scholarly journals Field Test and Numerical Studies on Influences of PVD Spacing on Vacuum Treatment Effects of Dredged Slurry

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yanming Yu ◽  
Junhui Sheng ◽  
Li Shi ◽  
Zhijun Hu
Keyword(s):  
Pore Water ◽  
Field Test ◽  
Treatment Effects ◽  
Pore Water Pressure ◽  
Numerical Models ◽  
Water Pressure ◽  
Vacuum Treatment ◽  
Vacuum Pressure ◽  
Numerical Studies ◽  
Consolidation Rate

A field test was conducted on vacuum treatment effects of a dredged slurry ground considering three PVD spacing, i.e., 700, 800, and 900 mm. The settlement and the pore water pressure dissipation were measured during the treatment period. As expected, the consolidation rate associated with closer PVD spacing case is higher than that of the larger spacing case. However, it is observed that the final and stable values of the settlement and the pore pressure dissipation of the close spacing case (e.g., 700 mm) are about 17% higher than the case of larger PVD spacing (e.g., 900 mm). The differences imply that enlarging the PVD spacing not only impedes the consolidation rate but also decreases the vacuum pressure in slurry. Numerical models incorporating the vacuum pressure attenuation effect and the clogging effect were established to reproduce the vacuum treatment process under the three PVD spacing. Good comparisons between the numerical and test results can be obtained given a proper account of vacuum attenuation and the clogging effect along the PVD depth. The comparison clarifies that, for vacuum treatment of slurry ground, the PVD spacing should be determined by due considerations both on the desired consolidation rate and on the pore water pressure that needs to be dissipated.

scholarly journals Field Test Investigation of the Pile Jacking Performance for Prefabricated Square Rigid-Drainage Piles in Saturated Silt Sandy Soils

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Xiangying Wang
Keyword(s):  
Pore Water ◽  
Field Test ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Tests ◽  
Excess Pore Water Pressure ◽  
New Type ◽  
Test Investigation ◽  
First Time ◽  
Excess Pore

The rigid-drainage pile, designed to accelerate the dissipation of excess pore water pressure around the pile, is a new type of pile that combines the bearing capacity of ordinary rigid piles and the draining capacity of gravel piles. Field tests of these new piles were performed for the first time at a construction site in the new campus of Jiangyin No. 1 High School. Numerous parameters were observed for the test piles in many trials, including the excess pore water pressures, horizontal soil pressures, and displacements. At the measuring position at 0.6 m from the pile center, the rigid-drainage pile dissipates 70% of the peak excess pore water pressure in 1000 s, whereas the ordinary pile requires nearly 4000 s to dissipate the identical amplitude. The field test results clearly demonstrate that the rigid-drainage pile can reduce the amplitude of the peak pressure caused by piling in the liquefiable layer, quickly dissipate the excess pore water pressure, reduce the loss of effective stress in the soil surrounding the pile, and maintain the foundation stability.

scholarly journals Implications of the principle of effective stress

2020 ◽  
Author(s):  
Gerd Gudehus
Keyword(s):  
Critical Phenomena ◽  
Pore Water ◽  
Effective Stress ◽  
Critical Points ◽  
Pore Water Pressure ◽  
Numerical Models ◽  
Water Pressure ◽  
Shear Bands ◽  
Triaxial Tests ◽  
Water Saturated

AbstractWhile Terzaghi justified his principle of effective stress for water-saturated soil empirically, it can be derived by means of the neutrality of the mineral with respect to changes of the pore water pressure $$p_w$$ p w . This principle works also with dilating shear bands arising beyond critical points of saturated grain fabrics, and with patterns of shear bands as relics of critical phenomena. The shear strength of over-consolidated clay is explained without effective cohesion, which results also from swelling up to decay, while rapid shearing of water-saturated clay can lead to a cavitation of pore water. The $$p_w$$ p w -neutrality is also confirmed by triaxial tests with sandstone samples, while Biot’s relation with a reduction factor for $$p_w$$ p w is contestable. An effective stress tensor is heuristically legitimate also for soil and rock with relics of critical phenomena, particularly for critical points with a Mohr–Coulomb condition. Therein, the $$p_w$$ p w -neutrality of the solid mineral determines the interaction of solid fabric and pore water, but numerical models are questionable due to fractal features.

Field Test on the New Method of Vacuum Dewatering with Lower-energy Dynamic Consolidation for Silty Soil Ground

2011 ◽  
Vol 243-249 ◽  
pp. 3306-3310 ◽  
Author(s):  
Hong Bo Zhang ◽  
Xiu Guang Song ◽  
Hong Hong Wang ◽  
Zheng Ma
Keyword(s):  
Pore Water ◽  
Field Test ◽  
Groundwater Level ◽  
Lower Energy ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Excess Pore Water Pressure ◽  
Dynamic Consolidation ◽  
Vacuum Dewatering ◽  
Excess Pore

The dynamic consolidation method has been used widely in various engineering domain. With this method, the velocity of reconsolidation settlement was enhanced, the consolidation result was good, and the cost was lower than other methods. However, in the flooded area of Yellow River, the groundwater level is higher, and the shallow saturated silty soil liquefaction will be happened with this single method of dynamic consolidation. It goes against the roadbed stability. According to engineering practice, the vacuum dewatering with lower energy dynamic consolidation method was proposed in this paper. In order to monitor the effect of this consolidation method, the water-level observation hole, pore water pressure gauge, standard guide pile, level gauge have been set up. They could be used to get the groundwater level, the excess pore water pressure, horizontal displacement and land subsidence, respectively. These monitors would last the whole period of the consolidation experiment. Field test results shows that the excess pore water pressure was reduced by 80%-90% during one to three days.

Development of Measuring Device and Field Test on Pore Water Pressure Fluctuation in the Seabed

1989 ◽  
Vol 32 (1) ◽  
pp. 91-101
Author(s):  
Yasuo Takagaki ◽  
Takujiro Miyamoto ◽  
Shigeru Yoshinaga ◽  
Yoshio Haruki ◽  
Mineo Sato
Keyword(s):  
Pore Water ◽  
Field Test ◽  
Pressure Fluctuation ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Measuring Device

scholarly journals Modelling of flowslides and debris avalanches in natural and engineered slopes: a review

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Sabatino Cuomo
Keyword(s):  
Numerical Methods ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Numerical Models ◽  
Water Pressure ◽  
Lateral Spreading ◽  
Slope Instability ◽  
Key Factors ◽  
Flow Type ◽  
Debris Avalanches

Abstract Background The landslides of the flow-type are dangerous and also challenging to study. A wide literature has been investigating the principal mechanisms governing each stage in which these phenomena can be ideally subdivided: failure, post-failure and propagation. However, holistic contributions and general overviews are very rare. In addition, a number of numerical methods have been issued and validated so that new chances exist to efficiently model those threats. The paper focuses on two classes of rainfall-induced landslides of the flow-type, namely debris flows and debris avalanches. The principal numerical methods are reviewed for modelling the landslide initiation and propagation and are later used for analyzing a series of benchmark slopes and real case histories which are successfully simulated. Results The rainfall from ground surface and water spring from the bedrock are key factors for slope instability. Pore water pressure plays a relevant role also during the propagation stage. The entrainment of further material makes the propagation patterns complex due to lateral spreading and slow-down of the front of flows. It is shown that the used models are capable to provide useful indications even for combined channelized and unchannelized flows. Conclusions Notwithstanding the complexity of flow-like landslides and the related challenges in modelling, the understanding and forecasting of such natural hazards is achievable with a satisfactory confidence. Among the key factors, rainfall, pore water pressure and bed entrainment deserves a special attention. Further improvements are expectable as the numerical models are becoming more efficient. Thus, more accurate descriptions of local effects will be possible and also additional mechanisms will be eventually analysed.

scholarly journals Radial consolidation response upon the application and removal of vacuum and fill loading

2015 ◽  
Vol 52 (12) ◽  
pp. 2156-2162 ◽  
Author(s):  
Kourosh Kianfar ◽  
Buddhima Indraratna ◽  
Cholachat Rujikiatkamjorn ◽  
Serge Leroueil
Keyword(s):  
Pore Pressure ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Vacuum Pressure ◽  
Excess Pore Pressure ◽  
Excess Pore Water Pressure ◽  
Removal Time ◽  
Excess Pore

This Note presents a laboratory study using a Rowe cell to compare the consolidation responses upon vacuum pressure and fill load application and removal. The influences of the duration of application and removal of fill load and vacuum pressures on radial consolidation were investigated using excess pore-water pressure, axial strain, and overconsolidation ratio. It is shown that the appropriate removal time for vacuum pressure can be determined based on excess pore pressure responses.

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

Conjectures, Hypotheses, and Theories of Drumlin Formation (In memory of Stanislaw Baranowski)

1981 ◽  
Vol 27 (97) ◽  
pp. 503-505 ◽  
Author(s):  
Ian J. Smalley
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Stress Level ◽  
Critical Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Glacial Till ◽  
Forming Process ◽  
Stress Levels

AbstractRecent investigations have shown that various factors may affect the shear strength of glacial till and that these factors may be involved in the drumlin-forming process. The presence of frozen till in the deforming zone, variation in pore-water pressure in the till, and the occurrence of random patches of dense stony-till texture have been considered. The occurrence of dense stony till may relate to the dilatancy hypothesis and can be considered a likely drumlin-forming factor within the region of critical stress levels. The up-glacier stress level now appears to be the more important, and to provide a sharper division between drumlin-forming and non-drumlin-forming conditions.

The temperature and pore water pressure in soil subjected to dynamic load

2018 ◽  
Vol 35 (2) ◽  
pp. 111
Author(s):  
Kun ZHANG ◽  
Ze ZHANG ◽  
Xiangyang SHI ◽  
Sihai LI ◽  
Donghui XIAO
Keyword(s):  
Pore Water ◽  
Dynamic Load ◽  
Pore Water Pressure ◽  
Water Pressure
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