scholarly journals Study on Flexural Bearing Capacity Calculation Method of Enclosure Pile with Partial Excision in Deep Foundation Pit

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Mingfeng Lei ◽  
Linghui Liu ◽  
Yuexiang Lin ◽  
Jin Li
Keyword(s):  
Flexural Strength ◽  
Bearing Capacity ◽  
Calculation Method ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Theoretical Derivation ◽  
Deep Foundation Pit ◽  
Practical Engineering ◽  
Capacity Calculation ◽  
Partial Excision

During deep foundation pit construction, the structural clearance intrusion, which is caused by the complex formation conditions and the inefficient drilling equipment, is usually detected due to the vertical deviation of piles. To meet construction requirements, pile parts intruding into the structural clearance are supposed to be excised. However, the sectional flexural strength of the pile is bound to decrease with partial excision, which would reduce the bearing capacity of the enclosing structure during construction. In this paper, a theoretical derivation of the normal sectional flexural strength of the partially excised circular pile is proposed. The derivation adopts the assumption of the plane section and steel ring equivalence and can be solved by the bisection method. Furthermore, the calculation method is applied to the pile evaluation of a practical engineering; also, the method is verified by the numerical method. The application results show that the excision of rebar and pile’s sectional area will cause a rapid linear decline in the sectional flexural strength. After excising 18 cm radial thickness of the circular pile (ϕ800 mm) and 6 longitudinal rebars, the sectional flexural strength of the pile decreases to 58% from the origin, which cannot meet the support requirement. The analysis indicates that pile reinforcements must be carried out to maintain the construction safety.

scholarly journals Analysis of Seepage Characteristics of a Foundation Pit with Horizontal Waterproof Curtain in Highly Permeable Strata

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1303
Author(s):  
Chenghua Shi ◽  
Xiaohe Sun ◽  
Shengli Liu ◽  
Chengyong Cao ◽  
Linghui Liu ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Theoretical Calculation ◽  
Calculation Method ◽  
Design Method ◽  
Water Pressure ◽  
Water Inflow ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Seepage Characteristics

At present, jet-grouted horizontal waterproof curtain reinforcement has become an essential method for deep foundation pit groundwater control. However, there is still a lack of an effective theoretical calculation method for horizontal waterproof curtain reinforcement, and there is little research on the seepage laws of foundation pits under different horizontal waterproof curtain conditions. Based on Darcy’s seepage theory, theoretical analysis models of deep foundation pit seepage were established considering the effect of a horizontal curtain in a highly permeable formation. Through the established models, the calculation method of the water inflow and the water pressure under the condition of a horizontal curtain was derived. Then through indoor tests, the reliability of the theoretical calculation method was verified. Furthermore, the established theoretical calculation method is used to analyze the influence of various factors on the water inflow and the water pressure, such as the ratio of hydraulic conductivity of the horizontal curtain to surrounding soil, thickness, and reinforcement position of the horizontal curtain. It is found that the hydraulic conductivity ratio has the most significant influence on the seepage characteristics of the foundation pit. Finally, the design method was applied to an example of the horizontal waterproof curtain of the foundation pit, which is located at Juyuanzhou Station in Fuzhou (China). The water inflow per unit area is 0.36 m3/d in the foundation pit, and this implies that the design method of the horizontal waterproof curtain applied for the excavation case is good and meets the requirements of design and safety.

Analysis on the Design and Application of Prestressed Concrete Supporting Piles

2010 ◽  
Vol 44-47 ◽  
pp. 173-176
Author(s):  
Dong Ming Yu ◽  
Zhi Qin Liu ◽  
Feng Guang Chen
Keyword(s):  
Prestressed Concrete ◽  
Deep Foundation ◽  
Engineering Project ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Concrete Piles ◽  
Adjacent Building ◽  
Practical Engineering ◽  
Concrete Materials ◽  
Actual Settlement

The supporting piles of deep foundation pits are usually made in reinforced concrete materials and rarely in prestressed concrete materials. But prestressed concrete materials have higher stiffness and less deformation and are suitable for controlling displacements or settlements. So, in this paper a practical engineering project as an example, the prestressed concrete supporting piles of the deep foundation pit are calculated and designed. Then, the settlement and inclination of the building adjacent the foundation pit with the prestressed concrete piles are calculated in the numerical software, FLAC. The results calculated in FLAC are compared with the actual settlement and inclination of the adjacent building during the foundation pit is excavated. The comparison confirms the feasibility of the supporting structure. This is a useful trial on the design of the prestressed concrete supporting piles.

Research on Application of Deep Foundation Pit Decompression Dewatering Technology and Impact on Surrounding Environment

2013 ◽  
Vol 671-674 ◽  
pp. 101-104
Author(s):  
Dong Dong Zhang ◽  
Jun Wen Ding ◽  
Rong Biao Wang
Keyword(s):  
Engineering Application ◽  
Pumping Test ◽  
Rail Transit ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Hydrogeological Parameters ◽  
Surrounding Environment ◽  
Practical Engineering ◽  
Research On Application

The studies application of deep foundation pit decompression technology focusing on special engineering geological and hydrogeological conditions. Taking foundation pit dewatering of certain rail transit station as an example, designs deep foundation pit decompression precipitation technology scheme with hydrogeological parameters obtained through pumping test, and assesses and monitors its impacts on surrounding environment according to measured data on project site, which has achieved good results in practical engineering application and provides foundation for construction of rail transit lines.

Study on Engineering Materials with the Comparison and Discussion of Support Scheme in a Foundation Pit

2013 ◽  
Vol 788 ◽  
pp. 623-626
Author(s):  
Zheng Zhen ◽  
Ren Wang Liang
Keyword(s):  
Numerical Simulation ◽  
Shear Force ◽  
Simulation Analysis ◽  
Bending Moment ◽  
Engineering Material ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Cost Performance ◽  
Deep Foundation Pit ◽  
Practical Engineering

Taking a deep foundation pit engineering in Taiyuan as research background, this paper used two different supporting structure of foundation pit to make numerical simulation analysis by using Li zheng software. The engineering material had high cost performance. In addition, the paper studied the displacement, bending moment, shear force with the change of the excavation depth, and it came to the conclusion that some outcome can be used for reference in the practical engineering.

Compared Analysis of Deformation Monitoring with Numerical Simulation on Pile-Anchor Supporting System of Deep Foundation Pit in Soil-Rock Dualistic Area

2013 ◽  
Vol 353-356 ◽  
pp. 3598-3605
Author(s):  
Xiao Dong Yi ◽  
Peng Huang ◽  
Zhi Chao Wang
Keyword(s):  
Deformation Monitoring ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Dual Structure ◽  
Deep Foundation Pit ◽  
Finite Element Software ◽  
Whole Process ◽  
Practical Engineering ◽  
Similar Location ◽  
Design Construction

Deep foundation pit supporting in soil-rock areas has been occurred commonly in Dalian. In the dual structure deep foundation pit in which platform is reserved, pile-anchor support as a typical form of foundation pit support, how to play its role effectively and make the design economical and safety is the subject which was explored continuously in recent years. Through a practical engineering case, this paper will use finite element software ABAQUS to simulate the whole process of pit excavation. Simulation results show that the boundary of the dual structure is the key position that caused the “sharp deformation” of the supporting structure. Compared with monitoring data, the results indicate that the reliability of the numerical model and the relevant deformation laws are verified, which can be used for the reference for the design, construction and monitoring of the deep foundation pit support in the similar location.

A Method of Calculation on the Deformation of Column Piles in Deep Foundation Pit

2013 ◽  
Vol 291-294 ◽  
pp. 1131-1134
Author(s):  
Lin Na Sun ◽  
Yan Liu ◽  
Li Ming Zhang
Keyword(s):  
Calculation Method ◽  
Bending Moment ◽  
Practical Case ◽  
Vertical Deformation ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Method Of Calculation ◽  
Overall Stability

During excavation of deep foundation pits, the effects of vertical deformation on column piles are often neglected while those uplifts may lead to destruction of internal supports. The factors leading to the column piles' vertical deformation mainly include basal uplift and vertical loads. In this paper, the causation and mechanism of the column piles' uplift are discussed. The influence of the additional bending moment due to the column piles' vertical deformation on the overall stability of the founda-tion pit is analyzed. A calculation method of the permissible value of vertical deformation is present¬ed. The method is verified by a practical case to be feasible.

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.

Vertical Displacement Accuracy Analysis of Foundation Pit Monitoring

2014 ◽  
Vol 608-609 ◽  
pp. 895-898
Author(s):  
Guang Zhang ◽  
Chang Chuan Chen ◽  
Yi Wen Yang ◽  
Xiu Ling Jiang
Keyword(s):  
Influence Factors ◽  
Vertical Displacement ◽  
High Light Intensity ◽  
Worker Safety ◽  
Monitoring Data ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Monitoring Point ◽  
Deep Foundation Pit ◽  
Practical Engineering

Foundation pit monitoring requirement for data accuracy is very high, especially the deep foundation pit. Monitoring data accurate or not directly related to the project of construction safety and worker safety. This paper analyzes the influence factors of foundation pit vertical displacement monitoring, Combined with practical engineering to improve the accuracy of monitoring, the conclusion: Reasonable layout of monitoring point reasonable ,Fixed observers,Fixed level and matched leveling rod,Take an umbrella when high light intensity,Observation in construction vibration is small, such measures can effectively improve the accuracy of monitoring data

The Analysis on the Deformation Predition of Pile-Anchor Retaining Structure in Deep Foundation Pit in Kunming

2012 ◽  
Vol 166-169 ◽  
pp. 1222-1225 ◽  
Author(s):  
Yin Hui Chen ◽  
Yu Wen Wang
Keyword(s):  
Horizontal Displacement ◽  
Deformation Characteristics ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Maximum Displacement ◽  
Deep Foundation Pit ◽  
Retaining Structure ◽  
Information Construction ◽  
Practical Engineering ◽  
Important Means

This article from deformation characteristics of deep foundation pit which support by the pile anchor, then using neural network and Matlab software to establish the time series model to prediction and analysis the deep horizontal displacement of soil. The prediction results show that the overall shape of the curve is similar to "bow” ,and with the depth of excavation the maximum displacement occurred by the beginning of the location of 0.5 m from the surface to move to about half of the excavation depth That is the H/2 up and down position. The results have some reference to the practical engineering in a certain extent, this explain that the prediction is a kind of important means to realize information construction.

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