scholarly journals Study on Stability of Exit Slope of Chenjiapo Tunnel Under Condition of Long-term Rainfall

2021 ◽  
Author(s):  
Tian-shun Hou ◽  
Xiang Duan ◽  
Hao-yu Liu
Keyword(s):  
Plastic Zone ◽  
Safety Factor ◽  
Horizontal Displacement ◽  
Natural State ◽  
Small Scale ◽  
Slope Surface ◽  
Front Edge ◽  
Unstable Slope ◽  
Continuous Rainfall

Abstract The exit slope of Chenjiapo Tunnel is located directly above the exit of Chenjiapo Tunnel on Enshi to Laifeng expressway. During the excavation of the exit of the right line of the tunnel, the left side of the front edge of the slope slips. Under the joint action of excavation and rainfall, a large landslide of 6.27×10 4 m 3 and a huge unstable slope of 8.69×10 5 m 3 are formed. The landslide body and unstable slope body not only cause the tunnel to be shut down, but also directly threaten the operation safety of the later expressway. Therefore, in order to study the stability change process of the exit slope of Chenjiapo tunnel under the condition of long-term rainfall, the finite element calculation of the slope is carried out by GeoStudio software. The results show that under the condition of long-term continuous rainfall, the safety factor of the slope decreases with the increased rainfall time, but the reduction rate gradually slows down, and finally tends to be stable. The safety factor of the slope is reduced from 1.187 in the natural state to 1.015, which indicates that the slope is still in a stable state under the condition of long-term continuous rainfall, but the safety reserve is not high, and it is easy to lose stability and damage due to the influence of external adverse factors. As the rainfall continues, the seepage line inside the slope is rising, and the saturated area of the soil at the toe of the slope is increasing. Until the slope begins to drain outwards, the seepage field inside the slope is basically stable. The maximum horizontal displacement of the slope increases with the increased rainfall time, but the increase rate gradually slows down until it tends to be stable. The maximum horizontal displacement of the slope occurred in the middle surface of the slope at the beginning of the rainfall, and gradually transferred to the toe of the slope within 7 days of the rainfall and continued until the end of the rainfall. At the end of the rainfall, the maximum horizontal displacement of the toe of the slope is 0.128 m, and the toe of the slope will be damaged first. At the beginning of the rainfall, the plastic zone of the slope is only scattered at the slope surface and the slope toe. And then as the rainfall continues, the distribution range of the plastic zone in the slope surface, the slope toe and the slide zone gradually widen, and the slope stability gradually decreases. The maximum horizontal displacement and plastic zone of the slope are concentrated at the toe of the slope, the slope presents obvious traction failure characteristics. According to the results of field survey, there are small-scale gravel soil collapses and shear outlets at the front edge of the slope, and the survey results are consistent with the simulation results. It is suggested to set up perfect drainage engineering in the middle and back of the slope, and set anti slide piles and drainage holes at the toe of the slope to reinforce the slope.

Research on Deformation Stability of Soft Rock Slope under Excavation Based on FLAC3D

2013 ◽  
Vol 275-277 ◽  
pp. 290-294 ◽  
Author(s):  
Fang Guo ◽  
Wei Gu ◽  
Jie Jun Tang ◽  
Ming Hai Murong
Keyword(s):  
Plastic Zone ◽  
Safety Factor ◽  
Rock Slope ◽  
Limit Equilibrium ◽  
Soft Rock ◽  
Horizontal Displacement ◽  
Excavation Process ◽  
Area Distribution ◽  
Slope Excavation ◽  
Deformation Stability

In order to study deformation and stability of soft rock slope in excavation process, the deformation, plastic area distribution, and the change of safety factor of example slope based on FLAC3D software were studied in this paper. Results show that: (1) the vertical and horizontal displacement of slope gradually increase with excavation; (2) in the process of slope excavation, tension plastic zone occurs in slope surface, and shear plastic zone with connected properties gradually forms internally; (3) based on the strength reduction method and limit equilibrium method calculation, the safety factor of slope gradually reduces with excavation, and adopting the construction form of excavation with supporting meantime is very necessary.

Numerical Simulation and Design Optimization Research of Slope Ratio and Platforms Influence on a High Rock Cut Slope Engineering Stability

2014 ◽  
Vol 1065-1069 ◽  
pp. 151-158
Author(s):  
Lei He ◽  
Yan Ren ◽  
Zi Xia Feng ◽  
Zhi Wei Han
Keyword(s):  
Numerical Simulation ◽  
Plastic Zone ◽  
Design Optimization ◽  
Safety Factor ◽  
Optimization Design ◽  
Horizontal Displacement ◽  
Engineering Practice ◽  
Cut Slope ◽  
Slope Ratio ◽  
Slope Excavation

According to the rock high-cut slope excavation engineering practice of a substation in Jiangxi, with the goals of stable and economic rational slope design, numerical simulation research of the slope ratio and unloading platform and design optimization work was carried out. The slope safety factor, displacement and plastic zone distribution changes of different slope ratio and platform setting programs were obtained. The results show that:(1) the adjustment of the slope ratio and platform can significantly affect the slope displacement and plastic zone distribution, reasonable slope ratio and platform can reduce the horizontal displacement and plastic zone of slope, increase the safety factor and stability;(2) the slope monitoring results show that numerical simulation optimization design is feasible, and the excavation slope maintain security and stability during the construction period, and economic benefit has been obtained. The research conclusions can provide technical support for the engineering design, and reference for design and research of high-cut slope excavation engineering with similar conditions in that region.

Small-Scale Deliberation and Mass Democracy: A Systematic Review of the Spillover Effects of Deliberative Minipublics

2021 ◽  
pp. 003232172110072
Author(s):  
Ramon van der Does ◽  
Vincent Jacquet
Keyword(s):  
Systematic Review ◽  
Empirical Evidence ◽  
Empirical Research ◽  
Spillover Effects ◽  
Future Research ◽  
Small Scale ◽  
Long Term Effects ◽  
Current Crisis ◽  
Mass Democracy

Deliberative minipublics are popular tools to address the current crisis in democracy. However, it remains ambiguous to what degree these small-scale forums matter for mass democracy. In this study, we ask the question to what extent minipublics have “spillover effects” on lay citizens—that is, long-term effects on participating citizens and effects on non-participating citizens. We answer this question by means of a systematic review of the empirical research on minipublics’ spillover effects published before 2019. We identify 60 eligible studies published between 1999 and 2018 and provide a synthesis of the empirical results. We show that the evidence for most spillover effects remains tentative because the relevant body of empirical evidence is still small. Based on the review, we discuss the implications for democratic theory and outline several trajectories for future research.

scholarly journals 106 - Environmental Influences on the Cognitive and Psychological Well Being of Older Adults with Dementia

2020 ◽  
Vol 32 (S1) ◽  
pp. 15-16
Author(s):  
William E. Reichman ◽  
L. Bradford Perkins ◽  
Hilde Verbeek
Keyword(s):  
Quality Of Life ◽  
Older Adults ◽  
Physical Environment ◽  
Culture Change ◽  
Long Term Care ◽  
Small Scale ◽  
Term Care

This symposium will review the latest data on the influence of environmental design and its attributes on the cognitive and psychological wellbeing of older adults living with dementia. The presenters will cover the myriad ways in which the physical environment of care can adapt to the changing demands of older adults with sensory, motor and cognitive deficits and foster optimal functioning and quality of life. The role of emerging technologies will also be reviewed as they complement the contribution of the design of the physical environment to the wellbeing of older adults with cognitive impairment. Information will be offered through a review of the existing research literature as well as case studies that illustrate the impact of environmental modification on fostering wellbeing and minimizing the emergence of the behavioral and psychological symptoms of dementia. The presenters will represent and integrate sensibilities that have emerged from the fields of architecture, cognitive neuroscience and psychology.How the Principles of the Culture Change Movement Inform Environmental Design and the Application of Technology in the Care of Older Adults Living with DementiaWilliam E. ReichmanThe culture change movement informs a number of principles that have been applied to more contemporary design concepts for the congregate care of older adults living with dementia. This talk will review the core tenets of the Culture Change Movement as exemplified by the Greenhouse, Dementia Village and other innovative models of congregate long-term care. Specific reference will be made to how these tenets have been operationalized around the world into the design of programming and the creation of residential care environments that foster a better quality of life for older adults and an enhanced work environment for care providers. This talk will also include the emerging role of technologies that complement innovative design of the environment and which foster optimized social and recreational functioning of older adults living with dementia.A Better Life Through a Better Nursing Home DesignL. Bradford PerkinsOver the last 20 years there has been extensive experimentation related to the role of the environment in the housing, care and treatment of persons with Alzheimer’s and other age related dementias. Prior to that time the typical housing and care environment was a locked unit in a skilled nursing or other restrictive senior living facility. In 1991 the Presbyterian Association on Aging in Western Pennsylvania opened Woodside Place on its Oakmont campus. This small 36 bed facility was designed to incorporate the latest research and care experience with persons suffering from these issues. This one small project, as well as the long post occupancy research led by Carnegie Mellon University, clearly demonstrated that individuals with Alzheimer’s and related forms of dementia could lead a healthier, happier, higher quality of life in a more residential, less restrictive environment. Not everything in this pioneering project worked, and five generations of living and care models have followed that have refined the ideas first demonstrated by Woodside Place. Bradford Perkins, whose firm designed Woodside Place and over 100 other related projects, will discuss what was learned from Woodside Place as well as the five generations of projects (and post occupancy research) that followed.Innovative dementia care environments as alternatives for traditional nursing homes: evidence and experiences from the NetherlandsHilde VerbeekKey goals of the dementia care environment focus on increasing autonomy, supporting independence and trying to enable one’s own lifestyle for as long as possible. To meet these goals, innovative, small-scale and homelike care environments have been developed that have radically changed the physical, social and organizational aspects of long-term care in the Netherlands. This presentation discusses various Dutch models that have implemented small-scale and homelike care environments, including green care farms, dementia village and citizen initiatives. The models reflect a common care concept, focusing on residents’ remaining strengths, providing opportunity for choice and aiming to sustain a sense of self and control. A small number of residents (usually 6 to 8) live together in a homelike environment and nursing staff are part of the household. Residents are encouraged to participate in daily household activities, emphasizing normalization of daily life with person-centred care. The physical environment resembles an archetypal home. This talk presents the scientific evidence on the impact and effects of these small-scale, homelike models on residents, their family caregivers and staff. Furthermore, the presentation will highlight working approaches and how these initiatives have positively influenced routine care across the long-term care spectrum.

scholarly journals Mapping Research Conducted on Long-Term Care Facilities for Older People in Brazil: A Scoping Review

2021 ◽  
Vol 18 (4) ◽  
pp. 1522
Author(s):  
Patrick Alexander Wachholz ◽  
Deborah Cristina De Oliveira ◽  
Kathryn Hinsliff-Smith ◽  
Reena Devi ◽  
Paulo José Fortes Villas Boas ◽  
...  
Keyword(s):  
Mixed Methods ◽  
Older People ◽  
Study Design ◽  
Scoping Review ◽  
Long Term Care ◽  
Assessment Tools ◽  
Small Scale ◽  
Term Care ◽  
Care Facilities

This scoping review aimed to explore the characteristics, strengths, and gaps in research conducted in Brazilian long-term care facilities (LTCFs) for older adults. Electronic searches investigating the residents (≥60 years old), their families, and the LTCF workforce in Brazil were conducted in Medline, EMBASE, LILACS, and Google Scholar, within the timescale of 1999 to 2018, limited to English, Portuguese, or Spanish. The reference lists were hand searched for additional papers. The Mixed Methods Appraisal Tool (MMAT) was used for critical appraisal of evidence. Data were reported descriptively considering the study design, using content analysis: 327 studies were included (n = 159 quantitative non-randomized, n = 82 quantitative descriptive, n = 67 qualitative, n = 11 mixed methods, n = 6 randomized controlled trials, and n = 2 translation of assessment tools). Regardless of the study design, most were conducted in a single LTCF (45.8%), in urban locations (84.3%), and in non-profit settings (38.7%). The randomized trials and descriptive studies presented the lowest methodological quality based on the MMAT. This is the first review to provide an overview of research on LTCFs for older people in Brazil. It illustrates an excess of small-scale, predominantly qualitative papers, many of which are reported in ways that do not allow the quality of the work to be assured.

scholarly journals Asymmetric competition causes multimodal size distributions in spatially structured populations

2016 ◽  
Vol 283 (1823) ◽  
pp. 20152404 ◽  
Author(s):  
Jorge Velázquez ◽  
Robert B. Allen ◽  
David A. Coomes ◽  
Markus P. Eichhorn
Keyword(s):  
Resource Competition ◽  
Structured Populations ◽  
Necessary Condition ◽  
Small Scale ◽  
Asymmetric Competition ◽  
Size Distributions ◽  
Long Term Study ◽  
Multimodal Distributions ◽  
Using Data

Plant sizes within populations often exhibit multimodal distributions, even when all individuals are the same age and have experienced identical conditions. To establish the causes of this, we created an individual-based model simulating the growth of trees in a spatially explicit framework, which was parametrized using data from a long-term study of forest stands in New Zealand. First, we demonstrate that asymmetric resource competition is a necessary condition for the formation of multimodal size distributions within cohorts. By contrast, the legacy of small-scale clustering during recruitment is transient and quickly overwhelmed by density-dependent mortality. Complex multi-layered size distributions are generated when established individuals are restricted in the spatial domain within which they can capture resources. The number of modes reveals the effective number of direct competitors, while the separation and spread of modes are influenced by distances among established individuals. Asymmetric competition within local neighbourhoods can therefore generate a range of complex size distributions within even-aged cohorts.

Species Responses to Grazing and Environmental-Factors in an Arid Halophytic Shrubland Community

1987 ◽  
Vol 35 (2) ◽  
pp. 135 ◽  
Author(s):  
RB Hacker
Keyword(s):  
Environmental Factors ◽  
Soil Salinity ◽  
Large Scale ◽  
Chemical Properties ◽  
Grazing Pressure ◽  
Aerial Photographs ◽  
Small Scale ◽  
Factors Affecting ◽  
Species Responses

Species responses to grazing and environmental factors were studied in an arid halophytic shrubland community in Western Australia. The grazing responses of major shrub species were defined by using reciprocal averaging ordination of botanical data, interpreted in conjunction with a similar ordination of soil chemical properties and measures of soil erosion derived from large-scale aerial photographs. An apparent small-scale interaction between grazing and soil salinity was also defined. Long-term grazing pressure is apparently reduced on localised areas of high salinity. Environmental factors affecting species distribution are complex and appear to include soil salinity, soil cationic balance, geomorphological variation and the influence of cryptogamic crusts on seedling establishment.

scholarly journals Local soil quality assessment of north-central Namibia: integrating farmers' and technical knowledge

SOIL ◽  
2018 ◽  
Vol 4 (1) ◽  
pp. 47-62 ◽  
Author(s):  
Brice Prudat ◽  
Lena Bloemertz ◽  
Nikolaus J. Kuhn
Keyword(s):  
Soil Quality ◽  
Soil Degradation ◽  
Clay Content ◽  
Small Scale ◽  
Technical Knowledge ◽  
Local Conditions ◽  
North Central ◽  
Local Soil ◽  
Soil Units

Abstract. Soil degradation is a major threat for farmers of semi-arid north-central Namibia. Soil conservation practices can be promoted by the development of soil quality (SQ) evaluation toolboxes that provide ways to evaluate soil degradation. However, such toolboxes must be adapted to local conditions to reach farmers. Based on qualitative (interviews and soil descriptions) and quantitative (laboratory analyses) data, we developed a set of SQ indicators relevant for our study area that integrates farmers' field experiences (FFEs) and technical knowledge. We suggest using participatory mapping to delineate soil units (Oshikwanyama soil units, KwSUs) based on FFEs, which highlight mostly soil properties that integrate long-term productivity and soil hydrological characteristics (i.e. internal SQ). The actual SQ evaluation of a location depends on the KwSU described and is thereafter assessed by field soil texture (i.e. chemical fertility potential) and by soil colour shade (i.e. SOC status). This three-level information aims to reveal SQ improvement potential by comparing, for any location, (a) estimated clay content against median clay content (specific to KwSU) and (b) soil organic status against calculated optimal values (depends on clay content). The combination of farmers' and technical assessment cumulates advantages of both systems of knowledge, namely the integrated long-term knowledge of the farmers and a short- and medium-term SQ status assessment. The toolbox is a suggestion for evaluating SQ and aims to help farmers, rural development planners and researchers from all fields of studies understanding SQ issues in north-central Namibia. This suggested SQ toolbox is adapted to a restricted area of north-central Namibia, but similar tools could be developed in most areas where small-scale agriculture prevails.

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