scholarly journals Injection Treatment for Tunneling Excavation in Sandy Soils with High Fines Content

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6930
Author(s):  
Johnatan González-García ◽  
Celestino González-Nicieza ◽  
Martina-Inmaculada Álvarez-Fernández ◽  
María-Belén Prendes-Gero

Instability and high permeability are two of the problems facing tunnelling excavations in soils with high fines content. Among the different techniques used to improve these soils, the injection of cement grouts stands out. In this work, a grouting treatment is designed to ensure the stability of the ground during the construction of two tunnels linking two municipalities in the north of Spain in Biscay, and to reduce the inflow of water from the aquifer located in the vicinity of these tunnels. First of all, the rock mass is analysed and the material to be injected is selected on the basis of the authors’ experience as well as setting time and compressive strength. Subsequently, with a test device designed by the DinRock research group of the University of Oviedo, two types of laboratory tests are carried out in order to analyse the effect of fines migration and washing on the water flows and the effect of re-injections of grouts with different densities on the permeability value. The results show that, in sandy materials, obtaining high degrees of waterproofing together with large stable zones can only be achieved by a combination of treatments and stages with different materials and densities. In addition, maximum values for both injection pressure and flow rate must be established depending on the type of grout and the permeability of the soil. Once the problem has been analysed, the injection treatment is designed and executed. The treatment consists of one pre-injection in four stages with 30 boreholes drilled in the top heading, 19–20 boreholes drilled in the bench, and one post-injection with boreholes drilled around the perimeter of the tunnel in those areas where the pre-injection does not achieve the desired degree of waterproofing.

1970 ◽  
Vol 7 (2) ◽  
pp. 157-168 ◽  
Author(s):  
S. Thomson

The need for new building sites at the University of Alberta required an investigation of the stability of the valley wall of the North Saskatchewan River within the limits of the campus.A geologic map and stratigraphic sections were drawn which show Upper Cretaceous shales and sandstones overlain by preglacial sands and gravels which, in turn, are overlain by till and glacial lake sediments.A large, buried preglacial valley on the western side of the study area enhances slope stability because it lowers the piezometric surface. Landslide analyses in this area indicate that effective strength parameters near peak values are being mobilized.On the eastern side of the study area old landslides are revealed by subdued slump topography. Residual strength parameters used in an infinite slope analysis result in low factors of safety.


Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5188
Author(s):  
Martín Pensado-Mariño ◽  
Lara Febrero-Garrido ◽  
Estibaliz Pérez-Iribarren ◽  
Pablo Eguía Oller ◽  
Enrique Granada-Álvarez

Accurate forecasting of a building thermal performance can help to optimize its energy consumption. In addition, obtaining the Heat Loss Coefficient (HLC) allows characterizing the thermal envelope of the building under conditions of use. The aim of this work is to study the thermal inertia of a building developing a new methodology based on Long Short-Term Memory (LSTM) neural networks. This approach was applied to the Rectorate building of the University of Basque Country (UPV/EHU), located in the north of Spain. A comparison of different time-lags selected to catch the thermal inertia has been carried out using the CV(RMSE) and the MBE errors, as advised by ASHRAE. The main contribution of this work lies in the analysis of thermal inertia detection and its influence on the thermal behavior of the building, obtaining a model capable of predicting the thermal demand with an error between 12 and 21%. Moreover, the viability of LSTM neural networks to estimate the HLC of an in-use building with an error below 4% was demonstrated.


2013 ◽  
Vol 2013 ◽  
pp. 1-12
Author(s):  
María-Belén Prendes-Gero ◽  
José Alcalde-Gonzalo ◽  
Pedro Ramírez-Oyanguren ◽  
Francisco-José Suárez-Domínguez ◽  
Martina-Inmaculada Álvarez-Fernández

Mechanised longwall mining is one of the more commonly employed exploitation methods in underground mines in the north of Spain as well as in the rest of the world. It is continuously changing and evolving, with new techniques, technology, equipment, and face management practices and systems appearing for the purposes of improving aspects such as operational and financial performances and, above all, the safety of the miners. Despite its importance, there are no regulations for the mining of longwall coal seams. This work aims to contribute to an advance in the design and optimisation of the roof support in longwall mining, analysing the stability of the roof using a method based on the resistance of materials, which considers the characteristics of the properties of the roof materials. The influence of not only the individual elements of support but also the coalface, which is considered one more supporting element, is investigated. The longitudinal and transverse spacings of the support and the number of walkways constituting the exploitation panel are analysed. The proposed formulation is validated by information gathered in a mine located in the region of Castilla-Leon.


Author(s):  
Daryl A. Cornish ◽  
George L. Smit

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.


2018 ◽  
Vol 34 (62) ◽  
pp. 66-81
Author(s):  
Adriana M. Moreno Moreno ◽  
Eduar Fernando Aguirre González

Social Responsibility is a concept that has been approached from different perspectives by theoreticians and institutions. Initially, this was limited exclusively to companies, however, the creation of the Social Capital, Ethics and Development Initiative by the Inter-American Development Bank (IDB) sought to make educational institutions aware that, like any other organization, they are responsible for the externalities they generate in their environment and their stakeholders. This research approaches the concept of University Social Responsibility (USR) from the scheme proposed by the IDB, which proposes four axes of action for Universities’ CR: Responsible Campus, Professional and Citizen Training, Social Management of Knowledge and Social Participation. The Universidad del Valle has a strategic plan entitled “Universidad del Valle’s Strategic Development Plan” and Regionalization attached thereto. It has also developed its action plan and in the five strategic issues raised herein, its socially responsible approach is clearly identifiable. The North Cauca Facility wherein this study is being developed, even though it does not have a University Social Responsibility Management Model, has attempted to align its practices with its strategic affairs that broadly conform to the four axes proposed by the IDB. This research addresses a relevant and current issue inasmuch as it proposes to develop a diagnosis on the relationship between the four axes of Social Responsibility proposed by the IDB and the practice of Social Responsibility applied at the Universidad del Valle, North Cauca Facility, for the period 2014-2015. In order to answer the research problem, a qualitative, exploratory and descriptive type of study is used, given that the work was based on the documentary information available at the University, while the interviews with the directors of the Institution are used as a tool for oral history. The research method used is the case study, which allows to address a unit of analysis in depth, in this case the USR within the Universidad del Valle, North Cauca Facility.


Author(s):  
Х.М. Хетагуров

Кленовники Северного Кавказа – особый тип лесных формаций. Особенность проявляется не только в структуре фитоценозов, но и в способах самовозобновления. Объект исследования – чистые и смешанные кленовники в нескольких урочищах РСО-Алания. Объекты расположены в различных условиях горного рельефа и на разной высоте над уровнем моря, от 1100 до 1900 м. Целью исследования является установление особенностей семенного возобновления кленовников, произрастающих в верхнем поясе распространения лесов на Северном Кавказе. Для достижения поставленной цели устанавливали время цветения и созревания семян по вертикальным поясам распространения кленовников. Обилие цветения и средний балл плодоношения устанавливали по В.Г. Капперу. Биометрические характеристики семян определяли по урочищам в трех повторностях. Учет подроста проводили на круговых учетных площадках по 10 м2, в соответствии с методикой А.В. Грязькина. Установлено, что цветение клена Траутфеттера начинается 10–14 мая и заканчивается в третьей декаде мая. Семена начинают созревать к концу августа – к началу сентября. Сроки опадения семян растянуты. Часть семян попадает на почву до начала листопада, поэтому они оказываются погребенными под опадом. Такие семена быстро теряют всхожесть, выпревают. Другая часть опадает вместе с листьями. Третья категория семян (самые легкие) держатся на деревьях до декабря и даже до весны. Естественное возобновление клена семенами под пологом материнского древостоя сильно затруднено из-за мощного травяного покрова. В древостое с сомкнутым пологом доля цветущих и плодоносящих деревьев составляет 2–3%, а средний балл плодоношения составляет 1,3. Освещенность на поверхности почвы не превышает 100 люкс, т. е. составляет 0,2–0,3% от освещенности на открытом месте; на высоте 1,3 м (над травостоем) освещенность несколько выше – от 1,2 до 1,6 тыс. люкс. Под пологом древостоя преобладает подрост вегетативного происхождения. У верхней границы кленового леса подрост семенного происхождения встречается в окнах, прогалинах и на открытых местах в количестве 430–630 экз./га. По высоте преобладает крупный подрост 50–60%, доля мелкого – 10–20%. The maple stands of the North Caucasus – a special type of forest formations. The peculiarity is manifested not only in the structure of phytocoenoses, but also in the ways of self-renewing. Object of research – pure and mixed maple stands in some areas of North Ossetia-Alania. The properties are located in various mountainous terrain and at different heights above sea level from 1100 to 1900 m. The aim of the study is to establish the characteristics of the seed the resumption of the maple stands growing in the upper belt of forests spread in the Northern Caucasus. To achieve this goal setting time of flowering and ripening of seeds on vertical zones distribution dominated. The abundance of flowering and the average score of fruiting was established by V.G. Capper. Biometric characteristics of the seeds was determined by the tracts in three replicates. Accounting for the undergrowth was carried out on a circular experimental plots at 10 m2, in accordance with the method of A.V. Grashkin. It is established that the flowering maple Trautvetter begins may 10–14 and ends in the third week of may. Seeds begin to ripen by late August – early September. The timing of subsidence of the stretched seed. Some of the seeds falls to the ground before the leaves, so they are trapped under the litter. These seeds quickly lose their germination, vypivaet. The other part falls along with the leaves. The third category of seeds (the light) stay on the trees until December and even till spring. Natural regeneration of maple seeds under the canopy of parent stand is very difficult due to the strong grass cover. In forest stands with dense canopy, proportion of flowering and fruit-bearing trees is 2–3%, and the average score of fruiting is 1.3. The illumination on the surface of the soil does not exceed 100 Lux, i. e. 0.2–0.3% of the light in the open, at a height of 1.3 m (on grass) the lighting is slightly higher, from 1.2 to 1.6 thousand Suite. Under the canopy of the forest the undergrowth is dominated by vegetative origin. At the upper boundary of the maple forest, saplings of seed origin occurs in Windows, clearings and open places in the number 430–630 ind./ha. In height dominated by large undergrowth of 50–60%, the share of small – 10–20%.


Author(s):  
Junhao Huang ◽  
Fang Fang ◽  
Zhihua Wang ◽  
Mingxuan Hang ◽  
Yibo Wang ◽  
...  

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 830
Author(s):  
William E. Lewis ◽  
Timothy L. Olander ◽  
Christopher S. Velden ◽  
Christopher Rozoff ◽  
Stefano Alessandrini

Accurate, reliable estimates of tropical cyclone (TC) intensity are a crucial element in the warning and forecast process worldwide, and for the better part of 50 years, estimates made from geostationary satellite observations have been indispensable to forecasters for this purpose. One such method, the Advanced Dvorak Technique (ADT), was used to develop analog ensemble (AnEn) techniques that provide more precise estimates of TC intensity with instant access to information on the reliability of the estimate. The resulting methods, ADT-AnEn and ADT-based Error Analog Ensemble (ADTE-AnEn), were trained and tested using seventeen years of historical ADT intensity estimates using k-fold cross-validation with 10 folds. Using only two predictors, ADT-estimated current intensity (maximum wind speed) and TC center latitude, both AnEn techniques produced significant reductions in mean absolute error and bias for all TC intensity classes in the North Atlantic and for most intensity classes in the Eastern Pacific. The ADTE-AnEn performed better for extreme intensities in both basins (significantly so in the Eastern Pacific) and will be incorporated in the University of Wisconsin’s Cooperative Institute for Meteorological Satellite Studies (UW-CIMSS) workflow for further testing during operations in 2021.


2021 ◽  
Vol 36 (1) ◽  
pp. 4-12
Author(s):  
Arno Pronk ◽  
Peng Luo ◽  
Qingpeng Li ◽  
Fred Sanders ◽  
Marjolein overtoom ◽  
...  

There has been a long tradition in making ice structures, but the development of technical improvements for making ice buildings is a new field with just a handful of researchers. Most of the projects were realized by professors in cooperation with their students as part of their education in architecture and civil engineering. The following professors have realized ice projects in this setting: Heinz Isler realized some experiments since the 1950s; Tsutomu Kokawa created in the past three decades several ice domes in the north of Japan with a span up to 25 m; Lancelot Coar realized a number of fabric formed ice shell structures including fiberglass bars and hanging fabric as a mold for an ice shell in 2011 and in 2015 he produced an fabric-formed ice origami structure in cooperation with MIT (Caitlin Mueller) and VUB (Lars de Laet). Arno Pronk realized several ice projects such as the 2004 artificially cooled igloo, in 2014 and 2015 dome structures with an inflatable mold in Finland and in 2016–2019, an ice dome, several ice towers and a 3D printed gridshell of ice in Harbin (China) as a cooperation between the Universities of Eindhoven & Leuven (Pronk) and Harbin (Wu and Luo). In cooperation between the University of Alberta and Eindhoven two ice beams were realized during a workshop in 2020. In this paper we will present the motivation and learning experiences of students involved in learning-by-doing by realizing one large project in ice. The 2014–2016 projects were evaluated by Sanders and Overtoom; using questionnaires among the participants by mixed cultural teams under extreme conditions. By comparing the results in different situations and cultures we have found common rules for the success of those kinds of educational projects. In this paper we suggest that the synergy among students participating in one main project without a clear individual goal can be very large. The paper will present the success factors for projects to be perceived as a good learning experience.


Author(s):  
Jorge L. Villacís ◽  
Jesús de la Fuente ◽  
Concepción Naval

A renewed interest in the study of character and virtue has recently emerged in the fields of Education and Psychology. The latest research has confirmed the association between virtuous consistent behaviours and academic positive outcomes. However, the motivational dimension of character (the intentions underlying the patterns of observed behaviours) has received little attention. This research aims to extend the knowledge on this topic by examining the predictive relationships between the behavioural and motivational dimensions of character, with reference to academic engagement, career self-doubt and performance of Spanish university students. A total of 183 undergraduates aged 18–30 (142 of whom were women) from the north of Spain completed specific parts of self-report questionnaires, including the Values in Action VIA-72, a Spanish translated and validated version of the Moral Self-Relevance Measure MSR, and the Utrecht Work Engagement Student Scale UWES-S9. The collected data were analysed using Structural Equation Modelling. The behavioural dimension of character (character strength factors of caring, self-control and inquisitiveness) showed positive associations with academic engagement and performance. The motivational dimension of character (phronesis motivation), was negatively related to career self-doubt. For the first time, the present study has provided support for the contribution of both dimensions of character to undergraduate academic outcomes.


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