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.

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 Deformation Law of the Diaphragm Wall during Deep Foundation Pit Construction on Lake and Sea Soft Soil in the Yangtze River Delta

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yuan Mei ◽  
Dongbo Zhou ◽  
Xueyan Wang ◽  
Liangjie Zhao ◽  
Jinxin Shen ◽  
...  
Keyword(s):  
Soft Soil ◽  
Yangtze River Delta ◽  
Diaphragm Wall ◽  
Lateral Deformation ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Deformation Law ◽  
Wall Deformation ◽  
Subway Stations

So far, there have been a large number of diaphragm walls in the Yangtze River Delta as engineering examples of deep foundation pit maintenance structures in subway stations, but there is a lack of systematic research and summary on the deformation characteristics of ground connecting walls. This study aimed to clarify the deformation law of the diaphragm wall during the excavation of a deep foundation pit in a soft soil region. Based on the monitoring data of the diaphragm wall of the deep foundation pit of the Hangzhou metro station, the monitoring data of the deep foundation pits of 15 subway stations in Shanghai and Ningbo cities around Hangzhou were considered. Grouping and classification methods were used to analyze the similarities and differences in the deformation characteristics of the diaphragm wall in the three regions. The results indicate the following: the maximum lateral deformation of the diaphragm wall in Hangzhou increases linearly with the relative depth of the maximum lateral deformation. The maximum lateral deformation of the foundation pit in Hangzhou is 0.072% H∼0.459% H, with a mean of 0.173% H. The wall deformation in Hangzhou varies significantly with the depth of the foundation pit, but the influence of the depth of the foundation pit on the wall deformation is considerably less than that in Shanghai and Ningbo. The corresponding position of the maximum lateral deformation in the excavation depth increases linearly with the excavation depth of the foundation pit, and the corresponding position of the lateral deformation of the diaphragm wall in Shanghai is more affected by the excavation depth of the foundation pit. The lateral deformation of the diaphragm wall increases rapidly in the range of 0 H–0.5 H, and the maximum lateral deformation occurs at 0.5 H–1.1 H.

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.

Research on the Deformation Monitoring of Deep Foundation Pit Engineering

2014 ◽  
Vol 889-890 ◽  
pp. 1383-1387
Author(s):  
Ya Jun Yin ◽  
Xiao Long Liu ◽  
Yong Mei Qian
Keyword(s):  
Deformation Monitoring ◽  
Reliable Data ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Engineering Construction ◽  
Deep Foundation Pit ◽  
Important Impact ◽  
Safety Risks ◽  
Depth Analysis ◽  
Deformation Law

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.

Numerical Analysis of the Deformation Law of Deep Foundation Pit of Subway Station by FLAC3D

2014 ◽  
Vol 915-916 ◽  
pp. 62-67
Author(s):  
Ya Long Liu
Keyword(s):  
Structural Type ◽  
Operating Conditions ◽  
Subway Station ◽  
Horizontal Deformation ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Deformation Law ◽  
Bored Piles ◽  
Supporting Structures

Taking the deep foundation pit engineering of a Subway Station as background. The paper introduces the projects surroundings,geological and hydrological conditions of the proposed field and the retaining structural type. According to the engineering characteristics,the project was divided into four typical operating conditions,the deformation rules of deep foundation pit at subway station in tunneling are studied with the method of FLAC3D numerical simulation,the supporting structures choose by the bored piles and interior support. The analysis of the horizontal deformation of the retaining structures, the settlement law and the influence sphere of surrounding soil. The conclusion in this paper can provides reference for the reasonable design and safety construction of deep foundation pit.

Research on Deformation Forecasting of Deep Foundation Pit Supporting Structure Based on BP Neural Networks

2011 ◽  
Vol 250-253 ◽  
pp. 2116-2119
Author(s):  
Yi Xue ◽  
Lei Xu ◽  
Zheng Zheng Cao
Keyword(s):  
Neural Network ◽  
Network Theory ◽  
Network System ◽  
Deep Excavation ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Maximum Deformation ◽  
Supporting Structure ◽  
Neural Network Theory

Excavation engineering is affected by many kinds of factors. It is becoming the key and difficult point in geotechnical engineering. This paper analyzes and predicts the deformation of supporting structure in urban deep excavation with artificial neural network theory, establishing network predictive model to predict the maximum deformation of supporting structure. The result shows that the network system has high precision, and it can be applied to practice.

Application of BP Neural Network to Risk Analysis of Deep Foundation Pit

2014 ◽  
Vol 556-562 ◽  
pp. 5989-5993
Author(s):  
Lu De Zou ◽  
Dong Wei Cao
Keyword(s):  
Neural Network ◽  
Bp Neural Network ◽  
Lateral Displacement ◽  
Uniform Design ◽  
Probability Density Distribution ◽  
Soil Parameters ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Random Samples

there are many uncertainty factors in the design process of the deep foundation pit engineering, such as the soil parameters, loading, which make the calculated displacement, settlement and safety factor have randomness and uncertainty. This paper combines uniform design (UD) with BP neural network. The UD structures random samples. Then, BP neural network trains random samples and the corresponding lateral displacement, settlement of ground and safety factors to get response relationship respectively. On this basis, the probability density distribution of each response parameter is obtained by predicting a large number of samples obtained by the Monte Carlo simulation. And then the Breadth Border Method, Narrow Bounds Method and PNET method are used to calculate system failure probability of foundation pit. The instance analysis shows that the method has high computing efficiency and the result is reasonable. It provides an effective way for the reliability analysis of the foundation pit engineering.

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 A Case Study on Field Monitoring Analysis of Deep Foundation Pit in Soft Soils

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Xiaoshuang Zhang ◽  
Xiuchuan Zhang ◽  
Yunshan Han
Keyword(s):  
Lateral Displacement ◽  
Ground Surface ◽  
Field Monitoring ◽  
Diaphragm Wall ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Ground Surface Settlement ◽  
Maximum Lateral Displacement

Field monitoring in the process of excavation of foundation pit is an important measure to reduce the risk. This paper describes a case study of the filed monitoring data during the process of deep foundation pit excavation in soft soil areas. The displacements of the diaphragm wall top were analysed and found that the horizontal displacement showed the convex shape, while the vertical displacement showed the concave shape. Based on the field monitoring data, the deformation mode of lateral displacement of the diaphragm wall belonged to the composite mode. The relationship between maximum lateral displacement and excavation depth showed a strong linear correlation. The horizontal displacements of bracing pillar decreased with the increasing of bracing stiffness, while the effect of bracing stiffness on vertical displacements of bracing pillar could be ignored. The settlement profile computed using the method of Hsieh and Ou was in good agreement with the field observations and better described the development trend of the ground surface settlement. The ratio of the maximum ground surface settlement (δvm) to the maximum lateral displacement of the diaphragm wall (δhm) was in the range of 0.74∼0.88, belonging to the range of 0.5∼1.0 proposed by Hsieh and Ou. This paper provides a reference basis and related guidance for similar projects.

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