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.

The Test Study to the Changes of Excess Pore Water Pressure during Precast Pile Construction

2012 ◽  
Vol 193-194 ◽  
pp. 1010-1013
Author(s):  
Shu Qing Zhao
Keyword(s):  
Pore Water ◽  
Clayey Soil ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Excess Pore Pressure ◽  
Soil Pressure ◽  
Excess Pore Water Pressure ◽  
Test Study ◽  
Excess Pore

The construct to precast pile in thick clayey soil can cause the accumulation of excess pore water pressure. The high excess pore pressure can make soil, buildings and pipes surrounded have large deflection, even make them injured. Combining with actual projects, this paper presents an in-situ model test on the changes of excess pore water pressure caused by precast pile construct. It is found that the radius of influence range for single pile driven is about 15m，the excess pore water pressure can reach or even exceed the above effective soil pressure, and there are two relatively stable stages.

In Situ Study on Soil Disturbance Induced by Shield Tunneling in Tianjin

2013 ◽  
Vol 368-370 ◽  
pp. 1674-1677
Author(s):  
Yong Hua Cao ◽  
Xiao Qiang Kou
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Disturbance ◽  
Ground Settlement ◽  
Soil Pressure ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Tunneling Process

In urban environment, the soil disturbance induced by shield tunneling can be sensitive because it can cause deformation of the ground and damage the near structure. To study this disturbance in the construction process of Tianjin metro line No.3, in-situ monitoring of pore water pressure, soil pressure and ground settlement were conducted. The pore water pressure was monitored for the soil around the tunnel. The soil pressure was monitored for the soil around the tunnel and on the tunnel face. It was revealed that the pore water pressure and soil pressure changed twice in the tunneling process and these changes were induced by cutting face and grouting at the shield tail. The soil pressure on the tunnel face reached its maximal value when the distance between the cutting face and the sensor elements was around the diameter of the tunnel. Ground settlement developed in the tunneling process. The shape of ultimate settlement trough is closed to the one obtained by Pecks method.

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>

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.

scholarly journals Numerical Simulation on the Whole Sinking Process of Open Caisson with an Improved SPH Method

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jiahe Zhang
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Dynamic Change ◽  
Soil Pressure ◽  
Shield Tunneling ◽  
Material Interfaces ◽  
Engineering Problems ◽  
Domain Truncation ◽  
Particle Hydrodynamics ◽  
Sph Simulation

The phenomena of dynamic change in the material interfaces and mechanical properties are often involved in the caisson construction. Using conventional methods to simulate these phenomena is quite difficult due to the extremely large deformation. In this study, we proposed an improved soil-water-caisson interaction algorithm with the method of smoothed-particle hydrodynamics (SPH). This algorithm dealt with the support domain truncation of the particles near the blade and applied δ − SPH to avoid the pressure fluctuation. Meanwhile, the application of dynamic particles birth and death method could simulate the whole sinking process of an open caisson with underwater soil excavation. According to the comparison between SPH simulation and centrifuge test, the distribution of sidewall effective soil pressure was consistent, which indicated promising applicability of the algorithm. It should be noted that the considerable excess pore water pressure appeared in the surrounding soil under the blade. With the dissipation of the pressure over time, the effective soil stress increased correspondingly, and it would lead to the increasing difficulty of the sinking process. Therefore, the caisson should be avoided to stop for a long time during the sinking process or it would cause the stagnation of sinking. This algorithm could simulate engineering problems involving underwater construction effectively and provide theoretical and technical support for underwater excavation, shield tunneling, and other engineering problems.

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.

Using earth-tide induced water pressure changes to measure in situ permeability: A comparison with long-term pumping tests

2016 ◽  
Vol 52 (4) ◽  
pp. 3113-3126 ◽  
Author(s):  
Vincent Allègre ◽  
Emily E. Brodsky ◽  
Lian Xue ◽  
Stephanie M. Nale ◽  
Beth L. Parker ◽  
...  
Keyword(s):  
Water Pressure ◽  
Earth Tide ◽  
Pumping Tests ◽  
In Situ Permeability ◽  
Pressure Changes

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.

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