Research on Influence of Span on Surrounding Rock Quality of Tunnels
1
Citation
3
Reference
10
Related Paper
Citation Trend
Abstract:
The influence of tunnel’s span on rock mass quality is getting more and more recognition along with increasing large span tunnels’ construction. As national standard of China, BQ qualification is generally applied. Based on the measured data and numerical experiment, the relationship between surrounding rock displacement and quality evaluation is studied, and span effect correction factor is established. The modified rock quality index can provide the basis of guiding the design and construction of tunnels.Three gorges
Rock mass rating
Assemblage (archaeology)
Country rock
Cite
Citations (26)
Abstract. Unmanned aerial vehicles (UAVs) provide a cost-effective way to fill in gaps between surface in situ observations and remotely sensed data from space. In this study, a novel portable CO2 measuring system suitable for operations on board small-sized UAVs has been developed and validated. It is based on a low-cost commercial nondispersive near-infrared (NDIR) CO2 sensor (Senseair AB, Sweden), with a total weight of 1058 g, including batteries. The system performs in situ measurements autonomously, allowing for its integration into various platforms. Accuracy and linearity tests in the lab showed that the precision remains within ± 1 ppm (1σ) at 1 Hz. Corrections due to temperature and pressure changes were applied following environmental chamber experiments. The accuracy of the system in the field was validated against a reference instrument (Picarro, USA) on board a piloted aircraft and it was found to be ± 2 ppm (1σ) at 1 Hz and ± 1 ppm (1σ) at 1 min. Due to its fast response, the system has the capacity to measure CO2 mole fraction changes at 1 Hz, thus allowing the monitoring of CO2 emission plumes and of the characteristics of their spatial and temporal distribution. Details of the measurement system and field implementations are described to support future UAV platform applications for atmospheric trace gas measurements.
Linearity
Cite
Citations (0)
Abstract. Unmanned aerial vehicles (UAVs) provide a cost-effective way to fill in gaps between surface in situ observations and remotely sensed data from space. In this study, a novel portable CO2 measuring system suitable for operations on board small-sized UAVs has been developed and validated. It is based on a low-cost commercial nondispersive near-infrared (NDIR) CO2 sensor (Senseair AB, Sweden), with a total weight of 1058 g, including batteries. The system performs in situ measurements autonomously, allowing for its integration into various platforms. Accuracy and linearity tests in the lab showed that the precision remains within ± 1 ppm (1σ) at 1 Hz. Corrections due to temperature and pressure changes were applied following environmental chamber experiments. The accuracy of the system in the field was validated against a reference instrument (Picarro, USA) on board a piloted aircraft and it was found to be ± 2 ppm (1σ) at 1 Hz and ± 1 ppm (1σ) at 1 min. Due to its fast response, the system has the capacity to measure CO2 mole fraction changes at 1 Hz, thus allowing the monitoring of CO2 emission plumes and of the characteristics of their spatial and temporal distribution. Details of the measurement system and field implementations are described to support future UAV platform applications for atmospheric trace gas measurements.
Linearity
Cite
Citations (0)
After the excavation of the rock , the rock mass stress state changes and the quality of rock mass damage deterioration. Rock excavation of spillway tunnel of the hydropower station may have some influence on the stability of the tunnel-face side slope. In this paper, combined with the engineering practice, based on the unloading rock mass theory and through two dimensional finite-difference method. Selected seven feature points near the excavation surface as monitoring points for calculation ,then calculated the effect on the stress and strain of the slope caused by the excavation of the spillway tunnel and analysed the changes in the distribution of the slope rock mass plastic zone and the point factor of safety. The results show that spillway tunnel excavation in excavated slope have some impact on the excavated slope stability, and it is more obvious for the effect on stability of excavated slope in considering rock mass unloading effect than do not consider the rock mass unloading effect.
Spillway
Safety factor
Cite
Citations (1)
Developments in theories and techniques for blasting are important to blasting industriesand construction of civil infrastructures.The basic concept of blasting in rock mass is defined and examined based on the theoretical developments and engineering applications of blasting over the last few decades.The explosive features,rock mass characteristics and their interactions are discussed in details.It is found that a well understanding of the in-situ geological conditions is essential to successful blasting.The explosive energy feature has to be allocated according to the rock mass characteristics so that the interaction of explosive and rock mass can be optimized for effectiveness.In terms of rock mass and the associated blasting features,the in-situ rock mass can be classified into two categories:(a) pseudo homogeneous and continuous rock mass,(b) discontinuous rock mass.Both test and practice have shown that blasting results in the pseudo homogeneous rock mass are controlled by local topographic minimum resistant line and they are by rock mass discontinuities in the discontinuous rock mass.The theory of blasting control in engineering geology includes developed the two categories of rock mass and their corresponding blasting features.
Classification of discontinuities
Country rock
Cite
Citations (2)
Rock mass classification and rock strength predication are widely applied in rock engineering. In this paper several classifications have been developed for rock mass, e.g. the RMR and Q-system, and the Hoek-Brown criteria is the most accepted for rock mass strength predication. A combination of the RMR and Q-system is related to ultrasonic velocity based on the foregoing investigations and experience formulae, so that the rock mass classification can be assessed according to the measured ultrasonic velocity of rock mass in situ. Also by the existed relationship between the RMR and Hoek-Brown criteria, a prediction for the strength parameters of rock mass is reached. An example taken from the Three Gorges Project of Yantze River has shown the application significance in rock engineering.
Rock mass rating
Geological Strength Index
Three gorges
Cite
Citations (3)
Abstract. Unmanned aerial vehicles (UAVs) provide a cost-effective way to fill in gaps between surface in situ observations and remotely sensed data from space. In this study, a novel portable CO2 measuring system suitable for operations on board small-sized UAVs has been developed and validated. It is based on a low-cost commercial nondispersive near-infrared (NDIR) CO2 sensor (Senseair AB, Sweden), with a total weight of 1058 g, including batteries. The system performs in situ measurements autonomously, allowing for its integration into various platforms. Accuracy and linearity tests in the lab showed that the precision remains within ± 1 ppm (1σ) at 1 Hz. Corrections due to temperature and pressure changes were applied following environmental chamber experiments. The accuracy of the system in the field was validated against a reference instrument (Picarro, USA) on board a piloted aircraft and it was found to be ± 2 ppm (1σ) at 1 Hz and ± 1 ppm (1σ) at 1 min. Due to its fast response, the system has the capacity to measure CO2 mole fraction changes at 1 Hz, thus allowing the monitoring of CO2 emission plumes and of the characteristics of their spatial and temporal distribution. Details of the measurement system and field implementations are described to support future UAV platform applications for atmospheric trace gas measurements.
Linearity
Cite
Citations (0)
Taking the TBM performance in four tunnels as case examples,this paper analyzes the two reasons that there are problems in using the conventional rock mass quality classification systems to predict the TBM performance.The first reason is the factors which control the rock mass quality are not the factors that influence the rock mass boreability.The second is that most of the factors in rock mass classification systems are semi-quantitative.As a result of the two reasons,the value of the rock mass quality cannot reflect the rock mass boreabilty.According to the purpose of the rock mass classification for tunnels tunneling by TBM and the features of the TBM cutting process,this paper suggests two systems to classify the rock mass:(a) the rock mass boreability classification system for estimating how difficulty the rock mass are bored by TBM and(b) the rock mass quality classification system for estimating the stability of surrounding rock mass.The factors which are used to classify the rock mass boreability group in the system(a) are lithology,weathering degree and joint characters.The factors which are used to classify the rock mass quality in the system(b) are factors which will cause geological problems in the cutting process.The system(a) predicts the net penetration rate(PR) of the TBM,the system(b) evaluates the utilization(U) of the TBM,then the advance rate(AR) of the TBM is calculated by PR and U.
Rock mass rating
Lithology
Cite
Citations (0)
Three gorges
Cite
Citations (22)
The engineering classification in rock slopes is not included in the current standard of engineering classification of rock masses(GB50218—94). This paper presents the engineering classification method for rock slopes(BQ-R Slope) based on the quality index of rock mass BQ. In this method,several modified factors are employed as to correct rock mass basic quality,and the engineering rock mass classifications for rock slopes are determined by the modified rock mass quality, and the evaluation for stand-up time of rock slope in correspondence with each class of rock mass is further proposed. The employed factors consist of the type and the persistence of major structural planes,the relationship between orientations of structural planes in rock mass and rock slope surface and the groundwater conditions in rock slope. The presented method is verified through applications to four rock slope projects and ten slope sections in total. It is found that the engineering classification and the corresponding evaluation results of each slope section with the method proposed are generally in good agreement with the practical situation. This indicates that the presented method for engineering rock mass classification of rock slopes based on BQ index is appropriate.
Rock mass rating
Geological Strength Index
Cite
Citations (5)