Deformation Analysis and Prediction of Foundation Pit in Soil-Rock Composite Stratum

Qin, Zehong; Tao, Zhe; Chen, Zechao; Zhang, Ziguang; Tang, C. P.; Ren, Qiangqiang

doi:10.3389/fphy.2021.817429

Cited by 4 publications

(3 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, horizontal deformation is generally considered to be the main deformation mode of piles [16][17][18]. Previous studies have shown that the maximum horizontal deformation of piles usually occurs near the pit bottom [19][20][21]. Therefore, this study assumes that the horizontal deformation curve of piles can be approximated by a quadratic curve fitting.…”

Section: Pile Deformationmentioning

confidence: 99%

Spatial Deformation Calculation and Parameter Analysis of Pile–Anchor Retaining Structure

Yin

2023

Applied Sciences

View full text Add to dashboard Cite

Scholars often consider the deformation of a foundation pit retaining structure as a significant indicator of its stability. However, the current theoretical prediction formula for pit with pile–anchorretaining structure deformation is not yet perfect. This study utilizes a simplified spatial deformation model of a pile–anchorretaining structure and the principle of minimum potential energy to derive a prediction formula for the retaining structure’s spatial deformation. Afterwards, a numerical simulation model is developed based on actual engineering practices. On-site monitoring data is compared with the results of theoretical calculation formulas and numerical simulation models to validate their applicability. The research findings reveal minimal discrepancies between the theoretical calculation results, numerical simulation outcomes, and on-site monitoring data, indicating a high level of accuracy. Those three results follow consistent rules. The horizontal deformation curve of the crown beam exhibits a ‘V’-shaped distribution, and as the distance from the calculation point to the centerline of the foundation pit decreases, the horizontal deformation of the crown beam increases. The horizontal deformation curve of the pile displays a ‘V’-shaped distribution, and the pile’s horizontal deformation increases as the distance to the centerline of the foundation pit decreases. The research findings indicate that increasing the size and material strength of the crown beam and waist beam has only a limited effect on controlling the retaining structure’s deformation. However, by increasing the size and material strength of the pile, the deformation of the retaining structure can be significantly reduced.

show abstract

Section: Pile Deformationmentioning

confidence: 99%

Spatial Deformation Calculation and Parameter Analysis of Pile–Anchor Retaining Structure

Yin

2023

Applied Sciences

View full text Add to dashboard Cite

show abstract

“…Terefore, numerical analysis tools, such as FlAC 3D , Midas GTS NX, and PLAXIS3D, are usually adopted to calculate stresses and deformations of the foundation pits to be excavated for the purpose of increasing analysis efciency meanwhile assuring the analysis accuracy [12][13][14][15]. At present, most numerical investigations are focused on deformations of foundation pit in soil strata or soil-rock composite strata [16][17][18][19]. Unlike foundation pit in soil strata or soil-rock composite strata, foundation pit in hard rock strata has good stability if the same supporting schemes for foundation pits in soil strata or soil-rock composite strata are adopted, which is because the surrounding rocks of the foundation pit in hard rock strata have certain strengths and antideformation abilities [20].…”

Section: Introductionmentioning

confidence: 99%

Deformation Characteristics of a Deep Subway Foundation Pit in Hard Rock Strata under a Delayed Supporting Condition

Li,

Ma,

Gao

et al. 2023

Shock and Vibration

View full text Add to dashboard Cite

In this investigation, deformations of a deep foundation pit in hard rock strata, respectively, under delayed and in-time supporting schemes of one-layer transverse reinforced concrete bracings at the top of the foundation pit, one-layer steel bracings at a depth of 8 m, and one-layer prestressed anchorages at a depth of 22.5 m during excavation were characterized according to lateral deformations of the foundation pit, settlements of the surrounding ground, and axial forces of the steel bracings according to numerical calculations and on-site monitoring. Numerical calculation results showed that the maximum lateral deformations of the foundation pit and settlements of the surrounding ground were, respectively, 10.34 mm and 8.49 mm at an excavation depth of 31 m, which were obviously larger than those under in-time supporting. Meanwhile, under delayed supporting conditions, lateral deformations of the foundation pit and settlements of the surrounding ground were far less than the allowed values, respectively, being 0.3% and 0.15% of the excavation depth, required in the Chinese standard of GB50007-2011, indicating that the foundation pit under delayed supporting conditions had good stability. Therefore, when excavating deep foundation pits in hard rock strata, proper delayed supporting schemes could be considered so that strengths of the surrounding hard rocks could be utilized to the fullest, and at the same time, more spaces for excavation could be freed up, and construction duration and construction costs could thus be lowered.

show abstract

“…Based on the construction space effect, the interaction between the foundation pit and the underlying tunnel in the soil-rock composite stratum is studied by numerical analysis method [20,21]. The local model of the pit angle is established to analyze the pit angle effect of the foundation pit in the soil-rock composite stratum and the influence of the support structure on the external angle deformation [22,23]. However, the results of the above study do not take into account the strong regional characteristics of foundation pit engineering.…”

Section: Introductionmentioning

confidence: 99%

Deformation Law and Spatial Effect of Deep Foundation Pits for Subway Construction in Soil-Rock Composite Strata in Seasonally Frozen Areas

2023

Teh. vjesn.

View full text Add to dashboard Cite

The stability and safety of metro deep foundation pit in the soil-rock composite stratum in the seasonally frozen area are the key issues in the design and construction of the foundation pit. In order to ensure the soil-rock composite stratum in the seasonally frozen area, the deformation of the supporting structure is within the safe range when the deep foundation pit is excavated. At the same time, it will reduce the impact of the construction of metro deep foundation pit on the surrounding buildings. During the construction of foundation pit, close monitoring shall be carried out and the actual monitoring data shall be studied and analyzed. During the excavation of each layer of the foundation pit, monitor the displacement change of the foundation pit support structure and the settlement change of the surrounding ground surface, study the deformation law of the subway deep foundation pit in the soil-rock composite layer, and discuss the spatial effect of the foundation pit excavation in the seasonally frozen area. This paper mainly takes the deep foundation pit project of Anxin Road Station of Changchun Metro Line 5 as the research object, and analyzes the actual monitoring results. The results show that: (1) With the long side of the foundation pit, the deformation of the retaining structure of the foundation pit increases with the distance from the pit corner, and the middle of the long side of the foundation pit is less constrained by the retaining structure. (2) During the excavation of soil-rock composite foundation pit in seasonally frozen soil area, the pile displacement, axial force of support and uplift of support structure caused by rock excavation are relatively small, while the lateral displacement of foundation pit below the rock surface and thawing settlement deformation of soil are basically unchanged. The maximum lateral displacement of the foundation pit at the upper part of the rock surface moves upward. During the construction of deep foundation pit, there is a large displacement before the erection of the third layer of steel support. Attention should be paid to the soil properties of the deep silty clay layer, as well as to the rapid construction and synchronous maintenance.

show abstract

Deformation Analysis and Prediction of Foundation Pit in Soil-Rock Composite Stratum

Cited by 4 publications

References 15 publications

Spatial Deformation Calculation and Parameter Analysis of Pile–Anchor Retaining Structure

Spatial Deformation Calculation and Parameter Analysis of Pile–Anchor Retaining Structure

Deformation Characteristics of a Deep Subway Foundation Pit in Hard Rock Strata under a Delayed Supporting Condition

Deformation Law and Spatial Effect of Deep Foundation Pits for Subway Construction in Soil-Rock Composite Strata in Seasonally Frozen Areas

Contact Info

Product

Resources

About