scholarly journals Quantitative Evaluation of the “Non-Enclosed” Microseismic Array: A Case Study in a Deeply Buried Twin-Tube Tunnel

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 2006 ◽  
Author(s):  
Hang Zhang ◽  
Chunchi Ma ◽  
Tianbin Li
Keyword(s):  
High Stress ◽  
Pso Algorithm ◽  
Maximum Error ◽  
Microseismic Monitoring ◽  
Source Location ◽  
Tunnel Engineering ◽  
Underground Engineering ◽  
Location Accuracy ◽  
Tube Arrays

The high-stress hazards of underground engineering have stimulated the exploration of microseismic monitoring and early warning methods. To achieve a good monitoring effect, the monitoring object is usually enclosed by a microseismic array (sensor array) (e.g., slope engineering, etc.). However, some characteristics of a buried tunnel, including “linear”, “deep-buried”, and “long”, make it difficult to deploy a reasonable microseismic array, which leads to the microseismic array being non-enclosed for the monitoring object. Application of the non-enclosed microseismic array yields decreases the accuracy of the source location. To solve the problem wisely, this paper deals with the feasibility of non-enclosed microseismic arrays (axial-extended, lateral-extended, and twin-tube arrays) by introducing a quantitative method. To this end, an optimized microseismic array with the best source location accuracy for a twin-tube expressway tunnel is proposed. The obtained results reveal that the non-enclosed microseismic arrays, which are unavoidable in expressway tunnel engineering, do not introduce errors but reduce the ability to resist them. Further, the twin-tube array achieves a better source location accuracy than the axial and lateral-extended arrays. In the application of the source location based on the particle swarm optimization (PSO) algorithm to the twin-tube array, microseismic events, which cluster in the rockburst section, are wholly gathered, and the maximum error is reduced by about 30–50 m, indicating its greater feasibility with respect to the single-tube array.

Study on Risk Trend Assessment of Metro Tunnel Crossing Underground Pipeline Based on Partial Connection Number

2014 ◽  
Vol 580-583 ◽  
pp. 1283-1287
Author(s):  
Hong Tao Xie ◽  
Bo Li ◽  
Yun Sheng Zhao
Keyword(s):  
Risk Assessment ◽  
Underground Pipeline ◽  
Tunnel Engineering ◽  
Underground Engineering ◽  
Connection Number ◽  
Underground Pipelines ◽  
Trend Assessment ◽  
Metro Tunnel ◽  
Partial Connection

A model of risk trend assessment for metro tunnel crossing underground pipelines is proposed in this paper based on the partial connection number. This paper fully considered the certainty and uncertainty of the index and used "partial connection number method" to analyze the risk developing trend and its sort of metro tunnel crossing underground pipelines. A case study was performed on a metro tunnel engineering of Shenzhen Line 9. The results showed that this model considered the dynamic characteristics of risk, enriching the contents of risk assessment of underground engineering, which can provide a reference for the risk management.

Effects of Microseismic Station Location on Source Location Accuracy in Microseismic Monitoring

2014 ◽  
Vol 638-640 ◽  
pp. 1789-1793
Author(s):  
Hai Tao Wang ◽  
Wen Xue Li ◽  
Ping Yan ◽  
Jing Gu
Keyword(s):  
Microseismic Monitoring ◽  
Source Location ◽  
Location Error ◽  
Global Optimization Algorithm ◽  
Swarm Optimization ◽  
Location Accuracy ◽  
Microseismic Source Location ◽  
The Difference ◽  
Station Location ◽  
The Relationship

The deviation of microseismic station location will affect the microseismic source location accuracy in microseismic monitoring. The relationship between microseismic station location deviation and source location accuracy is studied in the paper. A global optimization algorithm, particle swarm optimization (PSO), is used to search for the source location. Results show that PSO method is good. The source location error increases with the microseismic station location error. The relationship between them is nonlinear. The microseismic sources outside the microseismic station array are more sensitive to the microseismic station location deviation than inside the microseismic station array. The bigger the microseismic station location error, the greater the difference. Therefore, when the microseismic source is outside the microseismic station array, it is more necessary to ensure the accuracy of microseismic station location.

scholarly journals SOURCE LOCATION MECHANISM OF MICROSEISMIC MONITORING USING P-S WAVES AND ITS EFFECT ANALYSIS

10.6036/10370 ◽  
2022 ◽  
Vol 97 (1) ◽  
pp. 39-45
Author(s):  
Zhigang Wang ◽  
Ji Li ◽  
Bo Li
Keyword(s):  
Monitoring Network ◽  
Seismic Source ◽  
Microseismic Monitoring ◽  
Source Location ◽  
P Wave ◽  
Monitoring Networks ◽  
Distributed Monitoring ◽  
S Wave ◽  
Location Accuracy ◽  
Seismic Source Location

Seismic source location is the most fundamental and most important problem in microseismic monitoring. However, only P wave has been mostly applied in the existing microseismic monitoring networks, with low location accuracy and poor stability of location result for the microseismic events occurring beyond monitoring networks. The seismic source location was implemented using P wave and S wave in this study to expand the effective monitoring area of a microseismic monitoring network and improve its location accuracy for microseismic events nearby the monitoring network. Then, the seismic source location mechanism using P-S wave was revealed through theoretical derivation and analysis. Subsequently, the program development and numerical simulation were combined to analyze and compare systematically the location effects of differently distributed monitoring networks, those consisting of different quantities of sensors, and those with S wave contained in some sensors under two circumstances: combination of P wave and S wave and single use of P wave. Results demonstrate that adding S wave in the plane enhances the accuracy control in the radius direction of the monitoring network. After S wave is included, the location accuracy within a certain area beyond the monitoring network is improved considerably, the effective monitoring area of the whole network is expanded, and the unstable location zones using only P wave are eliminated. The location results of differently distributed monitoring networks and the influence laws of the quantity of sensors constituting the networks on the location results are acquired. This study provides evidence for microseismic monitoring to realize accurate and stable location within a larger range. Keywords: seismic source location, P wave and S wave, mechanism, location effect

scholarly journals Behavior of Offshore Pile in Calcareous Sand—Case Study

2021 ◽  
Vol 9 (8) ◽  
pp. 839
Author(s):  
Tarek N. Salem ◽  
Nadia M. Elkhawas ◽  
Ahmed M. Elnady
Keyword(s):  
Load Capacity ◽  
High Stress ◽  
Embedment Depth ◽  
Shear Stresses ◽  
Northern Coast ◽  
Compression Tests ◽  
Calcareous Sand ◽  
Element Analysis ◽  
Mixing Ratios

The erosion of limestone and calcarenite ridges that existed parallel to the Mediterranean shoreline forms the calcareous sand (CS) formation at the surface layer of Egypt's northern coast. The CS is often combined with broken shells which are considered geotechnically problematic due to their possible crushability and relatively high compressibility. In this research, CS samples collected from a site along the northern coast of Egypt are studied to better understand its behavior under normal and shear stresses. Reconstituted CS specimens with different ratios of broken shells (BS) are also investigated to study the effect of BS ratios on the soil mixture strength behavior. The strength is evaluated using laboratory direct-shear and one-dimensional compression tests (oedometer test). The CS specimens are not exposed to significant crushability even under relatively high-stress levels. In addition, a 3D finite element analysis (FEA) is presented in this paper to study the degradation offshore pile capacity in CS having different percentages of BS. The stress–strain results using oedometer tests are compared with a numerical model, and it gave identical matching for most cases. The effects of pile diameter and embedment depth parameters are then studied for the case study on the northern coast. Three different mixing ratios of CS and BS have been used, CS + 10% BS, CS + 30% BS, and CS + 50% BS, which resulted in a decrease of the ultimate vertical compression pile load capacity by 8.8%, 15%, and 16%, respectively.

Reliability-Based Analysis and Optimization of the Gravity Balancing Performance of Spring-Articulated Serial Robots with Uncertainties

2021 ◽  
pp. 1-32
Author(s):  
Vu Linh Nguyen ◽  
Chin-Hsing Kuo ◽  
Po Ting Lin
Keyword(s):  
Pso Algorithm ◽  
Reliability Based Design Optimization ◽  
Swarm Optimization ◽  
Reliability Based Design ◽  
Serial Robots ◽  
Simulation Based ◽  
Serial Robot ◽  
Simulation Results ◽  
Uncertainty Level

Abstract This article proposes a method for analyzing the gravity balancing reliability of spring-articulated serial robots with uncertainties. Gravity balancing reliability is defined as the probability that the torque reduction ratio (the ratio of the balanced torque to the unbalanced torque) is less than a specified threshold. The reliability analysis is performed by exploiting a Monte Carlo simulation (MCS) with consideration of the uncertainties in the link dimensions, masses, and compliance parameters. The gravity balancing begins with a simulation-based analysis of the gravitational torques of a typical serial robot. Based on the simulation results, a gravity balancing design for the robot using mechanical springs is realized. A reliability-based design optimization (RBDO) method is also developed to seek a reliable and robust design for maximized balancing performance under a prescribed uncertainty level. The RBDO is formulated with consideration of a probabilistic reliability constraint and solved by using a particle swarm optimization (PSO) algorithm. A numerical example is provided to illustrate the gravity balancing performance and reliability of a robot with uncertainties. A sensitivity analysis of the balancing design is also performed. Lastly, the effectiveness of the RBDO method is demonstrated through a case study in which the balancing performance and reliability of a robot with uncertainties are improved with the proposed method.

scholarly journals Patriarchy in the Digital Conjuncture: An Analysis of Google’s James Damore

2020 ◽  
Author(s):  
Ben Little ◽  
Alison Winch
Keyword(s):  
Scientific Method ◽  
Software Engineer ◽  
High Stress ◽  
Silicon Valley ◽  
High Status ◽  
The Core ◽  
Core Belief ◽  
The World ◽  
New Form

Our case study looks at the events surrounding the sacking ofGoogle engineer James Damore who was fired for authoring a memo which stated that women are biologically less suited to high-stress, high-status technical employment than men. Damore, asserting that his document ‘was absolutely consistent with what he’d seen online’, instantly became an ambivalent hero of the alt-right. Like the men who own and run the companies of Silicon Valley, the software engineer subscribes to the idea that the world can be understood and altered through the rigorous application of the scientific method. And as he draws on bodies of knowledge from evolutionary psychology and mathematical biology, we see how the core belief structures of Silicon Valley, when transferred from the technical to the cultural and social domain, can reproduce the sort of misogynistic ‘rationalism’ that fuels the alt-right. We argue that Damore’s memo is in line with Google’s ideology of ‘dataism’: that is the belief that the world can be reduced to decontextualised information and subject to quantifiable logics.Through its use of dataism, the memo reveals much about the similarities and continuities between Damore, the ideas laid out n his memo, and Google itself. Rather than being in opposition, these two entities are jostling for a place in the patriarchal structures of a new form of capitalism.

scholarly journals Hydraulic properties and energy dissipation of deep hard rock under H-M coupling and cycling loads

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 935-942 ◽  
Author(s):  
Cheng-Han Zhang ◽  
Shuang You ◽  
Hong-Guang Ji ◽  
Fei Li ◽  
Hong-Tao Wang
Keyword(s):  
Acoustic Emission ◽  
Osmotic Pressure ◽  
Hydraulic Properties ◽  
Coupling Effect ◽  
High Stress ◽  
Confining Pressure ◽  
In Situ Stress ◽  
Dissipated Energy ◽  
Underground Engineering ◽  
Loading And Unloading

The permeability of deep rock is closely related to the stability and safety of underground engineering. The rocks in deep stratum are mostly with high stress and high osmotic pressure. Therefore, it is necessary to consider the coupling effect between porewater pressure and in situ stress on rock mass. A series of triaxial cyclic loading and unloading experiments under hydraulic-mechanics coupling conditions are carried out to studied the mechanical and hydraulic properties of granite in the depth of 1300 m to 1500 m. Especially, the effect of the disturbance on the permeability of fractured rocks are investigated by unloaded the confining pressure. Tests results presented that the stress-strain curves of deep granite showed typical brittle characteristics. The principal stress of granite exhibited a linear relationship under the high confining pressure of 34-40 MPa and high osmotic pressure of 13-15 MPa. Dissipated energy of the rock decreased to a relatively low level after 2-3 loading cycles and then slowly increased. Permeability showed a decreasing trend as the loading and unloading cycles increase. Finally, acoustic emission technology was used to monitor the fracture evolution in rocks, the acoustic emission signal released as the fractures develop and energy dissipated. The results would provide basic data for the exploitation and excavation in the deep galleries.

Improving Well Completion via Real-Time Microseismic Monitoring: A West Texas Case Study

2010 ◽  
Author(s):  
Efejera Akpodiate Ejofodomi ◽  
Malcolm Yates ◽  
Robert Downie ◽  
Tarik Itibrout ◽  
O.A. Catoi
Keyword(s):  
Real Time ◽  
Microseismic Monitoring ◽  
Well Completion ◽  
West Texas
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