Investigating impacts of deep foundation pit dewatering on land subsidence based on CFD-DEM method

Zhang, Xuan; Wang, Lihua; Wang, Hualao; Feng, Chunlei; Shi, Haojie; Wu, Shengzhi

doi:10.1080/19648189.2021.1943535

Cited by 10 publications

(6 citation statements)

References 30 publications

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“…However, there has been a lack of attention given to water and sand leakage in foundation pit engineering. In terms of research on ground settlement due to pit excavation considering hydraulic factors, researchers are currently focusing on the pit dewatering process, with little consideration given to the combined loss of water and sand [16][17][18]. Thus, the hazards of water and sand loss in foundation pits warrant Shanghai Metro [5] A large number of cracks appeared on the ground surface outside the foundation pit, and the settlement of the buildings around the foundation pit and the ground surface exceeded 40 mm High groundwater level; incomplete wall brushing at the joint of the enclosure structure -Korean Metro [6] Two students fell into a 3 m × 3 m sinkhole outside the pit…”

Section: Location Overview Reason Picturementioning

confidence: 99%

“…However, there has been a lack of attention given to water and sand leakage in foundation pit engineering. In terms of research on ground settlement due to pit excavation considering hydraulic factors, researchers are currently focusing on the pit dewatering process, with little consideration given to the combined loss of water and sand [16][17][18]. Thus, the hazards of water and sand loss in foundation pits warrant Foshan Metro Line [7] A fan-shaped settlement area with a diameter of about 13 m was formed with a surge point at the center, and the maximum surface settlement was 70 cm after 24 h…”

Section: Location Overview Reason Picturementioning

confidence: 99%

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Study on the Mechanism of Water and Sand Leakage in a Foundation Pit Retaining Structure Based on the Computational Fluid Dynamics–Discrete Element Method

Xu,

Zhang,

Wang

et al. 2024

Buildings

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The existence of defects in the enclosure structure is the primary cause of water and sand leakage in foundation pits, as well as being a significant source of danger in pit construction, but current research lacks an in-depth investigation of the generation mechanism and gestation process. In this paper, which comprehensively considers the microscopic particles and macroscopic level, the development mechanism of a water and sand leakage disaster in a foundation pit with a water-rich sand layer was studied using the principle of computational fluid dynamics and discrete element method coupled analysis (CFD–DEM); moreover, based on the anisotropy of the particle force and fluid energy analysis, the deformation of the stratum and ground stress field were analyzed. The results show that the stress field will produce a plugging effect at a certain distance from the defect, and the strata exhibit a dominant displacement tendency in the vertical direction, resulting in the emergence of a gradually concave stress relaxation zone and an elliptical contour in the strata displacement map near the defect. The fluid energy describes the displacement of the sand layer very well, and it is separated into the sand layer’s centralized loss region and the major loss area based on the high and low levels of the fluid energy class. The impact of fluid at the defect reaches the maximum kinetic energy, which penetrates the structural weakness and causes the loss of sand particles, and the cross-section of the water influx near the defect gradually expands with the loss of particles, indicating that there is a danger of further expansion of the defect under the impact of water flow. These results have technical implications for the management of water and sand leakage disasters in foundation pit engineering.

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Section: Location Overview Reason Picturementioning

confidence: 99%

“…However, there has been a lack of attention given to water and sand leakage in foundation pit engineering. In terms of research on ground settlement due to pit excavation considering hydraulic factors, researchers are currently focusing on the pit dewatering process, with little consideration given to the combined loss of water and sand [16][17][18]. Thus, the hazards of water and sand loss in foundation pits warrant Foshan Metro Line [7] A fan-shaped settlement area with a diameter of about 13 m was formed with a surge point at the center, and the maximum surface settlement was 70 cm after 24 h…”

Section: Location Overview Reason Picturementioning

confidence: 99%

Study on the Mechanism of Water and Sand Leakage in a Foundation Pit Retaining Structure Based on the Computational Fluid Dynamics–Discrete Element Method

Xu,

Zhang,

Wang

et al. 2024

Buildings

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“…In the process of FP, groundwater is pumped out from the soil through the drainage pipe inserted into the soil, and soil particles are easily carried out. If effective filtration measures are not taken, the soil around the drainage pipe is prone to mass loss [42]. The duration of FP is long and the total amount of drainage is large.…”

Section: Construction Activitiesmentioning

confidence: 99%

An Analysis of Soil Erosion on Construction Sites in Megacities Using Analytic Hierarchy Process

Tang

Shi

2023

Sustainability

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The highly intensive construction activities in the process of urbanization have led to the risk of soil loss, which is due to the disturbance of urbanization on the soil; this makes the soil more vulnerable to erosion by rain and other factors, thus causing soil loss to the urban drainage pipe network or the river channels around the city. This process is affected by both natural and human factors. Based on engineering experience and existing research, 13 influencing factors were identified and classified into four dimensions: Natural Conditions (NC), Construction Activities (CA), Conservation Measures (CM) and Management Measures (MM). Fifteen experts from Shanghai, Guangzhou and Zhengzhou, three main cities in China, were invited to assess the weight of each influencing factor through pairwise comparison. Based on the analytic hierarchy process, the soil erosion risk evaluation model of construction sites in megacities was established, and the weight of each influencing factor was determined. According to the weights, the weighted summation method can be used to calculate the comprehensive scores of these sites and the soil erosion risks of the construction sites can be ranked according to the comprehensive scores for multiple construction sites. The analysis of the model shows that MM is the most important factor, and improving the management level is the key measure to control the soil erosion of construction site in megacities. In addition, in the four dimensions, the results of the weight of each influencing factor in the NC dimension are quite different; this is due to the different cities where the experts are from, indicating that the natural conditions of the location will affect empirical judgment. By inviting many experts to evaluate, the deviation in judgment results, caused by differences in natural conditions, can be reduced.

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“…Previous research has indicated that the primary factors influencing excavation deformation include the excavation geometry, support forms, seepage inflow rates, excavation soil, and excavation sequences [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Some scholars have optimized excavation design schemes through quantitative studies on individual influencing factors [ 28 , 29 , 30 , 31 , 32 ], providing new insights into excavation construction processes.…”

Section: Introductionmentioning

confidence: 99%

Research on the Deformation Law of Foundation Excavation and Support Based on Fluid–Solid Coupling Theory

Xia,

Zhao,

Wang

et al. 2024

Sensors

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To investigate the impact of underground water seepage and soil stress fields on the deformation of excavation and support structures, this study initially identified the key influencing factors on excavation deformation. Subsequently, through a finite element simulation analysis using Plaxis, this study explored the effects of critical factors, such as the excavation support form, groundwater lowering depth, permeability coefficient, excavation layer, and sequence on excavation deformation. Furthermore, a comprehensive consideration of various adverse factors was integrated to establish excavation support early warning thresholds, and optimal dewatering strategies. Finally, this study validated the simulation analysis through an on-site in situ testing with wireless sensors in the context of a physical construction site. The research results indicate that the internal support system within the excavation piles exhibited better stability compared to the external anchor support system, resulting in a 34.5% reduction in the overall deformation. Within the internal support system, the factors influencing the excavation deformation were ranked in the following order: water level (35.5%) > permeability coefficient (17.62%) > excavation layer (11.4%). High water levels, high permeability coefficients, and multi-layered soils were identified as the most unfavorable factors for excavation deformation. The maximum deformation under the coupled effect of these factors was established as the excavation support early warning threshold, and the optimal dewatering strategy involved lowering the water level at the excavation to 0.5 m below the excavation face. The on-site in situ monitoring data obtained through wireless sensors exhibited low discrepancies compared to the finite element simulation data, indicating the high precision of the finite element model for considering the fluid–structure interaction.

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Investigating impacts of deep foundation pit dewatering on land subsidence based on CFD-DEM method

Cited by 10 publications

References 30 publications

Study on the Mechanism of Water and Sand Leakage in a Foundation Pit Retaining Structure Based on the Computational Fluid Dynamics–Discrete Element Method

Study on the Mechanism of Water and Sand Leakage in a Foundation Pit Retaining Structure Based on the Computational Fluid Dynamics–Discrete Element Method

An Analysis of Soil Erosion on Construction Sites in Megacities Using Analytic Hierarchy Process

Research on the Deformation Law of Foundation Excavation and Support Based on Fluid–Solid Coupling Theory

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