scholarly journals Determination of Embedded Depth of Soldier Piles in Pile-Anchor Supporting System in Granite Residual Soil Area

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yiao Liu ◽  
Changming Wang ◽  
Xiaoyang Liu ◽  
Ruiyuan Gao ◽  
Bailong Li ◽  
...  
Keyword(s):  
Earth Pressure ◽  
Residual Soil ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Maximum Displacement ◽  
Deep Foundation Pit ◽  
The Earth ◽  
Granite Residual Soil ◽  
Surrounding Soil ◽  
Soil Area

Reasonable depth of pile embedment is one of the key factors for the success of deep foundation pit projects. This paper has taken a deep foundation pit project in a granite residual soil area in Shenzhen as an example and used physical model tests to study the deformation law of the piles and the surrounding soil during the excavation of the deep foundation pit, revealing the variation law of earth pressure in time and space in the pit and then verified it by numerical simulation. The influence of the embedded depth of the pile on the deformation and earth pressure of the deep foundation pit is then explicitly discussed. The study shows that the embedded depth has a significant effect on the deformation and earth pressure distribution of the foundation pit. The earth pressure in front of the pile tends to approach the passive earth pressure as the embedment depth decreases, while the earth pressure behind the pile is in between the Rankine active earth pressure and the static soil pressure; the settlement value and settlement range of the surrounding soil are doubled. The pile displacement increases as the maximum displacement point rises. The maximum displacement of the pile body was used as the basis for determining the instability of the foundation pit. The optimum embedded depth is obtained when the depth of embedment of the pile is 0.22 H (H is the excavation depth of the foundation pit).

scholarly journals Analysis of Situ Test Results of Earth Pressure and Pile Internal Force under Pile-Anchor Support in a Deep Foundation Pit in Xi’an

2022 ◽  
Vol 2148 (1) ◽  
pp. 012051
Author(s):  
Ruibin Yang ◽  
Xinsheng Li ◽  
Dongzhou Xie ◽  
Hongte Meng
Keyword(s):  
Earth Pressure ◽  
Internal Force ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Support Design ◽  
Limiting State ◽  
Obvious Effect ◽  
Deep Foundation Pit ◽  
The Earth ◽  
Monitoring Test

Abstract At present, in deep foundation pit engineering, on the one hand, practice is ahead of theory, and on the other hand, theory can not correctly reflect the actual construction process and environmental effects. In order to further study the distribution and change law of earth pressure and internal force of pile body in deep foundation pit pile-anchor supporting system, field monitoring test of earth pressure and pile body reinforcement stress was carried out. The monitoring results show that before excavation, the distribution of earth pressure has a great relationship with the layering of the soil, and it is distributed in sections along the depth. Compared with the theoretical static earth pressure, the measured data of the upper depth is relatively small; after excavation, the overall earth pressure is distributed along the depth in a “z” shape under the non-limiting state. As the excavation progresses, the magnitude of the reduction of the earth pressure varies from place to place, and the magnitude of the decrease of the soil with better properties is not large; after the excavation, the stress and earth pressure of the pile reinforcement correspond to each other, and the distribution is also nonlinear. The existence of anchor tension has an obvious effect on improving the internal force of the pile. The selected earth pressure calculation methods have some discrepancies in the calculation of the earth pressure value of the project, and they need to be further improved. The research in this paper can provide reference and reference for the calculation of earth pressure and support design of pile-anchor supported foundation pit.

scholarly journals Experimental Study for the Embedded Depth of Support Structure Foundation Pit in Granite Residual Soil Area

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yi-ao Liu ◽  
Chang-ming Wang ◽  
Rui-yuan Gao ◽  
Bai-long Li ◽  
Xiao-yang Liu ◽  
...  
Keyword(s):  
Earth Pressure ◽  
Horizontal Displacement ◽  
Diaphragm Wall ◽  
Residual Soil ◽  
Foundation Pit ◽  
Control Value ◽  
Physical Experiments ◽  
Soil Settlement ◽  
Granite Residual Soil ◽  
Soil Area

In order to deeply understand the appropriate embedded depth of the foundation pit diaphragm wall in granite residual soil area, a physical model of the diaphragm wall with inner support for foundation excavation was constructed according to the actual project in the proportion of 1 : 30. The distribution of Earth pressure, the horizontal displacement of the wall, and the settlement behind the wall were obtained by physical experiments. The numerical simulation was then performed to authenticate the results from physical modeling. It was observed that the embedded depth of the diaphragm wall had the most obvious influence on the horizontal displacement of the wall. Moreover, the final soil settlement and its influence were significantly increased with the decrease in embedded depth. The analysis results also suggested that the control value for the embedded depth of the wall should not be less than 0.36 H (H is the excavation depth of the foundation pit).

scholarly journals An Experimental Study on the Ecological Support Model of Dentate Row Piles

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Yousheng Deng ◽  
Zhihe Cheng ◽  
Mengzhen Cai ◽  
Yani Sun ◽  
Chengpu Peng
Keyword(s):  
Building Materials ◽  
Soft Soil ◽  
Earth Pressure ◽  
Shallow Foundation ◽  
Laboratory Model ◽  
Foundation Pit ◽  
Maximum Displacement ◽  
Single Row ◽  
The Earth ◽  
Soil Foundation

Bamboo is highly renewable and biodegradable with good short-term strength, which meets the requirement for temporal support structures in shallow foundation pits. Based on this, we conducted a laboratory model test on the dentate bamboo micropile support structure combined with environmentally friendly building materials and new type of piles, to explore the stress characteristics, stress change regularity, and the support effect of the system in soft soil foundation pits. The results show that the earth pressure on the pile sides above the excavation surface gradually decreases with an increase in the excavation depth. The bending deformation of the bamboo pile was also significant. The results also show that the earth pressure and the pile strain below the excavation surface change slightly during the excavation process. When the short sides of the foundation pit were loaded, the highest strain was recorded in the piles 4 and 11. A maximum strain of 358.93 με was recorded, and the maximum displacement of the pile in the top part was obtained to be only 2.14 mm. The most subsidence of dentate pile obtained is only 1.88 mm, whereas that of the single-row pile is 2.35 mm. Compared to the traditional single-row pile, the dentate piles can effectively reduce the horizontal deformation as well as the surface subsidence effectively. They can also support more external lateral load, and hence maintain the foundation stability and give better support. The results provide a theoretical basis for ecological bamboo support technology and have great value to be promoted.

scholarly journals Optimization Analysis of Deformation of Underlying Tunnel in Dewatering and Excavation of Phreatic Aquifer

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Jing Wang ◽  
Pengcheng Wang ◽  
Wenda Wang ◽  
Shouqiang Zhou ◽  
Xiang Fang
Keyword(s):  
Lateral Displacement ◽  
Beam Theory ◽  
Layer By Layer ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Maximum Displacement ◽  
Deep Foundation Pit ◽  
Maximum Deformation ◽  
Phreatic Aquifer ◽  
Deformation Law

This paper theoretically analyzed the deformation law of the underlying tunnel caused by dewatering and excavation of deep foundation pit in the phreatic aquifer area, which is based on the Mindlin solution and the double-sided elastic foundation beam theory, and used the finite difference method and the fluid-solid coupling principle to conduct three-dimensional numerical simulation of dewatering and excavation of deep foundation pit with fluid-solid coupling by using FLAC3D5.00. This research shows that the layered and segmented excavation method from the middle to the end by dewatering the skip layer has a better effect on optimizing the deformation of the underlying tunnel through the simulation of three excavation methods and two dewatering schemes crossing each other, which is about 2.5% less than the layer-by-layer dewatering scheme. In addition, the deformation law of the simulated value is the same as the theoretical value, and the simulated value is slightly larger than the theoretical value. Underlying tunnel only just exists vertical deformation at the direct center of the foundation pit, and the maximum deformation is about 3.054 mm under the dewatering well of the jumping layer and W3. With the dewatering of jumping layer and the third excavation mode (W3), underlying tunnel only just exists lateral displacement at the position where is the retaining structure, and the maximum displacement is 1.606 mm.

Study on Composite Soil Nailing Wall in Soft Soil Area of Complex Condition with Emphasis on Analysis by Finite Element Analysis

2012 ◽  
Vol 174-177 ◽  
pp. 2020-2023 ◽  
Author(s):  
Bing Wang
Keyword(s):  
Finite Element ◽  
Soft Soil ◽  
Horizontal Displacement ◽  
Deep Foundation ◽  
Circular Area ◽  
Foundation Pit ◽  
Soil Nails ◽  
Deep Foundation Pit ◽  
Soft Soil Area ◽  
Soil Area

Based on a typical projects, the horizontal displacement in depth, horizontal displacement and vertical subsidence of pile top, and settlements of surrounding buildings are monitored with the process on digging of deep foundation pit. The study on digging process of foundation pit is analyzed by using finite element software. Using mapped meshing method, from mixing the pile near the semi-circular area (radius = 50m), the meshing appropriate encryption in order to improve the accuracy of the external semi-circular area (radius = 65m) mesh is less appropriate sparse.Layer by layer to kill the layers of the soil unit and activate the soil nails (spring element), the simulated excavation and synchronization of soil nails construction.Verify the arc form of failure surface in side of deep foundation pit in soft soil area. Which is valuable for reference to similar structure engineering of foundation pit.

scholarly journals Correction of Earth Pressure and Analysis of Deformation for Double-Row Piles in Foundation Excavation in Changchun of China

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Yijun Zhou ◽  
Aijun Yao ◽  
Haobo Li ◽  
Xuan Zheng
Keyword(s):  
Physical Model ◽  
Model Test ◽  
Large Scale ◽  
Similarity Theory ◽  
Earth Pressure ◽  
Physical Model Test ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Double Row ◽  
The Earth

In order to study the earth pressure and the deformation behavior of the double-row piles in foundation excavation, a large-scale physical model test was introduced to simulate deformation of double-row piles in foundation excavation based on the principle of similarity theory in this paper. Represented by the deep foundation pit engineering of Changchun, the strain and the displacement of the double-row piles and the earth pressure are calculated by the above-mentioned physical model test. Then a numerical simulation has been carried out to validate practicability of the physical model test. The results show that the strain and the displacement of the front-row piles are larger than the back-row piles. The earth pressure of the front-row piles appears to be “right convex,” correcting the specification of the earth pressure and putting forward the coefficient of β. The results in this paper may provide constructive reference for practical engineering.

The Study of Deformation Law of a Super Deep Foundation Pit in the Process of Dismantling the Inner Support

2014 ◽  
Vol 638-640 ◽  
pp. 614-619
Author(s):  
Bo Liu ◽  
Qing Nan Liu ◽  
Yi Yan Zhao ◽  
Bing Hui Chen
Keyword(s):  
Horizontal Displacement ◽  
Deformation Monitoring ◽  
Maximum Point ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Supporting Structure ◽  
The Earth ◽  
Earth Pressures ◽  
Deformation Law

Dismantling the inner support of deep foundation pit is a risk point.It is of great importance to guarantee the safety of foundation pit when removing the inner support, and the deformation monitoring and analysis in the process of dismantling inner support is crucial. In this paper, a super deep foundation pit engineering as the research background.Through monitoring and analyzing the law of a deep horizontal displacement of the supporting structure,ground settlement, vertical settlement and axial force of support in the process of support demolition,which can be obtained that: the settlement of surface ground around the foundation shows spatial and temporal clearly and the distribution of deep horizontal displacement of supporting structure is similar to the parabolic which the maximum point constant upward shift with supporting continuous removed.Soil pressure of supporting shared with support removing process is changing, and the earth pressures support sharing is increasing. From the monitoring results, the demolition scheme is reasonable and effective and meets the requirements of design and environment.

Numerical Analysis of a Pile-Anchor Retaining Structure of Deep Foundation Pit Engineering

2014 ◽  
Vol 638-640 ◽  
pp. 496-502
Author(s):  
Ying Wang ◽  
Jiang Bo Shi
Keyword(s):  
Earth Pressure ◽  
Horizontal Displacement ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Deformation Control ◽  
Maximum Value ◽  
Negative Moment ◽  
Dip Angle ◽  
Pile Length

Based on a deep foundation pit engineering of Tangshan, considering the interaction of pile-anchor-soil, the finite difference software FLAC3D is adopted in this paper to simulate and analyze the effect of dip angle of anchor and the embedded depth of pile on the horizontal displacement and the variation laws of earth pressure, horizontal displacement of pile with the process of excavation. The results show that the maximum value of horizontal displacement and positive moment of pile appear in 0.85H (H stands for the depth of excavation) and the negative moment appears in 1.3H after the excavation; the maximum value of active and passive earth pressure appear in 1.3H rather than the bottom in the range of pile length; the requirements of deformation control and overall stability of foundation pit can be satisfied with 0.5H which as the embedded depth of the pile, and the dip angle of anchor is appropriate when it ranges from 5°to 25°but less than 30°.

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