scholarly journals Deformation Characteristic of a Supported Deep Excavation System: A Case Study in Red Sandstone Stratum

2021 ◽  
Vol 12 (1) ◽  
pp. 129
Author(s):  
Weizheng Liu ◽  
Tianxiong Li ◽  
Jiale Wan
Keyword(s):  
Horizontal Displacement ◽  
Spatial Effects ◽  
Deep Excavation ◽  
Ground Settlement ◽  
Foundation Pit ◽  
Short Side ◽  
Case Record ◽  
Red Sandstone ◽  
Anchor Cable ◽  
Vertical Excavation

A complete case record of a deep foundation pit with pile-anchor retaining structure excavated in red sandstone stratum is presented in this study. The horizontal displacement of pile top, the horizontal displacement at various depths, the axial force of anchor cable, and ground settlement during construction are measured. A three-dimensional numerical model is established to analyze the additional stress and deformation induced by the excavation and the accuracy of the FEM model is verified by comparing with field measured results. Both the measured and numerical simulation results show that the deformation of the pile-anchor supported deep excavation is significantly affected by the spatial effect. The results show that the deformation in the middle of the foundation pit is greater than the pit angle and that the deformation of the long side is greater than that of the short side and gradually decreases from the middle to the pit angle. The deformation and stress in the middle of the long side of the foundation pit are the largest, which is the most unfavorable part. With the increase of vertical excavation depth, the spatial effects tend to increase, and the influence scope of spatial effects is about five times the vertical excavation depth in the red sandstone stratum. The ground settlement outside the pit is mainly distributed in a groove shape, and the maximum settlement occurs about 8.5 m away from the pit edge. Finally, parametric studies of reinforcement parameters indicated that 1.5–2.0 times the initial elastic modulus and cohesive force of soil should be used for reinforcement. It is recommended that the ranges for pile diameter, pile spacing, anchor cable prestressing and inclination angle should be selected as 0.8–1.2 m, 1.4–2.0 m, 100–150 kN, and 10°–20°, respectively.

Analysis of Construction Monitoring of Jinzhou Underground Mall Excavation

2013 ◽  
Vol 848 ◽  
pp. 74-77
Author(s):  
Jin Kui Li ◽  
Yue Bo Fan ◽  
Yi Bing Wang
Keyword(s):  
Environmental Conditions ◽  
Horizontal Displacement ◽  
Ground Settlement ◽  
Foundation Pit ◽  
Construction Monitoring ◽  
Construction Period ◽  
Surrounding Environment ◽  
Information Construction ◽  
Real Time Information ◽  
Time Information

Cause the deformation of soil around the foundation pit excavation, have a great impact on the surrounding environment. At the same time, the excavation is limited by surrounding environmental conditions. Relying on the Jinzhou underground mall excavation monitoring project, after monitoring the ground settlement and horizontal displacement of pile top and measurement during the construction period, we realize the real-time information construction ,safe and smooth construction in the process of construction. And we conclude some useful conclusions, which can be a reference for similar engineering and reference.

Research on Deformation Law of Deep Excavation Supporting Structures in Beijing Metro Station

2011 ◽  
Vol 243-249 ◽  
pp. 2338-2344
Author(s):  
Qing Yuan Li ◽  
Yang Wang
Keyword(s):  
Horizontal Displacement ◽  
Internal Force ◽  
In Situ Monitoring ◽  
Deep Excavation ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Metro Station ◽  
Deep Foundation Pit ◽  
Deformation Law

Taking deep excavation engineering in North Region of Senlin Park Station of Beijing Olympic Subway branch as engineering background, deformation law of enclosure structure of deep excavation are studied by the in-situ monitoring means .It shows that the maximum horizontal displacement of retaining pile is closely related with excavation depth and time. When the deep foundation pit is excavated to a certain depth, and steel brace hasn’t been erected, horizontal displacement of the pile tops is maximum. The location of the maximum horizontal displacement shifts down with foundation pit excavation and steel brace erection. With steel brace application, steel axis force decrease, so steel brace can effectively control horizontal displacements of retaining pile and internal force of steel in the pile. In addition, temperature has a certain effect to axis force of steel brace.

scholarly journals Displacement Monitoring during the Excavation and Support of Deep Foundation Pit in Complex Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Zhouqiang Li
Keyword(s):  
Axial Force ◽  
Time History ◽  
Horizontal Displacement ◽  
Underground Water ◽  
Surface Settlement ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Anchor Cable ◽  
The North

Taking a super large deep foundation pit project as an example, the horizontal displacement of crown beam and driveway, surface settlement, axial force of anchor cable, and underground water level in the construction process of the foundation pit are dynamically monitored and analyzed. The excavation deformation rule of the deep foundation pit and the influence of excavation on surrounding buildings are analyzed. The results show that, with the excavation of the foundation pit, the crown beam and driveway of the foundation pit incline towards the direction of the pit and eventually tend to be stable. The variation of axial force of the prestressed anchor cable in the first layer of the foundation pit is basically consistent with the variation of horizontal displacement time history. The variation trend of the groundwater level at each side of the foundation pit is different but tends to be stable in a short time. In the whole monitoring period, the cumulative settlement value of each area of the foundation pit is within the controllable range, but the surface settlement of the north side of the foundation pit and a surrounding building has not reached stability, so it is suggested to extend the monitoring time of settlement in the relevant area.

scholarly journals Numerical Simulation and Optimization Design of End-Suspended Pile Support for Soil-Rock Composite Foundation Pit

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Qingchao Xu ◽  
Zhenhao Bao ◽  
Tu Lu ◽  
Huarui Gao ◽  
Jiakang Song
Keyword(s):  
Numerical Simulation ◽  
Optimization Design ◽  
Boundary Effect ◽  
Horizontal Displacement ◽  
Element Model ◽  
Composite Foundation ◽  
Ground Settlement ◽  
Foundation Pit ◽  
Simulation And Optimization ◽  
Geological Conditions

In order to design the soil-rock combination foundation pit more safely and effectively, this paper presents the investigations of the mechanical and deformational characteristics of end-suspended piles supporting the structures in Jinan CBD area. Based on the measured data, a finite element model was established through the two-dimensional numerical simulation method to study the deformational characteristics of the end-suspended piles, and the influences of the depth of socketed rock, the width of rock shoulder, and the prestress of anchor cables on the deformations and mechanical property of end-suspended piles were discussed. Some optimization methods are proposed based on these analyses. Results show the following: (1) Rock-socketed depths have boundary effect on end-suspended piles. Under the given geological conditions, the reasonable socketed ratio is within 0.158∼0.200. (2) The anchor cable prestress can effectively slow down the ground settlement, the force, and deformation of the pile body and can be set to 1P∼1.25P under the conditions of the site. (3) Rock-shoulder width has little influence on the ground settlement and horizontal displacement of piles. The reserved width of rock shoulder is suggested to be selected in the range of 1.0 m∼1.5 m.

Three-Dimensional Numerical Analysis of Excavation and Support of Deep Foundation Pit

2012 ◽  
Vol 446-449 ◽  
pp. 1922-1926
Author(s):  
Chang Zhi Zhu ◽  
Xing Lian Zheng
Keyword(s):  
Numerical Analysis ◽  
Finite Difference ◽  
Three Dimensional ◽  
Horizontal Displacement ◽  
Test Results ◽  
Deep Excavation ◽  
Analysis Model ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit

Based on a project, a numerical analysis model was established by the finite difference program and the process of the deep excavation and support was simulated by computer, the distribution of the horizontal displacement and settlement of the top of slope of the slope soil were obtained. The simulation result was consistent with the test results. It shows that the method of numerical analysis can be used to the simulation of the excavation and support of Deep Foundation Pit, and it will provide the basis for the design and construction of practice project.

Finite Element Analysis and Investigation of Double-Row Piles Supporting Structure

2013 ◽  
Vol 838-841 ◽  
pp. 779-785
Author(s):  
Liang Gu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Maximum Shear Stress ◽  
Horizontal Displacement ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Double Row ◽  
Element Analysis ◽  
Supporting Structure

The double-row piles supporting structure is a new type of supporting and protecting for deep foundation excavation. It is widely used to in design of deep foundation pit. Now how to simply and effectively design the structure of double-row piles is in a research and discuss stage. Using the Midas GTS finite element method, the displacement and stress distribution of double-row piles in the different stages of excavation are obtained, and the horizontal displacement and stress distribution of double-row piles in the different stages of excavation are calculated. The results of Midas GTS finite element analysis as follows: (1) after the excavation of foundation pit, the horizontal displacement of pile-top is maximum. The horizontal displacement decreases gradually with depth increases. And the displacement of front row piles is larger than that of back row piles; (2) the maximum shear stress is at the distance 5m to the foundation basement. The higher bending moment at the pile-top and the distance 10m to the foundation basement are consistent with the actual monitoring date. (3) the results of finite element analysis is close to the Richard software and actual monitoring data. It is show that using the finite element analysis to analyze the double-row piles supporting structure with is veritable and credible.

scholarly journals 3-D Numerical Study of Mechanical Behaviors of Pile-Anchor System

2014 ◽  
Vol 580-583 ◽  
pp. 238-242
Author(s):  
Ri Cheng Liu ◽  
Bang Shu Xu ◽  
Bo Li ◽  
Yu Jing Jiang
Keyword(s):  
Simulation Analysis ◽  
Numerical Study ◽  
Bending Moments ◽  
Mechanical Behaviors ◽  
Foundation Pit ◽  
Anchor System ◽  
Anchor Cable ◽  
Axial Forces ◽  
Toppling Failure ◽  
Potential Failure

Mechanical behaviors of pile-soil effect and anchor-soil effect are significantly important in supporting engineering activities of foundation pit. In this paper, finite difference method (FDM) was utilized to perform the numerical simulation of pile-anchor system, composed of supporting piles and pre-stressed anchor cables. Numerical simulations were on the basis of the foundation pit of Jinan’s West Railway Station, and 3D simulation analysis of foundation pit has been prepared during the whole processes of excavation, supporting and construction. The paper also analyzed the changes of bending moments of piles and axial forces of cables, and discussed mechanical behaviors of pile-anchor system, through comparisons with field monitoring. The results show that the parameters concluding vertical gridding’s number, cohesion of pile and soil, and pile stiffness have robust influences on supporting elements’ behaviors. Mechanical behaviors of supporting pile and axial forces of anchor cable changed dramatically, indicating that the potential failure form was converted from toppling failure to sliding failure.

scholarly journals Investigation on Dewatering of a Deep Shaft in Strong Permeable Sandy Pebble Strata on the Bank of the Yellow River

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yuchao Zheng ◽  
Jianyong Lei ◽  
Fei Wang ◽  
Liang Xiang ◽  
Jianfeng Yang ◽  
...  
Keyword(s):  
Permeability Coefficient ◽  
Yellow River ◽  
Pumping Test ◽  
The Yellow River ◽  
Construction Process ◽  
Deep Excavation ◽  
Ground Settlement ◽  
High Permeability ◽  
Reverse Analysis ◽  
Table Versus

This paper reports the dewatering scheme of a deep excavation in sandy pebble strata. The excavation is in high permeability strata and is close to the Yellow River, making the dewatering difficult during construction. At present, few researchers have specially studied the dewatering scheme of deep excavations in strong permeable strata near the water resource. Field pumping test was conducted before the excavation activity, and the permeability coefficient of the strata was obtained by reverse analysis. According to the characteristics of the project, the dewatering scheme of “ waterproof   curtain + base   grouting + pumping ” was proposed. The influence of vertical waterproof curtain and base grouting on dewatering was analyzed by numerical simulation. In the construction process, the field water table and ground settlement were measured. The results show that (1) the groundwater table versus permeability coefficient curve shows three different stages and (2) the dewatering scheme of “ waterproof   curtain + base   grouting + pumping ” is effective for deep excavation in strong permeable strata.

scholarly journals The Application of Sheet Steel Piles Combined with Soil-Cement Piles to Stabilize a Deep Excavation Pit’s Wall

2020 ◽  
Vol 55 (4) ◽  
Author(s):  
Nguyen Anh Tuan ◽  
Nguyen Thanh Dat ◽  
Nguyen Duc Anh
Keyword(s):  
Construction Projects ◽  
Sheet Steel ◽  
Water Environment ◽  
Horizontal Displacement ◽  
Simulation Software ◽  
Deep Excavation ◽  
Improvement Project ◽  
Soil Cement ◽  
Steel Piles ◽  
City Water

In recent years, owing to advances in technology, excavation pits have shown increased improvements. Taking advantage of advanced solutions combined with traditional ones has brought about considerable advantages for construction contractors and saves on expenses to carry out construction projects. Owing to their ability to analyze geotechnical problems, several calculation and simulation software, such as Plaxis, Bentley, along with many others, have grown in popularity. Among them, Midas is one such software, which is a set of solutions developed by the MIDAS IT company and is widely applied in many constructions. The authors evaluated the ability to use Midas software to calculate the stability of a wall in a deep excavation pit for the Ho Chi Minh City Water Environment Improvement Project. The results of these researches reveal that combining soil-cement piles and sheet steel piles decreases the internal forces in sheet steel pile walls. At the same time, this solution not only reduces horizontal displacement but also keeps the settlement of the soil around the excavation pit within the permissible range, which helps to ensure that the adjacent pavements are stable and will not crack. The results of this study can be applied to similar geological constructions.

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