Author: MW. Bo Publisher: ISBN: Category : Compression Languages : en Pages : 10
Book Description
Compression behavior and compression parameters in the ultra-soft soil stage are still not well understood. In ultra-soft soil stage, the process of compression does not follow Terzaghi's unique relationship of deformation and effective stress gain principle, and the large deformation with little or no effective stress gain occurred in this stage. One-step loading compression tests were conducted, using a large diameter hydraulic consolidation cell (Rowe Cell). Vertical displacement and pore pressure behavior were measured during the deformation process. The transition point between slurry and soil stage determined from various methods are discussed. Approximate determination of compression indices in slurry stage from one-step high pressure loading was described in the paper. Step loading compression tests were also carried out with hydraulic consolidation cells on an ultra-soft soil with radial drainage conditions. Based on these test results, new compression parameters C*c1, C*c2, and C*c3 are introduced in this paper. The correlation between e*10 and void ratio at liquid limit eL is proposed. With this information, the total settlement at various loadings can be determined using the proposed equations. The prediction of time-rate of settlement could even be made using the coefficient of large strain consolidation CF estimated from the void ratio-permeability relationship. The computed magnitude and time rate of settlement agreed well with measured data. The dimensionless time factor curves for various radial drainage conditions are also proposed.
Author: Myint Win Bo Publisher: World Scientific Publishing Company ISBN: 9813107057 Category : Technology & Engineering Languages : en Pages : 330
Book Description
The formation of an alluvial clay deposit normally goes through sedimentation and consolidation. While the bottom portion is undergoing self-weight consolidation, sedimentation continues to take place at the top. However, the compression behavior of such deposits upon loading is not well understood.This book describes the compression behavior of ultra-soft soil upon additional load application. Various types of laboratory compression tests suitable for this type of soil are discussed, such as tests using small- and large-scale consolidometers, hydraulic Rowe cells under different drainage conditions, constant rate of loading and constant rate of strain tests. It also explains how to determine the transition point, which differentiates the two distinct behaviors between slurry state and soil state deformation. Methods to determine the compression indices and coefficients of consolidation at different stress ranges, which are required for the prediction of magnitude of settlement and time rate of settlement, are developed. An equation for predicting settlement of ultra-soft soil in both the slurry and soil stages is elaborated upon. These proposed methods of characterization or analyses — which are validated against published data, laboratory measurements and a case study — serve as useful tools for designing and constructing embankments and for carrying out land reclamation on ultra-soft soil.
Author: Myint Win Bo Publisher: World Scientific ISBN: 9812771883 Category : Technology & Engineering Languages : en Pages : 330
Book Description
The formation of an alluvial clay deposit normally goes through sedimentation and consolidation. This book describes the compression behavior of ultra-soft soil upon additional load application. It also discusses various types of laboratory compression tests suitable for this type of soil.
Author: Myint Win Bo Publisher: ISBN: Category : Compression Languages : en Pages : 9
Book Description
The conventional consolidation test on ultra-soft soil takes a long time to complete due to the viscous effect in the early stage of compression. Instead of conducting the test until the end-of-primary (EOP) consolidation at each loading step, the testing time can be shortened if the test is carried out at a constant rate of loading (CRL). In this study the CRL tests were carried out at various loading rates. The settlement and pore pressure behavior were studied, and a suitable rate of loading (1 kPa/800 s) was determined. The proposed rate of loading is slightly slower than the rate of loading for natural clay suggested by others. The transition point between viscous stage and soil stage can be determined from the measured peak pore pressure. The compression indices, the large strain coefficient of consolidation, and the coefficient of permeability can also be determined from the CRL test with the proposed equations. This paper discussed the experimental test on ultra-soft soil at a CRL.
Author: Takashi Tsuchida Publisher: CRC Press ISBN: 9789058096135 Category : Technology & Engineering Languages : en Pages : 420
Book Description
This volume contains the papers contributed to the Nakase Memorial Symposium with the theme: Soft Ground Engineering in Coastal Areas, held in Yokusuka, Japan in November 2002. The meeting was organized as a tribute to Professor Ako Nakase, and was attended by 125 participants including his Japanese colleagues and friends from overseas. The topics covered included: fundamental Characteristics of Clay Soils; Estimation of consolidation settlement in large-scale reclamation; Soil improvement methods in coastal areas; Reuse of dredged soils and behaviour of coastal structures under earthquake; and Evaluation for the stability of coastal structures.
Author: A. Arulrajah Publisher: ISBN: Category : Consolidation Languages : en Pages : 9
Book Description
The Changi East Reclamation Project in the Republic of Singapore involves improvement of marine clay by means of installation of prefabricated vertical drains and subsequent preloading. The in situ testing site was located in the Northern area of the project where the thickest compressible marine clay layers existed. The in situ testing site comprises of a vertical drain area where vertical drains were installed at 1.5 m square spacing and an adjacent control area without vertical drains. Both areas were preloaded with the same magnitude of preload over and above of proposed finished level. In situ tests were carried out using the self-boring pressuremeter test (SBPT) to determine especially the undrained shear strength and overconsolidation ratio of the marine clay together with some other geotechnical parameters prior to reclamation and after 23 month of preloading. In situ dissipation tests were also undertaken with the SBPT to provide a means of evaluating the in situ coefficient of consolidation due to horizontal flow (ch) and horizontal hydraulic conductivity (kh) of Singapore marine clay at Changi. Degree of consolidation was assessed 23 months after preloading using SBPTs data. The SBPT test indicates that the degree of consolidation of the vertical drain area had attained a degree of consolidation of about 80 % while the control area had attained a degree of consolidation of about 20-30 %. The ch determined by the SBPT prior to reclamation is noted to be an order of magnitude greater than the laboratory data. The kh results from SBPT in the Singapore marine clay are in the 10-9 to 10-11 m/s range.
Author: Frank C. Townsend Publisher: ISBN: Category : Soils Languages : en Pages : 130
Book Description
The results of a series of consolidated-undrained (CU) triaxial compression tests performed on normally consolidated and overconsolidated specimes of two clays consolidated both isotropically (ICU tests) and anisotropically (ACU tests) are presented and analyzed in this report. The specimens were trimmed from samples of Vicksburg Buckshot clay (LL = 57) and a clay from the East Atchafalaya Basin Protection Levee (EABPL) project area (LL = 79), both of which had been consolidated from a slurry in large-diameter consolidometers under a maximum vertical consolidation pressure of 3.0 kg/sq cm. Data presented include stress-strain curves, pore pressure observations, final water content distributions within the specimens, and shear strength envelopes based on total and effective stresses. Test results indicate that the change in volume during consolidation and the water content at the end of consolidation are not a unique function of the vertical consolidation stresses but are related to the mean effective consolidation stress. Total stress envelopes based on Taylor's method of deriving strengths of anisotropically consolidated specimens from test results obtained from isotropically consolidated specimens slightly underestimate observed values. In this context, Taylor's method is an appropriate means of predicting strengths for various K sub c ratios from conventional ICU tests. Use of hyperbolic stress-strain relationships derived from ICU tests in finite element codes for ACU conditions will lead to erroneous results. Further testing of anisotropically consolidated soils under stress systems that better simulate in situ conditions is needed.
Author: MW. Bo
Author: Myint Win Bo
Author: Myint Win Bo
Author: Myint Win Bo
Author: Frank C. Townsend
Author: Takashi Tsuchida
Author: John F. Peters
Author: Rául F. Esquivel-Díaz
Author: A. Arulrajah
Author: Frank C. Townsend