scholarly journals A Fast Ray-tracing Method for Locating Mining-Induced Seismicity by Considering Underground Voids

2020 ◽  
Vol 10 (19) ◽  
pp. 6763
Author(s):  
Pingan Peng ◽  
Yuanjian Jiang ◽  
Liguan Wang ◽  
Zhengxiang He ◽  
Siyu Tu
Keyword(s):  
Travel Time ◽  
Ray Tracing ◽  
Induced Seismicity ◽  
Constant Velocity ◽  
Velocity Model ◽  
Surface Model ◽  
Location Accuracy ◽  
Ray Tracing Method ◽  
Mining Induced Seismicity ◽  
Tracing Method

The accurate localization of mining-induced seismicity is crucial to underground mines. However, the constant velocity model is used by traditional location methods without considering the great difference in wave velocity between rock mass and underground voids. In this paper, to improve the microseismicity location accuracy in mines, we present a fast ray-tracing method to calculate the ray path and travel time from source to receiver considering underground voids. First, we divide the microseismic monitoring area into two categories of mediums—voids and non-voids—using a flexible triangular patch to model the surface model of voids, which can accurately describe any complicated three-dimensional (3D) shape. Second, the nodes are divided into two categories. The first category of the nodes is the vertex of the model, and the second category of the nodes is arranged at a certain step length on each edge of the 3D surface model to improve the accuracy of ray tracing. Finally, the set of adjacent nodes of each node is calculated, and then we obtain the shortest travel time from the source to the receiver based on the Dijkstra algorithm. The performance of the proposed method is tested by numerical simulation. Results show that the proposed method is faster and more accurate than the traditional ray-tracing methods. Besides, the proposed ray-tracing method is applied to the microseismic source localization in the Huangtupo Copper and Zinc Mine. The location accuracy is significantly improved compared with the traditional method using the constant velocity model and the FMM-based location method.

Tsunami Ray Tracing Method for Shortest Travel-Time Path

2021 ◽  
Author(s):  
Tung-Cheng Ho ◽  
Shingo Watada ◽  
Kenji Satake
Keyword(s):  
Travel Time ◽  
Ray Tracing ◽  
Tsunami Wave ◽  
Wave Theory ◽  
Ray Tracing Method ◽  
Tsunami Early Warning ◽  
Time Path ◽  
Long Wave ◽  
Ray Path ◽  
Tracing Method

<p>We propose a ray-tracing method to solve the two-point boundary value problem for tsunamis based on the long-wave theory. In the long-wave theory, the tsunami wave velocity is proportional to the square root of water depth, which is available from global bathymetric atlases. Our method computes the shortest travel times starting from each of the two given points and calculates the local ray direction to trace the ray path. We utilize an explicit, non-iterative tracing scheme that exhibits robust results and applies to any tsunami-accessible locations, and the global-shortest travel-time path is derived. In simple and real bathymetry cases, our method demonstrates stable results with neglectable low uncertainties. The ray-tracing method is then applied to analyze the path of tsunamis from different directions to four important bays in Japan. The result shows that tsunami ray paths are significantly influenced by local bathymetry, and some crucial structures, such as trench and trough, behave as the primary routes of this region. Deploying stations near these routes will be most beneficial for tsunami early warning. The existing tsunami-observing system off the Honshu area works well for tsunamis from the east side but slightly deficient for tsunamis from the west side. The far-field ray tracing shows that tsunamis traveling from Chile to Japan through two main routes—one via north Hawaii and the other via the south— depending on the location of the source.</p>

A New Ray Tracing Method Based on Linear Travel-Time Interpolation

2015 ◽  
Vol 743 ◽  
pp. 845-851
Author(s):  
L.J. Liu ◽  
Z.H. Xie ◽  
C. Yang
Keyword(s):  
Travel Time ◽  
Ray Tracing ◽  
Flaw Detection ◽  
Reverse Direction ◽  
Ray Tracing Method ◽  
Error Accumulation ◽  
Ray Path ◽  
Multiple Cells ◽  
Tracing Method ◽  
Background Area

In the application of industrial flaw detection, the materials to be detected are often a collection of a background area and a small amount of defect areas. In traditional linear travel-time interpolation (LTI) method, the assumption of travel-time linearity will lead to error accumulation when the rays go through multiple cells. In order to reduce the cumulative error in this application, a new ray tracing method is proposed based on linear travel-time interpolation. In our method, calculation points are located on the boundaries between different areas to determine the angle of refraction. Moreover, the minimum travel-time of each point is computed by multidirectional loop strategy, which will make the traced ray path conforms to the condition of minimum travel-time when ray transports from the reverse direction. The simulation results show that using the proposed method to calculate travel-times and paths of tracing rays, it is more rapid and accurate than traditional LTI method and cross-scanning LTI method.

Field Estimation in Tunnel and Underground by Ray Tracing Method

2000 ◽  
Vol 54 (3) ◽  
pp. 46-56
Author(s):  
K. Uchida ◽  
D. Da ◽  
C. K. Lee ◽  
T. Matsunaga ◽  
T. Imai ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Ray Tracing Method ◽  
Field Estimation ◽  
Tracing Method
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