Final state of soils under vacuum preloading

2012 ◽  
Vol 49 (6) ◽  
pp. 729-739 ◽  
Author(s):  
Retnamony G. Robinson ◽  
Buddhima Indraratna ◽  
Cholachat Rujikiatkamjorn
Keyword(s):  
Lateral Pressure ◽  
Ground Improvement ◽  
Volumetric Strain ◽  
Lateral Deformation ◽  
Laboratory Studies ◽  
Vacuum Consolidation ◽  
Vacuum Preloading ◽  
Final State ◽  
State Of Stress ◽  
Clay Deposits

Vacuum preloading of clay deposits is becoming an increasingly popular ground improvement technique. Although many studies have been reported in literature, the mechanism of vacuum preloading is still not properly understood. Soil under vacuum preloading is expected to undergo an inward lateral deformation, therefore the influence of lateral deformation on volumetric strain requires further analysis. This paper addresses this aspect through laboratory studies on reconstituted samples of kaolinite. The Rowe cell apparatus was modified to measure lateral deformation under various states of stress because lateral and vertical deformation of soil depends on its state of stress and associated lateral pressure. A method for predicting the volumetric and lateral strains under vacuum consolidation is proposed and then applied to two case studies in China.

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.

Tension-field theory

1990 ◽  
Vol 429 (1876) ◽  
pp. 141-173 ◽  
Keyword(s):  
General Theory ◽  
Lateral Pressure ◽  
Geometrical Property ◽  
Stable Solution ◽  
Parabolic Type ◽  
Small Strain ◽  
Singular Limit ◽  
State Of Stress ◽  
Elastic Membranes ◽  
Tension Field Theory

A general theory of the tension field is developed for application to the analysis of wrinkling in isotropic elastic membranes undergoing finite deformations. The principal contribution is a partial differential equation describing a geometrical property of tension trajectories. This is one of a system of two equations which describes the state of stress independently of the deformation. This system is strongly elliptic at any stable solution, whereas the deformation is described by a system of parabolic type. Controllable solutions, i. e. those states that can be maintained in any isotropic elastic material by application of edge tractions and lateral pressure alone, are obtained. The general axisymmetric problem is solved implicitly and the theory is applied to the solution of two representative examples. Existing small strain theories are shown to correspond to a singular limit of the general theory, at which the underlying system changes from elliptic to parabolic type.

Gravitational stresses in accreted bodies

1963 ◽  
Vol 276 (1367) ◽  
pp. 571-576 ◽  
Keyword(s):  
Theory Of Elasticity ◽  
The Body ◽  
Final Size ◽  
Final State ◽  
Final Shape ◽  
State Of Stress ◽  
Body Forces ◽  
Stress And Deformation ◽  
Historical Element

The conventional treatment of body forces in continuum mechanics implies that these forces are applied to a structure having the dimensions of the final body. This treatment is quite satisfactory when the body forces arise from the presence of an acceleration field or of an electromagnetic field. It fails, however, when we turn to the determination of the state of stress in a body which grows to its final shape by the gradual accretion of layers of material. Then the weight of each new layer loads and deforms the earlier material before hardening and becoming a part of the final structure. Successive layers are applied not to an unstressed but to a partially complete structure which is in a state of initial stress and deformation. The final gravitational stresses in such an accreted body depend upon an historical element; that is, on the order and manner in which the final shape is attained. When the final state is achieved there is, in general, a non-vanishing dislocation tensor. An appropriate method of computing the final gravitational stresses due to own weight is indicated for the case in which the stresses and deformations are small enough to permit the use of the constitutive and geometric equations of the linear theory of elasticity. The method is illustrated for the case of a gravitating sphere that has grown to its final size by accretion of material.

scholarly journals Determination of the affected area of vacuum consolidation method for roadbed ground improvement to adjacent works

2020 ◽  
Vol 61 (HTCS6) ◽  
pp. 33-39
Author(s):  
Dat Chi Nguyen ◽  
Ngan Minh Vu ◽  
Hung Van Pham ◽  
Keyword(s):  
High Efficiency ◽  
Ground Improvement ◽  
Ho Chi Minh City ◽  
Viet Nam ◽  
Vacuum Consolidation ◽  
Technical Factor ◽  
Affected Area ◽  
Construction Works

Vacuum Consolidation Method (VCM) is one of the effective ground improvement treatments applied in construction works in Viet Nam recently. However, its affected area impacts to the adjacent works has not been studied in detail and standarised, leading to unexpected incidents. This paper proposes a method to determine the affected area of vacuum consolidation method then propose solutions to protect works. The result was demonstrated at approach road of Vam Sat 2 bridge project, located in Can Gio district, Ho Chi Minh city and shows high efficiency, ensuring economic-technical factor.

scholarly journals Large scaled field tests on soft Bangkok clay

2021 ◽  
Vol 44 (4) ◽  
pp. 1-23
Author(s):  
Arumugam Balasubramaniam
Keyword(s):  
Ground Improvement ◽  
Large Diameter ◽  
Soft Clay ◽  
Field Tests ◽  
Field Measurements ◽  
Deformation Analysis ◽  
Residual Soil ◽  
Kuala Lumpur ◽  
Vertical Drains ◽  
Clay Deposits

In this lecture the interpretations of fully instrumented tests embankments and their role in the development of appropriate ground improvement techniques for highways, motorways and airfields on soft clay deposits is illustrated through well documented case studies in Bangkok, Thailand and Muar Flat Site in Kuala Lumpur. For the Bangkok Plain and with sand backfills the performance of embankments with different schemes of vertical drains was evaluated over a period of 25 years. Aspects such as recharging effects due to the drains, inadequate measures in maintaining vacuum during vacuum applications and possible hydraulic connections with large diameter drains are discussed. For the Muar test embankments, the role of fill strength in residual soil embankment and the field deformation analysis in separating consolidation settlement from immediate settlement and creep settlements is presented. Novel interpretations of settlement from pore pressure dissipations, secondary settlement from field measurements and decay of lateral deformation rate with time were also made.

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