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 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 New approach of vacuum preloading with booster prefabricated vertical drains (PVDs) to improve deep marine clay strata

2018 ◽  
Vol 55 (10) ◽  
pp. 1359-1371 ◽  
Author(s):  
Yuanqiang Cai ◽  
Zhiwei Xie ◽  
Jun Wang ◽  
Peng Wang ◽  
Xueyu Geng
Keyword(s):  
Lateral Displacement ◽  
Water Pressure ◽  
Ground Improvement ◽  
Soft Soil ◽  
Marine Clay ◽  
Vacuum Preloading ◽  
Prefabricated Vertical Drains ◽  
New Approach ◽  
Study Results ◽  
Prefabricated Vertical Drain

This paper presented a new approach for ground improvement of deep marine clay in which the conventional booster tube in the current air booster vacuum preloading technology was replaced by a booster prefabricated vertical drain (PVD). In comparison to the ordinary PVD, the booster PVD could provide inflow channels for the compressed air when the booster pump was in operation. To examine the performance of this new air booster vacuum preloading technology, in situ field tests were conducted at Oufei sluice project in Wenzhou, China, where the thickness of the soft soil layers (i.e., marine clay) was more than 20 m. An extensive monitoring system was implemented to measure the vacuum pressure, pore-water pressure, settlement, and lateral displacement at this reclamation site. With the collected field monitoring data, a comprehensive data analysis was carried out to evaluate the extent of ground improvement. The study results depicted that this new air booster vacuum preloading technology was more effective for the ground improvement of the deep marine clay layers, in comparison to the conventional vacuum preloading technology.

Application of Vacuum Preloading for Soft Foundation Treatment in Grain Storage

2012 ◽  
Vol 190-191 ◽  
pp. 1207-1213
Author(s):  
Qi Xia Liu ◽  
Yang Zhao
Keyword(s):  
Soft Soil ◽  
Construction Method ◽  
Grain Storage ◽  
Vacuum Preloading ◽  
Obvious Effect ◽  
Foundation Construction ◽  
Foundation Treatment ◽  
Soft Foundation ◽  
Soil Foundation ◽  
Soft Soil Foundation

The application of vacuum preloading for soft foundation treatment in grain storage is introduced from its principle，design，construction and the inspections. Its obvious effect is proved by example. The east coast of China is the most developed economical area and major grain and oil manufacturers. Many grain and oil depots have been established. However, in the places where the depots located, soil is soft dirt with low strength grade, high compressibility, small permeability and high possibility of plastic flow, has increased difficulties of grain and oil depots foundation construction. Without enough knowledge of soft soil and lacking of proper foundation construction method and good technology, depots may slip due to foundation’s erosion, and big settlement. If the structure slips, equipments for aeration, dehumidifier, antivirus equipment cannot work well. Based on the statement above, reasonable and effective methods for soft soil foundation work is the key point for construction of high quality and high standard grain and oil depots. This paper mainly discussed when we do depots construction work on the soft soil foundation, exact calculation, construction method and result test of fasten method for the soft foundation under the vacuum circumstance of preloading.

The Application of Vacuum Preloading Method in Soft Soil Foundation Underwater

2014 ◽  
Vol 580-583 ◽  
pp. 209-212 ◽  
Author(s):  
Yu Qin Feng ◽  
Lu Zhang
Keyword(s):  
Soft Soil ◽  
Effective Means ◽  
Construction Technology ◽  
Strength Index ◽  
Engineering Project ◽  
Vacuum Preloading ◽  
Before And After ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Preloading Method

On the basis of engineering project in coastland, this article analyzes the construction technology and reinforcement mechanism of vacuum preloading reinforces soft soil foundation. By indoor soil test of Reinforcement of soil before and after processing, comparing the change of the physical and shear strength index, verify vacuum preloading method underwater is effective means in handing soft ground and provide some experience for regional development and promotion of underwater application of vacuum preloading technology.

Calculation Method of Bearing Capacity Improvement of Soft Soil Foundation under Vacuum Preloading

2013 ◽  
Vol 353-356 ◽  
pp. 352-356 ◽  
Author(s):  
Yang Shen ◽  
Wen Jun Huang ◽  
Yan De Li ◽  
Hai Dong Xu
Keyword(s):  
Bearing Capacity ◽  
Soft Soil ◽  
Strength Index ◽  
Stress Increment ◽  
Vacuum Preloading ◽  
Capacity Improvement ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Vertical Effective Stress ◽  
Consolidation Degree

The theory of vacuum preloading was mainly focused on calculations of settlement and consolidation degree, but not on the bearing capacity improvement under vacuum preloading. Based on the Mohr-Coulombs failure criterion and elastic-plastic theory, the formula of bearing capacity improvement of vacuum preloading foundation was deduced under undrained condition. The consolidation and vacuum attenuation degree were taken into the consideration, and a calculation formula with fewer parameters by using CU total stress strength index was derived. Meanwhile the relation between bearing capacity and undrained shear strength was presented as well as that of bearing capacity and vertical effective stress increment.

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.

scholarly journals The Settlement Models of Deep Vacuum Dewatering Method

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Feng Huang ◽  
Jianguo Lyu ◽  
Guihe Wang
Keyword(s):  
Soil Mechanics ◽  
Soft Soil ◽  
Theoretical Models ◽  
Vacuum Pressure ◽  
Elastic Model ◽  
Distribution Models ◽  
Vacuum Consolidation ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Vacuum Dewatering

The deep vacuum dewatering method is effective for groundwater control in projects. By now, although the vacuum consolidation in soft soil foundation treatment has been analyzed much, the settlement of deep vacuum dewatering has not been researched sufficiently. Because of the extra vacuum pressure, the settlement should be analyzed further. In this paper, the settlement models are derived and analyzed based on the 2 vacuum pressure distribution models (plane seepage model and Johnson’s model), Imai and Chai’s vacuum consolidation models, and elastic model of traditional soil mechanics. And then a project case is provided to verify the theoretical models. The results show that the proposed model is suitable to predict the settlement and provide new references for vacuum dewatering engineering.

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.

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