scholarly journals Consolidation Theory for a Stone Column Composite Foundation under Multistage Loading

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Shenggen Huang ◽  
Yingtao Feng ◽  
Hao Liu ◽  
Wenbing Wu ◽  
Guoxiong Mei
Keyword(s):  
Separation Of Variables ◽  
Special Property ◽  
Composite Foundation ◽  
Stone Column ◽  
Consolidation Theory ◽  
Present Solution ◽  
Long Time ◽  
Degree Of Consolidation ◽  
Site Test ◽  
Multistage Loading

The consolidation theories considering instant load cannot fully reveal the consolidation mechanism of a stone column composite foundation used in the expressway embankments due to the time effect of loading; that is, the expressway embankments are often constructed in several stages for a long time. Meanwhile, owing to the special property that the pile-soil stress ratio is larger than 1, the consolidation theory for sand drain well foundation cannot be used directly in the consolidation analysis of stone column composite foundation. Based on the principle that the vertical load applied on the composite foundation is shared by the stone column and the surrounding soil, the governing solutions for the stone column composite foundation under a multistage load are established. By virtue of the separation of variables, the corresponding solutions of degree of consolidation for loading stage and maintaining load stage are derived separately. According to the Carrillo theorem, the solution for the average total degree of consolidation of entire composite foundation is also obtained. Finally, the reasonableness of the present solution has been verified by comparing the consolidation curve calculated by the present solution with that measured by site test.

Consolidation theory for a composite foundation considering radial and vertical flows within the column and the variation of soil permeability within the disturbed soil zone

2010 ◽  
Vol 47 (2) ◽  
pp. 207-217 ◽  
Author(s):  
Meng-Meng Lu ◽  
Kang-He Xie ◽  
Biao Guo
Keyword(s):  
Soil Column ◽  
Composite Foundation ◽  
Stone Column ◽  
Governing Equations ◽  
Soil Zone ◽  
Disturbed Soil ◽  
Variation Patterns ◽  
Present Solution ◽  
Actual Design ◽  
Continuity Assumption

To remedy the contradiction between the equal strain assumption and the flow continuity assumption at a soil–column interface, the traditional flow continuity assumption was abandoned and the radial and vertical flows within a stone column were incorporated to consider the column consolidation and deformation in a coupled fashion. Moreover, two possible variation patterns of the horizontal permeability coefficient of soil within the disturbed soil zone were included, to reflect the detrimental influence on the surrounding soil due to column construction. In addition, a linearly changed total vertical stress along the column depth was assumed, to achieve a more realistic stress distribution in practice. By considering the above mentioned characteristics, the governing equations for this type of consolidation problem were developed. The solutions for the governing equations were subsequently derived by using a new initial condition obtained from the equilibrium condition and equal strain assumption. On the basis of this, the average degree of consolidation of the composite foundation was obtained and discussed. Finally, a parametric study was performed and an application example was introduced to help engineers better utilize the present solution when applied to an actual design.

Vibro-Stone Column Reinforcement Mechanism and Numerical Analysis

2012 ◽  
Vol 446-449 ◽  
pp. 1940-1943
Author(s):  
Yang Liu ◽  
Hong Xiang Yan
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Pore Pressure ◽  
Numerical Procedure ◽  
Numerical Results ◽  
Excess Pore Pressure ◽  
Stone Column ◽  
Reinforcement Mechanism ◽  
Consolidation Theory ◽  
Excess Pore

Numerical simulation of vibro-stone column is taken to simulate the installation of vibro-stone column. A relationship based on test is adopted to calculate the excess pore pressure induced by vibratory energy during the installation of vibro-stone column. A numerical procedure is developed based on the formula and Terzaghi-Renduric consolidation theory. Finally numerical results of composite stone column are compared single stone column.

Behavior of Sand Compaction Columns Installed in Cohesionless Deposits

2020 ◽  
Vol 14 (2) ◽  
Author(s):  
N. Aarthi
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Internal Friction ◽  
Critical Appraisal ◽  
Diameter Ratio ◽  
Composite Foundation ◽  
Stone Column ◽  
Fe Model ◽  
Angle Of Internal Friction ◽  
Settlement Behavior

A critical appraisal of the reviewed literature revealed that there are very limited studies avail-able on the strength characteristics focusing on the load-settlement behavior of sand compaction col-umns (SCCs) when installed in cohesionless deposits. The method, though contemporary to the reputed stone column technique, is not yet studied rigorously in the available past studies, more precisely on the load-bearing characteristics when compared to the latter. Therefore the present study focuses on studying the behavior of multiple column composite foundation supported by sand compaction columns installed in loose to medium dense sands on a lab-scale numerical model. The study is carried out using commercially available finite element (FE) code 3D PLAXIS. Spacing to diameter ratio (S/D) ranging from 1.5 to 3.5 and initial relative density (RD) from 30 to 60% was adopted to study the changes in the load-settlement behavior of the improved deposit. Extending the FE model to further parametric study, the effect of angle of internal friction of the column sand and diameter of the column on the bearing capacity and settlement characteristics were analysed with and without normalization. From the results obtained, it is found that, for the considered FE model, the improved deposit with 3D spacing between the SCCs behaves distinctly different from all other cases analyzed.

scholarly journals Analysis of groundwater flow and stream depletion in L-shaped fluvial aquifers

2018 ◽  
Vol 22 (4) ◽  
pp. 2359-2375 ◽  
Author(s):  
Chao-Chih Lin ◽  
Ya-Chi Chang ◽  
Hund-Der Yeh
Keyword(s):  
Steady State ◽  
Groundwater Resources ◽  
Separation Of Variables ◽  
Measurement Data ◽  
Steady State Solution ◽  
State Solution ◽  
Stream Depletion ◽  
Numerical Studies ◽  
Present Solution ◽  
Depletion Rate

Abstract. Understanding the head distribution in aquifers is crucial for the evaluation of groundwater resources. This article develops a model for describing flow induced by pumping in an L-shaped fluvial aquifer bounded by impermeable bedrocks and two nearly fully penetrating streams. A similar scenario for numerical studies was reported in Kihm et al. (2007). The water level of the streams is assumed to be linearly varying with distance. The aquifer is divided into two subregions and the continuity conditions of the hydraulic head and flux are imposed at the interface of the subregions. The steady-state solution describing the head distribution for the model without pumping is first developed by the method of separation of variables. The transient solution for the head distribution induced by pumping is then derived based on the steady-state solution as initial condition and the methods of finite Fourier transform and Laplace transform. Moreover, the solution for stream depletion rate (SDR) from each of the two streams is also developed based on the head solution and Darcy's law. Both head and SDR solutions in the real time domain are obtained by a numerical inversion scheme called the Stehfest algorithm. The software MODFLOW is chosen to compare with the proposed head solution for the L-shaped aquifer. The steady-state and transient head distributions within the L-shaped aquifer predicted by the present solution are compared with the numerical simulations and measurement data presented in Kihm et al. (2007).

Analysis on Consolidation and Settlement Characteristics of Composite Foundation with T-Shaped Bidirectional Soil-Cement Deep Mixing Columns

2013 ◽  
Vol 470 ◽  
pp. 942-949
Author(s):  
Pei Sheng Xi ◽  
Bo Liu
Keyword(s):  
Separation Of Variables ◽  
Soil Layer ◽  
Composite Foundation ◽  
Pile Head ◽  
Pile Spacing ◽  
Deep Mixing ◽  
Loading Mode ◽  
Soil Cement ◽  
Total Settlement ◽  
Cement Deep Mixing

Based on the solution of one-dimensional consolidation model of T-shaped bidirectional soil-cement deep mixing column composite foundation and its calculating program deduced by the separation of variables and Laplace method. This paper discussed the consolidation and settlement characteristics of composite foundation under the conditions of different loading modes, foundation reinforcement modes, diameter of enlarged pile head and pile spacing. The results indicate, the soil layer in the region of enlarged pile head hardly be influenced by above factors, the lower soil layer and soft substratum soil are influenced greatly. Loading mode has a large effect on the consolidation, when loading instantaneously, the rate of consolidation is faster than that of loading constantly. The consolidation and settlement behavior of composite foundation reinforced by T-shaped bidirectional soil-cement deep mixing column and traditional bidirectional deep mixing column is much better than the original natural foundation. When the other parameters stay the same, consolidation degree and total settlement decrease with the increase of enlarged pile head diameter. With the increase of pile spacing, consolidation rate of the composite foundation decreases significantly, but the settlement value increases rapidly on the contrary.

Rewetting Analysis of Hot Vertical Surfaces With Precursory Cooling by the Heat Balance Integral Method

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
S. K. Sahu ◽  
P. K. Das ◽  
S. Bhattacharyya
Keyword(s):  
Heat Balance ◽  
Integral Method ◽  
Separation Of Variables ◽  
Dimensionless Numbers ◽  
Present Solution ◽  
Heat Balance Integral Method ◽  
Varied Range ◽  
The Heat Balance ◽  
Nondimensional Temperature ◽  
Good Agreement

The effect of precursory cooling on conduction-controlled rewetting of both slab and solid cylinder is analyzed by the heat balance integral method. A constant heat transfer coefficient is assumed in the wet region behind the wet front, while an exponentially decaying heat flux is assumed in the dry region ahead of the wet front. The physical problem is characterized by two dimensionless constants describing the extent of precursory cooling and three dimensionless numbers, namely, Peclet number, Biot number, and the nondimensional temperature. Results of the present solution are found to be in good agreement with other analytical solutions obtained through the Weiner–Hopf technique and the separation of variables as well as with the published experimental data for different coolants over a varied range of coolant flow rate. It is seen that precursory cooling increases the rewetting velocity particularly at higher flow rates. If it is neglected, the model grossly underpredicts the quench velocities.

Reinforcement Effect of Vibration Replacement Stone Column Test in Test Pile Area for One Crude Oil Business Reserve Base

2014 ◽  
Vol 584-586 ◽  
pp. 1922-1932
Author(s):  
Shun Xiang Meng ◽  
Shi Ming Xiao ◽  
Wei Liang ◽  
Qian Kun Gao
Keyword(s):  
Crude Oil ◽  
Bearing Capacity ◽  
Composite Foundation ◽  
Engineering Properties ◽  
Stone Column ◽  
Foundation Soil ◽  
Oil Storage ◽  
Foundation Treatment ◽  
Deformation Properties ◽  
Foundation Pile

The crude oil storage tank foundation is always treated by using vibration replacement stone column composite foundation treatment, mainly to improve the engineering properties of foundation soil and the deformation properties of soil, improving the bearing capacity of composite foundation, and to ensure the normal use of tank in the superstructure loads from damage or excessive deformation. Before construction to carry out the vibration replacement stone column composite foundation pile test, the test shows that strengthening the foundation bearing capacity characteristic value of vibration replacement stone column can meet the design requirements.

Solution charts for the consolidation of circular footings embedded in a finite stratum

2009 ◽  
Vol 46 (6) ◽  
pp. 708-718 ◽  
Author(s):  
Wen-Wei Zhang ◽  
Guofu Zhu ◽  
Ren Wang ◽  
Qingshan Meng
Keyword(s):  
Finite Element Method ◽  
Time Factors ◽  
Maximum Error ◽  
Technical Note ◽  
The Finite Element Method ◽  
Present Solution ◽  
Consolidation Settlement ◽  
Soil Skeleton ◽  
Degree Of Consolidation ◽  
Biot’S Consolidation

This technical note used the finite element method to investigate the consolidation behaviour of circular footings embedded in a finite stratum based on Biot’s consolidation theory. The influence of three factors on the degree of consolidation settlement was examined: (1) the ratio of the buried depth to the thickness of the stratum, (2) the ratio of the footing radius to the thickness of the stratum, and (3) the Poisson’s ratio of the soil skeleton. Based on the results of analysis, new normalized time factors are suggested. It is shown that the degree of consolidation exhibits very good normalized behaviour using the time factors. The authors also present solution charts for determining the degree of consolidation settlement of circular footings embedded in a finite stratum. These charts can provide engineers with a quick answer to the design issues. The maximum error caused by using the solution charts is within 3%.

Consolidation theory for the stone column reinforced ground with time-dependent drainage boundary considering the foundation stiffness

2021 ◽  
Vol 136 ◽  
pp. 104218
Author(s):  
Yuan Chen ◽  
An-Feng Hu ◽  
Sen-Lin Xie ◽  
Yi-Yang Chen ◽  
Zhao-Qi Gong
Keyword(s):  
Time Dependent ◽  
Stone Column ◽  
Consolidation Theory

scholarly journals Analysis of groundwater flow and stream depletion in the L-shaped fluvial aquifer

2017 ◽  
Author(s):  
Chao-Chih Lin ◽  
Ya-Chi Chang ◽  
Hund-Der Yeh
Keyword(s):  
Steady State ◽  
Groundwater Resources ◽  
Separation Of Variables ◽  
Measurement Data ◽  
Steady State Solution ◽  
Design Tool ◽  
State Solution ◽  
Stream Depletion ◽  
Present Solution ◽  
Fluvial Aquifer

Abstract. Understanding the head distribution in aquifers is crucial for the evaluation of groundwater resources. This article develops an analytical model for describing flow induced by pumping in an L‐shaped fluvial aquifer bounded by impermeable bedrocks and two nearly fully penetrating streams. A similar scenario for numerical studies was reported in Kihm et al. (2007). The water level of the streams is assumed to be linearly varying with distance. The aquifer is divided into two sub-regions and the continuity conditions of hydraulic head and flux are imposed at the interface of the sub-regions. The steady-state solution describing the head distribution for the model without pumping is first developed by the method of separation of variables. The transient solution for the head distribution induced by pumping is then derived based on the steady-state solution as initial condition and the methods of finite Fourier transform and Laplace transform. Moreover, the solution for stream depletion rate (SDR) from each of the two streams is also developed based on the head solution and Darcy's law. Both head and SDR solutions in real time domain are obtained by a numerical inversion scheme called the Stehfest algorithm. The software MODFLOW-2005 is chosen to check the accuracy of the head solution for the L-shaped aquifer. The steady-state and transient head distributions within the L-shaped aquifer predicted by the present solution are compared with the numerical simulations and measurement data presented in Kihm et al. (2007). The SDR solution is employed to demonstrate its use as a design tool in determining well location for required amounts of SDR from nearby streams under a specific aquifer pumping rate.

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