Piezocone testing in underconsolidated clay

1989 ◽  
Vol 26 (4) ◽  
pp. 563-567 ◽  
Author(s):  
Yasuo Tanaka ◽  
Toshihiko Sakagami
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Excess Pore Pressure ◽  
Special Importance ◽  
Tip Resistance ◽  
Degree Of Consolidation ◽  
Excess Pore Pressures ◽  
Marine Clays ◽  
Excess Pore

This paper describes the results of piezocone testing that was carried out in underconsolidated soft marine clay in Osaka Bay. The obtained profiles of the tip resistance and the pore-water pressure were quite different from those for clay strata of normally consolidated state. It was apparent that a different approach is needed to interpret the test results for underconsolidated clay. The dissipation tests with the piezocone were performed at different elevations and indicated the excess pore-water pressures remaining in the stratum.The depth profile of excess pore pressure of underconsolidated clay is of special importance to the understanding of the degree of consolidation of the stratum. An effort was made in this paper to assess the excess pore pressures remaining in the clay based on the piezocone data obtained during penetration. An examination was made of available piezocone data of similar marine clays, of both normally consolidated and underconsolidated states. Based on this, a method was proposed for predicting the profile of pore-water pressure in underconsolidated clay using the piezocone data obtained during penetration. Key words: piezocone, field test, underconsolidated clay, excess pore-water pressure, interpretation.

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.

Excess Pore Pressures During Undrained Clay Creep

1973 ◽  
Vol 10 (1) ◽  
pp. 12-24 ◽  
Author(s):  
Thomas L. Holzer ◽  
Kaare Höeg ◽  
Kandiah Arulanandan
Keyword(s):  
Pore Pressure ◽  
San Francisco ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Excess Pore Pressure ◽  
Time Behavior ◽  
Pore Pressures ◽  
Undrained Creep ◽  
Excess Pore

The objective of this presentation is to examine experimentally how the excess pore-water pressure is related to the mechanism for undrained creep of San Francisco Bay mud. The results are discussed in the context of creep mechanisms previously suggested in the literature and based on laboratory testing.It is found that shear strains occurring during undrained creep are directly related to a gradual but significant increase in excess pore pressure and, hence, reduction in effective stresses. The increase in magnitude of the pore pressure is, except immediately after the creep shear stress is applied, solely a function of the initial consolidation stress and consolidation period. The magnitude of the long-term build-up may be related to the amount of secondary compression which would occur during drained conditions. It increases with the organic content of the soil and decreases with the degree of remolding. The mechanism for the increase in pore-water pressure may be explained by drainage of water from micropores in the microstructure into the macrostructure.Unless one accounts for the increase in pore pressures during undrained creep, it is unlikely that one will be successful in formulating a generally valid mathematical model for stress–strain–strength–time behavior based on laboratory testing.

scholarly journals Pore Pressure Response to Groundwater Fluctuations in Saturated Double-Layered Soil

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Hongwei Ying ◽  
Lisha Zhang ◽  
Kanghe Xie ◽  
Dazhong Huang
Keyword(s):  
Pressure Distribution ◽  
Pore Pressure ◽  
Dimensionless Parameter ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Layered Soil ◽  
Excess Pore Pressure ◽  
Groundwater Fluctuation ◽  
Excess Pore Pressures ◽  
Excess Pore

Analytical solutions are developed for one-dimensional consolidation of double-layered saturated soil subjected to groundwater fluctuations. The solutions are derived by an explicit mathematical procedure using Duhamel’s theorem in conjunction with a Fourier series, when groundwater fluctuation is described by a general time-dependent function and assumed to be the pore water pressure variations at the upper boundary. Taking as an example the harmonic groundwater fluctuation, the relevant response of the excess pore water pressure is discussed in detail, and the main influencing factors of the excess pore pressure distribution are analyzed. A dimensionless parameterθhas been introduced because it significantly affects the phase and the amplitude of excess pore pressures. The influences of the coefficients of permeability and compressibility of soil on the excess pore pressure distribution are different and cannot be incorporated into the coefficient of consolidation in double-layered soil. The relative permeability ratio of two clayey soils also plays an important role on the curves of the distributions of the excess pore pressures. The effects of the thickness of the soil layer on the excess pore pressure distribution should be considered together with the dimensionless parameterθand the permeability and compressibility of the double-layered soil system.

scholarly journals Behavior of Nonplastic Silty Soils under Cyclic Loading

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Nazile Ural ◽  
Zeki Gunduz
Keyword(s):  
Pore Pressure ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clay Content ◽  
Cyclic Stress ◽  
Excess Pore Pressure ◽  
Stress Ratios ◽  
Silty Soils ◽  
Excess Pore

The engineering behavior of nonplastic silts is more difficult to characterize than is the behavior of clay or sand. Especially, behavior of silty soils is important in view of the seismicity of several regions of alluvial deposits in the world, such as the United States, China, and Turkey. In several hazards substantial ground deformation, reduced bearing capacity, and liquefaction of silty soils have been attributed to excess pore pressure generation during dynamic loading. In this paper, an experimental study of the pore water pressure generation of silty soils was conducted by cyclic triaxial tests on samples of reconstituted soils by the slurry deposition method. In all tests silty samples which have different clay percentages were studied under different cyclic stress ratios. The results have showed that in soils having clay content equal to and less than 10%, the excess pore pressure ratio buildup was quicker with an increase in different cyclic stress ratios. When fine and clay content increases, excess pore water pressure decreases constant cyclic stress ratio in nonplastic silty soils. In addition, the applicability of the used criteria for the assessment of liquefaction susceptibility of fine grained soils is examined using laboratory test results.

Preconsolidation pressures in intertill glaciolacustrine clay near Blaine Lake, Saskatchewan

1988 ◽  
Vol 25 (4) ◽  
pp. 831-839 ◽  
Author(s):  
E. Karl Sauer ◽  
E. A. Christiansen
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Ice Thickness ◽  
Excess Pore Water Pressure ◽  
Stability Of Slopes ◽  
Preconsolidation Pressure ◽  
Insufficient Time ◽  
Degree Of Consolidation ◽  
Excess Pore

Soft, intertill, glaciolacustrine clays are of concern for stability of slopes and foundations. An intertill clay deposit between 32 and 54 m below the surface was continuously cored. Index properties were determined for 46 samples and 10 samples were tested on the oedometer. Stratigraphic evidence indicates that the glaciolacustrine clay (Blaine Lake Member), lying between the till of the Sutherland and Saskatoon groups, was glaciated three times. However, preconsolidation pressures of this intertill clay show the degree of consolidation is less than 20% based on a total stress from an estimated ice thickness extrapolated from the Cypress Hills. This low preconsolidation pressure suggests there was insufficient time for dissipation of excess pore-water pressure created by thickening of the advancing glacier. Key words: preconsolidation pressure, excess pore-water pressure, glaciers, intertill clay.

Finite Element Analysis for Subgrade Consolidation Settlement in Soft Soil

2013 ◽  
Vol 448-453 ◽  
pp. 1256-1259
Author(s):  
Feng Tan ◽  
Tai Quan Zhou
Keyword(s):  
Finite Element ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Soil Depth ◽  
Water Pressure ◽  
Soft Soil ◽  
Excess Pore Pressure ◽  
Excess Pore Water Pressure ◽  
Consolidation Settlement ◽  
Excess Pore

The two-dimensional finite element model for subgrade consolidation settlement analysis within soft soil pile is developed using ABAQUS. The numerical simulation on a highway subgrade deformation is performed to study the variation of consolidation settlement and the excess pore water pressure distribution in the central location and the part under centerline of the embankment. The results show that settlement develops gradually with the increasing period of soil consolidation. The excess pore water pressure of deep subgrade soils under embankment centerline rise due to the increased load. After each soil layer was filled, the excess pore water pressure increased in the first and was stable later along with the increase of soil depth. After the embankment soil was filled completely, excess pore pressure dissipated with time developing until the completion of consolidation.

scholarly journals EVALUASI SETTLEMENT MENGGUNAKAN SURCHARGE PRELOADING DENGAN PVD PADA PROYEK DI BANDUNG SELATAN

2020 ◽  
Vol 3 (3) ◽  
pp. 911
Author(s):  
Michael Christopher Yapriadi ◽  
Inda Sumarli ◽  
Ali Iskandar
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Improvement ◽  
Soil Layers ◽  
Excess Pore Water Pressure ◽  
Surcharge Preloading ◽  
Improvement Method ◽  
Degree Of Consolidation ◽  
Excess Pore

The development in Indonesia continues to grow. Hence, the feasible land for construction is drastically decreased. However, some projects must be constructed on that kind of land. One solution to solve this problem is by using a soil improvement. A project in Bandung Selatan chose to apply Surcharge Preloading with PVD soil improvement method. This project used a combination of 9,2 metres surcharge preload and a 28 metres depth PVD, with triangular formation and 1,2 metres spacing. The soil improvement was finished after 548 days. This analysis aims to evaluate the settlement from the soil improvement result, which is 1,297 metres. This analysis uses a finite difference method program. The excess pore water pressure from the analysis result is 0,229 T/m2 on the 548th day. Therefore, these soil layers have possibilities to settle again in future. The 90% degree of consolidation settlement for this soil layers is 2,31 metres, which will be reached on the 813,4th days. It is suspected that there are some mistakes either during the soil improvement designing or the soil improvement process. Pembangunan di Indonesia terus berkembang. Akibatnya jumlah tanah yang baik untuk proyek konstruksi semakin menipis. Kendati demikian, ada kalanya suatu proyek harus dilaksanakan di lokasi tersebut. Salah satu solusi yang dapat ditempuh adalah dengan melakukan perbaikan tanah. Sebuah proyek di Bandung Selatan melakukan perbaikan tanah dengan metode Surcharge Preloading dengan PVD. Proyek ini menggunakan kombinasi antara timbunan setinggi 9,2 meter dan PVD sedalam 28 meter, dengan formasi segitiga yang dipasang dengan jarak antar PVD 1,2 meter. Perbaikan tanah dilakukan selama 548 hari. Analisis ini bertujuan melakukan evaluasi terhadap kurang maksimalnya penurunan di lapangan yang hanya mencapai 1,297 meter. Analisis dilakukan dengan bantuan program beda hingga. Berdasarkan hasil analisis, besarnya excess pore water pressure pada hari ke-548 adalah 0,229 T/m,2, sehingga lapisan tanah tersebut masih memiliki potensi untuk mengalami penurunan. Adapun penurunan konsolidasi 90% yang dapat terjadi sebesar 2,31 meter pada hari ke-813,4. Diduga terdapat kesalahan baik dalam perhitungan perencanaan awal ataupun saat pelaksanaan di lapangan.

scholarly journals Analysis of Large-Strain Consolidation Behavior of Soil with High Water Content in Consideration of Self-Weight

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yupeng Cao ◽  
Jian Yang ◽  
Guizhong Xu ◽  
Jianwen Xu
Keyword(s):  
Pore Water ◽  
Void Ratio ◽  
Pore Water Pressure ◽  
Large Strain ◽  
Water Pressure ◽  
Average Degree ◽  
High Water Content ◽  
Excess Pore Water Pressure ◽  
Degree Of Consolidation ◽  
Excess Pore

Based on the axisymmetric large-strain consolidation (ALSC) model with the void ratio as the variable under equal strain condition, difference schemes of model’s equation, initial condition, and boundary condition were given. Taking phosphatic clay in Florida as a research object, the consolidation behaviors of soil with high water content by axisymmetric large-strain theory and one-dimensional large-strain theory were analyzed. The effect of different kinds of consolidation theories and self-weight stress on an average degree of consolidation was evaluated. The development of the void ratio and excess pore water pressure along the soil layer was clarified. The results show that the theoretical value of Terzaghi’s consolidation degree is always less than that of ALSC (Us, the average degree of consolidation defined by strain)-vertical drainage in the consolidation process. Terzaghi’s solution overestimates the dissipation rate of excess pore water pressure during the earlier consolidation period but underestimates it during the later consolidation period. The degree of consolidation calculated by Hansbo develops faster than ALSC (Up, the average degree of consolidation defined by stress)-radial drainage, but slower than ALSC (Us)-radial drainage. In the ALSC model, Us is always been faster than Up. The effect of self-weight on the consolidation degree of axisymmetric large-strain consolidation theory is relatively small (maximum error is less than 16%), while it can accelerate the consolidation rate of soil in one-dimensional large-strain consolidation theory largely. When only the vertical drainage occurs, the consolidation rate in the middle of the soil is obviously lagging the upper and lower parts, while the radial drainage can reduce the void ratio and the excess pore water pressure along the soil layer uniformly and more rapidly.

scholarly journals Radial consolidation response upon the application and removal of vacuum and fill loading

2015 ◽  
Vol 52 (12) ◽  
pp. 2156-2162 ◽  
Author(s):  
Kourosh Kianfar ◽  
Buddhima Indraratna ◽  
Cholachat Rujikiatkamjorn ◽  
Serge Leroueil
Keyword(s):  
Pore Pressure ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Vacuum Pressure ◽  
Excess Pore Pressure ◽  
Excess Pore Water Pressure ◽  
Removal Time ◽  
Excess Pore

This Note presents a laboratory study using a Rowe cell to compare the consolidation responses upon vacuum pressure and fill load application and removal. The influences of the duration of application and removal of fill load and vacuum pressures on radial consolidation were investigated using excess pore-water pressure, axial strain, and overconsolidation ratio. It is shown that the appropriate removal time for vacuum pressure can be determined based on excess pore pressure responses.

Numerical Analysis of MMP Piling with Wet-Jetting Method

2012 ◽  
Vol 446-449 ◽  
pp. 1718-1722
Author(s):  
Yao Yao Chen ◽  
De An Sun
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Excess Pore Pressure ◽  
Three Dimension ◽  
Three Dimensional Model ◽  
Excess Pore Water Pressure ◽  
Modified Cam Clay ◽  
Excess Pore

MMP pile is a method of foundation treatment, and driving pile brings the excess pore water pressure in the surrounding subgrade. By using a software ABAQUS to build a three-dimensional model, the process of MMP pile driven at a site of railway foundation in Shanghai is simulated using theory of Biot consolidation and modified Cam-clay model with three-dimension effect being considered. The changes in the excess pore pressure are obtained. Comparing the computed results with measured results in situ shows that the computed excess pore water pressure is consistency with that measured from in situ.

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