Study on Deformation Characteristics of Deep Foundation Pit in Unsaturated Soil

Cao, Hai Ying; Jia, Dian Bo; Chen, Tie Jun

doi:10.4028/www.scientific.net/amr.374-377.1809

Cited by 5 publications

(2 citation statements)

References 2 publications

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“…Chen et al [18] obtained on-site data of lateral and vertical displacement of retaining piles and peripheral ground subsidence by monitoring the excavation process of a foundation pit group, analyzed and compared the deformation characteristics of the deep foundation pit group and the interaction between foundation pits, and proposed optimization measures for deformation control. Cao et al [19] studied the control technology for deformation of super-deep excavation and investigated deformation control measures such as pre-stressing technology and post-strengthening technology. Yu [20] used finite element analysis to design and optimize the form of excavation support systems such as straight beam support system and large open-loop beam support system, providing valuable references for excavation support design.…”

Section: Introductionmentioning

confidence: 99%

Study on Deformation Characteristics of Retaining Structures under Coupled Effects of Deep Excavation and Groundwater Lowering in the Affected Area of Fault Zones

Niu

Zhang²,

Wang

et al. 2023

Sustainability

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In order to study the deformation characteristics of the retaining structure under the coupled effect of excavation and dewatering in the affected area of fault zones, this paper takes a deep excavation project in the F1322 fault zone influence area in Shenzhen as an example. The research methods of theoretical analysis, numerical simulation and field measurement are used to conduct in-depth research on the deformation of the retaining structure caused by the excavation and dewatering of the foundation pit. The results show that considering the coupled effect of dewatering in the foundation pit, the energy method based on elastic theory is more accurate in solving the deformation of the retaining pile. By comparing and analyzing the theoretical calculation results, numerical analysis results, and field measurement values, we found that the numerical laws of the three are basically the same. Simplified calculations that only consider rotational deformation and ignore the translational deformation of the wall lead to large deviations between the theoretical calculation results and the measured values of the wall bottom deformation. In order to reduce the deviation between numerical results and measured values, the construction of the foundation pit should strictly adopt measures such as “sectional excavation, avoiding peripheral loads, and optimizing construction deployment”, strengthen construction monitoring, and reduce the impact on the deformation of the retaining pile. The maximum deformation growth rate k (ΔSmax/Δ) of the retaining pile decreases approximately exponentially with the increase of the structural stiffness parameters (E and I) and the embedment ratio within a certain range. The sensitivity analysis of the lateral displacement of the retaining pile to different geological parameters is conducted, and the sensitivity factors of the geological parameters to the deformation of the retaining structure are obtained, namely the maximum internal friction angle, followed by the cohesion, and the elastic modulus is the smallest. Based on the original design plan, an optimization of the excavation design is proposed by reducing the stiffness of the support structure. Therefore, the research findings in this paper have significant theoretical and practical implications for the engineering design of excavation projects located in fault zones. By optimizing the excavation support system, not only can standardized construction procedures be achieved, but also investment costs can be reduced, and construction time shortened, which fully aligns with the current safety, economic, and sustainable design principles of excavation projects aiming to conserve resources.

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Section: Introductionmentioning

confidence: 99%

Study on Deformation Characteristics of Retaining Structures under Coupled Effects of Deep Excavation and Groundwater Lowering in the Affected Area of Fault Zones

Niu

Zhang²,

Wang

et al. 2023

Sustainability

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“…Loess is characterized by its loose structure, high porosity, and sensitivity to moisture [3][4][5]. Therefore, in conditions of sustained rainfall the structural strength of the soil undergoes a notable reduction which leads to a rapid decrease in both mechanical strength and deformation modulus [6][7][8][9][10][11]. Consequently, soil collapse will result in uneven settlement within loess roadbeds.…”

Section: Introductionmentioning

confidence: 99%

Laboratory Tests and Numerical Simulation on the Loess Subgrade Improved by Lime-Lignin

Jia,

Zhang,

et al. 2023

Preprint

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Conventional techniques individually incorporating the inorganic or organic modifiers are insufficient to achieve the amelioration of loess roadbed in practices, which has restricted the development of infrastructures. This paper utilizes the lime-lignin to modify the loess, for which a series of mixing samples with various additives dosages (i.e. 0,2%:1%,4%:2%,6%:3% and 8%:4%) was adopted. Laboratory experiments and numerical simulation were carried out to investigate the mechanical properties of amended loess. Test results showed that both the compressive and shear strengths of the improved loess exhibit an initial rise followed by a decline as the contents of lime and lignin increase, with the optimal improvement effect achieved at a lime-to-lignin mixing content of 2%:1%. The results also indicated that numerical simulation can well corroborate the laboratory results, which are manifested in reduced roadbed settlements and favourable stress transfer mechanisms. An intricate three-dimensional network structure established by lignin fibers and a cement-soil skeleton formed between lime hydrate and soil particles jointly improve the strength of the soil matrix. The main research findings can offer valuable theoretical references for the enhancement of the loess subgrade.

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The Influence of Different Excavation Methods on Deep Foundation Pit and Surrounding Environment

Yao¹,

Li²,

Chen³

2022

Lecture Notes in Civil Engineering

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Taking a deep foundation pit in Shijiazhuang, Beijing as the background of the project, combined with the excavation range of the deep foundation pit and the spatial location and geometry of the surrounding engineering bodies, FLAC3D software is used to establish a numerical model of the deep foundation pit excavation containing the deep foundation pit, surrounding buildings and underground tunnels and other engineering bodies. The numerical model truly reflects the geometric size and spatial location relationship between deep foundation pit and surrounding engineering bodies. Based on the numerical model, the numerical simulation of deep foundation pit excavation under different excavation methods was carried out. The analysis of the horizontal displacement of the support structure during the excavation of the deep foundation pit, the investigation of the surrounding buildings and surface settlement and the deformation of the metro tunnel. The influence mechanism of different excavation methods on the safety of deep foundation pit, surrounding buildings and tunnel were discussed. It is concluded that the excavation method has less influence on the deformation and displacement of the deep foundation pit and the surrounding buildings and tunnels under the condition of shallow excavation depth. As the excavation depth increases, the effect of the excavation method on the deformation of the deep foundation pit, buildings, tunnels and surface settlement increases. The layered excavation method is suitable for deep foundation pits with shallow excavation depths, while the layered section excavation method is more suitable for deep foundation pits with deep excavation depths. Deep foundation pit excavation has a smaller effect on the deformation of the tunnel. The surrounding buildings have a greater influence on the deformation during the excavation of the deep foundation pit, but the effect of the buildings on it is less than the limiting effect of the prestressing anchor cables on the deformation of the deep foundation pit.

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Study on Deformation Characteristics of Deep Foundation Pit in Unsaturated Soil

Cited by 5 publications

References 2 publications

Study on Deformation Characteristics of Retaining Structures under Coupled Effects of Deep Excavation and Groundwater Lowering in the Affected Area of Fault Zones

Study on Deformation Characteristics of Retaining Structures under Coupled Effects of Deep Excavation and Groundwater Lowering in the Affected Area of Fault Zones

Laboratory Tests and Numerical Simulation on the Loess Subgrade Improved by Lime-Lignin

The Influence of Different Excavation Methods on Deep Foundation Pit and Surrounding Environment

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