scholarly journals Influence of Foundation Pit Excavation and Precipitation on Settlement of Surrounding Buildings

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hongming Wei
Keyword(s):  
Lateral Displacement ◽  
Research Work ◽  
Soil Layer ◽  
Internal Force ◽  
Precipitation Process ◽  
Structural Members ◽  
Foundation Pit ◽  
Adjacent Buildings ◽  
Calculation Results ◽  
Excavation Methods

With the large-scale development of urban underground space, foundation pit engineering has become one of the important geotechnical engineering topics in urban construction. In this paper, the effects of foundation pit excavation and precipitation on adjacent buildings are studied in detail. The main research work includes the following aspects: summarizing and analyzing the soil consolidation theory, foundation pit excavation, and precipitation process; the influencing factors of the adjacent soil layer displacement; the influence mechanism and influence types of foundation pit excavation and precipitation on adjacent buildings. The finite element model considering the whole process of foundation pit excavation is established, and the variation law of the upper layer displacement around the foundation pit is analyzed. The deformation law of the retaining structure, the calculation results of precipitation and nonprecipitation, and different excavation methods will be analyzed and compared. The calculation results show that the displacement of the soil layer around the foundation pit is also different between different excavation methods. As the distance between the foundation pits increases, the lateral displacement of the underground continuous wall near the frame structure gradually decreases. The distance from the foundation pit wall is 30 m. The maximum value of the lateral shift is reduced by 4.7% compared with 5 m. The foundation pit is studied, as well as the law of internal force variation of adjacent buildings caused by digging and precipitation, and checking the safety and adaptability of structural members. The calculation results show that a large additional internal force will be generated on the bottom floor of the adjacent building, and some structural members will be damaged by the bearing capacity.

Comparative Analysis of the Influence of Different Construction Technology for Excavation on Adjacent Tunnels

2014 ◽  
Vol 638-640 ◽  
pp. 884-887
Author(s):  
Yong Gang Du ◽  
Jing Cao ◽  
Zu De Ding
Keyword(s):  
Lateral Displacement ◽  
Internal Force ◽  
Calculation Model ◽  
Construction Technology ◽  
Tunnel Structure ◽  
Lateral Deformation ◽  
Foundation Pit ◽  
Engineering Construction ◽  
Excavation Process ◽  
Calculation Results

Based on the project of a foundation pit engineering adjacent to existing tunnel of Kunming metro line 1, a 3D calculation model is established in consideration the interaction of foundation pit support structures, tunnel structure and soil. In this paper, the authors have simulated the foundation pit excavation process in three conditions, and analyzed the changing laws of the lateral displacement and internal force of the tunnel induced by adjacent excavation under different conditions. Calculation results show that the distributions and the values of the displacement and internal force of the tunnel are obviously different under three different construction technologies, and the “jump dig” is the optimum excavation scheme due to the restriction in the excavation of foundation pit, and the lateral deformation of tunnel structure is smallest in this condition. The conclusion can provide a theoretical basis for similar excavation engineering construction.

scholarly journals Comparative Study of Pile Pillared Support and Pile-anchor Retaining in Deep Pit

2020 ◽  
Vol 143 ◽  
pp. 01042
Author(s):  
Chengxiang Wang ◽  
Chengkun Lu ◽  
Wei Han ◽  
Hongsong Sun ◽  
Huailiang Kou
Keyword(s):  
Elastic Modulus ◽  
Internal Friction ◽  
Axial Force ◽  
Soil Layer ◽  
Friction Angle ◽  
Internal Force ◽  
Internal Friction Angle ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit

Support pattern is the most important factor affecting the stability of foundation pit. In order to study the stable state of deep foundation pit, this paper selects pile pillared support and pile-anchor retaining which are high accident rate for comparison, and optimizes the construction scheme combined with the actual deep foundation pit project. The deformation of the supporting structure and the settlement of the foundation pit of Huiquan Square are used to analyze by FLAC3D. The variation range and trend of the internal force of the steel support and the axial force of the anchor cable are analyzed under the different values of the soil layer parameters, such as elastic modulus, cohesion and internal friction angle. The results show that the internal force of pile pillared support is greatly affected by the change of cohesion and the anchor axial force is greatly affected by the change of elastic modulus and internal friction angle. Meanwhile, the influence degree of each soil layer parameter on the internal force of support structure is different, which provides reference suggestions for the selection of support pattern of deep foundation pit.

scholarly journals Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
High Strength ◽  
Element Model ◽  
Internal Force ◽  
Foundation Pit ◽  
Dimensional Finite Element ◽  
Influence Of Temperature On ◽  
Scale Experiment ◽  
Three Dimensional Finite Element

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

On Numerical Simulation of the Stepped Soil-Nail Wall

2013 ◽  
Vol 353-356 ◽  
pp. 692-695
Author(s):  
Chang Zhi Zhu ◽  
Quan Chen Gao
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Internal Force ◽  
Numerical Results ◽  
Analysis Model ◽  
Foundation Pit ◽  
Soil Nails ◽  
Soil Nail ◽  
Soil Nail Wall ◽  
Design And Construction

Based on an Engineering Example which was supported by the stepped soil-nail wall, a numerical analysis model was established by FLAC3D,and the process of the excavation and supporting was simulated, and the numerical results of the soil nails internal force and foundation pit deformation were obtained. The simulated result was consistent with the measured results. It shows that the method of FLAC3D numerical analysis can be used to the numerical analysis of foundation pit excavation and supporting, and it will provide the basis for the design and construction of practice project.

A Study on the Simplified Calculation Method for the Residual Ultimate Strength of Damaged Hull Structures

2016 ◽  
Author(s):  
Kimihiro Toh ◽  
Shunsuke Maeda ◽  
Takao Yoshikawa
Keyword(s):  
Ultimate Strength ◽  
Calculation Method ◽  
Fe Analysis ◽  
Structural Members ◽  
Average Strain ◽  
Non Linear ◽  
Compressive Loads ◽  
Calculation Results ◽  
Simplified Calculation ◽  
Simplified Calculation Method

In order to obtain the non-linear average stress-average strain relationships (σ-ε curves) of damaged structural members under both tensile and compressive loads, the systematical calculations are performed using the non-linear FE analysis (FEA) code, LS-DYNA, and the idealized σ-ε curves of damaged structural members are estimated from FEA results. In addition, by introducing the idealized σ-ε curves of damaged structural members to the simplified calculation program, which is developed by authors and based on the Smith’s method, the residual ultimate strength of damaged hull structures is calculated. The residual ultimate strength of damaged hull structures is also calculated utilizing FEA, the calculation results by the simplified calculation program are compared with the results obtained from FE analyses so as to examine the accuracy of simplified calculation method.

scholarly journals Wind turbine wake models' evaluation for different downstream locations

2021 ◽  
Vol 6 ◽  
pp. 40
Author(s):  
Panagiotis Triantafyllou ◽  
John K. Kaldellis
Keyword(s):  
Wind Speed ◽  
Research Work ◽  
Past Research ◽  
Wake Flow ◽  
Wake Effect ◽  
Calculation Results ◽  
Wind Park ◽  
Semi Empirical ◽  
Turbine Wake ◽  
Streamwise Distance

The land use limitations, especially for onshore applications, have led modern Wind Turbines (WTs) to be aggregated in wind parks under the scope of minimizing the necessary area required. Within this framework, the trustworthy prediction of the wind speed deficiency downstream the WTs' hub (known also as the “wake effect”) and the meticulous wind park micrositing are of uppermost importance for the optimized WTs siting across the available land area. In this context, substantial effort has been made by the academic and research community, contributing to the deployment of several analytical, numerical and semi-empirical wake models, attempting to estimate the wind speed values at different locations downstream a WT. The accuracy of several semi-empirical and analytical wake models, serving also as the basis for pertinent commercial software development, is investigated in the present work, by comparing their outcome with experimental data from a past research work that concerns the wake flow. The dimensionless streamwise distance (known also with the term “downstream distance”) from the WT's hub is used as benchmark in order to categorize and evaluate the calculation results. A dedicated comparison between the wind speed cases investigated is conducted, striving to properly assess the wake models' prediction accuracy. The notable findings obtained for the wake models examined designate the requirement for subsequent research to enlighten the wake effect dynamic behavior.

Analysis of the Effects on Optimization Design about Double-Row Piles Retaining Structure

2012 ◽  
Vol 204-208 ◽  
pp. 72-78
Author(s):  
Yu Wang ◽  
Yan Ting Yang ◽  
Feng Yu ◽  
Guang Lei Hu
Keyword(s):  
Optimization Design ◽  
Internal Force ◽  
Composite Foundation ◽  
Foundation Pit ◽  
Double Row ◽  
Retaining Structure ◽  
Supporting Structure ◽  
Arch Effect ◽  
Space Effect ◽  
Foundation Pile

Double-row piles retaining structure has been widely used in the project now, but the stress mechanism of double-row pile is more complex; Its internal force and deformation are affected by many factors. Understanding and mastering its effects has an important significance for the design and the optimization of double-row pile supporting structure. According to the comparison of the measured data and theoretical calculation about original support scheme and optimized support plan and combined with the soil test data, this paper takes the Jinan Cultural Arts Center(Theatre) stage bin foundation pit as an example to analyse the main effects of optimization design about double-pile supporting structure. The results show that soil shear strength, soil arch effect, influence of CFG composite foundation, pile-beam synergy effect and space effect of foundation pit play an important role for optimization design about double-pile supporting structure.

scholarly journals Intercropping cover crops with a poplar short rotation coppice: Effects on nutrient uptake and biomass production

2018 ◽  
pp. 126-133 ◽  
Author(s):  
Nicola Silvestri ◽  
Vittoria Giannini ◽  
Daniele Antichi
Keyword(s):  
Water Content ◽  
Cover Crops ◽  
Dry Matter ◽  
Soil Cover ◽  
Plant Cover ◽  
Central Italy ◽  
Research Work ◽  
Soil Layer ◽  
Soil Parameters ◽  
Short Rotation

The risks of soil erosion and nutrient leaching can be considered appreciable in short rotation coppices especially in the first growth phases because of the absence of any plant cover. The temporary intercropping with legumes or grasses used as cover crops can help to overcome these environmental issues. The present research work aims to evaluate the effects of the introduction of cover crops in a short rotation poplar (Populus deltoides W. Bartram ex Marshall) with two-year harvest cycle. The plantation was located in a Typic Xerofluvent, silty-loam soil of the coastal Central Italy. Two different species of cover crops, Trifolium subterraneum L. (TS) and Lolium perenne L. (LP), were compared along with an untreated control, colonised by spontaneous vegetation (CO). Several plant and soil parameters were evaluated: the above ground biomass and nutrient accumulation for the three different soil cover types, the nitrate and water content in two soil layers (0.00-0.30 and 0.30-0.60 m), the poplar yield and nutrient content in branches and leaves. TS returned to the soil about 70 kg ha–1 of nitrogen at the end of its biological cycle, thanks to the high N content (over 2%) and to the noticeable amount of dry matter produced (3.46 t ha–1 of dry matter). This value was considerably higher than those of the LP (23 kg ha–1 of N) or CO (10 kg ha–1). The different amount of nitrogen returned to the soil affected both nitrate concentration in topsoil (0.00-0.30 m) and accumulation of nitrogen in poplar organs. Concerning phosphorous, the differences among treatments were less evident and the amount of P returned to the soil ranged from 2 (CO) to 10 (TS) kg ha–1. However, the effect of soil cover type on P uptake in poplar was still appreciable. Generally, the soil water content was slightly affected by the soil cover types. Indeed, the differences between the cover crops and the control became significant only in the shallowest soil layer and over the summer season. In the first year, LP induced a significant decrease in poplar yield (10.1 t ha–1 of dry matter) in comparison with TS (14.7 t ha–1) and CO (13.4 t ha–1), whereas in the second year there were no significant differences among treatments due to the weak regrowth of cover crops. These results show how to make it feasible a long lasting coexistence between cover crops and SRC, a clever design of agro-forestry systems is therefore needed.

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