Soft Soil Mechanics and Foundation Consolidation

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Civil Engineering".

Deadline for manuscript submissions: closed (31 December 2023) | Viewed by 7710

Special Issue Editor

School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China
Interests: urban subway tunnel and underground engineering; soft soil foundation deformation; high railway embankment reinforcement; dynamic interaction between track and foundation; soil dynamics and artificial frozen soil

Special Issue Information

Dear Colleagues,

Soft clay foundation is widely distributed all over the world. Soft clay has the characteristics of high moisture content, high compressibility, and low permeability coefficient. Under the action of high-rise building load, groundwater precipitation, subway vibration, high-speed railway vibration, and seismic load, soft clay foundation is prone to deformation and settlement, and sand is liquefied under seismic load. Therefore, the mechanical properties of soil under dynamic and static load need to be further studied. In addition, artificial freezing and grouting reinforcement technology are often used in the construction of urban underground space engineering. The mechanical properties of frozen thawed clay and grouting reinforcement soil also need to be studied.

Prof. Dr. Zhen-Dong Cui
Guest Editor

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Keywords

  • urban underground engineering
  • artificial freezing method
  • foundation pit dewatering
  • static and dynamic consolidation
  • liquefaction and landslide

Published Papers (7 papers)

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Research

15 pages, 13067 KiB  
Article
Similarity Model Test on Rainfall Scouring Mechanism of High-Speed Railway Subgrade Slope
by Shao-Wei Wei, Song Lv, Jian-Jie Jiang, De-Gou Cai and Zhen-Dong Cui
Appl. Sci. 2024, 14(1), 244; https://doi.org/10.3390/app14010244 - 27 Dec 2023
Viewed by 514
Abstract
The subgrade slope, when exposed to the natural environment for a long time, is easily affected by rainfall scouring, which leads to a large loss of filling materials and soil sliding, affecting the stability of the subgrade slope. In this paper, the model [...] Read more.
The subgrade slope, when exposed to the natural environment for a long time, is easily affected by rainfall scouring, which leads to a large loss of filling materials and soil sliding, affecting the stability of the subgrade slope. In this paper, the model test of a high-speed railway subgrade slope under rainfall scouring was conducted to quantitatively study the occurrence and development process of subgrade slope erosion. Compared with the model test results and the theoretical results, the incipient flow velocity formula of coarse-grained soil was verified. Then, the curve of rainfall intensity varied with the incipient particle size under different rainfall intensities, slope gradients and soil particle grading conditions was analyzed. Results show that during rainfall scouring, the smaller the particle size, the earlier the scouring erosion occurs. In addition, the soil particles on the slope bottom were scoured more severely than those on the slope upper. With the increase in rainfall intensity, slope gradient, and the change in soil particle gradation (removing the minimum particle size), the incipient flow velocity of soil particles on the slope will be reduced. The curve of the rainfall intensity varied with the incipient particle size, which plays an early warning role in the analysis of slope erosion stability and reflects the particle size range of the scouring erosion incipient on the slope surface under different rainfall intensities, providing the basis for the analysis of slope erosion stability and the slope protection design of the high-speed railway subgrade slope. Full article
(This article belongs to the Special Issue Soft Soil Mechanics and Foundation Consolidation)
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16 pages, 5971 KiB  
Article
Fractional Calculus-Based Statistical Damage Model of Unsaturated Soil under the Coupling Effect of Moistening and Stress Fields
by Hua Zhang and Peng Wang
Appl. Sci. 2023, 13(16), 9156; https://doi.org/10.3390/app13169156 - 11 Aug 2023
Viewed by 683
Abstract
Unsaturated soil exhibits extremely complex engineering mechanical properties under the coupling effect of moistening and stress fields. Firstly, the effective stress principle and limit equilibrium conditions of unsaturated soil under the coupling effect of moistening and stress fields were discussed based on the [...] Read more.
Unsaturated soil exhibits extremely complex engineering mechanical properties under the coupling effect of moistening and stress fields. Firstly, the effective stress principle and limit equilibrium conditions of unsaturated soil under the coupling effect of moistening and stress fields were discussed based on the basic principles of unsaturated soil. Secondly, a fractional-order model considering the viscoelasticity and strain hardening of unsaturated soil was established based on the fractional calculus theory. Then, based on the principle of damage mechanics, the damage variable evolution equation under the coupling effect of moistening and stress fields was established, and the fractional calculus-based statistical constitutive damage model of unsaturated soil under the coupling effect of moistening and stress fields was developed. In turn, parameters of the developed model were solved using a triaxial test of unsaturated loess, and the calculated data using the developed model were compared with the experimental data, which demonstrated that the developed model in this paper performed well in describing the whole strain hardening process of unsaturated soil under the coupling effect of moistening and stress fields. Finally, the sensitivity of the main parameters of the developed model was discussed under the coupling effect of moistening and stress fields, which showed that the proposed model performed well in reflecting the main mechanical properties of unsaturated loess. Full article
(This article belongs to the Special Issue Soft Soil Mechanics and Foundation Consolidation)
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16 pages, 4670 KiB  
Article
A Comparative Case Study on Drainage Consolidation Improvement of Soft Soil under Vacuum Preloading and Surcharge Preloading
by Ling Fan, Zhize Xun and Shuquan Peng
Appl. Sci. 2023, 13(9), 5782; https://doi.org/10.3390/app13095782 - 08 May 2023
Cited by 2 | Viewed by 1370
Abstract
Based on an improvement project of soft soil ground in Zhuhai City on the Pearl River Delta, a comparative study on vacuum preloading and surcharge preloading was performed. The ground and stratified settlements, excess pore water pressure, and the degrees of consolidation of [...] Read more.
Based on an improvement project of soft soil ground in Zhuhai City on the Pearl River Delta, a comparative study on vacuum preloading and surcharge preloading was performed. The ground and stratified settlements, excess pore water pressure, and the degrees of consolidation of soft soil are analyzed, along with the horizontal displacement and soil strength. The results show that surcharge preloading results in smaller secondary consolidation settlements than vacuum preloading. Primary consolidation settlement quickly increases with increasing excess pore water pressure of less than −40 kPa in vacuum preloading, while also increasing between 20 kPa and 25 kPa in surcharge preloading. The sharp increase in the strata permeability coefficient will induce the increase in strata consolidation degree and has little effect on the ground consolidation degree. The surcharge preloading can be given priority to reduce the settlement foundation in the service stage. Full article
(This article belongs to the Special Issue Soft Soil Mechanics and Foundation Consolidation)
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8 pages, 2222 KiB  
Communication
Theoretical Evaluation for Soil Thrust of Single-Track System over Clay Slope via Upper Bound Analysis
by Seon Hong Na and Sang Inn Woo
Appl. Sci. 2023, 13(9), 5222; https://doi.org/10.3390/app13095222 - 22 Apr 2023
Viewed by 744
Abstract
This study aimed to theoretically evaluate soil thrust on a clay slope as a reaction force associated with the motion of an off-road tracked vehicle. The existing concept of the potential failure modes of a clay block on flat ground has extended to [...] Read more.
This study aimed to theoretically evaluate soil thrust on a clay slope as a reaction force associated with the motion of an off-road tracked vehicle. The existing concept of the potential failure modes of a clay block on flat ground has extended to determine the soil thrust of sloped clay ground. Based on the upper-bound limit analysis, the soil thrust under the most critical failure was derived for three potential failure modes: block, triangular-wedge, and trapezoidal-wedge failures. Specifically, the influence of the slope angle, the shear strength of clay, the weight of a vehicle, and the geometry of a track system on the soil thrust was investigated. Only the block and triangular wedge failure modes were able to occur, and the geometry of a single-track system could lead to different failure modes. Under the block failure mode, the soil thrust decreased as the slope became stiff, and the vehicle weight increased. On the other hand, the soil thrust decreased as the slope angle decreased under the triangular-wedge failure mode. Full article
(This article belongs to the Special Issue Soft Soil Mechanics and Foundation Consolidation)
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14 pages, 3197 KiB  
Article
Analytical and Numerical Study on the Stability of Highway Subgrade with Embedded Loading Berm in Soft Soil Area
by Feng Xiong, Xuebin Wang, Fan Yang, Jiaqiang Yang, Li Hu and Rui Li
Appl. Sci. 2022, 12(23), 12440; https://doi.org/10.3390/app122312440 - 05 Dec 2022
Viewed by 1100
Abstract
Loading berm is an effective method for improving highway subgrade stability in soft soil areas. However, this method requires lots of construction space. It is not applicable in some areas with narrow construction spaces. To address this problem, an embedded loading berm (ELB) [...] Read more.
Loading berm is an effective method for improving highway subgrade stability in soft soil areas. However, this method requires lots of construction space. It is not applicable in some areas with narrow construction spaces. To address this problem, an embedded loading berm (ELB) is proposed to improve highway subgrade stability, and the effects of ELB on the stability of the highway subgrade were investigated by analytical and numerical methods. Firstly, an analytical model was proposed to analyze the relationship between the ELB dimensions and subgrade stability factors. Then, numerical simulations were carried out to further reveal the stability factor of an actual subgrade with different ELBs. Lastly, ELB parameters’ sensitivity to the ELB stability factors was studied. The results show that the stability of the highway subgrade in soft soil areas can be significantly improved by the proposed ELB. With the loading berm width and height increasing, the subgrade stability factors can increase. The stability factors’ increase ratio with the increased ELB width is greater than that with the increased ELB height. The ELB parameter sensitivity order on the subgrade stability is as follows: width > height > density > cohesion > internal friction. In the design process, the ELB width and height can be mainly focused on. The research is significant for promoting the application of ELB in soft soil areas. Full article
(This article belongs to the Special Issue Soft Soil Mechanics and Foundation Consolidation)
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23 pages, 6670 KiB  
Article
Mechanical Properties of the Functionally Graded Lining for a Deep Buried Subway Tunnel
by De-Chun Li, Tong-Tong Zhang, Zhen-Dong Cui, Jin-Ming Chen, Xiang-Qing Xu, Chong Xu, Zhao-Wei Zhang and Gang Song
Appl. Sci. 2022, 12(21), 11272; https://doi.org/10.3390/app122111272 - 07 Nov 2022
Viewed by 970
Abstract
With the rapid development of the subway rail transit, tunnels are buried at an increasing depth, raising the requirements of bearing capacity and waterproofness for linings. Functionally graded materials are introduced into the design of linings to save costs, and concrete with different [...] Read more.
With the rapid development of the subway rail transit, tunnels are buried at an increasing depth, raising the requirements of bearing capacity and waterproofness for linings. Functionally graded materials are introduced into the design of linings to save costs, and concrete with different elastic moduli is equipped at different positions to reduce the waste of materials, compared to the homogeneous lining. The significance of this study includes that the functionally graded lining for the buried subway tunnel is under the non-uniform confining pressure and the calculation model of internal force and deformation for the functionally graded lining is established. The elastic modulus of the lining is set to vary with the angle in the form of a power function, and the function parameters are analyzed on the basis of this model. The results show that the radial displacement of the lining axis decreases with the increase in a and b, but the deformation mode remains the same, and the reduction in deformation is smaller and smaller. With the increase in a and b, the distribution trend of the moment remains the same. The lateral pressure coefficient λ has a great impact on the safety of the structure, which exceeds the influence of the function parameters on the safety of the structure. The displacement of the lining axis and the section moment change linearly with the increase in λ. With the increase in λ, the shape of the lining changes significantly, which shows that the side with larger pressure deforms to the inside and the side with smaller pressure expands to the outside. When the maximum deformation occurs at 0°, the parameter a should be larger than b. When the maximum deformation occurs at 90°, the parameter b should be larger than a, so as to minimize the cost of materials and reduce the structural deformation. Finally, the numerical simulation is conducted to verify the theoretical results, showing that the calculation model of internal force and deformation is suitable for the cylinder with t/R0.2, and there is a certain gap between the theoretical calculation and numerical simulation, but the largest gap of the displacement is within 8%. Compared with Function I, Function II has some advantages in reducing the maximum deformation of the structure, but the advantages are relatively low. The analysis results have significant reference value for designers and relevant scholars. Full article
(This article belongs to the Special Issue Soft Soil Mechanics and Foundation Consolidation)
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19 pages, 10147 KiB  
Article
Instability of High Liquid Limit Soil Slope for the Expressway Induced by Rainfall
by Jian-Jie Jiang and Zhen-Dong Cui
Appl. Sci. 2022, 12(21), 10857; https://doi.org/10.3390/app122110857 - 26 Oct 2022
Cited by 3 | Viewed by 1328
Abstract
The instability of high liquid limit soil slope is a common engineering problem in highway construction. This study focused on the slope at section K79 + 880 of the Guang-Le Expressway in Guangdong Province, China. In order to reduce the landslide and learn [...] Read more.
The instability of high liquid limit soil slope is a common engineering problem in highway construction. This study focused on the slope at section K79 + 880 of the Guang-Le Expressway in Guangdong Province, China. In order to reduce the landslide and learn the mechanism of the high liquid limited soil slope, the effects of different rainfall intensities and rainfall time on the high liquid limit soil slope were studied by in-site monitoring and numerical simulation. According to the characteristics of the slope deformation and the monitoring data, the slope landslide is divided into three grades. Numerical simulation results show that the influence of rainfall intensity on the safety factor of high liquid limit soil slope is greater than that of rainfall time. At the slope top, the cumulative changes of Mises stress in Group B and Group C were −2.19 kPa and −2.91 kPa, respectively, and the cumulative decreases were −7.22% and −9.60%, respectively. At the slope bottom, the cumulative changes of Mises stress in Group B and Group C were −2.05 kPa and −4.32 kPa, respectively, and the cumulative decreases were −4.50% and −9.48%, respectively. With the increase of rainfall for 24 h, the safety factor of Group C decreased by an average of 0.0408, and with the increase of rainfall time, the safety factor increased, and the safety factor of 96 h of rainfall in Group C was 0.1249 lower than that of 24 h of rainfall. The greater the rainfall intensity, the greater the change of matrix suction at the top of the slope, and the more prone the top of the slope to shallow landslides. For the high liquid limit soil slope, slope instability phenomena such as surface flow collapse occur easily and have little impact on the deep sliding surface. The dimensionless displacement coefficient K is proposed to quantify the landslide displacement under different rainfall. A general method is proposed to measure the cumulative displacement of the K79 + 880 slope where the sensor is not placed. Full article
(This article belongs to the Special Issue Soft Soil Mechanics and Foundation Consolidation)
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