scholarly journals Study on Unloading Relaxation Characteristics of Columnar Jointed Rock Masses Based on Displacement Back Analysis

2021 ◽  
Vol 9 ◽  
Author(s):  
Jun Yu ◽  
Qiang Zhang ◽  
Weiya Xu ◽  
Rubin Wang ◽  
Han Zhang
Keyword(s):  
Back Analysis ◽  
Jointed Rock ◽  
Equivalent Strain ◽  
Rock Masses ◽  
Diversion Tunnel ◽  
Columnar Joint ◽  
Excavation Process ◽  
Baihetan Hydropower Station ◽  
Relaxation Characteristics ◽  
Joint Rock

We aim to understand the relaxation of columnar joint rock masses during the excavation process of the diversion tunnel of the Baihetan hydropower station. This paper inverts the deformation parameters of the relaxed columnar joint rock based on the displacement monitoring data, and introduces a relaxation factor to describe the deterioration degree of anisotropic parameters of the relaxed columnar jointed rock. The equivalent strain is proposed as the criterion of unloading relaxation and the threshold is also given. Based on the software Flac3d, a program for calculating anisotropic elastoplastic model is developed. The distribution of the relaxation zone of the diversion tunnel after excavation is simulated, and compared with the results of the acoustic detection to verify the correctness and rationality of the program, which can provide a necessary reference for the design and construction of hydropower projects.

scholarly journals 3D Thermal Monitoring of Jointed Rock Masses through Infrared Thermography and Photogrammetry

2021 ◽  
Vol 13 (5) ◽  
pp. 957
Author(s):  
Guglielmo Grechi ◽  
Matteo Fiorucci ◽  
Gian Marco Marmoni ◽  
Salvatore Martino
Keyword(s):  
Surface Temperature ◽  
Infrared Thermography ◽  
Point Cloud ◽  
Engineering Geology ◽  
Point Clouds ◽  
Jointed Rock ◽  
Geometric Accuracy ◽  
Rock Masses ◽  
Natural Systems ◽  
Temperature Distributions

The study of strain effects in thermally-forced rock masses has gathered growing interest from engineering geology researchers in the last decade. In this framework, digital photogrammetry and infrared thermography have become two of the most exploited remote surveying techniques in engineering geology applications because they can provide useful information concerning geomechanical and thermal conditions of these complex natural systems where the mechanical role of joints cannot be neglected. In this paper, a methodology is proposed for generating point clouds of rock masses prone to failure, combining the high geometric accuracy of RGB optical images and the thermal information derived by infrared thermography surveys. Multiple 3D thermal point clouds and a high-resolution RGB point cloud were separately generated and co-registered by acquiring thermograms at different times of the day and in different seasons using commercial software for Structure from Motion and point cloud analysis. Temperature attributes of thermal point clouds were merged with the reference high-resolution optical point cloud to obtain a composite 3D model storing accurate geometric information and multitemporal surface temperature distributions. The quality of merged point clouds was evaluated by comparing temperature distributions derived by 2D thermograms and 3D thermal models, with a view to estimating their accuracy in describing surface thermal fields. Moreover, a preliminary attempt was made to test the feasibility of this approach in investigating the thermal behavior of complex natural systems such as jointed rock masses by analyzing the spatial distribution and temporal evolution of surface temperature ranges under different climatic conditions. The obtained results show that despite the low resolution of the IR sensor, the geometric accuracy and the correspondence between 2D and 3D temperature measurements are high enough to consider 3D thermal point clouds suitable to describe surface temperature distributions and adequate for monitoring purposes of jointed rock mass.

scholarly journals Analysis of displacement of excavation based on inclinometer measurements

2012 ◽  
Vol 34 (4) ◽  
pp. 3-16 ◽  
Author(s):  
Karolina Gorska ◽  
Marek Wyjadłowski
Keyword(s):  
Theoretical Calculations ◽  
Back Analysis ◽  
Field Measurements ◽  
Soil Medium ◽  
Geotechnical Parameters ◽  
Angle Of Internal Friction ◽  
Material Parameters ◽  
Bored Pile ◽  
Excavation Process ◽  
Excavation Support

Abstract The article presents back analysis to estimate geotechnical parameters of fill layer. The agreement between field measurements and theoretical calculations was examined. Displacements of a cantilever CFA bored pile wall were monitored. The inclinometric measurements were taken directly after pile construction and according to excavation process. Over 200 calculation series were performed, with changing fill parameters. The calculations employed the actual geometric and material parameters of the pile wall, as well as geotechnical parameters of layered soil. The parameters estimated through back analysis were the angle of internal friction and Young’s modulus of fill layer. In the case discussed, pile wall cap displacement was the response of the system, and soil medium parameters were the input data. The agreement between theoretical calculations and inclinometer measurements was assessed in accordance with two functions. The measured horizontal displacements of excavation support structure assumed different values at the two inclinometer sites analysed. Back analysis results for these sites are approximately convergent for a final excavation depth.

A Multivariate Technique for Evaluating the Statistical Homogeneity of Jointed Rock Masses

2014 ◽  
Vol 48 (5) ◽  
pp. 1821-1831 ◽  
Author(s):  
Yanyan Li ◽  
Qing Wang ◽  
Jianping Chen ◽  
Shengyuan Song ◽  
Yunkai Ruan ◽  
...  
Keyword(s):  
Jointed Rock ◽  
Rock Masses ◽  
Jointed Rock Masses ◽  
Multivariate Technique ◽  
Statistical Homogeneity
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