Deformation Of Foundation Pit Research Articles

Application of BP-ARMA Combined Model Based on Entropy Method in the Prediction of Circle Beam Displacement of Foundation Pit

The prediction of deformation of foundation pit’s supporting structure is the basis of construction control of deep foundation pit. Meanwhile, it is vital to the safe excavation of foundation pit. In the work, the 1st project of Huaqiao in Jiantao Square of Kunshan City is chosen. Besides, model of combination based on entropy method is built to predict the displacement of circle beam with BP neural network and ARMA time series model. Finally, the analysis shows that combination models improve overall prediction on the premise of better predicting accuracy. Thus, it is of practical value.

Research on Soil Nailing Method for Large Foundation Pit Treatment

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.

Numerical Simulation Analysis of Isolation Pile-Steel Shotcrete Combined Support of Deep Foundation Pit Excavation

The rapid development of deep foundation pit engineering, has become an important part of the urbanization construction, which brings deep excavation support of geotechnical engineering problem research also became a major issue. This paper uses the international well-known geotechnical engineering numerical simulation software FLAC3D, through 3D finite difference numerical calculation and analysis, to better simulation calculation and analysis of deep foundation pit construction site condition, forecast after excavation of the deep foundation pit deformation displacement and dangerous position, analysis of deep foundation pit excavation process isolation pile - steel shotcrete combined support effect. Three dimensional numerical model analysis and calculation in deep foundation pit engineering design and construction scheme optimization with economy is convenient wait for a obvious advantages, can for deep foundation pit excavation of deep foundation pit support design and construction to provide effective basis.

Study on the Rheological Properties and Constitutive Model of Shenzhen Mucky Soft Soil

In order to obtain the basic parameters of numerical analysis about the time-space effect of the deformation occurring in Shenzhen deep soft-soil foundation pit, a series of triaxial consolidated-undrained shear rheology tests on the peripheral mucky soft soil of a deep foundation pit support were performed under different confining pressures. The relations between the axial strain of the soil and time, as well as between the pore-water pressure of the soil and time, were achieved, meanwhile on the basis of analyzing the rheological properties of the soil, the relevant rheological models were built. Analysis results were proved that the rheology of Shenzhen mucky soft soil was generally viscous, elastic, and plastic, and had a low yield stress between 90 and 150 kPa. The increase in pore-water pressure made the rheological time effect of the mucky soft soil more remarkable. Thus, the drainage performance in practical engineering should be improved to its maximum possibility extent to decrease the soft-soil rheological deformation. Lastly, a six-component extended Burgers model was employed to fit the test results and the parameters of the model were determined. Findings showed that the extended Burgers model could satisfactorily simulate the various rheological stages of the mucky soft soil. The constitutive model and the determination of its parameters can be served as a foundation for the time-space effect analysis on the deformation of deep soft-soil foundation pits.

Foundation Pit Deformation during the Excavation and Simulation

Based on the background of foundation pit excavation of a village, the process of excavation is simulated by FLAC3D .And the calculation and analysis is combined with the engineering practice. The results show that the deformation of foundation pit is mainly composed of ground surface settlement, and the maximum deformation occurred in the middle of the pit wall at the top of the part. The surface subsidence with the ongoing of the excavation, the general surface subsidence trend is rising. When it comes to the foundation pit, when the settlement velocity is very large, the foundation turns to be unstable, which need supporting methods. Flac3D program applied on the excavation of rock and soil deformation law study is feasible. The result of the study to further relevant basis are provided for the practical engineering and have certain practical application value to the rock and soil deformation in the process of excavation research.

Time Series Forecast of Foundation Pit Deformation Based on BP Neural Network

Combined with the advantage of BP neural network, a time series forecast method of foundation pit deformation based on BP neural network is proposed. According to the excavation process of foundation pit, the deformation forecast model is built by analyzing the measured data of early working stage. Then, the model is used to forecast the deformation of later working stage. Through an engineering optimization example, it is showed that this method is not only efficient, but also with good economic and practical value.

Study on Effect of Excavation Depth on Internal Force of Retaining Structure of Arc Row Piles with Arc Ring Beam on the Pile Top

In order to control deformation of foundation pit effectively and guarantee safety of building around, utilizing the stress characteristics of arch, use the new spatial retaining structure of arc row piles with arc ring beam on the pile top. The arc ring beam can provide constraint to pile top, so internal force of pile body distribution is uniform, and improve the integrity stability of piles. The ring beam with compression mainly can give use of high compression capability of concrete. According to the high order statically indeterminate characteristics of the retaining structure, calculation model of ring beam and pile respectively is established by the redundant forces between beam and pile top. By using deformation compatibility to set up flexibility equation of the retaining structure, and solve the redundant forces, then calculate the internal force and displacement of ring beam and piles. Through calculating the practical engineering, research the effect of excavation depth on internal force and displacement of piles and the arc ring beam on the pile top.

Construction Technology of one Unsymmetrical Loaded Deep Foundation Pit Adjacent to Expressway Subgrade

One deep foundation pit in Hefei urban rail transit project is adjacent to the existed expressway subgrade, it's in the unsymmetrical loaded state. The control of foundation pit deformation and the safety of subgrade must be strictly ensured. Based on it, the design scheme of supporting system, the construction processes of earth excavation, top beam, concrete support and steel support was introduced. The horizontal displacement of fender piles and the settlement of subgrade was monitored. The field monitoring results indicate, there exists a great difference between the retaining structure deformation under the action of unsymmetrical load and the deformation under the action of symmetrical load, the horizontal displacement of fender piles on the side of subgrade is bigger than the other side, the upper pile appears to be a "drift" towards the lower-load side; although the absolute value of horizontal displacement of fender piles and settlement of subgrade seems to be a big number, the relative value is small compared to the whole length of fender pile and expressway, meeting relevant standard requirements. The deep foundation pit and expressway kept safe and stable in the all periods of construction, no one accident was occurred during that time. Thus, it can be seen that this construction technology is effective in controlling the deformation during excavation, which can provide a reference for similar projects in design and construction in the future.

Research on the Deformation Monitoring of Deep Foundation Pit Engineering

Because of the excavation of deep foundation pit will have an important impact on the surrounding buildings, causing serious safety risks, In this paper, though the deformation monitoring of deep foundation pit engineering in No.1 Hospital of Jilin University, It has an in-depth analysis and research on the deformation law of foundation pit and surrounding buildings at the stage of foundation pit construction. The results show that the deformation monitoring analysis of deep foundation pit engineering can not only realize the construction information of deep foundation pit , correctly guide the engineering construction, prevent engineering accidents, but also help to further improve the theory of foundation pit deformation, provide reliable data for the design.

Application of Axial Force Compensation for Steel Support System in Practical Project

The problem always exist in foundation pit engineering that the support axial force can not be regulated in the pit system in real time.According to setting the axial force compensation system,the problem would be solved perfectly and efficiently,realizing the fact control and adjust the support axial force and stability. The axial force compensation system which is constituted by jacks distributed in the pit has been confirmed the significant role to control foundation pit deformation and internal force monitoring combined with practical engineering

Analysis and Research the Influence about the Control from the Excavation Way to Deformation of Foundation Pit

Different excavation methods present different influence on the deformation of foundation pit.Combining with engineering example,it analyzes and researches the excavation way of the reserved soil after foundation pit excavation.And through the application of the finite element software MIDAS GTS,it carries on the numerical simulation for the impact of section excavation sequence and different section length on the deformation.Ultimately it determines the optimal excavation sequence and length,and achieves the purpose of control deformation during construction.

Finite Element Analysis on Lateral Deformation of Foundation Pit Influenced by Prestress of Fish-Bellied Beam Support

The problem of loss of prestress and compensation of prestress of Fish-Bellied Beam Support exist in foundation pit construction but seldom be considered in design. Finite Element Analysis on an existed foundation pit engineering of prestressed Fish-Bellied Beam Support by using finite element software ABAQUS. Discussed the influence on lateral deformation of foundation pit caused by loss of prestress and compensation of prestress.The results show that the influence on lateral deformation of foundation pit caused by loss of prestress and compensation of prestress is remarkable, and existing a critical loss percentage, lateral deformation of foundation pit will be well controlled by adjusting compensation of prestress in terms of considering the critical loss percentage.

Analysis of Foundation Pit Deformation Monitoring Results about Xia Shengou Station in Shenyang

In the northeast of China,the research of subway foundation pit is still infancy,which needs enriching. This paper relies on the deep foundation pit engineering of Xiashengou Subway Station in Shenyang. Through the analysis of deformation foundation pits to study deformation characteristics.Through the monitoring data,we can know that combined the bored and steel support the deformation of the retaining structure and the ground surface subsidence can be well controlled.The deformation of the envelope and the surface has a strong time effect and increases with time,in the excavation stage,pile deformation presented randomness. In the excavation stage, pile deformation presented randomness.When the excavation completed 45 days,from the top of the pile to the pile at 13m depth,the lateral volume is almost equal, and thus down to the pile end the lateral volume gradually becomes zero.

Simulation Analysis on Tension and Deformation of Composite Soil Nailing

For studying the mechanism of the composite soil nailing, this paper applies FLAC-3D to simulate pure soil nailing, soil nailing-soil anchor, soil nailing-micro pile-soil anchor. The analytical results as follows: (1)Because of the anchoring of the anchor, the axial tension of soil nailing in each row is much smaller than the one in the pure soil nailing supporting, and the tension of soil nailing which are closed to soil anchor decreases obviously. (2)The extrusion action of prestressed anchor makes the potential slip surface backward shifts and the sliding radius increases, which is better for the stability of foundation pit side (3)Micro-pile increases the strength of the soil in a certain range and improves the initial stress field before the excavation. (4)The inner force of the whole soil nailing and the prestress anchor declines but the drop is not large after the establishment of the micro-pile support in advance. (5)Prestressed anchor and micropile play a very important role in controlling the deformation of foundation pit.

Simulating Effect of Anchor Cable Pre-Tension to Supporting Structure

Since the pre-stressed anchor technology became to be used from the beginning of twentieth century, it is widely used with the advantages of its good applicability, high cost performance, good looking appearance and easy green. Pre-stressed anchor achieves the purpose of actively controlling foundation pit deformation by exerting pre-stress on steel strand of its free section. This thesis chooses deep foundation pit engineering, adopt Mohr-Coulomb ideal soil body by finite difference software FLAC3D, and select different anchor pre-tension values to simulate. It combines Lizheng software to do numerical simulation and analytic study on pile-anchor supporting structure. This thesis compares results coming from the two kinds of software, and analyze the impact on row piles' body bending moment, pile top deformation, anchor cable axial force and foundation pit deformation when pre-tension changes.

Prestressed Anchor Bolt Impact on the Deformation of Composite Soil Nailing

Finite element software was employed to establish a model to simulate the compound soil nailing. The model simulates the process of constructing prestressed compound soil nailing. Compared the condition prestressed with no prestress, analyzed the Impact of prestress anchor on the deformation in the process of construction and the effect on axial force of soil nail. Applying prestress is able to control the horizontal displacement obviously, but has not obvious effect on vertical displacement, especially place the anchor bolt at the lower part of the slope. In the process of construction, prestress has an advance effect on the deformation of foundation pit and the axial force of soil nails near the anchor bolt.

On Numerical Simulation of the Stepped Soil-Nail Wall

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.

Application of Mc Composite Retaining Structure in the Silt Soil Foundation

This pape combined with the engineering example of a supporting muddy soil foundation pit,used the finite element numerical analysis method, discussed on mechanical deformation characteristics of the cement-soil pile and concrete pile composite retaining structure (MC pile for short ) , Including the effect of section parameters of MC pile on the horizontal displacement of supporting structure, settlement of ground surface and bottom heave. The results show that, MC pile composite retaining structure are beneficial to control the deformation of foundation pit, and increase the stability of foundation pit; M pile retaining wall width to reduce the deformation of the retaining structure has obvious effect, which increase the width of wall can decrease the bending moment ,inclination deformation of supporting structure and lowe bottom heave and surface settlement. Moreover, in the same wall width, there is no C pile to control the deformation of the retaining structure and deformation of the foundation also has a great role.

Analysis and Research of Deep Foundation Pit Pars Horizontal Displacement Prediction Method

Deformation of foundation pit is a complex, can not be quantified, factors affecting multiple process. Using curve fitting model and time series AR ( n ) model for the combined model on deformation of foundation pit displacement prediction. By the depth of the pit excavation and supporting different direction condition, segmentation modeling prediction. With the development of foundation pit deformation, constantly adding new data, and delete the old data, to modeling, implementation of the whole process control of deformation and displacement prediction. Combined model to the prediction of first data, the relative error can be controlled within five percent. Therefore,the model can be used to control the deformation of foundation pit projects that require high, can also be used for other models predict data close to the alarm value of a contrast.

Control of Artificial Recharge on Foundation Pit Deformation due to Dewatering

In this paper, the currently available, feasible controlling measures for the deformation of foundation excavation and its surrounding environment are summarized systemically, which is mainly embodied in pit collapse, adjacent building differential settlement as well as underground pipeline cracking. Then first from the two aspects: artificial recharge used as prevention method and management measure separately, the paper illustrates the control principle, operation method and matters needing attention during artificial recharge. In addition, the difference between pumping well and recharge well are discusses. The research results will provide direction for the deformation control of deep foundation excavation and the operation of artificial recharge.