Cost Comparisons of Remedial Methods to Correct Track Substructure Instability

2000 ◽  
Vol 1713 (1) ◽  
pp. 10-14 ◽  
Author(s):  
Steven Chrismer ◽  
David Davis
Keyword(s):  
Layer Thickness ◽  
Granular Layer ◽  
Soft Clay ◽  
Cost Effective ◽  
Wheel Load ◽  
Service Testing ◽  
Effective Selection ◽  
Track Substructure ◽  
Soft Clay Subgrade ◽  
Lower Material

The effectiveness and costs of various remedies for stabilizing track over a soft clay subgrade were tested and compared. To date, the techniques of repeated tamping, increasing granular layer thickness, and placing a geoweb layer have been tested under 39-kip (170-kN) wheel-load traffic. Using typical industry cost figures, economic analysis shows that the most cost-effective selection depends on traffic volume. For the heavy-axle load conditions studied at the Facility for Accelerated Service Testing (located at FRA’s Transportation Technology Center, Inc., near Pueblo, Colorado), analysis indicates that continued tamping of the ballast can be the best choice when the annual tonnage is less than about 40 million gross tons (MGT; 360 GN). For annual tonnage levels greater than 50 MGT (450 GN), fixing the problem by use of a remedial technique is less costly. Of the two remedies tested, increasing the granular layer thickness appears to be the lower cost option, mainly because of the lower material cost compared with geoweb. The intent of this analysis is to help railroads decide whether to make temporary repairs with low initial costs or more permanent remediation with higher initial costs.

scholarly journals Numerical Study of Laterally Loaded Piles in Soft Clay Overlying Dense Sand

2021 ◽  
Vol 7 (4) ◽  
pp. 730-746
Author(s):  
Amanpreet Kaur ◽  
Harvinder Singh ◽  
J. N. Jha
Keyword(s):  
Layer Thickness ◽  
Soft Clay ◽  
Bending Moment ◽  
Layered Soil ◽  
Clay Layer ◽  
Pile Groups ◽  
Dense Sand ◽  
Lateral Capacity ◽  
Laterally Loaded ◽  
Pile Length

This paper presents the results of three dimensional finite element analysis of laterally loaded pile groups of configuration 1×1, 2×1 and 3×1, embedded in two-layered soil consisting of soft clay at liquid limit overlying dense sand using Plaxis 3D. Effects of variation in pile length (L) and clay layer thickness (h) on lateral capacity and bending moment profile of pile foundations were evaluated by employing different values of pile length to diameter ratio (L/D) and ratio of clay layer thickness to pile length (h/L) in the analysis. Obtained results indicated that the lateral capacity reduces non-linearly with increase in clay layer thickness. Larger decrease was observed in group piles. A non-dimensional parameter Fx ratio was defined to compare lateral capacity in layered soil to that in dense sand, for which a generalized expression was derived in terms of h/L ratio and number of piles in a group. Group effect on lateral resistance and maximum bending moment was observed to become insignificant for clay layer thickness exceeding 40% of pile length. For a fixed value of clay layer thickness, lateral capacity and bending moment in a single pile increased significantly with increase in pile length only up to an optimum embedment depth in sand layer which was found to be equal to three times pile diameter and 0.21 times pile length for pile with L/D 15. Scale effect on lateral capacity has also been studied and discussed. Doi: 10.28991/cej-2021-03091686 Full Text: PDF

Effect of a Strong Middle Layer on Spudcan Penetration

2014 ◽  
Author(s):  
Wen Gao ◽  
Tom Harrup ◽  
Yuxia Hu ◽  
David White
Keyword(s):  
Bearing Capacity ◽  
Layer Thickness ◽  
Soft Clay ◽  
Soil Layer ◽  
Strength Ratio ◽  
Top Soil ◽  
Flow Mechanisms ◽  
Soil Flow ◽  
Jack Up ◽  
Peak Resistance

The rapid penetration of one or more of the foundations of a mobile jack-up rig into the seabed is an ongoing major problem in the offshore industry, with the potential to cause major damage to the structure and endangering any personnel on board. A recent example is the jack-up drilling rig Perro Negro 6 incident happened near the mouth of the Congo river in July 2013 with one of the rig’s crew of 103 reported missing and six others injured. This uncontrollable displacement is due to a form of failure known as punch through failure and commonly occurs on stratified seabed profiles. It has been reported that unexpected punch-through accidents have resulted in both rig damage and lost drilling time at a rate of 1 incident per annum with consequential costs estimated at between US$1 and US$10 million [1]. This paper presents the bearing capacity profiles and associated soil flow mechanisms of a common spudcan foundation penetrating into a three layer soft-stiff-soft clay soil through the use of large deformation finite element (LDFE) analysis. The Remeshing and Interpolation with Small Strain (RITSS) [2, 3] technique was implemented in the software package AFENA [4] to conduct the LDFE analysis. Both soil layer thickness and soil layer strength ratios were varied to study their effect on the spudcan penetration responses. The LDFE results of spudcan penetration into the soft-stiff-soft clay soils were calibrated by existing centrifuge test data. A parametric study was then conducted to study the bearing capacity responses and soil flow mechanisms during spudcan large penetrations by varying the soil layer strength ratio and relative layer thickness to the diameter of spudcan. It was found that there were three types of bearing responses during continuous penetration of spudcan: (a) when the top soft layer is relatively thin, the spudcan bearing response was similar to that of two layer soils with stiff over soft clays; (b) when the top soil layer thickness is medium, a peak resistance is observed when spudcan penetrates into the middle stiff layer followed by reduction; (c) when the soil layer is thick, the peak resistance occurs when spudcan gets into the bottom soft soil layer. The critical thickness of top soil layer is a function of soil strength ratio and middle stiff soil layer thickness. The bearing response types were also corresponding to the soil cavity formations during spudcan initial penetration.

scholarly journals Compaction and Plasticity Comparative Behaviour of Soft Clay Treated with Coarse and Fine Sizes of Ceramic Tiles

2018 ◽  
Vol 34 ◽  
pp. 01012 ◽  
Author(s):  
Mohammed Ali Mohammed Al-Bared ◽  
Aminaton Marto ◽  
Indra Sati Hamonangan Harahap ◽  
Fauziah Kasim
Keyword(s):  
Soil Stabilization ◽  
Soft Soil ◽  
Soft Clay ◽  
Cost Effective ◽  
Dry Weight ◽  
Dry Density ◽  
Ceramic Tiles ◽  
Marine Clay ◽  
Maximum Dry Density ◽  
Stiff Soil

Recycled blended ceramic tiles (RBT) is a waste material produced from ceramic tile factories and construction activities. RBT is found to be cost effective, sustainable, environmental-friendly and has the potential to be used as an additive in soft soil stabilization. Recent reports show that massive amounts of RBT are dumped into legal or illegal landfills every year consuming very large spaces and creating major environmental problems. On the other hand, dredged marine clay obtained from Nusajaya, Johor, Malaysia has weak physical and engineering characteristics to be considered as unsuitable soft soil that is usually excavated, dumped into landfills and replaced by stiff soil. Hence, this study investigates the suitability of possible uses of RBT to treat marine clay. Laboratory tests included Standard proctor tests and Atterberg limits tests. The plasticity of marine clay was evaluated by adding 10%, 20%, 30% and 40% of 0.3 mm RBT. In addition, the compaction behaviour of treated marine clay was compared by adding two different sizes (0.3 mm and 1.18 mm diameter) of RBT. For both coarse and fine sizes of RBT, 10%, 20%, 30% and 40% of the dry weight of the soft clay were added. The mixture of each combination was examined in order to evaluate the Maximum Dry Density (MDD) and the optimum moisture content (OMC) for the treated soft clay. MDD and OMC for soft untreated samples were 1.59 Mg/m3 and 22%, respectively. Treated samples with 10%, 20%, 30% and 40% of 0.30 mm size RBT resulted in a significant reduction of OMC ranged from 19 to 15% while MDD resulted in increment ranged from 1.69 to 1.77 Mg/m3. In addition, samples treated with 10%, 20%, 30% and 40% of 1.18 mm size RBT resulted in major reduction of OMC ranged from 15 to 13.5% while MDD increased effectively from 1.75 to 1.82 Mg/m3. For all mix designs of soft clay-RBT, MDD was gradually increasing and OMC was sharply reducing with further increments of both sizes of RBT.

Investigation to some Preliminary Geotechnical Properties of Soft Clay Stabilized by Fly Ash Based Geopolymers

2020 ◽  
Vol 857 ◽  
pp. 259-265
Author(s):  
Jasim M. Abbas ◽  
Amer M Ibrahim ◽  
Abdalla M. Shihab
Keyword(s):  
Fly Ash ◽  
Specific Gravity ◽  
Soft Clay ◽  
Cost Effective ◽  
Geotechnical Properties ◽  
Experimental Program ◽  
Dry Density ◽  
Alkali Activation ◽  
Plastic Behavior ◽  
Maximum Dry Density

The civil engineering projects that includes soft clay within its activities has a serious concern of hazards, such hazards can be overcame by treating the existing soils by certain materials which are named as "stabilizers". The common materials that are highly used in this field are ordinary Portland cement, fly ash, lime and rice husk ash, etc. Each one of these stabilizers has its known shortcomings. The alkali activation of any alumina silicate source produces some kind of cost effective primary binding gel which is known as "Geopolymers". This study is devoted to investigate the role of liquid over fly ash ratio to some soil – FA based Geopolymers geotechnical properties. Such ratio is taken as 2.71, 3.167, 3.8 and 4.75 respectively within the experimental program and the investigated geotechnical properties are the specific gravity, liquid and plastic limit, compaction characteristics and California bearing ratio. The tests results showed that the maximum dry density decreased about 42 % at 2.71 liq/FA whereas this the specific gravity decreased 27 % at the same this ratio. In addition, the 3.8 and 4.75 of such limits revealed no plastic behavior due to the high presence of liquid.

scholarly journals An Improved Time-Series Model Considering Rheological Parameters for Surface Deformation Monitoring of Soft Clay Subgrade

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3073 ◽  
Author(s):  
Xing ◽  
Chen ◽  
Yuan ◽  
Shi
Keyword(s):  
Time Series ◽  
Surface Deformation ◽  
Soft Clay ◽  
Deformation Monitoring ◽  
Rheological Parameters ◽  
Deformation Model ◽  
Rheological Parameter ◽  
Functional Relationships ◽  
Soft Clay Subgrade ◽  
Deformation Models

Building deformation models consistent with reality is a crucial step for time-series deformation monitoring. Most deformation models are empirical mathematical models, lacking consideration of the physical mechanisms of observed objects. In this study, we propose an improved time-series deformation model considering rheological parameters (viscosity and elasticity) based on the Kelvin model. The functional relationships between the rheological parameters and deformation along the Synthetic Aperture Radar ( SAR) line of sight are constructed, and a method for rheological parameter estimation is provided. To assess the feasibility and accuracy of the presented model, both simulated and real deformation data over a stretch of the Lungui highway (built on soft clay subgrade in Guangdong province, China) are investigated with TerraSAR-X satellite imagery. With the proposed deformation model, the unknown rheological parameters over all the high coherence points are obtained and the deformation time-series are generated. The high-pass (HP) deformation component and external leveling ground measurements are utilized to assess the modeling accuracy. The results show that the root mean square of the residual deformation is ±1.6 mm, whereas that of the ground leveling measurements is ±5.0 mm, indicating an improvement in the proposed model by 53%, and 34% compared to the pure linear velocity model. The results indicate the reliability of the presented model for the application of deformation monitoring of soft clay highways. The estimated rheological parameters can be provided as a reference index for the interpretation of long-term highway deformation and the stability control of subgrade construction engineering.

On the Construction Technology and Quality Control of Vacuum Combined Surcharge to Foundation Reinforcement

2014 ◽  
Vol 1030-1032 ◽  
pp. 827-829 ◽  
Author(s):  
Ze Jun Liu ◽  
Ya Guo ◽  
Qi Wang Yuan ◽  
Bao Hai Chen ◽  
Xiang Yang Gu ◽  
...  
Keyword(s):  
Soft Soil ◽  
Soft Clay ◽  
Engineering Application ◽  
Economic Benefits ◽  
Engineering Practice ◽  
Strengthening Effect ◽  
Construction Technology ◽  
Soil Consolidation ◽  
Vacuum Preloading ◽  
Soft Clay Subgrade

The vast area of distribution of soft clay with poor engineering property of our country, on the soft clay subgrade treatment by drainage consolidation method. As a kind of drainage consolidation method, vacuum preloading consolidation of soft soil foundation in recent years have been widely used, and achieved very good engineering and economic benefits. The theory research about vacuum preloading behind the engineering practice, restricted the further development of the technology and engineering application, it is necessary to make a systematic study. Through the comparative analysis of the test results, the vacuum causes soil consolidation, on this basis, the surcharge preloading and vacuum preloading contrast of the vacuum preloading mechanism, analyzes various factors foundation reinforcement finally strengthening effect by vacuum preloading.

Evaluation of Bonded Concrete Overlay of Asphalt under Accelerated Loading

2020 ◽  
pp. 036119812096138
Author(s):  
Moinul Mahdi ◽  
Zhong Wu ◽  
Tyson D. Rupnow
Keyword(s):  
Cost Effective ◽  
Loading Path ◽  
Portland Cement Concrete ◽  
Wheel Load ◽  
Aged Asphalt ◽  
Interface Bond Strength ◽  
Cost Effective Alternative ◽  
Bonded Concrete Overlay ◽  
Falling Weight

Bonded concrete overlay of asphalt (BCOA), previously known as ultra-thin whitetopping (UTW), has been widely used to repair aged asphalt concrete (AC) pavements with moderate distresses. Because of the increasing costs of roadway maintenance, Louisiana has a great interest in determining whether thin BCOA (usually 2–6 in.) is a suitable and cost-effective alternative to the current practice of roadway maintenance. The objective of the study was to evaluate the performance of BCOA pavement and to identify the influence of in-situ interface bond strength on the performance of BCOA pavements. Three full-scale BCOA test sections with thicknesses of 6 in., 4 in., and 2 in. of Portland cement concrete (PCC) over an aged asphalt pavement were tested under accelerated pavement test (APT) loading under typical pavement conditions in southern Louisiana. Each section was trafficking-loaded to a failure (i.e., all the slabs in the loading path were cracked) under alternating load magnitudes of 9 kips and 16 kips of the ATLaS dual-tire wheel load. A falling weight deflectometer (FWD) backcalculated the effective thickness, a trench-cutting investigation was undertaken, and in-situ pull-off test revealed that a good bond was established initially between the PCC and AC layer. Several non-destructive test (NDT) methods indicated that the distresses of a BCOA slab could be coupled with a possible debonding at the PCC-asphalt interface. This paper mainly focuses on the APT results and the performance of BCOA test sections with different overlay thickness.

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