Inversion of Initial Geo-Stress in High and Steep Slope

2012 ◽  
Vol 170-173 ◽  
pp. 1325-1329
Author(s):  
Zhong Fan Yuan ◽  
Pei Hua Xu ◽  
Zhao Rong Ye
Keyword(s):  
Stress Field ◽  
Field Distribution ◽  
Decisive Role ◽  
Local Stress ◽  
Field Measurements ◽  
Tectonic Stress ◽  
In Situ Stress ◽  
Initial Stress Field ◽  
Principal Compressive Stress ◽  
Geological Conditions

At present, due to various reasons, cannot do a large number of field measurements, and the measured results often can only reflect the local stress field distribution. What’s more, the measured results has discreteness, it’s difficult to describe the law of the initial stress field distribution in the entire region. This paper combines topographic and geological conditions and the measured in-situ stress value of Jinping I hydropower station dam area, using FLAC3D4.0, select geological section profile of II1 exploration line for reference, to simulate the incised process of the valley. We get the stress field distribution when rock gravity acting alone, and exert horizontal tectonic stress based on the calculate result of gravity field in the VI terrace model. We inversion the distribution of current Valley stress field, and validate the rationality of the design after compare with the measured data. We obtain the features of stress field of current valley. And we also proved that the regional principal compressive stress plays a decisive role in the formation of the current valley stress field.

scholarly journals Local Stress Field Correction Method Based on a Genetic Algorithm and a BP Neural Network for In Situ Stress Field Inversion

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Tianzhi Yao ◽  
Zuguo Mo ◽  
Li Qian ◽  
Jianhua He ◽  
Jianhai Zhang
Keyword(s):  
Stress Field ◽  
Bp Neural Network ◽  
Local Stress ◽  
In Situ Stress ◽  
Regression Method ◽  
Geological Conditions ◽  
Multiple Regression Method ◽  
In Situ Stress Field ◽  
Local Stress Field

The in situ stress field is the fundamental factor causing deformation and damage in geotechnical engineering, so it is the main basis for underground engineering design and excavation. However, it is difficult to accurately obtain the in situ stress through most existing inversion methods in areas with complex geological conditions. For the problem of a relatively discrete and nonlinear relationship of measured stress in the Yebatan Hydropower Station area, a new in situ stress inversion method called the local stress field correction (LSFC) method combining a genetic algorithm (GA), backpropagation (BP) neural network, and submodel method is proposed. The inverted in situ stress results produced by this method show that the distribution of in situ stress is greatly influenced by tectonic movements in the Yebatan area, there is no obvious linear relationship with depth, and the stress release phenomenon occurs at the faults. By comparison with the multiple regression method, it is found that the method still has high inversion accuracy under complex geological conditions, and the average relative error of LSFC inversion results is 17.05%, which is much lower than the value of 43.58% via the multiple regression method. Therefore, the LSFC method can be used for the inversion of in situ stress in complex geological regions and provide a reference for engineering design and construction.

scholarly journals Activation of optimally and unfavourably oriented faults in a uniform local stress field during the 2011 Prague, Oklahoma, sequence

2020 ◽  
Vol 222 (1) ◽  
pp. 153-168 ◽  
Author(s):  
Elizabeth S Cochran ◽  
Robert J Skoumal ◽  
Devin McPhillips ◽  
Zachary E Ross ◽  
Katie M Keranen
Keyword(s):  
Stress Field ◽  
Compressive Stress ◽  
Local Stress ◽  
Wastewater Disposal ◽  
Principal Compressive Stress ◽  
Vertical Fault ◽  
Major Fault ◽  
Pressure Changes ◽  
Earthquake Sequences ◽  
Local Stress Field

SUMMARY The orientations of faults activated relative to the local principal stress directions can provide insights into the role of pore pressure changes in induced earthquake sequences. Here, we examine the 2011 M 5.7 Prague earthquake sequence that was induced by nearby wastewater disposal. We estimate the local principal compressive stress direction near the rupture as inferred from shear wave splitting measurements at spatial resolutions as small as 750 m. We find that the dominant azimuth observed is parallel to previous estimates of the regional compressive stress with some secondary azimuths oriented subparallel to the strike of the major fault structures. From an extended catalogue, we map ten distinct fault segments activated during the sequence that exhibit a wide array of orientations. We assess whether the five near-vertical fault planes are optimally oriented to fail in the determined stress field. We find that only two of the fault planes, including the M   5.7 main shock fault, are optimally oriented. Both the M 4.8 foreshock and M   4.8 aftershock occur on fault planes that deviate 20–29° from the optimal orientation for slip. Our results confirm that induced event sequences can occur on faults not optimally oriented for failure in the local stress field. The results suggest elevated pore fluid pressures likely induced failure along several of the faults activated in the 2011 Prague sequence.

scholarly journals Large Deformation Mechanics of Gob-Side Roadway and Its Controlling Methods in Deep Coal Mining: A Case Study

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jianwei Zheng ◽  
Wenjun Ju ◽  
Xiaodong Sun ◽  
Zhongwei Li ◽  
Shuai Wang ◽  
...  
Keyword(s):  
Stress Field ◽  
Large Deformation ◽  
Coal Mining ◽  
Tectonic Stress ◽  
In Situ Stress ◽  
Field Analysis ◽  
Underground Mines ◽  
Roof Structure ◽  
Deformation Mechanics

Maintaining surrounding rock mass stability of roadways is essential to the safety of deep coal mining. In this study, the No. 2-2092 roadway of the No. 2-209 mining face in Ganhe coal was taken as the target roadway for field analysis. The selected region can be considered a typical area with dominating geological tectonic stress, based on the geological survey and in situ stress results. A mechanical model of roadway overburdens was developed to analyse the large deformation and stress field distribution. It is found that the large deformation is caused by the combined superposed stress field including laterally transferred stress formed in structures at overlying strata, mining-induced advanced abutment pressure, and the regional in situ stress. Thus, a Two-Direction Hydrofracturing Technique (TDHT) was proposed to reduce the pressure of the No. 2-2092 roadway by altering the roof structure in the influenced zones. Compared with the original roadway without fracturing, it is found that the roof to floor convergence has dropped by nearly 47% after fracturing; the displacement of sidewalls has reduced by almost 31%, demonstrating the effectiveness of the proposed method in pressure relief. Results from this study can provide guidance on controlling the large deformation of roadways in deep underground mines.

scholarly journals The recent fault kinematics in the westernmost part of the Getic nappe system (Eastern Serbia): Evidence from fault slip and focal mechanism data

2014 ◽  
Vol 65 (2) ◽  
pp. 147-161 ◽  
Author(s):  
Ana Mladenović ◽  
Branislav Trivić ◽  
Milorad Antić ◽  
Vladica Cvetković ◽  
Radmila Pavlović ◽  
...  
Keyword(s):  
Stress Field ◽  
Active Fault ◽  
Local Stress ◽  
Tectonic Stress ◽  
Research Area ◽  
Strike Slip ◽  
Fault Slip ◽  
Focal Mechanisms ◽  
Fault Systems ◽  
Fault Kinematics

Abstract In this study we performed a calculation of the tectonic stress tensor based on fault slip data and all available focal mechanisms in order to determine the principal stress axes and the recent tectonic regime of the westernmost unit of the Getic nappe system (Gornjak-Ravanica Zone, Eastern Serbia). The study is based on a combined dataset involving paleostress analyses, the inversion of focal mechanisms and remote sensing. The results show dominant strike-slip kinematics with the maximal compression axis oriented NNE-SSW. This is compatible with a combined northward motion and counterclockwise rotation of the Adria plate as the controlling factor. However, the local stress field is also shown to be of great importance and is superimposed on the far-field stress. We managed to distinguish three areas with distinct seismic activity. The northern part of the research area is characterized by transtensional tectonics, possibly under the influence of the extension in the areas situated more to the northeast. The central and seismically most active part is dominated by strike-slip tectonics whereas the southern area is slightly transpressional, possibly under the influence of the rigid Moesian Platform situated to the east of the research area. The dominant active fault systems are oriented N-S (to NE-SW) and NW-SE and they occur as structures of either regional or local significance. Regional structures are active in the northern and central part of the study area, while the active fault systems in the southern part are marked as locally important. This study suggests that seismicity of this area is controlled by the release of accumulated stress at local accommodation zones which are favourably oriented in respect to the active regional stress field.

Inverse Analysis of Regional In Situ Stress Prediction Based on Multi-Points Measurement and BP Neural Network

2014 ◽  
Vol 510 ◽  
pp. 226-231 ◽  
Author(s):  
Wei Qun Liu ◽  
Ting Song ◽  
Yu Shou Li ◽  
Shu Fei Zheng ◽  
Jing Yang
Keyword(s):  
Neural Network ◽  
Stress Field ◽  
In Situ Stress ◽  
Engineering Problem ◽  
Regional Stress ◽  
Geological Conditions ◽  
Stress Prediction ◽  
Stress Estimation ◽  
In Situ Stress Field

Based on the measurement of in-situ stress and engineering-geological conditions, we built computing models with pre-exerting boundary loads and simulated the regional stress field involved. Boundary loads can be approximately determined by use of the multiple linear regressions, and be further optimized with the artificial neural network. By calculation, the corresponding initial in-situ stress field can reach ideal accuracy. As an example, we inversely analyzed an engineering problem in Chinese Wo-bei mine. The results shows that the simulation can meet the point measurement very well, and the regional-stress estimation may play an important role in engineering.

Inversion of Initial In Situ Stress Field by the Method of Multivariate Analysis and Engineering Application

2010 ◽  
Vol 44-47 ◽  
pp. 1203-1206
Author(s):  
Xiao Lei Yue ◽  
Yong Li ◽  
Han Peng Wang
Keyword(s):  
Stress Field ◽  
Engineering Application ◽  
In Situ Stress ◽  
Multivariate Regression Model ◽  
Geological Conditions ◽  
Stress Components ◽  
Internal Relations ◽  
In Situ Stress Field ◽  
First Time

Based on engineering geological conditions and measured data of the in-situ stress at a hydropower station, 3D geological models under each affecting factor are calculated by means of finite element computing tools ABAQUS and MATLAB. Then, a multivariate regression model is created between the measured and calculated value of in-situ stress at measurement points, and the optimal regression coefficient of the model is found. Consequently, the distributions of initial in-situ stress of this area are obtained. It is the first time to take into account the independence and internal relations among each stress components. Thus, the more reasonable distributions of initial in-situ stress of this area are obtained. The results indicate that the 3D calculating in-situ stress field is reasonable.

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