scholarly journals Effect of Micropiles on Clean Sand Liquefaction Risk Based on CPT and SPT

2020 ◽  
Vol 10 (9) ◽  
pp. 3111 ◽  
Author(s):  
Visar Farhangi ◽  
Moses Karakouzian ◽  
Marten Geertsema
Keyword(s):  
Soil Properties ◽  
Factor Of Safety ◽  
Standard Penetration Test ◽  
Strength Properties ◽  
Soil Liquefaction ◽  
Penetration Test ◽  
Sand Liquefaction ◽  
Abrupt Decrease ◽  
Novel Approach ◽  
Jet Grouting

Liquefaction is a hazardous seismic-based phenomenon, which causes an abrupt decrease in soil strength properties and can result in the massive destruction of the built environment. This research presents a novel approach to reduce the risk of soil liquefaction using jet-grouted micropiles in clean sands. The saturated soil profile of the study project mainly contains clean sands, which are suitable to more reliably employ simplified soil liquefaction analyses. The grouting is conducted using 420 micropiles to increase the existing soil properties. The effect of jet grouting on reducing the potential of liquefaction is assessed using the results of the cone penetration test (CPT) and the standard penetration test (SPT), which were conducted before and after jet grouting by implementing micropiles in the project sites. According to three CPT-based liquefaction analyses, the Juang method predicts the most effective improvement range of the factor of safety in the clean sand. The Boulanger and Idriss, and Eurocode methods show comparable evaluations. Results of the SPT-based analyses show the most considerable increase of the factor of safety following the Boulanger and Idriss, and NCEER approaches in the SP soil. CPT- and SPT-based analyses confirm the effectiveness of jet grouting by micropiles on enhancing soil properties and reducing the risk of liquefaction.

Probabilistic Safety Factor of Soil Liquefaction

2012 ◽  
Vol 217-219 ◽  
pp. 2414-2418
Author(s):  
Sanguan Vongchavalitkul
Keyword(s):  
Safety Factor ◽  
Factor Of Safety ◽  
Probabilistic Method ◽  
Standard Penetration Test ◽  
Soil Liquefaction ◽  
Probability Method ◽  
Penetration Test ◽  
Deterministic Method ◽  
Actual Measurement ◽  
Study Case

The most widely used method of liquefaction prediction are perform in deterministic process. The deterministic method according to seismic Chinese code is introduced by Z. CAO et al (2008). The deterministic method used the standard penetration test (SPT) to evaluate the liquefaction of soil. With this method, liquefaction of soil is predicted to occur if the factor of safety(FS), which in the ratio of critical SPT-N value(Resistance) over the actual measurement SPT-N(Load), is less than or equal to one. If the factor of safety greater than one, no soil liquefaction is predicted. Because the significant uncertainties in variable involved in the deterministic factor of safety, the probability method need to use. because the significant uncertainties in the random variables involved, the probabilistic method is needed to predict liquefaction. Probability of failure may be performed in which the liquefaction potential is assessed in term of probability safety factor (central safety factor). The study case is shown that the probabilistic method given the much more information for engineering decision than the deterministic method that given only the safety factor..

Probabilistic Assessment of Soil Liquefaction by Using Seismic Chinese Code

2012 ◽  
Vol 166-169 ◽  
pp. 2248-2252
Author(s):  
Sanguan Vongchavalitkul ◽  
Swein Kumpangta
Keyword(s):  
Safety Factor ◽  
Factor Of Safety ◽  
Standard Penetration Test ◽  
Soil Liquefaction ◽  
Probabilistic Assessment ◽  
Probability Method ◽  
Deterministic Method ◽  
Actual Measurement ◽  
First Order ◽  
First Order Second Moment

Deterministic safety factor are introduced by Z. CAO et al (2008) according to seismic Chinese code. The approach was deterministic method used the standard penetration test (SPT) to evaluate the liquefaction of soil. With this method, liquefaction of soil is predicted to occur if the factor of safety(FS), which in the ratio of critical SPT-N value(Resistance) over the actual measurement SPT-N(Load), is less than or equal to one. If the factor of safety greater than one, no soil liquefaction is predicted. Because the significant uncertainties in variable involved in the deterministic factor of safety, the probability method need to use. Probabilistic safety factor calculations provide a means of evaluating the combined effeces of uncertainties and provide a logical framework for choosing a factor of safety that is appropriate for the degree of uncertainty and consequences of failure. Then, a probabilistic assessment of soil liquefaction may be performed in which probability of failure and reliability index. By using the most widely reliability analysis as the First Order Second Moment (FOSM) method, the results of a probabilistic assessment of soil liquefaction can be used for engineering decision.

scholarly journals Probabilistic version of the Robertson and Wride method for liquefaction evaluation: development and application

2012 ◽  
Vol 49 (1) ◽  
pp. 27-44 ◽  
Author(s):  
Chih-Sheng Ku ◽  
C. Hsein Juang ◽  
Chi-Wen Chang ◽  
Jianye Ching
Keyword(s):  
Factor Of Safety ◽  
Probabilistic Models ◽  
Deterministic Model ◽  
Soil Liquefaction ◽  
Penetration Test ◽  
Cone Penetration ◽  
Liquefaction Potential ◽  
Additional Information ◽  
Extra Effort ◽  
Probabilistic Version

The Robertson and Wride method is the most widely used cone penetration test (CPT)-based method for soil liquefaction evaluation. This method is a deterministic model, which expresses liquefaction potential in terms of factor of safety. On many occasions, there is a need to express the liquefaction potential in terms of liquefaction probability. Although several probabilistic models are available in the literature, there is an advantage having a probabilistic version of the Robertson and Wride method so that the engineer who prefers to use this method can obtain additional information of liquefaction probability with minimal extra effort. In this paper, a simple model is developed, which links the factor of safety determined by the Robertson and Wride method to the liquefaction probability. The model, referred to as the probabilistic RW model, is developed, and verified, in a mathematically rigorous manner. Simplified equations for assessing the variation of liquefaction probability caused by the uncertainty in input parameters are also developed. Example applications are presented to demonstrate the developed models.

scholarly journals STRENGTH CHARACTERIZATION OF FOUNDATION SOILS AT FEDERAL UNIVERSITY LOKOJA BASED ON STANDARD PENETRATION TESTS DATA

2017 ◽  
Vol 36 (3) ◽  
pp. 671-676
Author(s):  
JA Sadeeq ◽  
AB Salahudeen
Keyword(s):  
Soil Properties ◽  
Estimation Method ◽  
Average Energy ◽  
Standard Penetration Test ◽  
Analytical Models ◽  
Penetration Test ◽  
Strength Characterization ◽  
Penetration Tests ◽  
Allowable Bearing Pressure

Strength characteristics of foundation soils in the Permanent site of the Federal University Lokoja in Kogi State were evaluated based on standard penetration test (SPT) results using some conventional analytical models proposed by different researchers. The study was carried out in order to take precise engineering decisions on the type of foundations suitable for the proposed structures and to determine the optimal depth of foundation embedment.  The SPT N-values were first corrected to the standard average energy of 60% (N60) before they were used to correlate soil properties. Evaluation of the soil properties were done at foundation embedment depths of 0.6, 2.1 and 3.6 m. Results show that bearing capacity generally increased with boring depth. Based on the Meyerhof allowable bearing pressure estimation method, foundation pressures in the range of 150 – 600  kN/m2 were evaluated for use in the study area at shallow depths (depths in the range of 0.6 - 3.6 m).http://dx.doi.org/10.4314/njt.v36i3.2

Reconsideration of case histories for estimating undrained shear strength in sandy soils

1999 ◽  
Vol 36 (5) ◽  
pp. 907-933 ◽  
Author(s):  
C E (Fear) Wride ◽  
E C McRoberts ◽  
P K Robertson
Keyword(s):  
Shear Strength ◽  
Sandy Soils ◽  
Standard Penetration Test ◽  
Undrained Shear Strength ◽  
Soil Liquefaction ◽  
Penetration Test ◽  
Case Histories ◽  
Original Case ◽  
Undrained Strength ◽  
Undrained Shear

When sandy soils respond in a strain-softening manner to undrained loading, an estimation of the resulting undrained shear strength (Su) is required to determine the potential for flow liquefaction at a given site. One of the most commonly used methods for estimating the undrained strength of liquefied sand is an empirical standard penetration test (SPT) based chart (originally proposed by H.B. Seed), which was developed using a number of case histories. The original interpretations of these case histories are viewed by many workers and regulatory agencies as the most authoritative measure of the liquefied strength of sand. Consequently, in comparison, other less conservative methods are generally held in an unfavourable light. This paper reexamines the original database of case histories in view of some more recent concepts regarding soil liquefaction. The objectives of this paper are to explore and reassess the issues involved in the original assessment and to offer alternative views of the case records. The conclusions presented here indicate that alternative explanations of the liquefied strength of sand are not inconsistent with the original case histories. Key words: sandy soils, soil liquefaction, undrained strength, standard penetration test (SPT).

scholarly journals Liquefiable Ground Treatment Using Cruciform Section Probe Resonant Compaction Method: A Case Study in the Xitong Expressway, Eastern China

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Guangyin Du ◽  
Han Xia ◽  
Jun Cai ◽  
Huangsong Pan ◽  
Changshen Sun
Keyword(s):  
Vibrational Energy ◽  
Eastern China ◽  
Strengthening Mechanism ◽  
Standard Penetration Test ◽  
Bridge Engineering ◽  
Penetration Test ◽  
Sand Liquefaction ◽  
Friction Resistance ◽  
Liquefiable Soil ◽  
Compaction Method

The foundation treatment of liquefiable soil has always been an important part of construction. Sand liquefaction decreases the foundation capacity and can cause severe building, highway, or bridge engineering accidents. This study used self-developed cruciform section probe resonant compaction equipment (CSPRCE) to evaluate the applicability and reinforcement effect of the Xitong Expressway foundation. The cone penetration test (CPT) results showed that this soil was liquefiable ground requiring treatment before construction. Laboratory tests illustrated that the clay particle content was nearly 10% in the surface layer, indicating that the traditional resonant compaction probe (RCP) would not provide effective reinforcement; therefore, we adopted the new resonant compaction method (RCM) for the reinforcement process. The CPT and standard penetration test (SPT) results after foundation reinforcement indicated that the cruciform section probe resonant compaction method (CSPRCM) is suitable for treating the Xitong Expressway liquefiable foundation. Before reinforcement, 7-8 liquefiable soil layers were observed, whereas after reinforcement, no foundation testing points were liquefiable. Cone resistance and unit sleeve friction resistance were both improved by a factor of nearly 3 after the CSPRCM reinforcement. The CSPRCM has wider applicability than traditional vibrating compaction methods, especially for sites with a high content of silt and clay particles. The strengthening mechanism of the CSPRCM is a vibration hammer that generates vibrational energy to obliterate the original soil structure and render the sand completely liquefied; the soil particles then rearrange to form a new structure.

scholarly journals Cramming the Specificities in Contemplating Safe Bearing Capacity for the Foundation Assessed from Borehole Samples in a Sandy-Moorum Zone

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Tarun Kumar Lohani ◽  
Melkamu Teshome Ayana ◽  
Abdella Kemal Mohammed ◽  
Jyotiranjan Pattanaik
Keyword(s):  
Soil Properties ◽  
Bearing Capacity ◽  
Laboratory Testing ◽  
Standard Penetration Test ◽  
Soil Samples ◽  
Clear Understanding ◽  
Foundation Settlement ◽  
Penetration Test ◽  
Spt Data ◽  
Allowable Settlement

Borehole samples drilled up to a depth of 10 m provide a clear understanding whether a foundation is safe for any structure. The main objective of the present study reconnoitered the soil bearing capacity and foundation settlement characteristics using the standard penetration test (SPT) data obtained from 3 boreholes at 1 m, 2 m, and 3 m depths to correlate soil properties and deterrents, if any, created by groundwater. The methodology of the research is to collect soil samples, and ensuing subsoil analysis was performed in order to obtain concrete information to optimize the foundation system within the safe bearing capacity of soil and its allowable settlement. The scope of the work encompasses conducting detailed soil investigation from drilling logs, laboratory testing, and conducting and estimating safe bearing capacity. The result of the research aims at providing safety to the foundation from the investigations of conclusive recommendation to be adopted which would be economically feasible and structurally secured.

scholarly journals Standard Penetration Test-Based Probabilistic and Deterministic Assessment of Seismic Soil Liquefaction Potential

2004 ◽  
Vol 130 (12) ◽  
pp. 1314-1340 ◽  
Author(s):  
K. Onder Cetin ◽  
Raymond B. Seed ◽  
Armen Der Kiureghian ◽  
Kohji Tokimatsu ◽  
Leslie F. Harder ◽  
...  
Keyword(s):  
Standard Penetration Test ◽  
Soil Liquefaction ◽  
Penetration Test ◽  
Liquefaction Potential
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