scholarly journals Experimental and Numerical Investigations on Hydraulic Barrier Bottom Plug for Deep Excavations: A Case Study

2021 ◽  
Vol 10 (4) ◽  
pp. 57-61
Author(s):  
An Phung Vinh
Keyword(s):  
High Reliability ◽  
Soft Soil ◽  
Soil Layer ◽  
Clayey Sand ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Geological Conditions ◽  
Reasonable Proportion ◽  
Hydraulic Barriers

In Vietnam, the solution of designing and constructing deep foundation pits with the geology of sandy or clayey sand is very difficult, especially in case soil mix mud. In some deep foundation pits, the unreasonable treatment solution causes the bottom plug of the foundation pit to be pushed up to the foundation pit or not to pump a foundation pit dried. Solving those problems, this article introduces a particular case study, sealing the bottom of the foundation pit for no 14 of Yen Xa drainage works with the Jet grouted bottom plug hydraulic barriers. To treat the soft soil layer, mix organic without breaking the upper soil layers, this solution uses Jet-grouting technology with a mixture of materials including cement, fly ash, blast furnace slag, lime in a reasonable proportion to ensure waterproof and not uplift the massive bottom plug hydraulic barriers when excavating soil in the pit. Results of calculation and acceptance after the foundation pit is completed show that this is a good solution, high reliability and can be applied to seal the bottom of the foundation pit in similar geological conditions.

Effect of Staged Excavation on Retaining Structure in Soft Soil Area

2012 ◽  
Vol 170-173 ◽  
pp. 633-636 ◽  
Author(s):  
Jie Liu ◽  
Xin Guang Xu
Keyword(s):  
Soft Soil ◽  
Horizontal Displacement ◽  
Structure Type ◽  
Operating Conditions ◽  
Deep Soil ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Retaining Structure ◽  
Geological Conditions

Based on a deep foundation pit in Tianjin, the authors introduced the retaining structure type, surrounding conditions, and the geological conditions of proposed field. According to the engineering characteristics, the excavation was divided into three typical operating conditions. Based on the monitoring of staged excavation of deep foundation pit, analysis on horizontal displacement, deep soil displacement, column settlement and bracing axial force was carried out. The general rules of the deformation and internal force of retaining structures induced by staged excavation were given, which will provide the references for similar engineering.

Selection Analysis of Enclosure Structure for Deep Foundation Pit under Complicated Geological Conditions

2012 ◽  
Vol 446-449 ◽  
pp. 1400-1403
Author(s):  
Qi Hu ◽  
Sheng Ming Luo ◽  
Zhu Jin Jiang
Keyword(s):  
Soft Soil ◽  
Structure Design ◽  
Soil Conditions ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Structure Selection ◽  
Geological Conditions ◽  
Soil Foundation ◽  
Soft Soil Foundation

By comprehensive consideration of soil conditions, geometric shape of deep foundation pit and many other kinds of factors, enclosure structure design needs to select optimal supporting and enclosure system with safety, economy and construction feasibility. On case study of enclosure structure selection about typical soft soil foundation, this paper researches effects of force- deformation of enclosure structure by brace layout, and of economy and construction feasibility. The research results may offer reference for similar projects.

Study on Methods for Deep Foundation Pit Supporting in Beijing

2013 ◽  
Vol 639-640 ◽  
pp. 608-614
Author(s):  
Wen Hui Tan ◽  
Cong Cong Li ◽  
Hong Bao Sun
Keyword(s):  
High Reliability ◽  
Small Displacement ◽  
Beijing City ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Underground Pipelines ◽  
Specific Analysis ◽  
Geological Conditions ◽  
Pulling Force

Abstract. Slope supporting piles and enlarged prestressed anchorage was used to support the deep foundation pit in Beijing which is a complicated engineering and influenced by many factors that locating in the midtown of Beijing city and nearby the construction, traffic trunk and underground pipelines based on the hydrological datum and geological conditions through the specific analysis of the actual conditions, surroundings and geological conditions of the site. Then taking full advantages of the large resist pulling force of single anchorage, small displacement and high reliability of enlarged prestressed anchorage and ensures the engineering be carried out safely and successfully.

scholarly journals Experimental Study on the Variation Law of Excess Pore Water Pressure at the Bottom of the Foundation Pit for Excavation

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Qizhi Hu ◽  
Qiang Zou ◽  
Zhigang Ding ◽  
Zhaodong Xu
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Confining Pressure ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Excess Pore Water Pressure ◽  
Accurate Expression ◽  
Excess Pore

The excavation unloading of deep foundation pits in soft soil areas often produces negative excess pore water pressure. The rebound deformation of soil on the excavation surface of the foundation pit can be predicted reliably through the accurate expression of relevant variation laws. In combination with the principle of effective stress and the general equation of unidirectional seepage consolidation, an equation for calculating the rebound deformation from the bottom in the process of foundation pit excavation unloading was obtained. Additionally, a triaxial unloading test was adopted to simulate the excavation unloading processes for actual foundation pit engineering. After studying the variation law of the excess pore water pressure generated by excavation unloading, it was found that the negative excess pore water pressure increased with increasing unloading rate, while the corresponding peak value decreased with increasing confining pressure. The equation for rebound calculation was verified through a comparison with relevant measured data from actual engineering. Therefore, it is considered that the equation can reliably describe the rebound deformation law of the base. This paper aims to guide the design and construction of deep foundation pits in soft soil areas.

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 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.

scholarly journals Stability analysis of rock slope and calculation of rock lateral pressure in foundation pit with structural plane and cave development

2021 ◽  
Author(s):  
Jin Xu ◽  
Yansen Wang
Keyword(s):  
Safety Factor ◽  
Rock Slope ◽  
Lateral Pressure ◽  
Rock Foundation ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Failure Characteristics ◽  
Karst Caves ◽  
Geological Conditions ◽  
The Stability

Abstract In this study, numerical simulations were carried out to analyze the influence of caves in different positions and shapes, in combination with structural planes, on the stability of the slope and the failure characteristics of a rock slope in a deep foundation pit with high inclination structural planes and cave development. The schemes for substituting a single karst cave for karst caves were constructed. Based on the penetration failure characteristics of karst caves between parallel structural planes, methods for calculating the safety factor of the rock foundation pit and the upper bound of the lateral pressure of the supporting structure under the combined influence of the caves and structural planes were developed, which can be used to assess the safety factor of a rock mass and to calculate the lateral pressure under complex geological conditions.

scholarly journals Numerical Simulation of Soil Displacement and Settlement in Deep Foundation Pit Excavations Near Water

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zhongjing Hu ◽  
Qingbiao Wang ◽  
Shuo Yang ◽  
Zhenyue Shi ◽  
Bo Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Yellow River ◽  
Soft Soil ◽  
Ground Surface ◽  
Horizontal Displacement ◽  
Simulation Method ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit

Advancing urbanization in China requires large-scale high-rise construction and underground transportation projects. Consequently, there is an increasing number of deep foundation pits adjacent to water bodies, and accidents occur frequently. This study uses a numerical simulation method to study the stability of the deep foundation pit near water based on the Biot three-dimensional seepage-stress coupling model, with the open-cut section on the south bank of the Jinan Yellow River Tunnel Project as the engineering field test. This indicates the following: (1) the maximum horizontal displacement of the diaphragm wall occurred in the fifth excavation stage, and a horizontal brace effectively controlled the inward horizontal displacement of the foundation pit; (2) considering the effect of seepage in the soft soil foundation, the maximum vertical displacement of the ground surface at each excavation stage occurred adjacent to the underground continuous wall. As the depth of the foundation pit increased, the vertical surface settlement decreases gradually in the direction away from the excavation face; (3) considering the seepage conditions, within each interval of excavation of the foundation pit, the horizontal displacement of the continuous underground wall and ground settlement declined; and (4) the numerical simulation and field monitoring data were in good agreement. Under the conditions of accurate model simplification and parameter selection, numerical simulations can adequately forecast conditions of the actual project.

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