Study on Stressed Characteristic of Gridding Concrete Retaining Wall Used in Excavation of Soft-Soil Foundation Pit

2011 ◽  
Vol 243-249 ◽  
pp. 2266-2270
Author(s):  
Guang Zhu Zhou ◽  
Xu Wei ◽  
Chen Yu
Keyword(s):  
Retaining Wall ◽  
Soft Soil ◽  
Side Wall ◽  
Building Envelope ◽  
Front Wall ◽  
Soil Pressure ◽  
Back Wall ◽  
Foundation Pit ◽  
Partition Wall ◽  
Finite Element Software

As a new type of building envelope, Gcrw is mainly used for excavation of foundation pit. It can stand by itself without the help of bracing, especially in soft soil area. Its stressed characteristic hasn’t been known yet. By using advanced big finite element software Abaqus/Cae, a simulation was made on model of Gcrw under soil pressure when a foundation pit is dug, while the whole excavation is divided into three continuous independent excavation stages. The result shows that Gcrw is a rather good building envelope, Gcrw and soil in the gridding form an integral earth-retaining structure and keep balance under soil pressure before or behind the structure, and have little displacement in horizontal direction. It is like a gravity-type retaining wall in its entirety, but takes on an elastic characteristic. The soil pressure presents a linear change, but its value is less than the theoretical value of calculation. The front wall of Gcrw, like a sheet, is the main flexural construction element, which is subjected to the pressure from side wall of foundation pit and produce curve deformation. The back wall of Gcrw has little displacement and almost is built in the clay. The partition wall endures the effect of the tensile force, its horizontal deformation increases with the build-in depth’s increasing. The back wall and the partition wall play a very important role in dragging back the front wall, the role of them is similar to a pair of anchor tie. The soil in the gridding not only provides soil pressure, but also can fix the back wall, so it is seen as a part of Gcrw and in favor of the Gcrw’s anti-overturn.

Analyses of Earth Pressure on Gridding Concrete Retaining Wall in the Excavation of Deep Foundation Pit in Soft Soil Area

2011 ◽  
Vol 52-54 ◽  
pp. 2181-2186
Author(s):  
Guang Zhu Zhou ◽  
Xu Wei ◽  
Chen Yu
Keyword(s):  
Retaining Wall ◽  
Soft Soil ◽  
Earth Pressure ◽  
Front Wall ◽  
Three Dimension ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Finite Element Software ◽  
The Earth ◽  
Practical Engineering

This paper is mainly to study earth pressure on Gcrw used as a new kind of supporting structures in the excavation of deep foundation pits in soft soil region. On the basis of the simulation of step by step excavation by using big finite element software Abaqus/CAE and considering three-dimension elastoplastic stress state, the characteristics of different earth pressure are systematically discussed upon practical engineering. By comparing simulation results with calculated results based on calculation formula of Rankine Theory, it can be seen that the earth pressure in active zone is different from theoretic active earth pressure and earth pressure at rest while walls and soil in the gridding are regarded as a whole, which is greater than the former and somewhere similar to the latter, the earth pressure in passive zone is bigger than theoretic value of passive earth pressure, it is the tensive force from partition wall that prevent the front wall from overturning. These conclusions will be helpful for design and construction of new retaining wall.

scholarly journals Soil Pressure and Deformation Analysis of Small Size Deep Foundation Pit

2022 ◽  
Vol 2148 (1) ◽  
pp. 012061
Author(s):  
Zhao Long ◽  
Yilei Shi ◽  
Weili Li ◽  
Shuaihua Ye
Keyword(s):  
Finite Element ◽  
Limit Equilibrium ◽  
Side Wall ◽  
Soil Pressure ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Finite Element Software ◽  
Pressure Calculation ◽  
Space Effect

Abstract In this paper, the influence of space effect on soil pressure and deformation of deep foundation pit was considered, and the finite soil pressure calculation model was established. The soil pressure of deep foundation pit was calculated by assuming the slip surface and using the finite soil limit equilibrium theory. Then, PLAXIS 3D finite element software was used to establish finite element models of different plane sizes and depths. The distribution regulation of side wall soil pressure and deformation of deep foundation pit was calculated. Finally, the results of finite soil pressure calculation was compared with finite element method. The results shown that: The soil pressure of small deep foundation pit was affected by space effect, and the soil pressure and deformation decrease significantly along the foundation pit depth. Shear fracture Angle was related to the ratio of width to depth of foundation pit, and it was no longer a constant value of 45°+φ/2. Therefore, the spatial effect should be considered in the calculation of soil pressure of small deep foundation pit. The research results can provide some guidance for the design and calculation of similar small size deep foundation pit.

Research on Soil Nailing Method for Large Foundation Pit Treatment

2014 ◽  
Vol 638-640 ◽  
pp. 538-541
Author(s):  
Zi Mao Peng
Keyword(s):  
Side Wall ◽  
Design Parameters ◽  
Soil Pressure ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Building Foundation ◽  
Backfill Soil ◽  
Soil Complex ◽  
Large Building

Based on the introduction of the characteristics of the supporting project of a large building foundation pit, the paper analyzed the main reasons for side wall collapse and pile fracture, including leakage water in the backfill soil, complex geological environment and unreasonable soil pressure value, low safety factor and improper design parameters, and then respectively proposed three kinds of treatment schemes for side wall sliding and pile breaking, landslides and other dangers. Finally, tracking observation showed that the satisfactory effect can strongly verify the suitability and validity of the main control parameters for the deformation of deep foundation pit, which may provide reference for the design and construction of similar projects.

scholarly journals Experimental and Numerical Investigation on the Effects of Foundation Pit Excavation on Adjacent Tunnels in Soft Soil

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zi-Tian Yu ◽  
Heng-Yu Wang ◽  
Wenjun Wang ◽  
Dao-Sheng Ling ◽  
Xue-Dong Zhang ◽  
...  
Keyword(s):  
Retaining Wall ◽  
Soft Soil ◽  
Shear Bands ◽  
Earth Pressure ◽  
Bending Moment ◽  
Surface Settlement ◽  
Diaphragm Wall ◽  
Foundation Pit ◽  
Obvious Effect ◽  
Diaphragm Walls

Excavations near an existing tunnel are often encountered in underground construction. The influence of the excavation on the adjacent tunnels is not yet fully understood. This study presented a centrifugal model test about excavation next to existing tunnels in soft soil foundation. The bending moment of diaphragm wall, surface settlement, tunnel deformation, and earth pressure around the tunnel were mainly studied. The influence of tunnel location is further studied by numerical simulation. During the stabilization stage of foundation pit, the diaphragm walls present convex deformation towards foundation pit, and the surface settlement outside the diaphragm wall appears to be the concave groove type. During the overexcavation stage, the diaphragm walls are almost damaged, and the shear bands are nearly tangent to the tunnels. The displacement of the tunnels and the surface settlement rapidly increase. The deformation of the diaphragm wall and the surface settlement are limited by the existing tunnel. The numerical results indicate that the change of tunnel location has little effect on the retaining wall but an obvious effect on the tunnel itself.

scholarly journals Bearing Characteristics of Moso Bamboo Micropile-Composite Soil Nailing System in Soft Soil Areas

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Zhihe Cheng ◽  
Yousheng Deng
Keyword(s):  
Axial Force ◽  
Slip Surface ◽  
Soft Soil ◽  
Side Wall ◽  
Moso Bamboo ◽  
Shallow Foundation ◽  
Soil Nailing ◽  
Foundation Pit ◽  
Soil Nails ◽  
Composite Soil Nailing

Based on the characteristics of moso bamboo including high short-term strength, stable performance, and ability to provide temporary support for shallow foundation pits in soft soil, the stress characteristics and supporting effects of the ecological composite supporting system have been explored through model tests and numerical calculation analysis of the moso bamboo micropile-composite soil nailing structure. The results showed that the bamboo pile can effectively control the horizontal deformation of the side wall of the foundation pit and the ground surface settlement, achieving a relatively satisfactory supporting effect. Furthermore, the bamboo pile has visibly bent in middle and lower parts, where the regional shear point is most likely to appear, the axial force of the soil nail is distributed in an oval pattern with a smaller force on both sides and a larger force in the middle part, the maximum axial strain is 447.3 με, and the axial force of the soil nails in each row follows a similar trend. The synergy of piles and soil nails can delay the formation of the slip surface, therefore enhancing the overall bearing capacity of the foundation pit. These results can shed light on the support mechanism and engineering design of bamboo piles in shallow soft soil foundation pits.

Analysis of the Interaction of Foundation Pit Supporting Structure and Soil

2014 ◽  
Vol 580-583 ◽  
pp. 401-404
Author(s):  
Yu Qin Feng ◽  
Chen Xi Liu
Keyword(s):  
Soft Soil ◽  
Earth Pressure ◽  
Large Area ◽  
Soil Pressure ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Supporting Structure ◽  
Distribution Mode ◽  
Measure Soil Pressure

This paper analyzes an engineering in an area of China which was processed by vacuum preloading technology in the silt soft soil. This engineering was used rigid supporting structure technology of piles in row and bolts for large area of deep foundation pit supporting. It compared the realistic measure soil pressure and theoretical concluded soil pressure, and got the soil pressure distribution mode which is suitable for silt soft soil processed in this way. The conclusion can provide a reference for similar supporting structure system to calculate earth pressure.

The Analysis on Monitoring Data and Finite Element Simulation of the Deep Foundation Pit in Tianjin

2011 ◽  
Vol 243-249 ◽  
pp. 2543-2547
Author(s):  
Shi Lun Feng ◽  
Yong Han ◽  
Jun Li ◽  
Pu Lin Li ◽  
Jie Liu
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Retaining Wall ◽  
Soft Soil ◽  
Monitoring Data ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Element Simulation ◽  
Excavation Process

Through the analysis on monitoring data of the deep foundation pit in Tianjin, it was observed that the lateral deformation of the retaining wall at the corner was smaller than the deformation in the middle. Based on the analysis of the results drawn from finite element simulation of the excavation process and the monitoring data, appropriate supporting structure stiffness parameters values used in Plaxis and Qimingxing are recommended for designing deep foundation pits in soft soil area.

scholarly journals Analysis of Lateral Displacement Law of Deep Foundation Pit Support in Soft Soil Based on Improved MSD Method

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Gang Lei ◽  
Xiaonan Gong
Keyword(s):  
Finite Element ◽  
Data Analysis ◽  
Calculation Method ◽  
Retaining Wall ◽  
Soft Soil ◽  
Analysis Method ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Data Analysis Method

Foundation pit envelope and foundation pit excavation solution design is a multidisciplinary problem that could be linked to a series of safety issues in the geotechnical engineering of an actual construction project. Moreover, the construction of large deep foundation pit in soft soil often faces greater risks and challenges as the support structure deforms more easily and unpredictably. In order to improve the deformation prediction of deep foundation pit engineering precision and efficiency and to ensure that the construction of deep foundation pit engineering is safe and efficient, in this article the traditional MSD (mobilizable strength design) theory research and analysis, combined with the Jinan formation characteristics of a tunnel in JInan, and new parameters were introduced to the original MSD method theory: the wall itself within the bending strain energy U and support compression elastic potential energy of V. A new law of conservation of energy is constructed, and finally, an optimized MSD method has been proposed, this method is shown in the article. Finally, the results of foundation pit deformation calculation were compared among the optimized MSD method, finite element calculation method, and field monitoring data analysis method, so as to demonstrate the reliability of the prediction system of optimized MSD method and finite element analysis method. The results show that, by optimizing the MSD calculation method, the horizontal displacement of the retaining wall varies depending on the excavation depth of the foundation pit and the form of internal support with the overall peak value of displacement between 0∼0.2% H (H being the excavation depth); the deformation of retaining wall increases gradually with the increase of excavation depth of the foundation pit, and the peak position of deformation gradually moves down with the excavation of foundation pit. The trend of these changes is consistent with the results of the finite element method and field data analysis method, proving that the optimized MSD method is reliable in predicting the deformation of the foundation pit under specific stratum conditions.

scholarly journals Design, construction and analysis for super-wide, deep and large foundation pit

2021 ◽  
Vol 72 (1) ◽  
pp. 117-126
Author(s):  
Shi Shenjie ◽  
Tian Angran ◽  
Zheng Yongsheng ◽  
Yin Peng ◽  
Qi Weilin ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Side Wall ◽  
Developed Countries ◽  
Underground Space ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Maximum Deformation ◽  
Retaining Structure ◽  
Finite Element Software ◽  
Design And Construction

Both developing and developed countries are facing a series of difficulties and challenges in the process of urbanization. In recent years, in order to alleviate the problem of urban congestion, underground space has developed rapidly, and the excavation of foundation pit is the most important step in the development of underground space. This paper takes the foundation pit of the tunnel under construction in Suzhou as a research object. The design width of the foundation pit reaches 61.5 m and the depth reaches 18 m, so it belongs to the super wide and deep foundation pit. Numerical analysis is performed by finite element software to calculate the deformation of the foundation pit. The research shows that the main problem to be solved is the deformation of the foundation pit, and the deformation of side wall of foundation pit tunnel is the most obvious. The maximum deformation of the side wall of the main tunnel and the auxiliary tunnel reached the maximum at 15 m. The maximum deformation of the main tunnel is about 1.3 cm, and that of the auxiliary tunnel is about 0.9 cm. Through targeted design and construction, the mechanical performance of the foundation pit retaining structure is optimized, and the stability of the foundation pit is strengthened. The reasonable retaining structure can ensure the good construction quality. The design and construction of the project can provide reference for related engineering construction.

Innovative approaches in the organization of closed waste-free production of organic pork using cultural and natural agricultural land

2020 ◽  
pp. 15-25
Author(s):  
Volodymyr Ivanov ◽  
Andrii Onyshchenko ◽  
Liudmyla Ivanova ◽  
Liudmyla Zasukha ◽  
Valerii Hryhorenko
Keyword(s):  
Agricultural Land ◽  
Side Wall ◽  
Front Wall ◽  
Lower Edge ◽  
Metal Mesh ◽  
Two Phase ◽  
Transparent Plastic ◽  
Pork Production ◽  
Young Pigs ◽  
Side Walls

The mobile house for two-phase litter rearing piglets was developed in the conditions of pasture their housing, the feature of which is that its side walls and roof are made in the form of two similar in shape and length of arched panels. In the back wall of the inner shield is a litter box, a self-feeder for piglets, a feed unit for a sow and a wicket, and in the front wall of the outer shield are doors with a wicket. Along with this, all walls and the roof of the litter box are made of transparent plastic, and the wall located near the self-feeding trough is also made perforated. In addition, the lower edge of the side wall of the inner arch-shaped shield has slides in which the lower edge of the side wall of the outer arc-shaped shield is inserted. A house with transformable fences has been developed to rear the young pigs. The structural feature of the house is the presence on the outside of the walls of the bobbins with a metal mesh edged at the bottom with a flexible sleeve. In order to ensure the conditions of gentle etching of the vegetation cover and to prevent damage to the turf of the pasture, the house can be completed with another type of hedge consisting of two hinged sections with doors on each side of the fence. In addition, the horizontal wings are rigidly attached to the hedge and connected by a metal mesh around the perimeter, the size of the cells of which ensures that the grass is eaten but prevents the turf of the pasture from being undermined. The developed devices for camp-pasture and feeding of maternal stock, suckling pigs, weaning pigs, repair and fattening pigs are well suited for year-round closed non-waste organic pork production using cultural and natural agricultural land. Key words: housing, feeding, devices, sows, piglets, young animals, pasture, organic pork.

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