Working characteristics of concrete-cored deep cement mixing piles under embankments

Wang, Chi; Xu, Yongfu; Dong, Ping

doi:10.1631/jzus.a1400009

Cited by 36 publications

(4 citation statements)

References 12 publications

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“…Piled embankments, with or without geosynthetic reinforcement, have been widely used to overcome several issues (e.g., insufficient bearing capacity, local instability, and unacceptable settlement), encountered in the construction of railways and highways over weak soils (e.g., highly compressible soil, alluvial clay, and peat) (Chen et al, 2010;Ling et al, 2010;Briançon and Simon, 2012;Liu et al, 2012;Wang C. et al, 2014). Soil arching plays a very important role in reducing the embankment load shared by the weak soil between piles, which is essentially a stress redistribution phenomenon caused by the pile-subsoil relative displacement (Δs), and has been proven to be a key load-transfer mechanism in embankments.…”

Section: Introductionmentioning

confidence: 99%

Visualization of the formation and features of soil arching within a piled embankment by discrete element method simulation

Zheng

Zhang

Cui

2016

J. Zhejiang Univ. Sci. A

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Piled embankments are widely used in highway and railway engineering due to their economy and efficiency in overcoming several issues encountered in constructing embankments over weak soils. Soil arching, caused by the pile-subsoil relative displacement (Δs), plays an important role in reducing the embankment load falling on weak soil, however, the fundamental characteristics (e.g., formation and features) of soil arching remain poorly understood. In this study, a series of discrete element method (DEM) modellings are performed to study the formation and features of soil arching with the variation of Δs in piled embankments with or without geosynthetic reinforcement. Firstly, calibration for the modelling parameters is carried out by comparing the DEM results with the experimental data obtained from the existing literature. Secondly, the analysis of the macroand micro-behaviours is performed in detail. Finally, a parametric study is conducted in an effort to identify the influences of three key factors on soil arching: the friction coefficient of the embankment fill (f), the embankment height (h), and the pile clear spacing (s−a). Numerical results indicate that Δs is a key factor governing the formation and features of soil arching in embankments. To be specific, soil arching gradually evolves from two inclined shear planes at a small Δs to a hemispherical arch at a relatively large Δs. Then, with a continuous increase in Δs, the soil arching height gradually increases and finally approaches a constant value of 0.8(s−a) (i.e., the maximum soil arching height). For a given case, the higher the soil arching height, the greater the degree of soil arching effect. The parametric study shows that the friction coefficient of the embankment fill has a negligible influence on the formation and features of soil arching. However, embankment height is a key factor governing the formation and features of soil arching. In addition, pile clear spacing has a significant effect on the formation of soil arching, but not on its features.

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Section: Introductionmentioning

confidence: 99%

Visualization of the formation and features of soil arching within a piled embankment by discrete element method simulation

Zheng

Zhang

Cui

2016

J. Zhejiang Univ. Sci. A

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“…Stiffened deep mixed (SDM) column is formed by inserting a precast concrete core pile into the center of a deep mixed (DM) column. Due to its good engineering performance, SDM columns have gained wide acceptance of effectiveness for improving soft clay [1], [2], [3] .…”

Section: Introductionmentioning

confidence: 99%

Basic Mechanical Properties of Unit Cell-based Stiffened Deep Mixed Column

Zhang,

Xu,

et al. 2024

IOP Conf. Ser.: Earth Environ. Sci.

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As a composite column, stiffened deep mixed (SDM) column is formed by inserting a precast concrete core pile into the center of a deep mixed (DM) column. When SDM columns are used to support embankments over soft soil, they would be failed by shearing, compression, tension, and bending. This study conducted a series of laboratory tests to investigate the basic mechanical properties of a unit cell of SDM column, including uniaxial compression, direct shear and tension tests. The results reveal that the impact on improvement was minimal at a core ratio of 9.8%, subsequently followed by a substantial rise. In addition, the radial compression strength reached the maximum at a core ratio of 25%, and the shear strength approached to a constant value when the core element ratio exceeded 25%. Increasing the area ratio resulted in the change of failure modes of core element. Finally, a relationship among the different strength was discussed.

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“…Wang et al [19] proposed a modified p-y curve model to calculate the lateral bearing capacity of the PCCS based on field tests of the PCCSs and indicated that cemented soil could reduce the bending moment and lateral deflections. Based on tested results, Wang et al [33] found that the stiffened deep mixing (SDM) column-supported embankment could significantly reduce the postconstruction settlement by 27.3%-68.3 compared to the conventional DM column-reinforced composite foundation. Ye et al [26] established a series of finite element (FE) models to analyze the bearing mechanism of the SDM column-supported embankment.…”

Section: Introductionmentioning

confidence: 99%

Analytical Solution for Consolidation Behaviors of Combined Composite Foundation Reinforced with Penetrated PCCSs and Floating DM Columns

Zhang

Liu

et al. 2023

Geofluids

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As the composite pile, the precast concrete piles reinforced with cement-treated soil (PCCS) is formed by driving the precast cement (PC) pile into the deep mixing (DM) column, which has been successfully and widely utilized to support buildings and embankments over soft soil. To increase the pile spacing and give full play to the economic merits of the PCCS, a reinforcement scheme, which involves the combined use of rigid piles and flexible columns, employing penetrated PCCSs and floating DM columns is proposed and utilized for soft soil ground treatment. However, there is a lack of feasible method for consolidation behaviors of this combined composite foundation (CCF) reinforced with penetrated PCCSs and floating DM columns under flexible loads. This paper developed an analytical solution to predict the average consolidation degree of this CCF based on a cylinder consolidation model and double-layer ground consolidation theory. The excess pore pressure and average consolidation degree were calculated by considering the composite pile penetration into the cushion. The analytical method agrees well with results obtained by numerical analysis. Additionally, a parametric study was conducted systematically to analyze the effect of key influence factors on the average consolidation degree of this CCF. The results indicate that the consolidation rate of this CCF can be much faster than that of the natural ground. The consolidation rate strongly depends on the compressive modulus and area replacement ratio of PCCSs. The increasing inner core-outer core modulus ratio and the inner core-subsoil modulus ratio increase the consolidation rate of this CCF. In addition, the consolidation rate increases with the gravel cushion-subsoil modulus ratio, while it decreases with the loading period.

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Working characteristics of concrete-cored deep cement mixing piles under embankments

Cited by 36 publications

References 12 publications

Visualization of the formation and features of soil arching within a piled embankment by discrete element method simulation

Visualization of the formation and features of soil arching within a piled embankment by discrete element method simulation

Basic Mechanical Properties of Unit Cell-based Stiffened Deep Mixed Column

Analytical Solution for Consolidation Behaviors of Combined Composite Foundation Reinforced with Penetrated PCCSs and Floating DM Columns

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