scholarly journals Instability Mechanism of Extraction Structure in Whole Life Cycle in Block Caving Mine

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Zhi-Yuan Xia ◽  
Zhuo-Ying Tan ◽  
Lei Zhang
Keyword(s):  
Life Cycle ◽  
Rock Mass ◽  
Stress Concentration ◽  
Shear Failure ◽  
Three Dimensional ◽  
Instability Mechanism ◽  
Block Caving ◽  
Mine Site ◽  
Three Stages ◽  
Whole Life Cycle

In the whole life cycle of the extraction structure in block caving mine from the beginning of roadways excavation to the end of ore drawing, there are many factors affecting the stability of the extraction structure. The investigation in the mine site shows that the extraction structure often presents the law of repeated instability. In order to reveal the mechanism of repeated instability of the extraction structure, the whole life cycle of extraction structure can be divided into three stages, namely, the formation stage of extraction structure, the undercutting stage without initial caving, and the ore caving and drawing stage. The three-dimensional finite difference software FLAC3D was used to establish the numerical model of the extraction structure in the whole life cycle in the block caving method. The process of ore caving and ore drawing was replaced by manual excavation of the caving area above the undercut space and applying stress on the major apex. The stress and displacement evolution laws of the extraction structure in three stages of the whole life cycle were studied and compared with the instability characteristics of the extraction structure on mine site. The whole life cycle instability mechanism of the extraction structure in Tongkuangyu mine is revealed; the research results show that the extraction structure near the advancing undercut front is prone to producing compressive stress concentration under the action of the surrounding rock stress arch in the stope; if the rock mass shear failure condition is reached, the instability of the extraction structure occurs. The extraction structure near the advancing undercut front is gradually transferred to the area under the undercut space with undercut increase, and the tensile stress concentration gradually appears in the sidewall of ore loading roadway and the tip of major apex; if the tensile strength of the rock mass in the extraction structure is exceeded, the instability occurs again. It is helpful to reduce the probability of the instability of the extraction structure to promote the overburden ore caving as soon as possible after the undercutting begins.

scholarly journals Life cycle carbon emission of monorail transit and its comparison in operation stage with other city transit modes

2021 ◽  
Vol 272 ◽  
pp. 01013
Author(s):  
Teng Li ◽  
Eryu Zhu ◽  
Haoran Liu
Keyword(s):  
Life Cycle ◽  
Carbon Emissions ◽  
Carbon Emission ◽  
Light Rail ◽  
Operation Stage ◽  
Three Stages ◽  
Operation Phase ◽  
Whole Life Cycle ◽  
Manufacturing Stage ◽  
Beijing Subway

In this paper, carbon emissions of a monorail transit are calculated using the method of whole life cycle, which can be divided into four stages: material manufacturing stage, construction stage, operation stage and demolition stage. In the operation phase, the units are PKT (Passenger Kilometers Travelled) and VKT (Vehicle Kilometers Travelled), while in other three stages, the unit is 1 km. The results show that the carbon emissions from the 1km length monorail are 6271.204 tons. In addition, in the operation stage, it is found that the PKT index and VKT index of Chongqing monorail transportation are 0.07468 and 3.31933 respectively, far lower than those of subways in the same city. For PKT indicators of other rail transits, from small to large, they are light rail, tram, subway, APM and maglev. As for VKT indicators, from small to large, they are tram, light rail, subway, APM and maglev. The PKT index of Beijing subway is the lowest compared with that of other cities.

scholarly journals Study on Instability Mechanism of Extraction Structure under Undercut Space Based on Thin Plate Theory in Block Caving Method

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhi-Yuan Xia ◽  
Zhuo-Ying Tan
Keyword(s):  
Stress Concentration ◽  
Thin Plate ◽  
Plate Theory ◽  
Side Wall ◽  
Tectonic Stress ◽  
Tension Stress ◽  
Instability Mechanism ◽  
Block Caving ◽  
Thin Plate Theory ◽  
Floor Heave

The instability of extraction structure under the undercut space in the block caving stope presents specific characteristics: rib spalling and floor heave in ore-loading roadway and collapse of major apexes. In order to study the stress and displacement evolution law of extraction structure under undercut space and reveal the instability mechanism of extraction structure, the numerical simulation model of block caving stope was established using the finite difference software FLAC3D. According to the postundercutting strategy in Tongkuangyu Mine in China, extraction structure was formed first in the simulation process, and then the undercut level was divided into eight units for excavation step by step. The stress and displacement of extraction structure after each step of undercutting were monitored and analyzed. Based on the thin plate theory, the mechanism of stress change and deflection deformation of extraction structure was revealed. The research results show that, under the action of high horizontal tectonic stress and vertical stress, the extraction structure under undercut space produces vertical upward bending deformation after undercutting during the block caving. The tension stress concentration gradually appears in the side wall of the ore-loading roadway and the tip of the major apexes; with the increase of the undercutting area, the degree of tensile stress concentration gradually becomes strong; when the tensile strength of the rock mass in extraction structure is exceeded, extraction structure presents instability. It is necessary to make the overlying ore collapse on extraction structure as soon as possible after undercutting, which is beneficial to release the tension stress in the extraction structure under undercutting space.

Research on Shear Failure Criterion for Layered Rock Mass

2012 ◽  
Vol 446-449 ◽  
pp. 1491-1496 ◽  
Author(s):  
Zhi Zeng Zhang ◽  
Lan Lan Zhou ◽  
Zhen Xia Yuan ◽  
Zhong Hua Sun
Keyword(s):  
Rock Mass ◽  
Failure Criterion ◽  
Shear Failure ◽  
Three Dimensional ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Layered Rock ◽  
Layered Rock Mass ◽  
The Stability ◽  
Confining Pressure Effect

In order to study the stability of layered rock mass, a shear failure criterion for layered rock mass is presented and its program is compiled in C language. The shear failure criterion consists of two parts: firstly, four empirical expressions are suggested in which shear strength parameters vary with the direction; secondly, a pilot calculation method is developed to judge whether a shear failure plane in layered rock mass occurs or not and give its occurrence under three dimensional stress condition. A triaxial numerical experiment on layered rock mass is designed to test the shear failure criterion, and its results reflect the characters including obliquity effect, confining pressure effect and failure mode which conform to the previous triaxial tests.

scholarly journals Construction of exchange integrated information chain management model leading by information nurse for large instrument and equipment in operating room

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jinghua Dai ◽  
Xiaoqiang Ren ◽  
Peng Wu ◽  
Xiangdong Wang ◽  
Jiang Li ◽  
...  
Keyword(s):  
Life Cycle ◽  
Life Cycle Management ◽  
Management Model ◽  
Control Group ◽  
Equipment Management ◽  
Observation Group ◽  
Chain Management ◽  
Information Chain ◽  
Whole Life Cycle ◽  
Running Mode

Abstract Background This study aims to explore the information chain management model of large instrument and equipment inter-working in the operating room (OR) led by information nurses. Methods Through the chain management process of large instruments and equipment in the OR, which was based on information nurses, the management model of inter-working and integrating information chain was established, the key links were controlled, and the whole life cycle management of instruments and equipment from expected procurement to scrapping treatment was realized. Using the cluster sampling method, 1562 surgical patients were selected. Among these patients, 749 patients were assigned to the control group before the running mode, and 813 patients were assigned to the observation group after the running mode. The related indexes for large instrument and equipment management in the department before and after the running mode were compared. Results In the observation group, the average time of equipment registration was (22.05 ± 2.36), the cost was reduced by 2220 yuan/year, and the satisfaction rate of the nursing staff was 97.62%. These were significantly better, when compared to the control group (P < 0.05). Furthermore, the awareness rate of the whole staff for equipment repair application was 95.12%, and the arrival time of maintenance personnel and the examination and approval time of equipment management were greatly shortened (P < 0.05). Conclusion The integrated management model of large instrument and equipment interworking in the OR based on chain flow realizes the whole life cycle management of instruments and equipment, which is essential to improve management efficiency.

scholarly journals Correction to “Life-Cycle Assessment of Gingko-Wood Three-Dimensional Membrane for Wastewater Treatment”

ACS Omega ◽  
2020 ◽  
Vol 5 (42) ◽  
pp. 27733-27733
Author(s):  
Faiza Niaz ◽  
Qasim Khan ◽  
Mustafa Ali ◽  
Wenxing Shen
Keyword(s):  
Wastewater Treatment ◽  
Life Cycle Assessment ◽  
Life Cycle ◽  
Three Dimensional

scholarly journals BIM-Based Tools for Managing Construction and Demolition Waste (CDW): A Scoping Review

2021 ◽  
Vol 13 (15) ◽  
pp. 8427
Author(s):  
Bahareh Nikmehr ◽  
M. Reza Hosseini ◽  
Jun Wang ◽  
Nicholas Chileshe ◽  
Raufdeen Rameezdeen
Keyword(s):  
Life Cycle ◽  
Scoping Review ◽  
Construction And Demolition Waste ◽  
Future Research ◽  
Demolition Waste ◽  
Scant Attention ◽  
Intellectual Deficiencies ◽  
Whole Life Cycle ◽  
Point Of Reference ◽  
Design And Construction

This article provides a picture of the latest developments in providing BIM-based tools for construction and demolition waste (CDW) management. The coverage and breadth of the literature on offering BIM-based tools and technologies for dealing with CDW throughout the whole life cycle of construction are investigated, and gaps are identified. Findings reveal that, although various BIM-based technologies are closely associated with CDW, much of the existing research on this area has focused on the design and construction phase; indeed, the problem of CDW in post-construction stages has received scant attention. Besides, the now available tools and technologies are lacking in cross-phase insights into project waste aspects and are weak in theoretical rigor. This article contributes to the field by identifying the intellectual deficiencies in offering BIM-based tools and technologies when dealing with CDW. So, too, it points to major priorities for future research on the topic. For practitioners, the study provides a point of reference and raises awareness in the field about the most advanced available BIM-based technologies for dealing with CDW problems.

Innovation and Corporate Social Responsibility in SMEs

2015 ◽  
Vol 808 ◽  
pp. 359-363
Author(s):  
Cristina Feniser ◽  
Florin Lungu
Keyword(s):  
Corporate Social Responsibility ◽  
Life Cycle ◽  
Open Innovation ◽  
Social Goals ◽  
New Approach ◽  
Rational Management ◽  
Corporate Social ◽  
Qualitative Exploration ◽  
Whole Life Cycle ◽  
The Relationship

So far little attention has been given the differences or the compatibilities between CSR and innovation. Few works treats CSR in combination with innovation. What exactly is the relationship between CSR and innovation? Recent phenomena such as open innovation is based on the concept that the stakeholder's dialogue that overlaps with some dimensions of CSR. Being innovative means to bring organizational and technical improvements which will translate into a better position in the market. These improvements don't just aim the product, but the process by which it is obtained and its whole life-cycle. We're talking about a new approach to innovation, namely its orientation towards sustainability. Although SMEs have many features which facilitate implementation of CSR, activities of this type in such organizations are still limited. SMEs managers often make choices that are related to rational management. This leads to divergence between economical and social goals. Through a qualitative exploration of the concepts of CSR and innovation, we wanted to find out from some managers whether there is a link between innovation and CSR in SMEs and whether the activities corresponding to the two concepts overlap in a certain measure.

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