The Behavior of Piles Driven in Clay. I. An Investigation of Soil Stress and Pore Water Pressure as Related to Soil Properties

1972 ◽  
Vol 9 (4) ◽  
pp. 351-373 ◽  
Author(s):  
J. I. Clark ◽  
G. G. Meyerhof
Keyword(s):  
Soil Properties ◽  
Load Transfer ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Full Scale ◽  
Approximate Theory ◽  
Model Pile ◽  
Stress Changes ◽  
Low Sensitivity ◽  
Large Model

This paper outlines research on large model piles and some full-scale piles driven into insensitive clay to study the phenomena of load transfer and the effect of pile driving on the soil. It is divided into two parts. Part I deals with the stress field set up by driving a large model pile into an instrumented clay bed and the stresses measured for some full-scale timber piles. Part II presents an evaluation of the load carrying capacity of the model pile and compares the results with full-scale pile load tests. The soil properties are evaluated in terms of effective stress for an estimate of the bearing capacity of the piles.The measured soil displacements near the shaft and base agree well with plastic theory, while the observed magnitude of the pore pressures in the clay due to driving are smaller and the rate of pore pressure dissipation is greater than expected theoretically.The magnitude of the total and effective radial stresses surrounding the pile is mainly related to the stress changes in the soil due to placing the pile and subsequent stress changes are relatively small. On the other hand, the tangential and vertical stresses vary appreciably with time and the latter stresses depart considerably from estimates based on elastic theory, due to locked-in-soil stresses.An approximate theory is presented to estimate the average effective radial stress on the pile shaft in connection with the ultimate shaft capacity. This proposed approach is supported by observations in some clays of low sensitivity, but requires further research in other type of clays.

The Behavior of Piles Driven in Clay. II. Investigation of the Bearing Capacity Using Total and Effective Strength Parameters

1973 ◽  
Vol 10 (1) ◽  
pp. 86-102 ◽  
Author(s):  
J. I. Clark ◽  
G. G. Meyerhof
Keyword(s):  
Bearing Capacity ◽  
Load Transfer ◽  
Full Scale ◽  
Approximate Theory ◽  
Strength Parameters ◽  
Pile Shaft ◽  
Model Pile ◽  
Shearing Strength ◽  
Low Sensitivity ◽  
Large Model

This paper outlines research of large model piles and some full scale piles driven into insensitive clay to study the phenomenon of load transfer and the effect of pile driving on the soil. It is divided into two parts. Part I dealt with the stress field set up by driving a large model pile into an instrumented clay bed and the stresses measured for some full scale timber piles. Part II presents an evaluation of the load carrying capacity of the model pile and compares the results with full scale load tests. Soil properties are evaluated in terms of effective stress for an estimate of the bearing capacity of the piles.The short term bearing capacity of the pile shaft and base can be estimated by conventional methods based on the undrained shearing strength of the clay at the time of driving. However, after several load cycles and for long term bearing capacity, closer estimates are obtained by use of the effective skin friction and shearing strength parameters from drained tests. Previous bearing capacity theory can be used for estimating the ultimate base capacity and an approximate theory is presented to estimate the average effective radial stress on the pile shaft in connection with the ultimate shaft capacities. This proposed approach is supported by observations in some clays of low sensitivity, but requires further research in other types of clays.

Characteristics of nonlinear response of deep saturated soil deposits

1997 ◽  
Vol 87 (2) ◽  
pp. 342-355 ◽  
Author(s):  
Shean-Der Ni ◽  
Raj V. Siddharthan ◽  
John G. Anderson
Keyword(s):  
Resonant Frequency ◽  
Soil Properties ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Saturated Soil ◽  
Soil Conditions ◽  
Base Excitation ◽  
Soil Deposits ◽  
Stress Dependent

Abstract Recent EPRI seismic design guidelines call for dynamic soil properties (shear modulus ratio and damping) and liquefaction strength curves to be characterized as a function of the effective vertical stress (or depth). A modified version of the DESRA2 constitutive model for saturated soil has been applied to study the nonlinear seismic response including liquefaction of medium dense soil deposits of various thicknesses. The results of the stress-dependent soil properties model show lower deamplification and higher first-mode (resonant) frequency than that of the stress-independent soil properties model. By using the stress-dependent model with impulse base excitation, the nonlinear behavior of various soil deposits has been investigated under a variety of conditions. The results show that (1) the saturated soil deposit has a smaller surface amplitude and significantly lower resonant frequency than the unsaturated soil deposit of the same thickness; (2) for the saturated soil conditions, the larger the base excitation, the lower the surface amplification and the resonant frequency; (3) the deep soil deposits show lower surface amplification and resonant frequency compared to the response of shallow deposits; (4) when shallow and deep deposits are compared, the shallow deposits develop much higher residual pore-water pressure; and (5) the amplification and residual pore-water-pressure response of deposits deeper than 100 m or so are very similar. The application of the method has also been illustrated using a strong synthetic base excitation applied to the base at a site near Reno. The results in general are consistent with those computed using the impulse loading. The study reveals that the response predicted from the conventionally used stress-independent soil properties model is unconservative for deep deposit.

Measuring the load–deformation response of rockfill columns by a full-scale field test on a natural riverbank

2011 ◽  
Vol 48 (7) ◽  
pp. 1032-1043
Author(s):  
Kendall J. Thiessen ◽  
Marolo C. Alfaro ◽  
James A. Blatz
Keyword(s):  
Field Test ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Site Investigation ◽  
Test Site ◽  
Full Scale ◽  
Shear Stresses ◽  
Scale Field ◽  
Column Technology ◽  
Rockfill Columns

A full-scale field test loading of a riverbank stabilized with rockfill columns was used to measure the load–deformation characteristics of the reinforced slope. The test site is located on the natural banks of the Red River in the city of Winnipeg. Rockfill column technology has evolved from granular shear key methods for stabilizing slopes. The relatively weak lacustrine clays are stabilized with compacted columns of limestone rockfill. The columns typically extend through the clay stratum and are anchored in the underlying till. The project involved an extensive site investigation, and soils characterization program in preparation for the field test. Eleven 2.1 m diameter columns were tested by loading the bank with 1920 t of fill. The deformations were measured with standard and in-place inclinometers. The pore-water pressure response of the in situ soils was continuously monitored with vibrating wire piezometers. The results have shown that shear stresses are mobilized along the entire length of the column when subjected to loading, and that complete densification is important in minimizing deformations. This paper discusses the design and construction of the field test and presents the results of the monitoring programs.

Geogrid in Flexible Pavements

2008 ◽  
Vol 2045 (1) ◽  
pp. 102-109 ◽  
Author(s):  
Imad L. Al-Qadi ◽  
Samer H. Dessouky ◽  
Jayhyun Kwon ◽  
Erol Tutumluer
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Moving Load ◽  
Flexible Pavements ◽  
Visual Observation ◽  
Full Scale ◽  
Base Layer ◽  
Pavement Performance ◽  
Horizontal Shear ◽  
Structural Capacity

Full-scale accelerated testing was used to provide new insight into quantifying the effectiveness of geogrids on low-volume flexible pavement performance. Although several previous studies report that geogrids improve pavement performance by enhancing structural capacity and reducing distress potential, the new study addresses how to maximize the benefits and cost-effectiveness of geogrid. To perform full-scale testing, three cells of flexible pavements, each having three pavement sections, were constructed. The granular base and hot-mix asphalt (HMA) layer thicknesses varied, and each cell had at least one control and one geogrid-reinforced pavement section. Instruments were embedded during construction to measure stress, strain, deflection, moisture, pore-water pressure, and temperature and were used to monitor pavement response to moving load. A moving dual-tire at 8 km/h and 44 kN was used to apply accelerated traffic loading. The performance of the various pavement sections when exposed to accelerated loading is presented. On the basis of pavement measured response as well as visual observation of the pavement cross section after excavation, the study showed that geogrid is very effective in reducing the horizontal shear deformation of the aggregate layer, especially in the traffic direction. Hence, the effectiveness of geogrid is clear for aggregate base layers with thicknesses ranging from 203 to 457 mm, and geogrid is expected to show similar effectiveness for greater base thickness given that thin HMA layer is used. The study also found that the optimal geogrid location in a thin aggregate layer is at the unbound aggregate-subgrade interface. For a thicker base layer, it is optimal to install a single geogrid at the upper third of the layer; the addition of another geogrid at the subgrade-base layer interface may be needed for stability.

Numerical Simulation of Land Subsidence in Hangu-Tianjin

2013 ◽  
Vol 275-277 ◽  
pp. 371-374
Author(s):  
Long Qin ◽  
Pei Hua Xu ◽  
Zhi Shuang Yang
Keyword(s):  
Land Subsidence ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Rapid Development ◽  
Soft Soil ◽  
Research Area ◽  
Stress Changes ◽  
Elevation Changes ◽  
Increasing Demand ◽  
Pressure Changes

The Hangu research area is belonged to the typical inshore soft soil area. The engineering geological properties of soil in the research area is rather poor. With the rapid development of Tianjin and the improvement of people’s living standards, with the increasing demand of people’s lives of with water and industrial water, a lot of groundwater exploited caused groundwater elevation changes and resulted in pore water pressure changes and leaded to effective stress changes of soil, which eventually caused land subsidence . Numerical analysis method is used to this paper to research land subsidence of Hangu,Tianjin.

Pore-water pressures in soft to firm clay during driving of piles into underlying dense sand

1996 ◽  
Vol 33 (2) ◽  
pp. 209-218 ◽  
Author(s):  
K D Eigenbrod ◽  
T Issigonis
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Pile Driving ◽  
Dense Sand ◽  
Clay Deposit ◽  
Stress Changes ◽  
Small Pore ◽  
Sand And Gravel

During driving of steel piles through soft, sensitive clay into very dense sand and gravel, pore-water pressure responses were monitored. As a result of the large length of the piles and also because of the high sensitivity of the soft clays, the piles were driven in two stages. During the initial stage of driving in the soft clay, only very small pore-water pressure increases were recorded together with very low pile driving resistances; however, during the second stage of driving, high pore-water pressure increases were observed in the clay as soon as the piles penetrated into the underlying very dense sand and gravel. It was concluded that the clay deposit was loaded from below, as the piles were driven into very dense sand. The total stress changes and the resulting pore-water pressure changes in the clay were analyzed, assuming that the pile driving load was equivalent to a flexible load acting on the surface of an elastic half-space, which represents the soft clay deposit. This interpretation of the pore-water pressure increases is important for the assessment of the bearing capacity of engineering structures affected by piles driven through soft soils into very dense deposits. The potential for high pore-water pressure increases in the clay during undrained loading as well as for volume increases in the dense sand due to pile driving can be predicted from piezocone test data. Key words: pile driving, pore-water pressure, piezocone testing, soft sensitive clays, dense sand deposits.

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