scholarly journals Engineering Geological Investigation of dam site of proposed Sunkoshi-2 Hydropower Project, Khurkot area, eastern Nepal

2019 ◽  
Vol 58 ◽  
pp. 181-188
Author(s):  
Bipin Adhikari ◽  
Ujjwal Acharya ◽  
Kamala Kant Acharya ◽  
Subesh Ghimire
Keyword(s):  
Rock Mass ◽  
Geological Mapping ◽  
Hydropower Project ◽  
Rock Masses ◽  
Geological Investigation ◽  
Dam Foundation ◽  
Rock Types ◽  
Stability Against Sliding ◽  
Dam Site ◽  
Selection Of

The dam site of proposed Sunkoshi-2 Hydropower Project and its surrounding mainly comprise the Tawa Khola Formation, which is the basal formation of the Bhimphedi Group. Although garnet schist and micaceous quartzite bands are the main rock types; three rock units namely- Schist Unit, Quartzite Unit, and Gneiss Unit were identified. Engineering geological mapping followed by discontinuity survey were carried out. The result exhibited differences in fracture intensity and discontinuity characteristics of rock masses according to rock type. Since joint orientations were found to be consistent over fairly large areas, surface studies of joints were used in predicting subsurface orientations. Rock mass classification was made in line with the Rock Mass Rating System (RMR) and the Dam Mass Rating (DMR) classification for the dam foundation. The rock masses were classified onto fair to good rock classes according to RMR value. Dam foundation analysis regarding stability against sliding using DMR classification helped in selection of suitable dam-axis among two alternatives. Water Quality Standards (2005).

scholarly journals Geology and rockmass condition of Dhulikhel-Panchkhal area, Kavre District, Central Nepal Lesser Himalaya

2013 ◽  
Vol 15 ◽  
pp. 1-14
Author(s):  
Prem Nath Paudel ◽  
Naresh Kazi Tamrakar
Keyword(s):  
Rock Mass ◽  
Rock Type ◽  
Physical And Mechanical Properties ◽  
Geological Mapping ◽  
Rock Mass Rating ◽  
Lesser Himalaya ◽  
Rock Masses ◽  
Northern Limb ◽  
Rock Types ◽  
Central Nepal

A geological mapping was carried out and the rock mass characteristics of the Lesser Himalayan rocks distributed in the Dhulikhel-Panchkhal area (Kavre Distric) were studied along with their physical and mechanical properties. The lithological units distributed in the study area belong to the Benighat Slate of the Upper Nawakot Group and the Bhimphedi Group as separated by the Chak-Rosi Thrust. The lithological units strike NW-SE and dip southwards forming the eastern closure of part of the northern limb of the Mahabharat synclinorium. The area comprises mainly micaceous quartzite, psammitic schist, metasandstone and metasiltstone. Micaceous quartzite is a rock type of the Kalitar Formation, Chisapani quartzite and the Markhu Formation. The Markhu quartzite is slightly calcareous. Psammitic schist is a rock type of the Kulekhani Formation and the Markhu Formation. Metasandstone and metasiltstone are the rock types of the Tistung Formation. The rock masses consist mainly of three to four major joint sets including the joint parallel to foliation. The discontinuity characteristics indicate that the rocks are blocky in nature, and nearly smooth to rough surface with soft filling aperture. The rock mass is nearly fresh, indurated and stiff. The slopes are influenced by stable and unstable wedges, plane and toppling failures. The rock masses are classified into fair to good rock classes according to rock mass rating system. DOI: http://dx.doi.org/10.3126/bdg.v15i0.7412 Bulletin of the Department of Geology, Vol. 15, 2012, pp. 1–14

scholarly journals Influence of Natural Cavities on the Design of Shallow Foundations

2020 ◽  
Vol 10 (3) ◽  
pp. 1119
Author(s):  
Jesús Luis Benito Olmeda ◽  
Javier Moreno Robles ◽  
Eugenio Sanz Pérez ◽  
Claudio Olalla Marañón
Keyword(s):  
Rock Mass ◽  
Bearing Capacity ◽  
Ultimate Bearing Capacity ◽  
Shallow Foundation ◽  
Rock Masses ◽  
Volcanic Origin ◽  
Rock Types ◽  
Geometric Configurations ◽  
Relative Eccentricity ◽  
Decisive Parameter

When inner cavities of significant dimensions exist in natural rocks, problems arise when a shallow foundation for a building, bridge or other structure is builtonthem. Thus, taking one of the most representative cavity geometries in nature, the ellipsoidal horizontal shape, the main objective of this study is to obtain the ultimate bearing capacity of the foundation with cavities of different sizes and positions, on rock masses with different strengths and deformation characteristics. The study focuses on natural rocks of karst origin (in limestones, dolomites or gypsums) and of volcanic origin. The ultimate bearing capacity is determined relative to a situation without the existence of the cavity for different cavern positions and sizes, rock types (mi), strengths (UCS), and states (GSI) of the rock mass. The results showed that the most decisive parameter is the relative eccentricity. The influence of the rock type (Hoek’s parameter mi) is, for practical purposes, negligible (lower than 10%). The strength and condition of the rock mass (parameters UCS and GSI) have relatively little influence on the results obtained. This study aims to provide a simple design criteria for universal use, with different geometric configurations and qualities of rock masses that can be used directly without the need for sophisticated calculations by the designer.

scholarly journals Tunneling in Khimti Hydropower Project, central Nepal

1996 ◽  
Vol 14 ◽  
Author(s):  
S. C. Sunuwar ◽  
B. O'Neill
Keyword(s):  
Rock Mass ◽  
Correct Choice ◽  
The Self ◽  
Hydropower Project ◽  
Supporting Capacity ◽  
Rock Support ◽  
Geological Investigation ◽  
Tunnel Support ◽  
Central Nepal

The role of geology is very important in any underground excavation. Proper geological investigation reduces the overall cost of a project and saves time. It is important to understand and be able to predict the behaviour of a rock mass before designing the support system. In good quality rock, the self-supporting capacity of rock mass should be used to its maximum advantage and the amount of rock support kept to a minimum. In the Khimti Hydropower Project the tunnel support will be designed to take optimum advantage of the self-supporting capacity of rock mass and the correct choice of support systems. The rocks encountered in the tunnels at Khimti will be logged in accordance with the Q-classification system. The experience in desigining tunnel support that has been developed in Norway will be used to this project as well.

scholarly journals Stability Analysis and Reliability Evaluation in Cataclastic Loose Rock Mass Blocks

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Liguo Zhang ◽  
Dong Wang ◽  
Guanghe Li ◽  
Jiaxing Dong ◽  
Junpeng Zhang
Keyword(s):  
Rock Mass ◽  
System Reliability ◽  
Laser Scanning ◽  
Failure Modes ◽  
Reliability Evaluation ◽  
Rock Slopes ◽  
Hydropower Project ◽  
Rock Masses ◽  
Cataclastic Rock ◽  
Key Block

Cataclastic rock masses with multiple failure modes and mechanisms are critical geological problems in the construction of rock slopes. Cataclastic rock masses are widely distributed in slopes of a hydropower project located on Lancang River, which is located in Tibet, China. In this study, the potentially unstable block of the slope is divided into key block and secondary key block based on the key block theory, and the system reliability evaluation theory is introduced. The method for quantitatively analyzing the rock mass stability of cataclastic slopes with sliding failure is established. Then, the spatial distribution of cataclastic rock masses and discontinuities in several rock slopes of a hydropower project are determined using traditional geological surveying and 3D laser scanning. At last, combining the BATE 2.0 software and the stereographic projection of the vector, the proposed method is applied to the study area. The results show that the main failure mode of the studied slope is wedge failure, and the system reliability is 1.69. With the increase in the instability probability of the key block, the increase in the instability probability of the system block is obvious, which reflects the controlling effect of the key block on the stability of the system block. The calculated system instability probability is slightly larger than the key block instability probability.

scholarly journals Engineering geological characteristics based on rock mass rating (RMR) and geological strength index (GSI) in Tunnel Number 1 of the Sigli-Aceh toll road

2021 ◽  
Vol 325 ◽  
pp. 01014
Author(s):  
Jabnes Satria ◽  
I Gde Budi Indrawan ◽  
Nugroho Imam Setiawan
Keyword(s):  
Rock Mass ◽  
Poor Quality ◽  
Geological Mapping ◽  
Geological Strength Index ◽  
Rock Mass Rating ◽  
Strength Index ◽  
Geological Investigation ◽  
Tunnel Support ◽  
Toll Road ◽  
Tunnel Number

This paper presents engineering geological investigation results in the form of rock mass characteristics for tunnel number 1 of the Sigli-Aceh toll road. The investigation was carried out through geological mapping, core drill evaluation, and laboratory tests. In this research, the rock mass rating (RMR) and Geological Strength Index (GSI) were applied for the rock mass classifications. The measurement of rock mass quality is then used to determine the excavation method and tunnel support system on the SigliAceh toll road. The results showed that the research location consisted of calcareous sandstone with poor to good-quality (GSI (21.7 - 85.5), RMR (32.0 - 67.6)), and sandstone with good quality (GSI (86.3 - 86.9), RMR (64.0 - 65.0)). The poor quality rock masses were mainly caused by weathering effect. In addition, this research also analyzes the relationship between RMR and GSI based on the type and quality of rocks in the research location so that this correlation can be used in other areas with similar rock type and quality to this research location.

scholarly journals Methodologies for geological-geotechnical characterization of rock masses: role of geomechanical classifications and indexes

2021 ◽  
Vol 942 (1) ◽  
pp. 012025
Author(s):  
C Santa ◽  
I Fernandes ◽  
HI Chaminé
Keyword(s):  
Rock Mass ◽  
Site Investigation ◽  
Classification Systems ◽  
Rock Masses ◽  
Rock Types ◽  
Work Cycle ◽  
Definition Of ◽  
Engineering Projects

Abstract The geological and geotechnical description and evaluation are fundamental in engineering projects and the extractive industry, emphasizing underground environments where the rock mass is subjected to high stresses. In excavating rock masses, the classification systems contribute to parameterizing the rock material and rock mass characteristics. In addition, it is essential to the definition of the support to be applied, which limits are often based on the value of the geomechanical classifications. Therefore, determining the characteristics demands structured techniques to reconcile rigour, accuracy, and efficiency in the execution of the site investigation to obtain reliable data in an integrated action of the work cycle. This study analyses the applicability and feasibility of the Geological Strenght Index (GSI), based on field data collected in different underground projects. Various geological environments and distinct excavation purposes were selected to evaluate the possibility of expanding this version of the GSI to other rock types with the inclusion of the influence of groundwater on this classification.

scholarly journals Comparison between deformation modulus of rock mass measured by plate jacking and dilatometer tests

2017 ◽  
Vol 26 (3) ◽  
pp. 317-325
Author(s):  
Mohsen Rezaei ◽  
Rasoul Ajalloeian ◽  
Mohammad Ghafoori
Keyword(s):  
Rock Mass ◽  
Deformation Modulus ◽  
Rock Masses ◽  
Sarvak Formation ◽  
In Situ Data ◽  
Geotechnical Investigations ◽  
Two Samples ◽  
Dam Site

For determination of the in-situ deformation modulus of rock mass at Bakhtiari Dam site, located in south-west of Iran, plate jacking tests (PJT) and dilatometer tests (DLT) carried out during the geotechnical investigations. In this study, the results of PJTs and DLTs were compared. This comparison involves 89 vertical and horizontal PJTs and 83 DLTs carried out in 6 rock units of Sarvak formation. Although, both PJTs and DLTs in the Bakhtiari Dam site were performed in same geological and geotechnical conditions, but there are not sufficient side by side data to make a paired two samples correlation. Therefore, the mean of in-situ data was compared at each rock unit. Besides Mann–Whitney U tests were performed to compare in-situ test results. The comparison shows that the deformation modulus measured by both methods has no significant differences. However, in low quality rock masses the moduli measured by the use of DLTs were greater than the modulus measured by PJTs. Conversely, in high quality rock masses the results of PJTs were greater than DLT’s.

Sign in / Sign up

Export Citation Format

Share Document