International Journal of Rock Mechanics and Mining Sciences
Microseismic monitoring and stability analysis of the left bank slope in Jinping first stage hydropower station in southwestern China
Highlights
► We use microseismic monitoring technique to assess rock slope stability. ► Tempo-spatial distribution and characteristics of microseismicity are analyzed. ► Microseismicity shows strong correlation with pre-existing structures of rock slope.► Results between numerical simulation and microseismic monitoring are similar. ► The hazardous regions of rock slope can be identified and delineated.
Introduction
As one of the three natural disasters such as earthquakes, floods and landslides debris flow, the landslide hazard endangers the safety of state property and people's lives. Prediction of slope failure is a worldwide problem. So far, systematical and mature theory and methods have not been developed to study the mechanism of slope failure. Slope failure monitoring and forecasting of landslides have been always one of the most significant subjects of slope engineering, and also one of the hottest and most difficult topics in geotechnical engineering research. How to effectively predict and control instability of the rock slope and ensure safety of these engineering projects is a significant task that people often probe. Currently, extensive use of measurement technology, such as Global Positioning System (GPS) and displacement meter, is found to be very useful in surface deformation monitoring of slopes. However, it is difficult for them to perform effective monitoring of micro-fractures in deep rock mass prior to a macroscopic rock fracture outside slope surface. With regard to rock slope, these internal micro-fractures may often lead to macroscopic instability of slope. Therefore, there must be an intrinsic correlation between rock slope instability and its internal microseismicity. It is well known that rocks loaded in testing machine and rock masses that are stressed near underground excavations emit detectable acoustic or seismic signals, and microseismic monitoring techniques have been thus used to locate damage in rock engineering practice [1].
During the past two decades, microseismic monitoring technique emerged from a pure research means to a mainstream industrial tool for daily safety monitoring at various fields of geotechnical engineering. It has a wide application in South Africa, Canada, Japan, Australia and North America. Significant achievements have been obtained in mining [2], [3], [4], [5], [6], [7], [8], tunnels [9], oil and gas exploration and development [10], electricity generation by hot dry rock [11], etc. Urbancic and Trifu [4] provided an overview of the current status of seismic monitoring instrumentation employed in Canadian underground mines. They outlined how seismic monitoring techniques were used to evaluate fractures and stress conditions associated with ore extraction at depth based on several case studies. In addition, advances into the characterization of excavation zone of influence through deformation state analysis and the use of seismic hazard analysis to evaluate the potential for ground instability were also discussed. Fabriol and Beauce [12] used the study of microearthquakes as an exploration tool to investigate the geothermal potential of the Chipilapa area and to evaluate the main characteristics of the seismic activity, prior to and during the exploitation tests. Attempting to investigate the mechanisms of the seismic events induced during the controlled collapse in field II at Ocnele Mari, Romania, Shumila and Trifu [13] analyzed the reliability of the seismic moment tensor inversion of the uniaxial geophone recordings and examined spatial distribution of different failure components. Hence, an estimate of the seismic deformation field was obtained. Additionally, Trifu and Suorineni [14] also described the practical application of seismic systems for the management of seismicity at Vale Inco mines in the Sudbury Basin. Seismic data was applied for the calibration of numerical models and to evaluate mined development activities by optimized stope sequencing, distress blasting and ground support. Recently, economy has developed rapidly in China. Mines proceed to ever greater depth and into more and more complex geological settings. Meanwhile, civil engineering projects, particularly hydroelectric engineering, are being advanced at greater depth, and these projects are also challenged by violent rock mass failure processes. In response to such problems, microseismic monitoring technique was thus widely used for a better understanding of deep rockmass fractures mechanism through identifying, locating and quantifying microseismicity from the 1990s. The application and the related theory of microseismic monitoring system have been investigated by plenty of researchers. Some experts [15], [16], [17], [18], [19], [20], [21], [22] have studied the relationship between strata fracturing and rockburst in underground mines and discussed the possibility of forecasting rock burst based on the rules of strata fracturing monitoring by different microseismic monitoring systems. In order to investigate the progressive failure of geological structures (faults, karst collapse colums) and predict their microseismic activities associated with water inrush, some researches [23], [24], [25] applied microseismic monitoring in deep mines. The technique was also adopted by Tang et al. [26] for rockburst prediction of the drainage tunnels with a maximum buried depth of 2500 m in Jinping II hydropower station, which is also situated in Sichuan province, southwestern China. Some promising achievements have been thus gained.
Although much research on microseismic monitoring has been carried out, little work was found to investigate slope stability of large-scale water conservancy projects, especially high rock slopes. Hence, this study attempts to investigate stability analysis of high rock slope in a large-scale hydraulic project using microseismic monitoring technique. The microseismic survey was carried out from June 2009, with two main objectives: (a) to monitor deformation of deep rock mass in the left bank slope and perform early warning and advance support measures, and (b) to record microseismicity during construction and impoundment of the dam in order to determine the existence of microseismic events related to stress buildup, stress shadow and stress transfer in deep rockmass. Microseismic monitoring system was also employed to identify and delineate active structures, study the failure mechanism of rock slope in the presence of excavation of the dam foundation and tunnels, and characterize stress variations during sequential stages of excavations. Furthermore, in order to validate the correlation between microseismicity and potential slip surface of the slope, a two dimensional numerical model was implemented into RFPA-SRM code to analyze the failure processes and stability of the slope.
Section snippets
Engineering background
The proposed Jinping first stage hydropower station is located at the sharp bend of Jinping on the middle reach of Yalongjiang River, near Xichang (27°32′–28°10′N, 101°46′–102°25′E), about 500 km southwest of Chengdu, Sichuan province, PR China. It is situated within the slope transition zone from the Qinghai-Tibet Plateau to the Sichuan Basin. The project has a double-curvature arch dam with a maximum height of 305 m and a total installed capacity of 3300 MW, which will be the highest arch dam in
Microseismic monitoring
Development and application of modern high-precision microseismic monitoring technique originates from the South African gold mining activities in the mid-1980s [30]. The objective was to solve plenty of rockburst and rock destruction problems induced by deep gold mining (more than 1000 m) at the Welkom area in South Africa and thus to avoid operational personnel and equipment damage. The principle of this technique consists of four aspects as given in the following: (1) using sensors to acquire
Stability analysis for the rock slope based on RFPA
The stability analysis of slope is an important issue for geotechnical engineers. How to in-depth analyze failure mechanism of deep rock mass and effectively control surface deformation of high rock slope in order to diminish the risk of these projects is a task that people often probe. In recent decades, a variety of numerical techniques such as the methods of finite element, finite difference, infinite element, boundary element (for continuous geotechnical media), discrete element, block
Conclusions
In the present study, microseismicity occurred in the left bank slope of Jinping first stage hydropower station in southwest China between June 2009 and January 2010 was analyzed. The original catalog from the monitoring system recorded 689 seismic events whose moment magnitudes range from −2.0 to −0.2. Meanwhile, RFPA-SRM was employed in-depth to investigate the failure mechanism of the rock slope. The simulation results coincide with spatial distribution of microseismicity recorded by the
Acknowledgements
Financial supports from the National Natural Science Foundation of China (Grant nos. 10672028, 50820125405, and 50804006) and National Basic Research Program of China (973 Program, Grant no. 2007CB209400) are greatly appreciated. The authors thank Tang Liexian in Dalian Mechsoft Co., Ltd., and other coworkers in HydroChina Chengdu Engineering Corporation and Jinping First Stage Administration Bureau of Ertan Hydropower Development Co., Ltd., for their involvement during the installation and
References (62)
- et al.
Quantification of rock mass damage in underground excavations from microseismic event monitoring
Int J Rock Mech Min Sci
(2001) - et al.
Recent advances in seismic monitoring technology at Canadian mines
J Appl Geophys
(2000) - et al.
Acoustic emission/microseismic source location analysis for a limestone mine exhibiting high horizontal stresses
Int J Rock Mech Min Sci
(2008) Efficient mine microseismic monitoring
Int J Coal Geol
(2005)- et al.
Seismic and geotechnical investigations following a rockburst in a complex French mining district
Int J Coal Geol
(2005) - et al.
Stress estimated using microseismic clusters and its relationship to the fracture system of the Hijiori hot dry rock reservoir
Eng Geol
(2000) - et al.
Temporal and spatial distribution of local seismicity in the Chipilapa–Ahuachapan geothermal area, EL Salvador
Geothermics
(1997) - et al.
A review of mining-induced seismicity in China
Int J Rock Mech Min Sci
(2007) - et al.
Mechanism of deep cracks in the left bank slope of Jinping first stage hydropower station
Eng Geol
(2004) - et al.
Enhanced NURRS modeling and visualization for large 3D geoengineering applications: an example from the Jinping first-level hydropower engineering project, China
Comput Geosci
(2006)
Time-dependent strength degradation of granite
Int J Rock Mech Min Sci
Application of a microseismic monitoring system in deep mining
J Univ Sci Tech B
An improved search strategy for the critical slip surface using finite element stress fields
Comput Geotech
Developments in the characterization of complex rock slope deformation and failure using numerical modeling technique
Eng Geol
Numerical analysis of slope stability based on the gravity increase method
Comput Geotech
A practical procedure for searching critical slip surfaces of slopes based on the strength reduction technique
Comput Geotech
Numerical simulation of progressive rock failure and associated seismicity
Int J Rock Mech Min Sci
Numerical simulation of cumulative damage and seismic energy release during brittle rock failure—part I: fundamentals
Int J Rock Mech Min Sci
Numerical studies of the influence of microstructure on rock failure in uniaxial compression—part I: Effects of heterogeneity
Int J Rock Mech Min Sci
A numerical study of the influence of heterogeneity on the strength characterization of rock under unixaxial tension
Mech Mater
Finite element slope stability analysis by shear strength reduction technique
Soils and Foundations
Results from microseismic monitoring, conventional instrumentation, and tomography surveys in the creation and thinning of a burst-prone sill pillar
Pure Appl Geophys
Seismic monitoring of a simulated rockburst on a wall of an underground tunnel
J S Afr I Min Metall
Space-time clustering of seismic events and hazard assessment in the Zabrze–Bielszowice coal mine, Poland
Int J Rock Mech Min Sci
Safety management based on detection of possible rockbursts by AE monitoring during tunnel excavation
Rock Mech Rock Eng
Discussion on microseismic monitoring technology and its application to underground project
Chin J Undergr Space Eng
Event mechanism analysis for seismicity induced by a controlled collapse in field II at Ocnele Mari, Romania
Use of microseismic monitoring for rockburst management at VALE INCO mines
Prediction method of rock burst based on microsesimci monitoring and stress field analysis
Chin J Rock Mech Eng
Research of mining based on microseimic monitoring technology in high–stress area
Chin J Rock Mech Eng
Study on rule of geostatic activity based on microseismic monitoring technique in deep mining
Chin J Rock Mech Eng
Cited by (212)
Microseismic activity characteristics and range evaluation of hydraulic fracturing in coal seam
2024, Gas Science and EngineeringQuantitative investigation of crack propagation and fracture mechanism of fissured granite from the mesoscopic perspective
2024, Theoretical and Applied Fracture MechanicsFailure mechanism and deformation forecasting of surrounding rock mass in an underground cavern based on engineering analogy method
2024, Tunnelling and Underground Space TechnologyAn end-to-end DNN-HMM based system with duration modeling for robust earthquake detection
2023, Computers and GeosciencesAnalysis of rockburst mechanism and warning based on microseismic moment tensors and dynamic Bayesian networks
2023, Journal of Rock Mechanics and Geotechnical EngineeringVisualization and early warning analysis of damage degree of surrounding rock mass in underground powerhouse
2023, International Journal of Mining Science and Technology