scholarly journals A simplified 3D model for existing tunnel response to piles construction

2021 ◽  
Vol 16 (2) ◽  
pp. 87-103
Author(s):  
Bousbia Nawel ◽  
Messast Salah ◽  
Houssou Noura
Keyword(s):  
3D Model ◽  
Considerable Effect ◽  
Geometrical Parameters ◽  
Deep Foundations ◽  
Linear Elastic ◽  
High Rise ◽  
Pile Diameter ◽  
Coulomb Model ◽  
The Impact ◽  
Interaction Problem

Abstract The construction and loading of deep foundations (piles) of high-rise buildings causes a considerable effect in terms of stresses and deformation and requires assessing their impact on the response of adjacent tunnels to deformations, particularly for pile foundations, which are often constructed in locations very close to existing tunnels. The execution process for piles structures generates displacements, stresses, and forces, which are transferred through the piles’ soil surrounding a nearby existing tunnel. The research presented in this paper has led to a significantly improved understanding of pile-tunnel interaction problem. It is crucial for the analysis of the impact of the pile construction on an existing tunnel. The treated topic appears in a setting of an urban environment, where we construct numerous profound foundations, sometimes in contact or adjacent to a. In this paper, the response of the existing tunnel under constructed pile process is studied. Numerical modeling was carried out using Plaxis3D software in which the Mohr-Coulomb Model (MC) has been used for modeling, while the piles/ tunnels are modeled as a linear elastic material. Furthermore, a parametric study is conducted, and its cases are investigated. The displacements and the stresses generated on the tunnel lining decreases with the increase in relative distance between pile and tunnel (spacing), the location/length of the pile from the tunnel, the pile diameter, the number of piles. We have also identified two geometrical parameters of the tunnel: shape section and thickness lining which play a prominent role in the interaction between an existing tunnel and a new pile to excavate.

THEORETICAL STUDY OF THE EFFECT OF GEOMETRICAL PARAMETERS AND LOCATION OF ROTOR IMPACT ELEMENTS OF AN IMPACT-CENTRIFUGAL GRINDER ON SPEED AND ANGLES OF CRUSHED PARTICLES FLIGHT

2020 ◽  
Keyword(s):  
Granulometric Composition ◽  
Theoretical Study ◽  
Process Efficiency ◽  
Geometrical Parameters ◽  
Grinding Process ◽  
Main Work ◽  
Impact Element ◽  
The Impact ◽  
Positive Effect ◽  
Efficiency Indicators

One of efficiency indicators of grain grinders is grain granulometric composition. The basis of mixed fodder is crushed grain, the particles of which must have a leveled granulometric composition for subsequent mixing and obtaining a high-quality feed mixture. In agricultural production, hammer crushers are widely used, in which the destruction of grain occurs due to the impact of a hinged hammer. The main disadvantage of these crushers is that not the entire surface of the hammers is involved in grinding, thus reduces grinding process efficiency. A slightly different principle of material destruction is laid down in the basis of the proposed design of the shock-centrifugal grinder. Main work is performed by flat impact elements located on the rotor, which serve to accelerate crushed particles with subsequent impact of them on the bump elements. An important step in the design of new constructions of shock-centrifugal grinders is to determine size and location of the impact elements on the rotor, without which the grinding process is not possible. In the calculation method presented, the dependencies for determining the velocities and angles of a single particle flight from the surface of a flat impact element for its specified dimensions are proposed. Two variants of an impact element location on the rotor are considered and analyzed: radial and at an angle in the direction of rotor rotation. As a result of research carried out, it is noted that in the case of inclined position of an impact element on the rotor an increase in flight speed and flight angles change in crushed particles, which gives the opportunity to have a positive effect on grinding process.

Assessing the effect of night ventilation on PCM performance in high-rise residential buildings

2019 ◽  
Vol 43 (3) ◽  
pp. 229-249 ◽  
Author(s):  
Shahrzad Soudian ◽  
Umberto Berardi
Keyword(s):  
Thermal Energy ◽  
Phase Change Materials ◽  
Positive Impact ◽  
Residential Buildings ◽  
Solidification Rate ◽  
Operative Temperature ◽  
High Rise ◽  
Ventilation Strategies ◽  
Night Ventilation ◽  
The Impact

This article investigates the possibility to enhance the use of latent heat thermal energy storage (LHTES) as an energy retrofit measure by night ventilation strategies. For this scope, phase change materials (PCMs) are integrated into wall and ceiling surfaces of high-rise residential buildings with highly glazed facades that experience high indoor diurnal temperatures. In particular, this article investigates the effect of night ventilation on the performance of the PCMs, namely, the daily discharge of the thermal energy stored by PCMs. Following previous experimental tests that have shown the efficacy of LHTES in temperate climates, a system comprising two PCM layers with melting temperatures selected for a year-around LHTES was considered. To quantify the effectiveness of different night ventilation strategies to enhance the potential of this composite PCM system, simulations in EnergyPlusTM were performed. The ventilation flow rate, set point temperature, and operation period were the main tested parameters. The performance of the PCMs in relation to the variables was evaluated based on indoor operative temperature and cooling energy use variations in Toronto and New York in the summer. The solidification of the PCMs was analyzed based on the amount of night ventilation needed in each climate condition. The results quantify the positive impact of combining PCMs with night ventilation on cooling energy reductions and operative temperature regulation of the following days. In particular, the results indicate higher benefits obtainable with PCMs coupled with night ventilation in the context of Toronto, since this city experiences higher daily temperature fluctuations. The impact of night ventilation design variables on the solidification rate of the PCMs varied based on each parameter leading to different compromises based on the PCM and climate characteristics.

scholarly journals Monitoring the Impact of the Large Building Investments on the Neighborhood

2021 ◽  
Vol 11 (14) ◽  
pp. 6537
Author(s):  
Marian Łupieżowiec
Keyword(s):  
Groundwater Level ◽  
Soil Improvement ◽  
Deep Excavation ◽  
Large Area ◽  
Safety Measures ◽  
High Rise ◽  
The Impact ◽  
Large Building ◽  
Additional Safety ◽  
Made In

The article presents the concept of monitoring buildings and infrastructure elements located near large construction investments (the construction of high-rise buildings of the Oak Terraces housing estate in Katowice and the construction of a tunnel under the roundabout in Katowice along the intercity express road DTŚ). The impacts include deep excavation, lowering of the groundwater level over a large area, and dynamic influences related to the use of impact methods of soil improvement. The presented monitoring includes observation of the groundwater level with the use of piezometers, geodetic measurements of settlement and inclinations, as well as the measurement of vibration amplitudes generated during the works involving shocks and vibrations. It was also important to observe the development of cracks on the basis of a previously made inventory of damage. The results of the monitoring allow corrections to be made in the technology of works (e.g., reduction of vibration amplitudes, application of additional protections at excavations, etc.) or the use additional safety measures. Currently, there are also monitoring systems used during the operation of completed facilities.

Influence of nozzle exit geometrical parameters on supersonic jet decay

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Prasanta Kumar Mohanta ◽  
B. T. N. Sridhar ◽  
R. K. Mishra
Keyword(s):  
Aspect Ratio ◽  
Nozzle Exit ◽  
Ambient Air ◽  
Schlieren Image ◽  
Geometrical Parameters ◽  
Image Study ◽  
Aspect Ratios ◽  
Core Length ◽  
Supersonic Core Length ◽  
The Impact

Abstract Experiments and simulations were carried on C-D nozzles with four different exit geometry aspect ratios to investigate the impact of supersonic decay characteristics. Rectangular and elliptical exit geometries were considered for the study with various aspect ratios. Numerical simulations and Schlieren image study were studied and found the agreeable logical physics of decay and spread characteristics. The supersonic core decay was found to be of different length for different exit geometry aspect ratio, though the throat to exit area ratio was kept constant to maintain the same exit Mach number. The impact of nozzle exit aspect ratio geometry was responsible to enhance the mixing of primary flow with ambient air, without requiring a secondary method to increase the mixing characteristics. The higher aspect ratio resulted in better mixing when compared to lower aspect ratio exit geometry, which led to reduction in supersonic core length. The behavior of core length reduction gives the identical signature for both under-expanded and over-expanded cases. The results revealed that higher aspect ratio of the exit geometry produced smaller supersonic core length. The aspect ratio of cross section in divergent section of the nozzle was maintained constant from throat to exit to reduce flow losses.

Implementation of new high-rise building staircase pressure differential system improvements

2021 ◽  
pp. 014362442110446
Author(s):  
Dorota Brzezinska ◽  
Marcin Fryda
Keyword(s):  
Differential System ◽  
Technical Note ◽  
Pressure Differential ◽  
Test Results ◽  
High Rise ◽  
Lab Experiments ◽  
Improvement Method ◽  
System Improvement ◽  
The Impact ◽  
New Buildings

The following technical note demonstrates full-scale staircase test results of the pressure differential system improvement method described by Fryda et al. in 2021. It is a continuation of experimental research on the impact of the escape route’s leakages on the pressure differential systems for staircases. Based on the lab experiments, it has been found that an additional throttle of the leak implemented in the pressure differential system improves its effectiveness and allows it to be more precisely adjusted to the required overpressure. The results presented in this article have confirmed this hypothesis and provided the opportunity to apply for new patent solutions of a special throttle of the leak control and pressure regulating system. The proposed new leakage-based improvements could increase the efficiency of existing systems based on proportional-integral-derivative controller and could also be installed in new buildings.

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