Field Tests on Influencing Factors of Negative Skin Friction for Pile Foundations in Collapsible Loess Regions

Xing, Huaizhong; Liu, Liangliang

doi:10.1007/s40999-018-0294-z

Cited by 38 publications

(13 citation statements)

References 30 publications

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“…For example, the engineering experience shows that the additional settlement of loess between the piles occurs because of the inundation with construction on bored pile foundations in the self-weight collapsible loess area. en, the negative friction of the piles [32][33][34], which develop during the collapse of loess, reacts on the loess and reduces the vertical stress of loess around the piles.…”

Section: Introductionmentioning

confidence: 99%

Collapse Potential of Loess under Unloading Effect

Jin

Wang

Zhao

et al. 2021

Advances in Civil Engineering

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Collapsible loess is generally characterized by a sudden and substantial decrease in volume that occurs when is applied under constant stress. To evaluate the loess collapse potential, the self-weight collapse and collapse coefficients have been defined by the code for building construction in collapsible loess regions. However, the method in the code does not account for the vertical stress variation. The loess collapse process commonly occurs with stress variation in practice. This paper documents a low-cost, quantitative evaluation scheme using regression analysis to evaluate the loess collapse potential by varying the unloading levels. The results show that the factors that prominently account for loess collapse deformation are the initial pressure, unloading ratio, and collapse completed-ratio. At a constant collapse-completed ratio, the remnant collapse coefficient significantly decreases with the decreasing unloading ratio; at a constant unloading ratio, the remnant collapse coefficient increases with a decreasing collapse-completed ratio. Decreasing unloading and collapse-completed ratios decreased the loess collapse potential with an initial pressure that exceeds the threshold value. Finally, an unloading collapse deformation calculation of loess was prepared to analyze practical project problems of loess based on the unloading collapse test.

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Section: Introductionmentioning

confidence: 99%

Collapse Potential of Loess under Unloading Effect

Jin

Wang

Zhao

et al. 2021

Advances in Civil Engineering

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“…e settlement of superstructures is especially a concern for bridges that require high design accuracy for the foundation design. However, the nonuniform compressibility of loess often results in significant pile settlement [3][4][5]. As a means of increasing the bearing capacity and reducing the settlement of pile foundations, the postgrouting technique has become a popular method for cast-in-place pile foundation construction [6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…In order to study the compression modulus improvement coe cient ϕ of soil around the grouting point, formula P ch can be used to calculate the soil gravity stress P in the range of 1 m at pile tip, in which c is 18.5 g/cm 3 Advances in Civil Engineering 11 E s,z calculated by P with the measured value of E s,z after grouting; the reference value of ϕ in this area is given in Table 6 after inverse calculation. e modi ed compression modulus E s ′ of the soil layers can be obtained by multiplying the compression modulus of the soil layers obtained from the abovementioned two methods and the corresponding improvement coe cient.…”

mentioning

confidence: 99%

Optimization Analysis of Settlement Parameters for Postgrouting Piles in Loess Area of Shaanxi, China

Zhou

Zhu

Kong

et al. 2019

Advances in Civil Engineering

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The settlement calculation of postgrouting piles is complex and depends on the calculation method and parameters. Static load tests were conducted to compare the settlement characteristics of nongrouting and postgrouting piles, and three vital parameters in the layer-wise summation method were revised to predict the settlement of postgrouting piles. The elastic compression coefficient was deduced based on the Mindlin–Geddes method by considering the influence of the change in the pile side resistance distribution and end resistance ratio on the elastic compression after grouting. The relationship between the compression modulus and soil gravity stress and cone penetration resistance were established, respectively, using experimental data. The optimum value of the settlement empirical coefficient was determined using regional data. Finally, we used the postgrouting pile of the Wuqi–Dingbian expressway as a practical example. The results obtained from the layer-wise summation method after parametric optimization were close to the measured values. The results of this study provide reference data and guidance for the settlement calculation of postgrouting piles in this area.

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“…Zhang et al [24] found that down-hole dynamic compaction pile could improve 50 m collapsible loess when the pile spacing is reasonable by field tests. Xing and Liu [25] carried out water immersion tests to study the different pile types on negative skin friction of pile foundations in loess regions and found NSF of the bored concrete pile was smallest. Zhou et al [26] used static load test and post-grouting technology; the settlement parameters of post-grouting piles in loess area were analyzed and optimized.…”

Section: Introductionmentioning

confidence: 99%

Effect of Steel Casing on Vertical Bearing Characteristics of Steel Tube-Reinforced Concrete Piles in Loess Area

Feng

Dong

et al. 2019

Applied Sciences

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This study aims at investigating the effect of steel casing on vertical bearing characteristics of steel tube-reinforced concrete piles in loess area by centrifugal model test. Five piles were selected, one of them was a conventional reinforced concrete pile which was 35 cm in length and 2.5 cm in diameter as a contrast pile, and the length of steel casing for the remaining four steel tube-reinforced concrete piles was 8 cm, 12 cm, 16 cm, and 20 cm respectively. The results show that the axial force, unit skin friction, tip resistance, and shaft resistance of steel tube-reinforced concrete piles with different steel casing lengths were different from conventional reinforced concrete pile. Additionally, the ultimate bearing capacity of steel tube-reinforced concrete piles was compared with a conventional reinforced concrete pile. Moreover, advantages of steel casing in pile foundation engineering were summarized. The results of this study can provide reference for vertical bearing characteristics of steel tube-reinforced concrete piles in loess area.

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Field Tests on Influencing Factors of Negative Skin Friction for Pile Foundations in Collapsible Loess Regions

Cited by 38 publications

References 30 publications

Collapse Potential of Loess under Unloading Effect

Collapse Potential of Loess under Unloading Effect

Optimization Analysis of Settlement Parameters for Postgrouting Piles in Loess Area of Shaanxi, China

Effect of Steel Casing on Vertical Bearing Characteristics of Steel Tube-Reinforced Concrete Piles in Loess Area

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