scholarly journals Local Failure and Reliability Analysis of Horizontal Struts in Deep Excavation Based on Redundancy Theory

2021 ◽  
Author(s):  
Jianhua Liu ◽  
Shaoming Wu ◽  
Linfeng Wang ◽  
Xiaohan Zhou
Keyword(s):  
Numerical Calculation ◽  
Reliability Analysis ◽  
Calculation Model ◽  
Local Failure ◽  
Deep Excavation ◽  
Large Area ◽  
Supporting Structure ◽  
The Third ◽  
Diaphragm Walls ◽  
Supporting Structures

The instability failure of many deep excavations supported by diaphragm walls (retaining piles) and horizontal struts is caused by the local failure of struts and the following large area chain effect. The lack of redundancy of struts is an important reason for the overall failure of supporting structures. In this paper, based on an actual excavation project, the numerical calculation model is established by Flac3D5.0, and the reliability of the supporting structure is analyzed based on the redundancy theory. The main conclusions are as follows: the redundancy of single support is large, and strut (6) (close to the middle of the excavation) is the most important. The redundancy is reduced due to continuous failure, and the redundancy is only 3.50 when strut (1)–(7) are all failed (half of the struts). The second row of the struts has the smallest redundancy, while the third row has the biggest redundancy.

Study of Seismic Design Method for Slope Supporting Structure of Soil Nailing

2013 ◽  
Vol 353-356 ◽  
pp. 2073-2078
Author(s):  
Tian Zhong Ma ◽  
Yan Peng Zhu ◽  
Chun Jing Lai ◽  
De Ju Meng
Keyword(s):  
Seismic Design ◽  
Calculation Method ◽  
Retaining Wall ◽  
Earth Pressure ◽  
Calculation Model ◽  
Soil Nailing ◽  
Case Record ◽  
Analysis And Design ◽  
Supporting Structure ◽  
Earthquake Action

Slope anchorage structure of soil nail is a kind of economic and effective flexible slope supporting structure. This structure at present is widely used in China. The supporting structure belong to permanent slope anchorage structure, so the design must consider earthquake action. Its methods of dynamical analysis and seismic design can not be found for the time being. The seismic design theory and method of traditional rigidity retaining wall have not competent for this new type of flexible supporting structure analysis and design. Because the acceleration along the slope height has amplification effect under horizontal earthquake action, errors should be induced in calculating earthquake earth pressure using the constant acceleration along the slope height. Considering the linear change of the acceleration along the slope height and unstable soil with the fortification intensity the influence of the peak acceleration, the earthquake earth pressure calculation formula is deduced. The soil nailing slope anchorage structure seismic dynamic calculation model is established and the analytical solutions are obtained. The seismic design and calculation method are given. Finally this method is applied to a case record for illustration of its capability. The results show that soil nailing slope anchorage structure has good aseismic performance, the calculation method of soil nailing slope anchorage structure seismic design is simple, practical, effective. The calculation model provides theory basis for the soil nailing slope anchorage structure of seismic design. Key words: soil nailing; slope; earthquake action; seismic design;

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.

scholarly journals Exploring the bulk of the BL Lacertae object population

2018 ◽  
Vol 618 ◽  
pp. A175
Author(s):  
F. D’Ammando ◽  
M. Giroletti ◽  
S. Rainó
Keyword(s):  
Radio Emission ◽  
Test Statistic ◽  
Large Area ◽  
Bl Lacertae ◽  
The Third ◽  
Long Baseline ◽  
Photon Index ◽  
Multi Wavelength ◽  
Doppler Factor ◽  
Bl Lacs

Aims. We are studying an unbiased sample of 42 nearby (z < 0.2) BL Lacertae objects with a multi-wavelength approach. The results of Very Long Baseline Interferometry observations were presented in the first paper of this series. In this paper, we study the γ-ray properties of the sample. Methods. We analyse data collected by the Fermi-Large Area Telescope (LAT) during its first 8.5 yr of operation in the energy range 0.1−300 GeV. Results. We reveal 23 sources with a test statistic greater than 25 (corresponding to ~4.6-σ) out of 42, with 3 sources not detected in the third LAT active galactic nucleus (AGN) catalogue, and fluxes between 3.5 × 10−10 and 7.4 × 10−8 ph cm−2 s−1. The majority of the sources have hard spectra (Γ ≤ 2), with only four having values in the range 2.1–2.4. The three newly detected sources have fluxes in the range between 0.54 × 10−9 and 1.35 × 10−9 ph cm−2 s−1 and photon index 1.7–1.9. Among the 23 LAT-detected sources, 19 are included in the third catalogue of hard Fermi-LAT sources, with a spectrum that connects relatively smoothly from 0.1 GeV to 2 TeV. LAT-detected BL Lacs are more luminous on parsec scales with respect to non-LAT-detected sources and have larger core dominance according to the unified models. Conclusions. The LAT-detected BL Lacs seem to be composed of a bulk of “classical” sources dominated by Doppler boosting and characterised by compact and bright radio emission as well as hard γ-ray spectra. Moreover, we have identified a possible population of low-luminosity BL Lacs not detected by LAT, lacking a VLBI core, and with a small Doppler factor. Furthermore, three LAT-detected sources show non-classical properties for γ-ray emitting BL Lacs (no evidence of relativistic jet, low Doppler factor in radio images, relatively low core dominance) and three other sources, while showing radio emission on parsec scales, are not detected in γ rays so far.

Numerical calculation of crack width in prestressed concrete beams with bond-slip effect

2019 ◽  
Vol 15 (2) ◽  
pp. 523-536
Author(s):  
Jinliang Liu ◽  
Yanmin Jia ◽  
Guanhua Zhang ◽  
Jiawei Wang
Keyword(s):  
Numerical Calculation ◽  
Numerical Model ◽  
Prestressed Concrete ◽  
Calculation Method ◽  
Crack Width ◽  
Calculation Model ◽  
Content Type ◽  
Bond Slip ◽  
Stress Calculation ◽  
Bonding Performance

Purpose The calculation of the crack width is necessary for the design of prestressed concrete (PC) members. The purpose of this paper is to develop a numerical model based on the bond-slip theory to calculate the crack width in PC beams. Design/methodology/approach Stress calculation method for common reinforcement after beam crack has occurred depends on the difference in the bonding performance between prestressed reinforcement and common reinforcement. A numerical calculation model for determining the crack width in PC beams is developed based on the bond-slip theory, and verified using experimental data. The calculation values obtained by the proposed numerical model and code formulas are compared, and the applicability of the numerical model is evaluated. Findings The theoretical analysis and experimental results verified that the crack width of PC members calculated based on the bond-slip theory in this study is reasonable. Furthermore, the stress calculation method for the common reinforcement is verified. Compared with the model calculation results obtained in this study, the results obtained from code formulas are more conservative. Originality/value The numerical calculation model for crack width proposed in this study can be used by engineers as a reference for calculating the crack width in PC beams to ensure the durability of the PC member.

scholarly journals COMPARISON OF THREE CALCULATION METHODS OF ENERGY PERFORMANCE CERTIFICATES IN SLOVENIA

2018 ◽  
Vol 13 (1) ◽  
Author(s):  
Wadie Kidess
Keyword(s):  
Numerical Calculation ◽  
Energy Performance ◽  
Heat Losses ◽  
Calculation Methods ◽  
The Third ◽  
Simplified Method ◽  
Calculation Results ◽  
Thermal Bridges ◽  
Simplified Calculation ◽  
Family House

In order to get the authorization for issuing energy performance certificates in Slovenia, the expert candidate has to attend the prescribed course and pass the exam. The simplified method for heat losses calculation that is taught at this course neglects the thermal bridges, raising concerns whether the calculation results are reliable. In this paper we have compared three methods for calculation of thermal losses for a “typical” family house. The first is the above mentioned simplified calculation using a correctional factor; the second takes into account the thermal bridges, using linear thermal transmittances obtained by numerical calculation, and the third takes into account the thermal bridges, using default values for linear thermal transmittances. Noting that the second method returns the most exact values, we have found that the first method results are too large, yet still smaller than the third method results.

Numerical Calculation Model of Single Wafer Wet Etcher Using Swinging Nozzle

2013 ◽  
Vol 58 (6) ◽  
pp. 39-46 ◽  
Author(s):  
H. Habuka ◽  
S. Ohashi ◽  
K. Mizuno ◽  
T. Kinoshita
Keyword(s):  
Numerical Calculation ◽  
Calculation Model
Sign in / Sign up

Export Citation Format

Share Document