scholarly journals Deformation Characteristics of Raising, Widening of Old Roadway on Soft Soil Foundation

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2117
Author(s):  
Keke Li ◽  
Wenyuan Xu ◽  
Liang Yang
Keyword(s):  
Lateral Displacement ◽  
Soft Soil ◽  
Ground Surface ◽  
Surface Settlement ◽  
Deformation Characteristics ◽  
Construction Methods ◽  
Ground Surface Settlement ◽  
Total Settlement ◽  
Soil Foundation ◽  
Soft Soil Foundation

The deformation characteristics of a raised and widened old Chinese roadway on a soft soil foundation are investigated in this study via finite element numerical simulation. The rules of ground surface settlement, slope foot lateral displacement, and ground surface settlement evolution of the roadbed under three modes (one-time construction of an eight-lane expressway, widened four-lane expressway, and raised/widened four-lane expressway) are compared. The ground surface settlement process of the eight-lane road foundation, which is formed by first widening and then raising the road, is highly complex. The ground surface settlement curve under the old road foundation increases and then decreases. The lateral displacement of the slope foot also interacts with the widening and raising of the eight-lane roadbed foundation. The range of lateral displacement is 70.05, 42.58, 124.81, 104.54 mm. Fifteen years after construction, the total settlement of the raised and widened roadbed is much larger than that of the one built directly. The total settlement values at the center of the two roadbeds are 297.05 and 234.85 mm, respectively. This manuscript provides data support for the reconstruction and expansion of roads on soft soil foundations, for choosing appropriate construction methods to build roads, and for avoiding major road damage, which is of great significance to the construction of road infrastructure in the future.

scholarly journals Estimation of Influence Scope of Lateral Displacement of Soft Ground under Vacuum Pressure with PVD

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jingyun Liu ◽  
Hongtao Fu ◽  
Jun Wang ◽  
Yuanqiang Cai ◽  
Xiuqing Hu
Keyword(s):  
Clayey Soil ◽  
Lateral Displacement ◽  
Soft Soil ◽  
Ground Surface ◽  
Vacuum Pressure ◽  
Vacuum Preloading ◽  
Treated Area ◽  
Prefabricated Vertical Drain ◽  
Soil Foundation ◽  
Soft Soil Foundation

The application of vacuum pressure to a treated area not only induces vertical settlement and inward lateral displacement but also causes the formation of tension cracks near the ground surface. In general, the strain method is applied to calculate the lateral displacement at the boundary of a treated area; however, the influence scope of lateral displacement has not yet been presented. Based on the in situ data of soft clayey soil foundation treated by vacuum consolidation, lateral displacement was estimated in the influence scope in this study. To calculate the influence scope of lateral displacement induced by vacuum pressure, the ratio of the lateral displacement within the influence scope to the ground surface settlement under the centre of the treated area is defined as the maximum value of the lateral displacement (ELD) within the influence scope. This paper proposes a direct relationship between ELD and the distance from the treated area boundary (Lx), considering the length of the prefabricated vertical drain. In addition, the FEA (finite-element analysis) is used to simulate the process of vacuum preloading to reinforce soft soil foundation. The influence scope simulated is almost close to the calculated value Lx. Accordingly, the safety distance between the boundary of the treated area and the surrounding building can be estimated when the soft soil foundation is consolidated by using a vacuum preloading method.

scholarly journals Consolidation and Deformation Characteristics of Soft Rock Foundation in Hydrological Wetland Environment

2020 ◽  
Vol 24 (2) ◽  
pp. 183-190
Author(s):  
Bin Liu ◽  
Xiugen Jiang
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soft Rock ◽  
Rock Foundation ◽  
Deformation Characteristics ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Rock And Soil

The widespread distribution of soft rock and soft soil in hydrological wetland environment is a common geotechnical engineering problem encountered in coastal engineering construction. To solve this problem, a study method for consolidation and deformation characteristics of soft rock and soft soil foundation in hydrological wetland environment is proposed. Taking K9+280-K11+120 section along Fu-Nehe section of National Highway 111 as the research object, the consolidation and deformation characteristics and loading conditions of soft soil foundation under embankment filling load, treatment methods of soft rock foundation, stratum conditions, temperature changes and time effects are analyzed. The results show that although the wetland soft rock and soil layer is not thick, the settlement of soft rock and soil accounts for more than 80% of the total settlement. Negative temperature has a certain influence on the consolidation settlement of soft rock foundation, which is mainly manifested in the difference between the settlement process of the central separation zone and the roadbed soft soil foundation; the pore water pressure of soft rock foundation dissipates to varying degrees. According to the monitoring results of settlement and pore water pressure, bagged sand wells are more suitable for soft rock foundation engineering treatment in hydrological wetland. The research results can provide a reference for the study, calculation and design of consolidation and deformation of soft rock foundation in hydrological wetland.

Optimization of Construction Method for Shijiazhuang Xinbai Subway Station

2014 ◽  
Vol 580-583 ◽  
pp. 1203-1206
Author(s):  
Chun Yan Gao ◽  
Jian Guang Niu ◽  
Dong Yang Geng
Keyword(s):  
Environmental Influence ◽  
Fuzzy Optimization ◽  
Ground Surface ◽  
Optimization Theory ◽  
Construction Method ◽  
Surface Settlement ◽  
Subway Station ◽  
Construction Methods ◽  
Ground Surface Settlement ◽  
The Impact

To choose an appropriate construction scheme for subway, it,s feasible to use fuzzy optimization theory and comprehensively consider the security of four construction methods as well as such factors as environmental influence, construction period, construction difficulty and construction cost, etc. to set up a mathematical model for the construction method of subway station. An analysis is made on the impact of group-effect in the excavation construction of pilot tunnel presented in PBA construction method on arch crown settlement and ground surface settlement, and a study is made on the arch crown settlement and ground surface settlement caused by the four construction methods in construction process. In addition, a contrastive analysis is made to draw a conclusion that PBA construction method is the most suitable construction method for Xinbai Square Subway Station in Shijiazhuang.

Effect of Geotextile and Prefabricated Vertical Drains Used in Soft Soil Foundation

2011 ◽  
Vol 197-198 ◽  
pp. 981-986
Author(s):  
Jie Qun Liu ◽  
Jin Long Liu
Keyword(s):  
Pore Pressure ◽  
Lateral Displacement ◽  
Soft Soil ◽  
Excess Pore Pressure ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Lateral Displacements ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Excess Pore

Based on the generalized formulation of two dimensional Biot′s theory of consolidation, the effect of geotextile and prefabricated vertical drains (PVDs) using in soft soil foundation was studied with nonlinear finite element method. The dissipation of excess pore pressure, vertical settlement and lateral displacement of foundation were contrasted between foundations with and without PVDs. It is found that the vertical settlements become lager, the lateral displacements become less and the bulges at the toe of embankment become less at the same time of consolidation when PVDs are used. And the stability of embankment improved for the bearing capacity of soil enhanced with excess pore pressure dissipated fast. Meanwhile, the axial force of geotextile become less when PVDs are used. Those changes showed that the design of foundation can be optimized by shortening the time of consolidation when PVDs are used.

The Responses of Soft Ground Materials Subjected to Dynamic Loading

2012 ◽  
Vol 591-593 ◽  
pp. 977-981
Author(s):  
Jun He ◽  
Bing Bai ◽  
Quan Fei Chen
Keyword(s):  
Pore Pressure ◽  
Dynamic Loading ◽  
Soft Soil ◽  
Soil Layer ◽  
Ground Surface ◽  
Vertical Displacement ◽  
Dynamic Compaction ◽  
Soft Ground ◽  
Soil Foundation ◽  
Soft Soil Foundation

The responses of saturated soft soil foundation under dynamic loading are analyzed using numerical method. The distributions of pore pressure in space are given, and the variations of pore pressure with time are also discussed. Besides, the distributions of vertical stresses and vertical displacement are also given. Studies show that during the period of dynamic loading, the pore pressure and stress in soil layer grows very fast, and also decreases rapidly in the unloading phase. With the increase of dynamic compaction time, the locations of the maximum values gradually move down. Moreover, the pore pressure and stress gradually decreases with the increase of the distance away from hammer point. On the other hand, the tamping pit in ground surface under dynamic loading has a larger settlement, and furthermore decreases with the increase of depth.

Character of the Lateral Displacement of Soft Soil Foundation under Embankment

2011 ◽  
Vol 197-198 ◽  
pp. 987-991
Author(s):  
Jie Qun Liu ◽  
Jin Long Liu
Keyword(s):  
Finite Element Method ◽  
Lateral Displacement ◽  
Soft Soil ◽  
Soil Layer ◽  
Measuring Method ◽  
Vertical Surface ◽  
Nonlinear Finite Element ◽  
Nonlinear Finite Element Method ◽  
Soil Foundation ◽  
Soft Soil Foundation

In order to analyze the characteristic of lateral displacement of soft soil foundation under embankment, a typical embankment is studied systemically with nonlinear finite element method, and the location of maximal lateral displacement and its measuring method is also discussed. It is pointed that lateral displacement would be reduced possibly at consolidation stage with strong dry crust and thick soft soil layer, which happened synchronously with vertical settlement increased rapidly. This phenomena could not be measured conveniently with inclinometer pipe, for there are many shortcomings within this technique, although which has been used in engineering widely. It is also shown that the location of the maximal lateral displacement is changeable at different construction stages, which more likely lies in the vertical surface between the toe and the middle of slope of embankment. In order to get the maximal lateral displacement reasonably, it is suggested that the inclinometer pipes should be placed in that area of embankment.

Mechanism and Application on Extra-Long Sand Wells for Deep Soft Foundation Treatment in Highways

2011 ◽  
Vol 250-253 ◽  
pp. 3128-3133
Author(s):  
He Cheng Liang ◽  
Li Jia Chang ◽  
Ai Guo Zhou
Keyword(s):  
Soft Soil ◽  
Monitoring Data ◽  
Dynamic Monitoring ◽  
Foundation Treatment ◽  
Soft Foundation ◽  
Total Settlement ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Consolidation Degree ◽  
Better Than

The soft base in the testing section of Jiang-zhu highwaysis 55 meters deep, and its mechanical property is not better than that of silt soil, the sand-wick drained length is one of the crucial factors for this highwaywhich influences the consolidation speed. Based on the characteristic of soft foundation, experiences and the interrelationship between the processing area and the subjacent bed effecting on draining, the mechanism of extra-long sand-wick for the extra-deep soft foundation is studied. The theoretical consolidation degree in the deep soft foundation treating with extra-long sand-wick drain had been calculated, the designed depth of sand-wick drain were 25 and 22 meters. Moreover, the total settlement will be predicted. According to the monitoring data of displacement and settlement during loading, the characteristic of consolidation settlement of the soft soil foundation had been analyzed. The results indicated that the settlement was very sensitive to the loading speed. The sedimentation became fast with the increasing loading. The sedimentation speed was always very high, which was 15 to 25mm/day on the average. During the prophase of pre-compaction, the consolidation degree of section K53+242.47 (h=25m) was up to 80% in 350 days, which was much faster than the section K53+402.47 (h=22m). Moreover, the soft soil foundation was consolidated stably according to the strict dynamic monitoring data. By using hyperbolic theory to analyze monitoring data, the predictive settlement value of post-project can meet the designed requirement. The treating effect of the 25m depth sand-wick drain was better than that of 22m, which provided available data for extra thick soft foundation treatment.

Experimental Research for the Soft Soil Foundation Reinforced by Vibro-Replacement Stone Pile

2014 ◽  
Vol 501-504 ◽  
pp. 101-106
Author(s):  
Hai Ying Hu ◽  
Yu Cheng Zhang ◽  
Zhi Xing Huang
Keyword(s):  
Soft Soil ◽  
Earth Pressure ◽  
Standard Penetration Test ◽  
Load Test ◽  
Composite Foundation ◽  
Penetration Test ◽  
Liquefaction Resistance ◽  
Total Settlement ◽  
Soil Foundation ◽  
Soft Soil Foundation

With the background of the foundation treatment engineering of a river dam in a reservoir, the thesis introduced the site experiments for soft soil foundation reinforced by vibro-replacement stone piles. Moreover, the study had also conducted inspection and analysis of the reinforcing effect of the composite foundation being reinforced by vibro-replacement stone piles including the inspections like the stress ratio between the vibro-replacement stone pile and earth among pile and the ratio between the vibro-replacement stone pile and the pile earth. Finally, the study came to below results after comprehensively considering the results of the heavy dynamic penetration test, standard penetration test, load test, reading of earth pressure cell and etc. The reinforcement of the vibro-replacement stone piles could reach the expected reinforcement effect for the soft earth foundation. After the application of the piles, the carrying fore of the composite foundation is higher than the design requirements and the liquefaction resistance has experienced significant improvement. Moreover, this kind of composite soil foundation could effectively reduce the total settlement of the foundation, accelerate the consolidation of the foundation and improve the hydraulic conductivity of the foundation.

scholarly journals Analysis on Deformation and Stress Characteristics of a Multibraced Pit-in-Pit Excavation in a Subway Transfer Station

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Xin Shi ◽  
Chuanxin Rong ◽  
Hua Cheng ◽  
Linzhao Cui ◽  
Bin Wang ◽  
...  
Keyword(s):  
Ground Surface ◽  
Lateral Wall ◽  
Surface Settlement ◽  
Lateral Deformation ◽  
Monitoring And Control ◽  
Foundation Pit ◽  
Wall Displacement ◽  
Transfer Station ◽  
Ground Surface Settlement ◽  
Total Settlement

As an important part of subway transfer station construction, pit-in-pit (PIP) excavation has always been a key object of monitoring and control. In this study, taking the PIP excavation project of Hefei metro line 4 and line 7 transfer station as the background, combined with on-site monitoring and numerical simulation, the variation law of lateral wall displacement, ground surface settlement, and strut force during the PIP excavation were analyzed. The results showed that the maximum lateral deformation of the pile caused by the excavation of the external pit accounted for 80%–90% of the total deformation and the surface settlement accounted for 70% of the total settlement. The excavation of the inner pit only made the maximum lateral wall displacement of the outer pit and the surface settlement behind the wall increase slightly, the growth rate tended to zero, and the maximum lateral deformation depth was all above the excavation surface, which indicated that, for this project, the inner excavation had little effect on the outer pit retaining structure. In addition, the increased exposure time of the soil at the bottom of the pit and the presence of the corner effect will cause the further development of the structure displacement and the surface settlement. Based on strut force measurements, using the tributary area load distribution procedure, it was obtained that 0.3γHe was used as the upper limit index of strut force in the region, where γ is the weight of the soil and He is the excavation depth of the foundation pit. The research conclusions were helpful for the construction and sustainable development of the PIP project.

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