Observed performance of a 30.2 m deep-large basement excavation in Hangzhou soft clay

Cheng, Kang; Xu, Riqing; Ying, Hongwei; Gan, Xiaolu; Zhang, Lisha; Liu, Sijie

doi:10.1016/j.tust.2021.103872

Cited by 39 publications

(18 citation statements)

References 33 publications

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“…The AEP peak value of the project is small, and the distribution is concentrated. Different from the triangular or trapezoidal AEP envelope, the AEP envelope with a linear distribution along the depth proposed by Cheng et al (2021) and Liu et al (2019b) can better explain the distribution mode of earth pressure behind the foundation pit wall of stations in Suzhou.…”

Section: Analysis Of Apparent Earth Pressurementioning

confidence: 86%

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Analysis of the Deformation Law of Deep and Large Foundation Pits in Soft Soil Areas

et al. 2022

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Taking a deep excavation in Suzhou soft soils adopting three support schemes as the background, the excavation performance metrics, including the heave and lateral deformation of diaphragm walls, surface vertical deformation, vertical deformation of surrounding buildings, and earth pressure, are thoroughly investigated based on 15 excavation cases collected in the soft soil area of Suzhou. Based on the analysis of monitoring data, some findings were achieved: the foundation pit deformation is greatly affected by the spatial effect. The existing station can constrain the foundation pit deformation. Benefiting from the combination of various support solutions, the average maximum deflection of the diaphragm wall is 0.10% He. The maximum lateral movement depth of the diaphragm wall (δhm) is mainly located at (He-7, He+12.5). The vertical deformation of the wall top is greatly affected by the excavation exposure time and soil conditions. The heave range of the wall top is (−0.08∼0.26%) He. Under the action of the displacement of the diaphragm wall to outside the pit and the upward displacement of the wall top, the ground surface is uplifted, and the maximum uplift is (0.02∼0.14%) He, ranging from 0.12δhm to 1.13δhm. The maximum surface settlement is (−0.01% ∼ −0.15%) He, ranging from −0.22δhm to −3.11δhm. The form of building heave is mainly affected by the surface heave and the distance from the diaphragm wall (d). When d is within a certain range, there is a heave settlement difference between the adjacent side and the opposite side of the excavation, and the adjacent side undergoes mostly subsidence, while the opposite side undergoes mostly uplift. The peak value of the apparent earth pressure (AEP) envelope is 0.59γHe, which falls within (0.47∼0.78) He. The calculation scheme proposed by Kim can be used to predict the AEP for multiple soil types.

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Section: Analysis Of Apparent Earth Pressurementioning

confidence: 86%

“…The AEP calculation scheme proposed by Kim et al (2021) can be used to predict the AEP distribution mode of many types of soil. The AEP envelope distribution model given by Cheng et al (2021) can interpret the AEP distribution model of the station foundation pit in Suzhou.…”

Section: Discussionmentioning

confidence: 99%

Analysis of the Deformation Law of Deep and Large Foundation Pits in Soft Soil Areas

et al. 2022

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“…Peck [3] and Ou [4] studied the environmental effect of softclay area and sandy area. Several investigations [5][6][7][8][9] focused on the foundation pit cases in Shanghai, Hangzhou and Fuzhou and so on, and summarized the deformation law of foundation pit structure in soft clay area. Because the complexity of engineering geology has an obvious impact on the deformation law of foundation pit, the criterion of slope excavation stability in foundation pit design still needs to be classified and discussed.…”

Section: Introductionmentioning

confidence: 99%

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

Qin

Tao²,

Chen

et al. 2022

Front. Phys.

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The deformation prediction of foundation pit is still an open issue in geotechnique engineering. This paper focuses on a new deformation prediction method of foundation pit in soil-rock composite stratum in Nanjing area. To do so, the field monitoring deformation data of deep foundation pit adjacent to the railway in a soil-rock combined stratum is firstly analyzed. Based on these field data, the characteristics of horizontal displacement and surface settlement of rock-socketed support pile, as well as its relationship with Earth excavation are discussed. Results show that the average value of maximum horizontal displacement of support pile in zone with shallow rock depth (soil layer >15 m) is relatively large, which is 3.5 times of that with shallow soil depth (10–12 m into moderately-weathered mudstone). The depth of maximum horizontal displacement is obviously linearly related to the thickness of soil layer (H), while the surface settlement does not change with the increase of soil/rock layer thickness ratio. Utilizing the relationship between the maximum water level displacement and excavation depth, a new Gaussian-type empirical formulation is established to predict horizontal deformation of soil-rock composite stratum with rock-socketed support pile. By comparison with two other methods, it is found that the improved Gaussian curve is in good agreement with the measured horizontal displacement curve. This indicates that the new method can provide a valid reference for the design and construction of foundation pit with rock-socketed support pile in Nanjing area.

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“…With the development of urbanization around the world, the demand for extensive underground space utilization has increased dramatically in recent years. To meet these demands, deep excavations are widely used for the construction of geotechnical infrastructures such as tunnels [1], basements [2], bridge foundations [3], and launch shafts for piping [4]. Piles are often installed beneath these infrastructures to bear the uplift or compression loads.…”

Section: Introductionmentioning

confidence: 99%

Analysis on Response of a Single Pile Subjected to Tension Load Considering Excavation Effects

Liu

et al. 2022

Applied Sciences

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With the development of urbanization, numerous excavations are carried out to facilitate the development of underground space. As a support for tunnel structures, uplift piles are often installed prior to tunnel excavation. The excavation inevitably causes disturbance to the soil below the excavation surface, changing the soil’s mechanical behavior and stress state significantly. However, there is still a lack of a method to evaluate the change in pile capacity due to excavation. This paper proposes a semi-analytical approach for estimating the change in load-settlement behavior of an uplift pile considering the effects of excavation. A hyperbolic model was adopted to simulate the nonlinear interaction of the pile–soil interface. The nonlinear shear-induced soil displacement outside the pile–soil interface is introduced to obtain a more realistic load-displacement behavior of the uplift pile. An effective iterative program was implemented based on the proposed semi-analytical approach. The comparisons between the results from the proposed methods, well-documented field tests, centrifuge tests, and other analytical methods showed that the proposed approach is suitable for analyzing an uplift pile considering excavation effects. A parametric study was conducted to investigate the effects of main soil properties on the pile capacity loss caused by excavation. The results showed that the soil friction angle and the ratio of the excavation depth to the pile effective length have a great influence on the loss in pile uplift capacity caused by excavation. However, the loss of pile uplift capacity caused by excavation is not affected by the soil’s shear modulus or Poisson’s ratio.

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Observed performance of a 30.2 m deep-large basement excavation in Hangzhou soft clay

Cited by 39 publications

References 33 publications

Analysis of the Deformation Law of Deep and Large Foundation Pits in Soft Soil Areas

Analysis of the Deformation Law of Deep and Large Foundation Pits in Soft Soil Areas

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

Analysis on Response of a Single Pile Subjected to Tension Load Considering Excavation Effects

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