Soil improvement for a storage yard using the combined vacuum and fill preloading method

2005 ◽  
Vol 42 (4) ◽  
pp. 1094-1104 ◽  
Author(s):  
S.-W Yan ◽  
J Chu
Keyword(s):  
Ground Improvement ◽  
Soil Improvement ◽  
Undrained Shear Strength ◽  
Foundation Soil ◽  
Surcharge Preloading ◽  
Clay Slurry ◽  
Degree Of Consolidation ◽  
Preloading Method ◽  
Undrained Shear

This paper presents a case study of using the combined vacuum and fill surcharge preloading method to improve the foundation soil for a storage yard at Tianjin Port, China. A vacuum load of 80 kPa was applied for 4-8 weeks before fill surcharge was added in stages. The site to be improved was recently reclaimed using dredged clay slurry. Both the consolidated clay slurry fill and the seabed soils were very soft. After the combined vacuum and fill surcharge preloading, the ground settled more than 1 m. The average degree of consolidation achieved was more than 80%. The undrained shear strength of the soil increased twofold. The water content of the soil also decreased substantially. The soil improvement procedure using the combined vacuum and fill surcharge preloading method and the instrumentation scheme are described, the field monitoring data are presented and analyzed, and methods to estimate the degree of consolidation and several other issues related to the combined preloading method are discussed.Key words: case history, consolidation, ground improvement.

Quality Control Indexes Study of Vacuum Combined with Fill Surcharge Preloading Method

2012 ◽  
Vol 209-211 ◽  
pp. 1459-1462
Author(s):  
Shang Yu Han ◽  
Li Hong
Keyword(s):  
Vacuum Pressure ◽  
Soil Consolidation ◽  
Vertical Load ◽  
Foundation Soil ◽  
Load Pressure ◽  
Surcharge Preloading ◽  
Soil Settlement ◽  
Consolidation Effect ◽  
Preloading Method

The consolidation effect of vacuum combined with fill surcharge preloading always influenced by many factors including vacuum pressure, vertical load pressure and vertical drainage depth. As the way to improve the reliability of the method, based on the soil consolidation mechanisms and actual data getting from the laboratory test and in-situ test, the main indexes of the method were studied in this paper. The test results show that the ratio of the vacuum pressure and vertical load pressure can cause difference soil settlement-deformation, if the ratio close to 1 the consolidation effect of the foundation can be gradually advanced. The soil outside the embankment always has displacement to reinforcement region in the upper depth of the foundation soil when the vacuum pressure equals to the vertical load pressure.

scholarly journals APPLICATION THE POINT FOUNDATION (PF) METHOD FOR SOFT SOIL IMPROVEMENT: A CASE STUDY FROM VETNAM

2020 ◽  
Vol 53 (2D) ◽  
pp. 1-18
Author(s):  
Bui Truong Son
Keyword(s):  
Bearing Capacity ◽  
Ground Improvement ◽  
Soft Soil ◽  
Soil Improvement ◽  
Static Compression ◽  
Successful Case ◽  
Soft Ground Improvement ◽  
Final Settlement ◽  
Shallow Footing

The point foundation method is the head enlarged cement deep mixing columns with high-quality control which can be used for soft ground improvement. The article aims to present the application of this method to treat soft soil for the foundation of Samse Vina factory, Ninh Binh province. The thickness of soft soil varies from 5.4 m to 7.4 m with high compressibility and low shear strength. Thus, point foundation was used to improve this layer. The prediction methods of soil bearing capacity and the settlement on the point foundation were calculated. After the treatment of soil, the unconfined compression strength of the point foundation column was determined and the static compression test for the point foundation column was also performed. The research results show that this method can significantly reduce the settlement of shallow footing and improved the bearing capacity of the soil. The final settlement of shallow footing was smaller than 2.54 cm and the bearing capacity of soil treatment can be satisfied with the requirement of construction building. This is a successful case of the application of point foundation to improve soft soil in Vietnam.

scholarly journals Detailed Geophysical Mapping and Hydrogeological Characterisation of the Subsurface for Optimal Placement of Infiltration-Based Sustainable Urban Drainage Systems

Geosciences ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 446
Author(s):  
Theis Raaschou Andersen
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Optimal Placement ◽  
Urban Drainage ◽  
Cohesive Soils ◽  
Continuous Growth ◽  
Infiltration Tests ◽  
Geophysical Mapping ◽  
Undrained Shear

The continuous growth of cities in combination with future climate changes present urban planners with significant challenges, as traditional urban sewer systems are typically designed for the present climate. An easy and economically feasible way to mitigate this is to introduce a Sustainable Urban Drainage System (SUDS) in the urban area. However, the lack of knowledge about the geological and hydrogeological setting hampers the use of SUDS. In this study, 1315 ha of high-density electromagnetic (DUALEM-421S) data, detailed lithological soil descriptions of 614 boreholes, 153 infiltration tests and 250 in situ vane tests from 32 different sites in the Central Denmark Region were utilised to find quantitative and qualitative regional relationships between the resistivity and the lithology, the percolation rates and the undrained shear strength of cohesive soils at a depth of 1 meter below ground surface (m bgs). The qualitative tests enable a translation from resistivity to lithology as well as a translation from lithology to percolation rates with moderate to high certainty. The regional cut-off value separating sand-dominated deposits from clay-dominated deposits is found to be between 80 to 100 Ωm. The regional median percolation rates for sand and clay till is found to be 9.9 × 10−5 m/s and 2.6 × 10−5 m/s, respectively. The quantitative results derived from a simple linear regression analysis of resistivity and percolation rates and resistivity and undrained shear strength of cohesive soils are found to have a very weak relationship on a regional scale implying that in reality no meaningful relationships can be established. The regional qualitative results have been tested on a case study area. The case study illustrates that site-specific investigations are necessary when using geophysical mapping to directly estimate lithology, percolation rates and undrained shear strength of cohesive soils due to the differences in soil properties and the surrounding environment from site to site. This study further illustrates that geophysical mapping in combination with lithological descriptions, infiltration tests and groundwater levels yield the basis for the construction of detailed planning maps showing the most suitable locations for infiltration. These maps provide valuable information for city planners about which areas may preclude the establishment of infiltration-based SUDS.

Effects of Electro Osmotic Consolidation in South West of Johor: Small Laboratory Scale

2014 ◽  
Vol 803 ◽  
pp. 255-264
Author(s):  
Khairul Nizar Mohd Yusof ◽  
Fauziah Ahmad ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Muhammad Faheem Mohd Tahir
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Clay Soil ◽  
Soft Clay ◽  
Soil Improvement ◽  
Undrained Shear Strength ◽  
Engineering Structures ◽  
Vertical Loading ◽  
South West ◽  
Undrained Shear

Clay soil is one of the problematic soils due to its natural states which have low bearing capacity and high compressibility. The effect and problem of the clay soil characteristic creates a problem for construction especially excessive settlement and this can lead to unstable and potential cracks of engineering structures. At presents, there are few of soil improvement types can be carried out to overcome these problems, and electro osmotic consolidation is one of the options. This method has been applied many years ago especially in european countries. The study encompasses the determination of water content, atterberg’s limits and undrained shear strength after electro osmotic consolidation treatment of clay soils taken from 0.5 m and 1.5 m at southwest part of johor. All the samples were tested according to BS1377:1990. An experimental study was implemented in a pvc cylinder tube having dimensions of 300 mm height and 100 mm diameter. In the results of electro osmotic consolidation tests by installing copper spring electrodes, the measured undrained shear strength was increased considerably at the anodes especially compared to the initial undrained shear strength due to electro osmosis process and consolidation. As laboratory studies of its measurement have shown, the application of electro osmotic consolidation after the application of a direct current applied voltage of 10 volts, at the anodes especially: (i) a decrease by approximately 35% in water content; (ii) an increase around 29% in undrained shear strength; and (iii) a decrease about 21% in index plasticity. The results obtained in this study shows that the electro osmotic enhanced 15 kpa vertical loading consolidation is a feasible approach in strengthening of south west soft clay in johor. It can be clearly suggested that the higher the voltage applied in the system, the higher readings of undrained shear strength and the lower of water content especially at the anodes.

scholarly journals Design procedure for vertical drains considering a linear variation of lateral permeability within the smear zone

2009 ◽  
Vol 46 (3) ◽  
pp. 270-280 ◽  
Author(s):  
Cholachat Rujikiatkamjorn ◽  
Buddhima Indraratna
Keyword(s):  
Shear Strength ◽  
Design Procedure ◽  
Undrained Shear Strength ◽  
Soil Consolidation ◽  
Linear Variation ◽  
Vertical Drains ◽  
Multi Stage ◽  
Surcharge Preloading ◽  
Zone Ii ◽  
Undrained Shear

A system of vertical drains with surcharge preloading is an effective method for promoting radial drainage and accelerated soil consolidation. This study presents a procedure for the design of vertical drains that significantly extends the previous technique proposed by the authors to include: (i) a linear reduction of lateral permeability in the smear zone, (ii) the effect of overlapping smear zones in a closely spaced drain network, and (iii) the gain in undrained shear strength due to consolidation. Design examples are provided for both single stage and multi-stage embankment construction demonstrating the convenient use of the proposed solutions in practical situations.

Performance of clay samples reinforced with vertical granular columns

2007 ◽  
Vol 44 (1) ◽  
pp. 89-95 ◽  
Author(s):  
J Black ◽  
V Sivakumar ◽  
J D McKinley
Keyword(s):  
Shear Strength ◽  
Ground Improvement ◽  
Stress Path ◽  
Undrained Shear Strength ◽  
Replacement Ratio ◽  
Replacement Method ◽  
Single Column ◽  
Undrained Strength ◽  
Area Replacement Ratio ◽  
Undrained Shear

This paper reports an experimental study in which samples of soft kaolin clay (100 mm in diameter and 200 mm in height) were reinforced with vertical columns of sand and tested under triaxial conditions. Samples were reinforced with either a single column of sand of 32 mm diameter or three columns of sand, each of 20 mm diameter. The replacement method was used to form the columns. The columns were installed in the clay to depths of 120 and 200 mm. Tests were also carried out on samples that were not reinforced with sand columns. The samples were compressed under both drained and undrained conditions. It was found that the undrained shear strength of samples containing full-depth columns was greatly improved compared with that of the unreinforced samples. In the fully drained tests, the sample installed with a single column of 32 mm diameter exhibited better performance than the sample with three columns of 20 mm diameter, although the area replacement ratio in the case of the three 20 mm diameter columns was higher than that of the single 32 mm diameter column. However, the undrained strength of the composite material was not particularly affected by the number of columns.Key words: Ground improvement, undrained shear strength, consolidation, stress path, settlement.

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