for further application of empirical rock mass assessment methods in real-world conditions are determined by generalization of theory and practice, research results and analytical calculations based on the assessment of fracture formation in rock masses. Results. The main empirical methods such as Deere's method (RQD) of structural failure evaluation, the method relating strain rate to RMR rating system and the method relating strain rate to geomechanical classification of rock mass Q were found and chosen for comparison. Several types of rocks such as limestone, diorite, granite, basalt, tuff, andesite in different geotechnical conditions are chosen for comparison of the methods. Comparison of different empirical methods of rock mass condition assessment is carried out. Evaluations of each method are given. Ways of application of empirical research methods are recommended. It is concluded that it is necessary to apply several methods in order to get a more accurate picture of the rock mass condition. Recommendations for the initial assessment of the state of rocks are given. Conclusions. There are a large number of empirical methods of rock mass condition estimation. The results obtained by some methods for some types of rocks under different mining and geological conditions are very different from each other, this is due to the fact that the considered methods were created on the basis of different sources. It is necessary to take into account the stresses acting in the rock mass, which also influence the results obtained.

This research aims to develop a methodology of selecting and validating support system designs for different purpose roadways by means of synthesizing the rock mass quality index Q and the stability categories which are in application in mines in Russia. The existing approaches to rock mass quality evaluation based on different combinations of complementary classification criteria are reviewed and generalized. It is found that the stability categories in use in Russian mines comply with the Q-index, which enables their flexible adaptation to specific features of a deposit and allows revealing of average mining conditions for different mines. The multi-factor rock mass quality rating and classification made it possible to justify mine designs per different categories. On this basis, the safe shapes and cross-section sizes are determined for the face entries for the prevalent geological conditions of ore mining under equicomponent (hydrostatic) stress state. The analysis and generalization of actual data from operating mines in the ore provinces in Yakutia, Russian Far East, Krasnoyarsk Krai and Eastern Kazakhstan allowed correlating the maximum permissible widths and cross-section shapes of roadways, as well as the roadway purpose and the rock mass quality by the Q-system by Barton. The revealed patterns of rock mass stability effect on the roadway roof span size made it possible to define rockbolting design variables for the face entries of operating mines in rock masses characterized by the widely ranging Q-index. The implementation of the integrated approach to rock mass stability estimation can improve reliability of the pre-project and project design solutions aimed to enhance safety and efficiency of roadways in different geological and geomechanical conditions of mineral mining.

For the October deposit conditions extraction of the gently-sloping deposit of copper-nickel ores within the wings numerous faults intersecting the ore body is connected with increased danger of rock bursts and the requirement for carrying out a considerable amount of labor-consuming driving of dead ends. Mining is carried out in a continuous sequence by layers and chambers with stowing of the worked-out space with consolidating mixtures. Previously by driving and filling parallel cross drifts over the upper contact of the deposit a continuous concrete layer is built. The workings are orientated almost along the strike of tectonics fractures [1]. In seeking the possibility of reducing the volume of driving in zones of tectonic faults industrial experiments were carried out in two areas of the deposit intersected by faults. In contrast to the traditional scheme for constructing a protective slice there was simultaneous erection of sections of a protective slice within the wings of a fault before approaching the extraction front of the main reserves towards the tectonic fault zone. It was assumed that presence of an additional front of a protective slice leads to mutual shifting of the wings of a tectonic fault with loosening of the ore mass. As a result of this treatment of the reserves in the wings of the fault was accomplished without creating a protective slice beneath part of the ore bounded by the overlaying strata. The set of instrument and full-scale observations confirmed this assumption. In test areas both in stopes created beneath the protective slice and in the overworked part of the ore body no signs of increased mine pressure were noted [2]. However, industrial experiments were limited by the specific mining and geological conditions. Observations and measurements made in the test areas give information about the mechanical state of the rock mass at a limited number of points. Transfer of the technology to other conditions and depths requires additional substantiation and studies connected with considerable expenditure and organizational difficulties. In this situation it is possible most simply by means of mathematical modelling to reveal the most common features of stress field formation within the vicinity of a fault. Calculations of the stress-strain state for a rock mass were performed by the finite element method. In the mathematical describing material deformation the rock mass outside the plane of a tectonic fault was represented by elastic materials with corresponding mechanical properties. This assumption is correct in view of the fact that the rocks comprising the rock mass have high elasticity constants and the theological properties appear to an insignificant extent. The deformation of a tectonic fault was described by an elastoplastic material reflecting the main features of fault behavior under load [3, 4]. The original stressed state for the ore and surrounding rock masses is characterized by the presence of tectonic forces. Horizontal compressive stresses are 0.6-1.7"rH, and vertical stresses are 0.6-1.43,H (H is working depth). The most clearly expressed regions of disturbance of the original stressed state are confined to large amplitude faults. According to measured data in them both horizontal and vertical stresses may predominate which may lead to a marked difference in the mechanism of rock mass deformation within the vicinity of a fault on introducing mine working. In the present work the case is considered when within the vicinity of a tectonic fault horizontal stresses predominate. The original stress field in all of the calculations discussed below is adopted as follows: Cry = 3'H, a x = 1.53,H, rxy = 0. Corresponding to this at the outer boundary of the calculation region normal and tangential force components were prescribed. The stress -strained state of the rock mass was determined for the plane strain condition which is fulfilled here due to the considerable extent of a tectonic fault, and stoping and preparatory workings in direction perpendicular to the section in question. Values of mechanical properties for the ore body, the surrounding rocks, and stowing material were taken as typical for the October deposit conditions [5]. The corresponding values of Young's modulus were 5" 104, 8- 104 and 3.104 MPa, and for Poisson's ratio they were 0.25, 0.2, and 0.4. The ore body thickness was 25 m.

The article presents an innovative procedure for the joint stress-strain and elasticity modulus analysis in high-strength rock masses with spacing from a few to tens meters. The procedure includes measurement of elastic convergence of rock walls due to deeper penetration of the foot of a vertical shaft and the analysis of measured displacements of check points along the shaft cross-section perimeter with subsequent two-stage solution of an inverse geomechanical problem. In the first stage, in the lobed diagram of measured displacements of check points, the azimuths of axes of the principal horizontal stresses in surrounding rock mass are determined. In the second stage, the process of deeper penetration of the shaft foot is modeled with different scenarios of the rock mass stress-strain behavior set as varied principal horizontal stresses at the known azimuths of their main axes. Then, the model and in-situ measurement results are compared using the analysis of variance ANOVA. The wanted variant of the stress-strain behavior and the associated modulus of elasticity, such that deviation of the actually measured displacements of check points from the model values is minimal, is identified by the extremum analysis of the experimental diagrams. The procedure was successfully tested in Vspomogatelny and Skipovoi vertical shafts of the Tenth Anniversary of Independence of Kazakhstan mine within Donskoy Mining and Processing Plant, in qualitatively different geological conditions: high-strength rock mass areas categorized as unstable and stable. In unstable rocks, the measured elasticity modulus Е = 3,5 ± 0,7 GPa made 6 %-16 % of the elasticity modulus in samples. In the stable rock mass, the measured modulus Е = 36,6 ± 7,7 GPa almost coincided with the elastic modulus of samples.

Purpose. Study of the process of destruction and collapse of rocks of the main roof during cleaning operations in difficult mining and geological conditions. Justification of the method of determining the time of roof destruction taking into account the crack resistance of rocks. Method. The method of laboratory studies of rock fracture toughness; the method of physical modeling of rock mass collapse processes over the created space, analytical studies of the process of layering and destruction of rock mass. Results. As a result of laboratory experiments, the results of fracture viscosity, specific energy of crack formation for sandstone were obtained. As a result of physical modeling studies, analytical calculations, dependencies were established: the step of the collapse of the main roof, the height of delamination, for each scheme under different technological and geological working conditions, and the time of destruction of the roof layers, taking into account the crack resistance of the rocks. A justified expression for determining the height of delamination taking into account the crack resistance of rocks. A well-founded method of determining the rate and time of destruction of the roof layers above the created space, taking into account the crack resistance of rocks. Reasoned formulas for determining the parameters of primary and periodic collapse of roof layers over the created space, taking into account the crack resistance of rocks in complex mining and geological conditions. Scientific novelty. For the first time, the dependencies of the main roof collapse step were established for each scheme, under different technological and geological working conditions, taking into account the crack resistance of the rocks. For the first time, the dependence of the height of delamination, taking into account the crack resistance of rocks, was established. For the first time, the dependence of the time of destruction of the roof layers, taking into account the crack resistance of the rocks, was established. Practical significance. The practical significance lies in forecasting the processes of layering, destruction and collapse of the main roof rocks in the complex mining and geological conditions of working out coal seams. Establishing the time of destruction of the immediate and main roof will allow determining the nature of the destruction of the roof, and will allow adjusting the further management of the roof. Key words: main roof, crack resistance, fracture toughness, specific energy of crack formation, delamination height, roof collapse step, time of destruction of rock layers of the roof

The objectives of the present studies are (a) to investigate the guidelines of instrumentation for application of a vibration test for detecting invisible damage in bridges and (b) to discuss the application of the results of vibration measurement in safety assessment. Finite element models have been set up to find out the change of natural frequencies and mode shapes of bridges with damaged structural members. It is found that the mode shapes can be used as the indicator for detecting damage or deterioration of the superstructure of a bridge and that natural frequencies can be used for detecting damages in the piled foundation of a bridge. The required values of accuracy of frequency control for an exciter used in the test are 0.05 Hz for the former and 0.1 Hz for the latter. In addition, the safety assessment of bridges, based on their response data during severe earthquakes, is also discussed.

Successful application of a TBM in a project requires investigating both the ground conditions and the machine and backup system design features. Prediction of the machine performance is very important as it has a big effect on the duration of the project and the costs. In this respect, both penetration rate and advance rate must be estimated. Utilization factor, which depends on the type of operation, management, maintenance, geological conditions, mucking delays and other downtimes, correlates the advance rate and penetration rate. Adverse rock mass conditions such as mixed face condition, water problem and instability of rock have a great role in TBM downtimes and reduce the machine utilization considerably. Based on detailed engineering geological reports and maps and daily site reports taken from Karaj-Tehran Water Conveyance Tunnel ( Lots 1 and 2), this paper evaluates, main rock mass properties utilized for the estimation of TBM performance and discusses their effect on the machine utilization. . More specifically it uses the developed database also contains daily boring time, different rock mass related downtimes, daily advance and length of bored tunnel in each engineering geological units. It is concluded that the percentage of the rock mass related downtimes can be estimated via RMR within reliable coefficient of determination.

Indonesian government through the National Atomic Energy Agency has planned to build a nuclear power plant. One of the proposed sites is in West Bangka Regency, Bangka Belitung Archipelago Province. The engineering geology of this area is, however, not fully understood and requires further investigations. Engineering geology investigations were carried out by assessing the rock mass quality and bearing capacity based on field observation and drilling data. The assessment was conducted using Rock Mass Rating (RMR) and Geological Strength Index (GSI) classification. The rock mass in the study area was divided into four units, namely Units of Sandstone, Granite, Mudstone and Pebbly Sandstone. The RMR and GSI values in the study area are influenced by the parameters of discontinuity space density, the slope of discontinuity orientation, grade of weathering and groundwater conditions. The assessment shows that the Granite Unit has the best quality which is shown by the average RMR value of 53 and GSI value of 66. Based on the average RMR value, the Granite Unit is estimated to have cohesion value between 0.2 and 0.3 MPa, friction angle between 25° and 35°, and allowable bearing pressure between 280 and 135 T/m2. Based on the GSI value, the Granite Unit is estimated to have uniaxial compressive strength value between 1.0465 and 183.8 MPa, tensile strength between (-0.0122) and (-5.2625) MPa, rock mass strength values between 24.5244 and 220.351 MPa, and modulus of deformation within a range of 1.73–86.68 GPa. The Granite Unit is considered to be the most appropriate location for the nuclear power plants. Keywords: Nuclear power plant foundation, geological strength index, rock mass rating, rock mass quality

1. Scope of the paper. The present paper is a continuation of an earlier sequence in these Proceedings, entitled ‘ The inverse square law of gravitation, I, II and III’ (Milne 1936, 1937c), which itself was connected with another sequence entitled ‘Kinematics, dynamics and the scale of time, I, II and III ’(Milne 1937a,b). In the latter sequence the relations between t-dynamics and r-dynamics were obtained. In the former sequence a formula for the gravitational potential energy of two particles was isolated which was Lorentz-invariant for transformations from any one fundamental observer in the expanding substratum to any other fundamental observer; and the corresponding equations of motion in t-measure were obtained. In the present paper I obtain relations which correspond to the integrals of linear and angular momentum in the many-body problem of classical gravitational theory. I conclude that Einstein’s form of the conservation of linear momentum in special relativity holds good in the universe at large only in the case of a collinear set of particles moving along their line of collinearity, and I give the modification of the law of conservation which should hold good in other cases.