Effect of groundwater on the displacements of axially loaded pile in clayey soil

Abstract The displacement of a loaded pile could be vertical (axial) or horizontal (lateral); these displacements are sensitive to groundwater presence within the soil mass. This paper presents a theoretical study to investigate vertical and horizontal displacement of piles embedded in a clayey soil for different levels of groundwater under the ground surface. The study was performed using the commercial finite element package PLAXIS-3D. Three diameters of the concrete piles were considered: 0.5, 0.75 and 1 m, and were subjected to 1,000 kN axial load. The effect of 0, 5, 10, 15 and 20 m groundwater along the 20 m pile in length from the ground surface on the vertical and horizontal displacements was investigated. The results indicated that the vertical and horizontal displacements increase when the ground water level increases towards the base of pile. Also, there is a significant increase in the horizontal displacement up to 15 m of groundwater level from ground surface and decreased at levels from 15 to 20 m.

Method of Calculating the Compensation for Rectifying the Horizontal Displacement of Existing Tunnels by Grouting

Applied Sciences ◽

10.3390/app11010040 ◽

2020 ◽

Vol 11 (1) ◽

pp. 40

Author(s):

Yongjie Qi ◽

Gang Wei ◽

Feifan Feng ◽

Jiaxuan Zhu

Keyword(s):

Volume Expansion ◽

Soil Layer ◽

Horizontal Displacement ◽

Soil Mass ◽

Calculation Model ◽

Additional Stress ◽

Corrective Effect ◽

Engineering Data ◽

Subway Tunnels ◽

Good Agreement

Sleeve valve pipe grouting, an effective method for reinforcing soil layers, is often employed to correct the deformation of subway tunnels. In order to study the effect of grouting on rectifying the displacement of existing tunnels, this paper proposes a mechanical model of the volume expansion of sleeve valve pipe grouting taking into consideration the volume expansion of the grouted soil mass. A formula for the additional stress on the soil layer caused by grouting was derived based on the principle of the mirror method. In addition, a formula for the horizontal displacement of a tunnel caused by grouting was developed through a calculation model of shearing dislocation and rigid body rotation. The results of the calculation method proposed herein were in good agreement with actual engineering data. In summary, enlarging the grouting volume within a reasonable range can effectively enhance the grouting corrective effect. Further, with an increase in the grouting distance, the influence of grouting gradually lessens. At a constant grouting length, setting the bottom of the grouting section at the same depth as the lower end of the tunnel can maximize the grouting corrective effect.

Contrôle de la stabilité des remblais par la mesure des déplacements horizontaux

10.1139/t74-011 ◽

1974 ◽

Vol 11 (1) ◽

pp. 182-201 ◽

Cited By ~ 9

Author(s):

René Marche ◽

Robert Chapuis

Keyword(s):

Factor Of Safety ◽

Soft Clay ◽

Ground Surface ◽

Soft Layer ◽

The Stability ◽

The horizontal displacements measured at the toe of eight embankments are analyzed as a function of the factor of safety. The embankments are built on layers of soft clay. Only the undrained stage is studied.When the factor of safety of the embankments is higher than about 1.4, the horizontal displacements on the ground surface, at the toe of the embankment seem to follow an elastic law which is highly dependent on the ratio of the thickness of the soft layer to the width of the embankment. When the factor of safety is lower than about 1.4, the horizontal displacements do not follow an elastic law, they increase considerably. Consequently, it is suggested that the horizontal displacements be precisely measured at the toe of embankments during construction. These measurements are simple and sensitive to the approach of failure, they can be efficiently used to control the stability of embankments. This study also gives some information concerning the variation of horizontal displacements versus depth.

The Interaction Features of the Multi-Level Retaining Walls with Soil Mass

Civil and Environmental Engineering Reports ◽

10.1515/ceer-2017-0045 ◽

2017 ◽

Vol 26 (3) ◽

pp. 179-190

Author(s):

Igor Boyko ◽

Liudmyla Skochko ◽

Veronica Zhuk

Keyword(s):

Numerical Modelling ◽

Numerical Simulations ◽

Variable Stiffness ◽

Retaining Walls ◽

Soil Mass ◽

Soil Base ◽

Deep Foundation ◽

Multi Level ◽

Abstract The interaction features of multi-level retaining walls with soil base were researched by changing their geometric parameters and locality at the plan. During excavation of deep foundation pits it is important to choose the type of constructions which influences on the horizontal displacements. The distance between the levels of retaining walls should be based on the results of numerical modelling. The objective of this paper is to present a comparison between the data of numerical simulations and the results of the in-situ lateral tests of couple piles. The problems have been solved by using the following soil models: Coulomb-Mohr model; model, which is based on the dilatation theory; elastic-plastic model with variable stiffness parameters.

Representative Elementary Length to Measure Soil Mass Attenuation Coefficient

The Scientific World JOURNAL ◽

10.1155/2014/584871 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 4

Author(s):

J. A. R. Borges ◽

L. F. Pires ◽

J. C. Costa

Keyword(s):

Attenuation Coefficient ◽

Gamma Ray ◽

Clayey Soil ◽

Physical Property ◽

Soil Mass ◽

Mass Attenuation Coefficient ◽

Soil Bulk Density ◽

Elementary Length ◽

Increasing Demand ◽

Mass Attenuation

With increasing demand for better yield in agricultural areas, soil physical property representative measurements are more and more essential. Nuclear techniques such as computerized tomography (CT) and gamma-ray attenuation (GAT) have been widely employed with this purpose. The soil mass attenuation coefficient (μs) is an important parameter for CT and GAT analysis. When experimentally determined (μes), the use of suitable sized samples enable to evaluate it precisely, as well as to reduce measurement time and costs. This study investigated the representative elementary length (REL) of sandy and clayey soils forμesmeasurements. Two radioactive sources were employed (241Am and137Cs), three collimators (2–4 mm diameters), and 14 thickness (x) samples (2–15 cm). Results indicated ideal thickness intervals of 12–15 and 2–4 cm for the sources137Cs and241Am, respectively. The application of such results in representative elementary area (REA) evaluations in clayey soil clods via CT indicated thatμesaverage values obtained forx > 4 cm and source241Am might induce to the use of samples which are not large enough for soil bulk density evaluations (ρs). As a consequence,ρsmight be under- or overestimated, generating inaccurate conclusions about the physical quality of the soil under study.

3D Visual Technology of Geo-Deformation Disasters Induced by Mining Subsidence Based on ArcGIS Engine

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.500.428 ◽

2012 ◽

Vol 500 ◽

pp. 428-436 ◽

Cited By ~ 2

Author(s):

Ke Ming Yang ◽

Jun Ting Ma ◽

Bo Pang ◽

Yi Bin Wang ◽

Ran Wang ◽

...

Keyword(s):

Coal Mining ◽

Surface Deformation ◽

Ground Deformation ◽

Ground Surface ◽

Horizontal Displacement ◽

Mining Subsidence ◽

Underground Coal Mining ◽

Vertical Movements ◽

Probability Integral Method ◽

Arcgis Engine

Mining subsidence often produces significant horizontal and vertical movements at the ground surface, the surface deformation induced by underground coal mining can be predicted by probability integral method, and the surface geo-deformation disasters can be visualized based on GIS components. A three dimensional (3D) visualizing system of surface geo-deformation information is designed and developed with ArcGIS Engine and C# in the study. According to the surface deformation-predicted data induced by underground coal mining in Guobei Coalmine of Huaibei mine field, the extents and degrees of ground deformation disasters are visualized in 3D views for surface vertical subsidence, slope, curvature, horizontal displacement and horizontal strain based on the GIS-developed application platform.

CONCERNING THE EXTRACTION OF A SLACK SOIL LAYER FROM COMPRESSIBLE THICKNESS OF FOUNDATION STRATUM OF FINITE WIDTH FOUNDATIONS

Construction and Architecture ◽

10.29039/2308-0191-2019-7-4-49-56 ◽

2019 ◽

Vol 7 (4) ◽

pp. 49-56

Author(s):

Zaven Ter-Martirosyan ◽

Armen Ter-martirosyan ◽

Valery DEMYANENKO

Keyword(s):

Analytical Solutions ◽

Soft Soil ◽

Soil Layer ◽

Horizontal Displacement ◽

Creep Model ◽

Shear Stresses ◽

Finite Width ◽

Relative Depth ◽

Weak Layer ◽

The paper provides a quantitative assessment of the deflected mode of foundation stratum of finite width foundation, in the compressible thickness of which there is a slack clay soil layer. A number of criteria for assessing the possibility or impossibility of extruding a slack layer depending on its strength and rheological properties, as well as the relative thickness of the layer to its length (h/l) and the relative depth of the layer (h/d) have been given. Closed analytical solutions are given to determine the rate of Foundation precipitation depending on the rate of extrusion of the weak layer, including taking into account the damped and undamped creep. The analytical solutions in the article are supported by the graphical part made with the help of the Mathcad program. Plots of changes in shear stresses in the layer along the x axis at different distances from the axis and at different values 0, contours of horizontal displacement velocities in the weak layer at different distances from the x axis, plots of horizontal displacement velocities in the middle of the weak layer and plots of horizontal displacement velocities in the weak layer at different distances from the x axis are given. As a calculation model for describing the creep of a slack layer, rheological ones of the soil using power and hyperbolic functions and their modifications have been considered. In addition, most modern rheological models that take into account soil hardening during creep have been considered. Based on these models, the problem is solved by means analytical and numerical methods using the Mathcad PC and the PLAXIS PC according to the Soft Soil Creep model. The graphical part shows the isofields of horizontal displacements for 300 days and 600 days and the corresponding contours of horizontal displacements.

Characteristics of groundwater seepage with cut-off wall in gravel aquifer. I: Field observations

10.1139/cgj-2014-0285 ◽

2015 ◽

Vol 52 (10) ◽

pp. 1526-1538 ◽

Cited By ~ 77

Author(s):

Yong-Xia Wu ◽

Shui-Long Shen ◽

Ye-Shuang Xu ◽

Zhen-Yu Yin

Keyword(s):

Hydraulic Conductivity ◽

Clayey Soil ◽

Retaining Wall ◽

Ground Surface ◽

Test Site ◽

Second Phase ◽

Confined Aquifer ◽

Test Results ◽

Sandy Gravel ◽

High Hydraulic Conductivity

This paper presents a case history of the leakage behavior during dewatering tests in the gravel strata of an excavation pit of a metro station in Hangzhou, China. The groundwater system at the test site is composed of a phreatic aquifer underlain by an aquitard and a confined aquifer with coarse sand and gravel. The sandy gravel stratum has very high hydraulic conductivity. The maximum depth of the excavation is 24 m below the ground surface, which reaches the middle of the aquitard strata, where the thickness of the clayey soil is insufficient to maintain the safety of the base of the excavation. To understand the hydrological characteristics of gravel strata, single- and double-well pumping tests were conducted, where a cut-off wall was installed 43 m deep with its base penetrating 2 to 3 m into the aquifer. Test results show that this partial cut-off of the aquifer cannot effectively protect the base of the excavation from the upward seepage force of the groundwater during excavation. Therefore, a new cut-off wall (second phase) was constructed to a depth of 54 m to cut off the confined aquifer. A second pumping test was conducted after the construction of the second phase cut-off wall, and test results show that this full cut-off combined with dewatering can control groundwater effectively during excavation. This finding indicates that when a deep excavation is conducted in a confined aquifer with high hydraulic conductivity, determination of the depth of the retaining wall should be based on three factors: the stability of the base, the upward seepage stability, and settlement control.

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

10.1139/t93-040 ◽

1993 ◽

Vol 30 (3) ◽

pp. 464-475 ◽

Cited By ~ 7

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.

Stability of a single tunnel in cohesive–frictional soil subjected to surcharge loading

10.1139/t11-078 ◽

2011 ◽

Vol 48 (12) ◽

pp. 1841-1854 ◽

Cited By ~ 48

Author(s):

Kentaro Yamamoto ◽

Andrei V. Lyamin ◽

Daniel W. Wilson ◽

Scott W. Sloan ◽

Andrew J. Abbo

Keyword(s):

Upper Bound ◽

Limit Analysis ◽

Ground Surface ◽

Soil Mass ◽

Building Technology ◽

Surcharge Loading ◽

Large Size ◽

Surcharge Load ◽

The Stability ◽

Frictional Soils

This paper focuses mainly on the stability of a square tunnel in cohesive–frictional soils subjected to surcharge loading. Large-size noncircular tunnels are quickly becoming a widespread building technology by virtue of the development of advanced tunneling machines. The stability of square tunnels in cohesive–frictional soils subjected to surcharge loading has been investigated theoretically and numerically, assuming plane strain conditions. Despite the importance of this problem, previous research on the subject is very limited. At present, no generally accepted design or analysis method is available to evaluate the stability of tunnels or openings in cohesive–frictional soils. In this study, a continuous loading is applied to the ground surface, and both smooth and rough interface conditions between the loading and soil are modelled. For a series of tunnel geometries and material properties, rigorous lower and upper bound solutions for the ultimate surcharge loading of the considered soil mass are obtained by applying recently developed numerical limit analysis techniques. The results obtained are presented in the form of dimensionless stability charts for practical convenience, with the actual surcharge loads being closely bracketed from above and below. As a handy practical means, upper bound rigid-block mechanisms for square tunnels have also been developed, and the obtained values of collapse loads were compared with the results from numerical limit analysis to verify the accuracy of both approaches. Finally, an expression that approximates the ultimate surcharge load of cohesive–frictional soils with the inclusion of shallow square tunnels has been devised for use by practicing engineers.

The Coupling Effect of Composite Material with Foundation Pile and Soil Mass

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.580.477 ◽

2012 ◽

Vol 580 ◽

pp. 477-480

Author(s):

Yong Suo Li

Keyword(s):

Skin Friction ◽

Stress Responses ◽

Computer Aided Design ◽

Mechanical Response ◽

Coupling Effect ◽

Design Method ◽

Ground Surface ◽

Friction Stress ◽

Soil Mass ◽

Positive Skin

The computer-aided design method is used in modeling for the interaction between pile and geotechnical material soil. The behavior of the shear coupling springs is identical to the shear behavior of a grouted cable. Then a numerical model is founded by FLAC3D, deformation and stress responses are obtained as well as the mechanical response of pile during calculation, whose result reveals the mechanism of pile with soil under the load of gravitation and load transferring mode along pile shaft for different ground surface surcharge load, during simulation, the soil consists of two types, the less consolidated soil and normal consolidated soil, both the negative skin friction stress and positive skin friction stress are studied.