Material heterogeneity and shear strength variability are the main stability analysis considerations for the interbedded sedimentary rock slope due to interlayer slip potential. In this study, an interbedded sedimentary rock slope located in Terengganu, Malaysia, was examined. The composite stratified geostructure was projected for 2D surface morphology using point cloud photogrammetry, thus plane segmentation for dip measurement. The inter-bedded rock slope was modeled explicitly, where the location of rock beddings and potential weak layer materials are well defined. The limit equilibrium analysis for factors of safety determination was extended with sensitivity and probabilistic analyses for a wider range of failure potential factors. The validation using finite element analysis significantly justified the stability analysis result based on the shear strain behavior.

Reliable prediction of excavation impacts on surrounding rock mass is one of the crucial sub-ject in rock engineering. In this paper, the impacts of new tunnel construction intersecting an old tunnel is studied using the numerical modeling for case study of the Tehran-Shomal free-way project. The numerical modeling is performed by utilizing FLAC to evaluate the induced displacement and damaged zones surrounding the tunnel as a function of horizontal to vertical stress ratio (k). The results indicate that, both horizontal and vertical displacements induced by excavation and also the plastic zone show asymmetric spatial distribution around the tunnels due to the especial shape of tunnels intersection. The increase of k ration shows direct and re-verse effect on the horizontal and vertical displacement, respectively. In addition, by increasing the k ratio, the total displacement of observation points increases and the mechanism of yield-ing of surrounding rock is converted from shear to tension

This paper focuses on a case study of the use of numerical modelling to assess the influence of in-situ stresses and rock mass mechanical properties on the behaviour of a sill pillar in an underground metal mine. The loading conditions on the pillar are a result of a multiple panel, bottom-up advancing open stoping mining sequence with cemented paste fill. The sill pillar is exposed to increased induced horizontal stresses, which could result in rock mass damage or depending on the rock mass strength and geometry of the pillar. In extreme cases, the pillar may collapse, leading to ore loss or compromised worker safety. The numeri-cal modelling analysis in the case study was used to predict the rock mass deformation as af-fected by the mining sequence, in situ and induced stress conditions, and rock mass and paste fill properties to assess the pillar stability from stress-related damage.

Piezometers are instruments that can produce high-quality information if suitable installation and monitoring procedures are followed. Attention must be paid when prescribing the type of piezometer and the installation procedure in order to minimize errors and optimise the quality of the obtained information. The use of piezometers as geotechnical instruments is a commodity. However, attention needs to be paid to the installation procedure as highlighted in the ISO/EN18674 standards. The aim of the paper is to exemplify how the use of piezometers can be optimized and how the most standard errors can be avoided.

Mining and geomechanical conditions during mining operation in underground mine are changing all the time. The changes depend on many factors, as e.g.: the buried depth, type of rocks, geomechanical parameters of rocks, the size of mining face, the type of exploitation system or the space layout of mining in a field. However, as the result, all these factors influence on the state of stress. They determine the value of abundant stress and the direction of principal stresses. What is interesting, there is not only change in the primary stress next to the exploitation panel, but the rotation of the principal stresses as well. This fact is very often omit, because it’s impossible to solve this problem analytically. One can only assess it using numerical methods or carrying out expensive and time consuming rock mass monitoring underground in a mine. Employing numerical calculations the state of stress around the roadway is often determined in 2D models, which cannot show the stress rotation. This information can be found only using 3D models. However, the most valuable results can be received with the help of in situ measurements, which can be carried out with some biaxial or triaxial stress meters. The paper presents the results of underground monitoring and numerical analyses of state of stress in the rock mass during longwall panel advance in a coal underground mine. The in situ stress measurements were conducted with the help of biaxial stressmeters with vibrating wire installed in the coal ribs of a maingate, approx. 10 m deep in a non-fractured rock. The measurement data were registered automatically every 6 hours. This data allow to calculate not only the value of major and minor stresses but also changes of the angle of a major stress. The results of stress monitoring, together with the results of geomechanical parametrs of rocks done in the laboratory, were the base for 3D numerical modelling. Thanks to modelling the rule of principal stress rotation were shown. Conclusions are of a crucial importance for planning mining operations. The knowledge about the stress regime and its possible change can help in support system design for gates and improve the staff safety.

Ryukyu Islands constitute the south-west part of the Japanese archipelago. The age of the basement is pre-Cenozoic and the basement rocks are chert and schists. Cenozoic sandstone, shale and limestone overlay the basement rocks. These rock units are followed by Tertiary Shimajiri formation and all formations are covered by Quaternary Ryukyu limestone and Holocene deposits. The geo-engineering issues are mainly associated with the Shimajiri formation and Ryukyu Limestone. Particularly, landslides and stability issues of open or underground excavations in Shimajiri formation are major geo-engineering problems. It is well known that mudstone of the Shimajiri formation are subjected to degradation due to cyclic wetting and drying in relation to the water content variation. They also have time-dependent characteristics. The intact mudstone has uniaxial compressive strength (UCS) ranging between 0.6-3.6 MPa under natural water content conditions. Particularly, younger mudstone belonging to Shinzato Formation has lower UCS while older mudstone belonging to Yonabaru Formation has higher UCS. When mudstone layers are exposed to atmospheric conditions they absorb or desorb water and they exhibit volumetric swelling or shrinkage. This interaction with water causes their degradation and the physico-mechanical properties become a function of water content. The authors have been involved with a project where the mudstone layers belonging to Shinzato Formation and having some small normal faults caused some instability problems during a construction of a deep open-cut waste storage facility as a result of groundwater level changes during a heavy rainy period. New horizontal borings were done and cores from these borings utilized for tests on uniaxial compressive strength and Brazilian tests under different water content. The experimental studies involved the evaluation of physico-mechanical properties as a function of water content. Furthermore, groundwater diffusion characteristics of mudstone and related volumetric changes are experimentally investigated. During experiments, it is observed that some samples failed along some existing structural weakness planes. A multi-parameter monitoring system was installed and measurements were carried out for almost one-year. On the basis of these studies, some limit equilibrium analyses on the stability of the open-cut excavation and discrete finite element analyses (DFEM) on its measured deformation response were carried out. The outcomes of this integrated study involving various experiments, monitoring and numerical analyses are presented and their implications in practice are discussed.