scholarly journals Pengaruh Beban Kendaraan sebagai Beban Terbagi Rata terhadap Deformasi Geogrid sebagai Perkuatan Embankment

2012 ◽  
Vol 8 (1) ◽  
pp. 31
Author(s):  
Adhe Noor Patria
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Vertical Displacement ◽  
Soil Mass ◽  
Vehicle Load ◽  
Surcharge Load ◽  
The Difference ◽  
High Level

<p>Soft soil such as clay was sensitive soil. Public contructions built in this kind of soil would face some problemssuch as long period consolidation time, unstable embankment slope, not easily compacted and high level settlement. Some solution that could be suggested were the usage of vertical drain, or the usage of geosynthetics material such as geogrid combined with floating  piles.Analysis was carried out by using plaxis version 7.2. soil for embankment and embankment foundation was modelled in plane strain. Also geogrid andfloating piles were modelled in palne strain too. Surcharge load on top of embanknet were variated, they were 20, 35 and 50 kPa. The simulation was carried out in staged contruction mode.Final vertical displacement in geogrid due to 50  kPa vehicle load as surcharge load and long term load period (in this case excess pore water pressure was small) was -0,9062 m for  rigid embankment and -1,4206 for interface embankment. The difference occured due to slip at the interface of geogrid and soil. It  leaded to adding soil mass supportd by geogrid, furthermore the deflection of geogrid became bigger.</p>

In Situ Test on Effective Stress Principle for Ultra Soft Soil

2013 ◽  
Vol 291-294 ◽  
pp. 2641-2644
Author(s):  
Zhang Ming Li ◽  
Wen Xiu Zeng
Keyword(s):  
Effective Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soil Pressure ◽  
Important Conclusion ◽  
Action Mode ◽  
Existing Problems

The effective stress principle for soil is inspected by examining the original concept and derivation of the principle from the perspective of the ultra-soft soil engineering applications; and the existing problems of the principle were discussed in accordance with the general methodology of mechanics, and relative engineering phenomena observed. The changes of pore water pressure and soil pressure with time were obtained based on series of long term in-situ test in a large ultra-soft ground treatment works directed by the first author; and then an important conclusion has acquired from the test, i.e. the effective stress principle is not a self-contained principle and it’s related to the medium constitutive characteristics and loading action mode.

Evolution of the factor of safety following excavation in clay

2009 ◽  
Vol 46 (5) ◽  
pp. 487-493 ◽  
Author(s):  
J. S. L’Heureux ◽  
S. Leroueil ◽  
J. F. Laflamme
Keyword(s):  
Pore Pressure ◽  
Factor Of Safety ◽  
Clayey Soil ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Mass ◽  
Eastern Canada ◽  
Soft Clays ◽  
Clay Deposits ◽  
The Difference

Numerical analyses have been performed to study the evolution of the factor of safety following the excavation of a cut in clay. The analyses consider variable thickness of the clayey soil deposit under the excavation. The results show that, for a given clayey soil, there is a relation between the time for full dissipation of excess pore-water pressure from the soil mass following the excavation and the geometry of the cut (Htot/Hexc). The analytical results agree reasonably well with pore pressure measurements made in excavations in clay deposits from eastern Canada. This suggests that time to reach full pore pressure equilibration following the excavation of a cut in homogenous clayey soil deposits can be predicted when knowledge of the coefficient of swelling–consolidation is available. Lastly, results obtained in the present study show that 50% of the difference between the short- and long-term factors of safety may be lost at values as low as about 8% of the time to reach equilibration of pore pressures. This means that the time during which one can rely on the short-term strength of the clayey soil following the excavation may be relatively short, especially for soft clays.

scholarly journals Analysis of settlement prediction due to preloading and vertical drain applications on runway construction

2020 ◽  
Vol 156 ◽  
pp. 02002
Author(s):  
Adriyati Meilani ◽  
Rifa’i Ahmad ◽  
Faris Fikri
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soil Layer ◽  
Soil Mass ◽  
Research Area ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Consolidation Settlement ◽  
Primary Consolidation

Consolidation settlement is a general geotechnical problem particularly found in the area where is composed of soft soil. It is caused by the discharge of pore water pressure induced by the increase of stress in the soil mass. Construction of runway above soft soil requires analysis for stability related to the reduction of consolidation settlement and the recovery. This study aims to analyze the settlement comprehensively using empirical methods of Prefabricated Vertical Drains (PVD) and preloading installation. Preloading is a technique by which consolidation of soil can be achieved to a substantial amount before the imposition of actual construction load. According to soil investigation, the characteristic of the soil layer is clay soil, which has the potential to consolidation settlement. The result of the settlement analysis of the taxiway in the research area is from 33 cm to 214 cm. It takes ten years for primary consolidation to reach a 90% degree of consolidation. However, in the Hansbo method of Prefabricated Vertical Drains (PVD) and preloading are applied, with triangular configurations in depth of 11 meters and duration for variation embankment spacing of 1 m is 79 days, 1.5 m is 202 days and 2 m is 390 days. The conclusion of efficient distance of PVD installation and preloading is spacing of 1 m with 79 days for primary consolidation.

Geosynthetic Encased Column: comparison between numerical and experimental results

2021 ◽  
Vol 44 (4) ◽  
pp. 1-12
Author(s):  
Nima Alkhorshid ◽  
Gregório Araújo ◽  
Ennio Palmeira
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Ground Improvement ◽  
Soft Soil ◽  
Experimental Tests ◽  
High Permeability ◽  
Soft Soils ◽  
Column Comparison ◽  
Surrounding Soil ◽  
Granular Column

The use of granular column is one of the ground improvement methods used for soft soils. This method improves the foundation soils mechanical properties by displacing the soft soil with the compacted granular columns. The columns have high permeability that can accelerate the excess pore water pressure produced in soft soils and increase the undrained shear strength. When it comes to very soft soils, the use of granular columns is not of interest since these soils present no significant confinement to the columns. Here comes the encased columns that receive the confinement from the encasement materials. In this study, the influence of the column installation method on the surrounding soil and the encasement effect on the granular column performance were investigated using numerical analyses and experimental tests. The results show that numerical simulations can reasonably predict the behavior of both the encased column and the surrounding soil.

scholarly journals Prediction of long-term settlement and evaluation of pore water pressure using particle filter

2019 ◽  
Vol 59 (1) ◽  
pp. 67-83 ◽  
Author(s):  
Toshifumi Shibata ◽  
Takayuki Shuku ◽  
Akira Murakami ◽  
Shin-ichi Nishimura ◽  
Kazunori Fujisawa ◽  
...  
Keyword(s):  
Particle Filter ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure

scholarly journals Perbandingan Pengujian Konsolidasi Menggunakan Alat Rowe Cell dan Oedometer pada Tanah Lanau Lunak

2020 ◽  
Vol 22 (2) ◽  
pp. 149-155
Author(s):  
Iskandar ◽  
Rabiya
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soil Samples ◽  
Soil Parameters ◽  
Soil Consolidation ◽  
Test Results ◽  
Soft Soils ◽  
Better Than ◽  
Rowe Cell

Soil consolidation testing using an oedometer and rowe cell. Oedometers are often used on clay and soft soils. However, in the development of the rowe cell device, the results of lowering soft soil were better than the oedometer. The advantage of this rowe cell is that it can determine the saturation value of the soil samples tested. The rowe cell tester can measure the pore water pressure at the beginning and end of each consolidation stage. This rowe cell can provide suitable settlement for soft soils. This consolidation test to obtain soil parameters such as Cv and Cc by using the rowe cell tool. After that, from the test results, the two tools were compared.

Study on Artificial Island Ground Improvement Method and Effect

2014 ◽  
Vol 1030-1032 ◽  
pp. 1037-1040
Author(s):  
Jin Fang Hou ◽  
Ju Chen ◽  
Jian Yu
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Ground Improvement ◽  
Soft Soil ◽  
Horizontal Displacement ◽  
Treatment Method ◽  
Surcharge Preloading ◽  
Porosity Ratio ◽  
Improvement Method ◽  
Consolidation Degree

The artificial island ground on an open sea is covered by thick soft soil. It must be improved before using. In accordance with a designing scheme, the ground treatment method is inserting drain boards on land and jointed dewatering surcharge preloading, the residual settlement is not more than 30cm after improvement and the average consolidation degree is more than 85%. In order to estimate ground improvement effect and construction safety, instruments are buried to monitor the whole ground improving processes. By monitoring settlement and pore water pressure, it is shown that the total ground settlement in construction is 2234mm, its final settlement is 2464mm, and consolidation degree and residual settlement respectively satisfy requirements. In ground improvement, horizontal displacement is small and construction is safe. Meanwhile, the results of soil properties and vane shear strength detection tests show the soft soil ground is greatly reduced in water content and porosity ratio, and improved in strength. It is named that the ground improvement method is reasonable and reaches expected effect.

Downslope movements at shallow depths related to cyclic pore-pressure changes

1993 ◽  
Vol 30 (3) ◽  
pp. 464-475 ◽  
Author(s):  
K.D. Eigenbrod
Keyword(s):  
Pore Water ◽  
Slip Surface ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Ground Surface ◽  
Soil Mass ◽  
Passive Resistance ◽  
Pressure Changes ◽  
Timber Piles

Slow, shallow ground movements in a slope near Yellowknife caused excessive tilting of timber piles that supported an engineering structure. To avoid damage to the structure, the pile foundations had to be replaced by rigid concrete piers that were designed to resist the forces of the moving soil mass. Downhill movements were rather slow and, during an initial inspection, were indicated only by soil that was pushed up against a series of piles on their uphill sides, while gaps had formed on their downhill sides. No open cracks or bulging was observed on the slope. A stability analysis indicated that the slope was not in a state of limit equilibrium. To obtain a better understanding of the creep movements in the slope and their effect on the rigid concrete piers, extensive instrumentation was carried out after the construction of the piers. This included slope indicators, piezometers, thermistors, and total-pressure cells against one of the concrete piers. In addition, a triaxial testing program was undertaken in which the effect of cyclic pore-water pressure changes on the long-term deformations of the shallow clay layer was investigated. From the data collected in the field and laboratory, it could be concluded that (i) tilting of the original timber piles was caused by downslope movements related to cyclic pore-water increases; (ii) the lateral soil movements increased almost linearly with depth from 2 m below the ground surface, with no indication of a slip surface; and (iii) the pressures exerted by the moving soil mass against the rigid concrete piers within the soil mass were equal to the passive resistance activated within the moving soil mass. Key words : soil creep, slope movements, soil pressures, pore-water pressures, freezing pressures, permafrost, cyclic loading.

scholarly journals Experimental Study on the Variation Law of Excess Pore Water Pressure at the Bottom of the Foundation Pit for Excavation

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Qizhi Hu ◽  
Qiang Zou ◽  
Zhigang Ding ◽  
Zhaodong Xu
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Confining Pressure ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Excess Pore Water Pressure ◽  
Accurate Expression ◽  
Excess Pore

The excavation unloading of deep foundation pits in soft soil areas often produces negative excess pore water pressure. The rebound deformation of soil on the excavation surface of the foundation pit can be predicted reliably through the accurate expression of relevant variation laws. In combination with the principle of effective stress and the general equation of unidirectional seepage consolidation, an equation for calculating the rebound deformation from the bottom in the process of foundation pit excavation unloading was obtained. Additionally, a triaxial unloading test was adopted to simulate the excavation unloading processes for actual foundation pit engineering. After studying the variation law of the excess pore water pressure generated by excavation unloading, it was found that the negative excess pore water pressure increased with increasing unloading rate, while the corresponding peak value decreased with increasing confining pressure. The equation for rebound calculation was verified through a comparison with relevant measured data from actual engineering. Therefore, it is considered that the equation can reliably describe the rebound deformation law of the base. This paper aims to guide the design and construction of deep foundation pits in soft soil areas.

scholarly journals Experiment Study of Lateral Unloading Stress Path and Excess Pore Water Pressure on Creep Behavior of Soft Soil

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Wei Huang ◽  
Kejun Wen ◽  
Dongsheng Li ◽  
Xiaojia Deng ◽  
Lin Li ◽  
...  
Keyword(s):  
Pore Water ◽  
Creep Behavior ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Stress Path ◽  
Deviatoric Stress ◽  
Excess Pore Water Pressure ◽  
Pore Water Pressures ◽  
Excess Pore

The unloading creep behavior of soft soil under lateral unloading stress path and excess pore water pressure is the core problem of time-dependent analysis of surrounding rock deformation under excavation of soft soil. The soft soil in Shenzhen, China, was selected in this study. The triaxial unloading creep tests of soft soil under different initial excess pore water pressures (0, 20, 40, and 60 kPa) were conducted with the K0 consolidation and lateral unloading stress paths. The results show that the unloading creep of soft soil was divided into three stages: attenuation creep, constant velocity creep, and accelerated creep. The duration of creep failure is approximately 5 to 30 mins. The unloading creep behavior of soft soil is significantly affected by the deviatoric stress and time. The nonlinearity of unloading creep of soft soil is gradually enhanced with the increase of the deviatoric stress and time. The initial excess pore water pressure has an obvious weakening effect on the unloading creep of soft soil. Under the same deviatoric stress, the unloading creep of soft soil is more significant with the increase of initial excess pore water pressure. Under undrained conditions, the excess pore water pressure generally decreases during the lateral unloading process and drops sharply at the moment of unloading creep damage. The pore water pressure coefficients during the unloading process were 0.73–1.16, 0.26–1.08, and 0.35–0.96, respectively, corresponding to the initial excess pore water pressures of 20, 40, and 60 kPa.

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