Identification of potential high-stress hazards in deep-buried hard rock tunnel based on microseismic information: a case study

Author(s):  
Wen-jing Niu ◽  
Xia-Ting Feng ◽  
Ya-xun Xiao ◽  
Guang-liang Feng ◽  
Zhi-bin Yao ◽  
...  
Keyword(s):  
2012 ◽  
Vol 30 ◽  
pp. 132-144 ◽  
Author(s):  
Hernqvist Lisa ◽  
Butrón Christian ◽  
Fransson Åsa ◽  
Gustafson Gunnar ◽  
Funehag Johan

2021 ◽  
Vol 9 (8) ◽  
pp. 839
Author(s):  
Tarek N. Salem ◽  
Nadia M. Elkhawas ◽  
Ahmed M. Elnady

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.


2018 ◽  
Vol 10 (1) ◽  
pp. 168781401875472 ◽  
Author(s):  
Wei Sun ◽  
Xiaobang Wang ◽  
Maolin Shi ◽  
Zhuqing Wang ◽  
Xueguan Song

A multidisciplinary design optimization model is developed in this article to optimize the performance of the hard rock tunnel boring machine using the collaborative optimization architecture. Tunnel boring machine is a complex engineering equipment with many subsystems coupled. In the established multidisciplinary design optimization process of this article, four subsystems are taken into account, which belong to different sub-disciplines/subsytems: the cutterhead system, the thrust system, the cutterhead driving system, and the economic model. The technology models of tunnel boring machine’s subsystems are build and the optimization objective of the multidisciplinary design optimization is to minimize the construction period from the system level of the hard rock tunnel boring machine. To further analyze the established multidisciplinary design optimization, the correlation between the design variables and the tunnel boring machine’s performance is also explored. Results indicate that the multidisciplinary design optimization process has significantly improved the performance of the tunnel boring machine. Based on the optimization results, another two excavating processes under different geological conditions are also optimized complementally using the collaborative optimization architecture, and the corresponding optimum performance of the hard rock tunnel boring machine, such as the cost and energy consumption, is compared and analysed. Results demonstrate that the proposed multidisciplinary design optimization method for tunnel boring machine is reliable and flexible while dealing with different geological conditions in practical engineering.


Author(s):  
Hongwei Zhou ◽  
Yang Ju ◽  
Heping Xie ◽  
Geng Ma ◽  
Zhengliang Dong ◽  
...  

2020 ◽  
Author(s):  
Ben Little ◽  
Alison Winch

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.


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