Showing papers on "Standard penetration test published in 2006"

Support vector machines‐based modelling of seismic liquefaction potential

Abstract: This paper investigates the potential of support vector machines (SVM)-based classification approach to assess the liquefaction potential from actual standard penetration test (SPT) and cone penetration test (CPT) field data. SVMs are based on statistical learning theory and found to work well in comparison to neural networks in several other applications. Both CPT and SPT field data sets is used with SVMs for predicting the occurrence and non-occurrence of liquefaction based on different input parameter combination. With SPT and CPT test data sets, highest accuracy of 96 and 97%, respectively, was achieved with SVMs. This suggests that SVMs can effectively be used to model the complex relationship between different soil parameter and the liquefaction potential. Several other combinations of input variable were used to assess the influence of different input parameters on liquefaction potential. Proposed approach suggest that neither normalized cone resistance value with CPT data nor the calculation of standardized SPT value is required with SPT data. Further, SVMs required few user-defined parameters and provide better performance in comparison to neural network approach. Copyright © 2006 John Wiley & Sons, Ltd.

Prediction of Soil Composition from CPT Data using General Regression Neural Network

Abstract: Soil type is typically inferred from the information collected during a cone penetration test (CPT) using one of the many available soil classification methods. In this study, a general regression neural network (GRNN) was developed for predicting soil composition from CPT data. Measured values of cone resistance and sleeve friction obtained from CPT soundings, together with grain-size distribution results of soil samples retrieved from adjacent standard penetration test boreholes, were used to train and test the network. The trained GRNN model was tested by presenting it with new, previously unseen CPT data, and the model predictions were compared with the reference particle-size distribution and the results of two existing CPT soil classification methods. The profiles of soil composition estimated by the GRNN generally compare very well with the actual grain-size distribution profiles, and overall the neural network had an 86% success rate at classifying soils as coarse grained or fine grained.

Subsurface Exploration using the Standard Penetration Test and the Cone Penetrometer Test

Abstract: The Standard Penetration Test (SPT) and Cone Penetrometer Test (CPT) have become industry standards for subsurface geotechnical investigations using small diameter (<8-in. [20-cm]) borings and soundings. Both procedures have evolved over a period of 100 and 70 years, respectively, and have been adopted as ASTM standards. Each procedure has certain advantages over the other, but both can elicit incorrect data under particular subsurface conditions that are often overlooked, depending on the experience of field personnel operating or logging the tests. This paper seeks to explain the operative assumptions employed in both procedures, highlight the various corrections that are commonly employed, and warn the reader of common errors in interpretation. The article concludes by stating that, under most conditions, the joint employment of SPT and CPT together has the greatest potential for characterizing sites correctly.

Accounting for soil aging when assessing liquefaction potential

Abstract: It has been recognized that liquefaction resistance of sand increases with age due to processes such as cementation at particle contacts and increasing frictional resistance resulting from particle rearrangement and interlocking. As such, the currently available empirical correlations derived from liquefaction of young Holocene sand deposits, and used to determine liquefaction resistance of sand deposits from in situ soil indices standard penetration test SPT, cone penetration test CPT, shear wave velocity test Vs, are not applicable for old sand deposits. To overcome this limitation, a methodology was developed to account for the effect of aging on the liquefaction resistance of old sand deposits. The methodology is based upon the currently existing empirical boundary curves for Holocene age soils and utilizes correction factors presented in the literature that comprise the effect of aging on the in situ soil indices as well as on the field cyclic strength CRR. This paper describes how to combine currently recorded SPT, CPT, and Vs values with corresponding CRR values derived for aged soil deposits to generate new empirical boundary curves for aged soils. The method is illustrated using existing geotechnical data from four sites in the South Carolina Coastal Plain SCCP where sand boils associated with prehistoric earthquakes have been found. These sites involve sand deposits that are 200,000 to 450,000 years in age. This work shows that accounting for aging of soils in the SCCP yields less conservative results regarding the current liquefaction potential than when age is not considered. The modified boundary curves indicate that old sand deposits are more resistant to liquefaction than indicated by the existing empirical curves and can be used to evaluate the liquefaction potential at a specific site directly from the current in situ properties of the soil.

Soil liquefaction susceptibility and hazard mapping in the residential area of Kütahya (Turkey)

Abstract: This study presents the results of both field and laboratory tests that have been undertaken to assess liquefaction susceptibilities of the soils in Kutahya city, located in the well-known seismically active fault zone. Liquefaction potentials of the sub-surface materials at Kutahya city were estimated by using the geological aspect and geotechnical methods such as SPT method of field testing. And, the data obtained have been mapped according to susceptibility and hazard. The susceptibility map indicated “liquefable” and “marginally liquefable” areas in alluvium, and “non-liquefable” areas in Neogene unit for the magnitude of earthquake of M=6.5; whereas, liquefaction hazard map produced by using of liquefaction potential index showed the severity categories from “very low” to “high.” However, a large area in the study area is prone to liquefy according to liquefaction susceptibility map; the large parts of the liquefable horizon are mapped as “low” class of severity by the use of the liquefaction potential index. It can be said that hazard mapping of liquefaction for a given site is crucial than producing liquefaction susceptibility map for estimating the severity. Both the susceptibility and hazard maps should be produced and correlated with each other for planning in an engineering point of view.

A semi-empirical model for the estimation of maximum horizontal displacement due to liquefaction-induced lateral spreading

Abstract: During the 1906 San Francisco Earthquake, liquefaction-induced lateral spreading and resultant ground displacements damaged bridges, buried utilities and lifelines, conventional structures, and other developed works. This paper presents an improved engineering tool for the prediction of maximum displacement due to liquefaction-induced lateral spreading. A semi-empirical approach is employed, combining mechanistic understanding and data from laboratory testing with data and lessons from full-scale earthquake field case histories. The principle of strain potential index, based primarily on correlation of cyclic simple shear laboratory testing results with in-situ Standard Penetration Test (SPT) results, is used as an index to characterize the deformation potential of soils after they liquefy. A Bayesian probabilistic approach is adopted for development of the final predictive model, in order to take fullest advantage of the data available and to deal with the inherent uncertainties intrinsic to the back-analyses of field case histories. A case history from the 1906 San Francisco Earthquake is utilized to demonstrate the ability of the resultant semi-empirical model to estimate maximum horizontal displacement due to liquefaction-induced lateral spreading.

Relationship between s-wave velocities and geotechnical properties of alluvial sediments

Abstract: Shear wave velocities of surficial unconsolidated sediments were investigated in correlation with geotechnical properties determined by laboratory testing. The S-wave velocity data, all of them were accurately measured in boreholes using the PS suspension logging tool, were collected from two regions, seven sites, 128 boreholes, and more than 6,000 points. We tried to obtain the original waveform data wherever possible and reanalyzed them to have high quality and precision on S-wave velocities. N-values obtained by in situ Standard Penetration Test (SPT), bulk densities, solidities, and mean grain sizes measured by the standard soil test, and elastic constants determined by tri-axial dynamic loading tests were correlated with the S-wave velocities at the same horizons in the same boreholes. Lithofacies based on detailed core investigation were taken account of in the correlation analysis. Conventionally, S-wave velocities were correlated to N-values. However the dynamic range and measurement accuracy of SPT is too low to compare with S-wave velocity data obtained using the suspension logging tool. So it is possible to estimate N-values from S-wave velocity data using an empirically synthesized equation, but is very hard to estimate S-wave velocities from the low quality SPT data. A clear relationship was recognized between S-wave velocities and solidities, and it varies with lithofacies and depositional age. This means that S-wave velocities are good indicators for the evaluation of depositional environments.

The use of the Mackintosh Probe for site investigation in soft soils

Abstract: Dynamic probing can have an important role in geotechnical site investigation. The Mackintosh Probe is a lightweight and portable penetrometer. It is a considerably faster and cheaper tool than boring equipment especially when the depth of exploration is moderate and the soils under investigation are soft or loose. This paper presents the capabilities of the Mackintosh Probe for the investigation of soft deposits. A methodology for the use of the Mackintosh Probe is discussed and the repeatability of test results is studied. Correlations are developed between Mackintosh Probe results and those of the Standard Penetration Test (SPT), as well as, undrained shear strength ( c u ). The study concludes that the application of the Mackintosh Probe for site investigation in soft deposits is appropriate and cost effective.

Discussion of "Review of Standard Penetration Test Short Rod Corrections"

Abstract: values for rods shorter than10.0 m.The standard penetration test SPT International ReferenceTest Procedure IRTP Decourt et al. 1988 has been mentionedin this paper; and the discusser, as one of the authors of thatdocument, would like to offer additional information on thismatter.First, the document mentioned in the paper was not actuallythe official SPT International Reference Test Procedure. Rather, itwas just a preview of the official document that the SwedishGeotechnical Society published one year later, during the 12thInternational Conference of Soil Mechanics and FoundationEngineering, held in Rio de Janeiro in 1989.The former document presented an analysis of energy mea-surements that was based on the pioneer work by Schmertmannand Palacios 1979 ; and, as mentioned by the authors, used the

Urban geology: a case study of khulna city corporation, bangladesh

Abstract: The Khulna City Corporation (KCC) in southwestern Bangladesh lies on the Late Holocene- Recent alluvium of the Ganges deltaic plain in the north and Ganges estuarine plain in the south. Lithologically the area is composed of coarse to very fine sand, silt, silty clay and clay in various porportion upto a depth of 300m. Stratigraphically shows seven cycles of sedimentation having age connotation from Upper Miocene to Recent age. The SPT (Standard Penetration Test) value of the investigated area range between 1 and 9 from surface to 5m deep and 1 to 27 from 5m to 15m below which was used to prepare a SPT zonation map that clearly delineates the KCC area into 4 zones. Here, the liquid limit, plasticity index and the natural moisture content (NMC) range from 38 to 59%, 9 to 30% and 16.5% to 42% respectively. The shear strength of the upper subsoil horizons in the investigated area is low. Low shearing strength in the upper soil horizon with compressive index from 0.123 to 0.335 is indicative of soil vulnerability to excessive settlement under high load. The cohesive nature of soil in the KCC area with high colloidal content, high liquid and plastic limit indicate medium to high sensitivity of the soil to moisture that could not support heavily loaded buildings and structures. The problems can be avoided by considering special type of foundation, increasing the width of basements of structures and granular backfilling. Based on geomorphology , stratigraphic litho-succession, soil types, percentage of sand, silt and clay in the soil, liquid limit, plasticity index, NMC, liquefaction, settlement and SPT zonation, the study area have been classified into four geotechnical units, where unit-I is best and unit-IV is rank lowest for urbanization. Considering the factors of geotechnical parameters and environmental degradation by natural and anthropogenic hazards a future land suitability map has been prepared for future urban planning of the Khulna City area. Key Wards: Urban Geology, Khulna City Corporation, Bangladesh.

Performance of bored piles with different construction methods

Abstract: The design of bored piles in residual soil is usually based on empirical correlation with the results of the standard penetration test, regardless of the construction method of the bored pile. This paper presents the pile load test results of two bored piles with different construction methods. A preliminary bored pile of 1000 mm diameter was constructed using a wet method with bentonite as the stabilising fluid. The static pile load test result shows that the shaft friction could be overestimated by the empirical method. A 1200 mm diameter bored pile was constructed about 5 m away from the preliminary bored pile but using the dry method. The static pile load test result shows that higher shaft friction can be obtained. The empirical method could underestimate the shaft friction in this case.

Artificial neural network methodology for soil liquefaction evaluation using CPT values

Abstract: With the 413 soil liquefaction records with cone penetration testing values collected after strong earthquakes, the Bayesian Regularization Back Propagation Neural Networks (BRBPNN) method was presented to evaluate the soil liquefaction potential in this paper. Cone resistance (qc), equivalent dynamic shear stress (τ / σ′0), mean grain size (D50), total stress (σ0), the effective stress (σ′0), earthquake magnitude (M) and the normalized acceleration horizontal at ground surface (a / g) are used as input parameters for networks. Four networks are constructed for different source of input data. The model M7 seems more efficient for the given data, since it only contain 109 records. The model M5 contains 413 samples, and the correct ratio for training data and testing data are 88.5% and 90% respectively. By compared with the square of the weight of the input layer for each network, the importance order of the input parameters should be qc,M,σ′0,σ0,a / g,τ / σ′0 and D50.

Probabilistic estimation of sand liquefaction based on neural network model of radial basis function

Abstract: Based on the 344 liquefaction data of the twenty-five strong earthquakes in the world,through training and testing the neural network model of Radial Basis Function(RBF),the nonlinear relation between corrected blow count N1 of standard penetration test and cyclic resistance ratio CRR of saturated sand was analyzed,and empirical equation CRRcri of liquefaction limit state curve or critical cyclic resistance ratio curve of saturated sand was also constructedBy statistic analysis,probability density functions of liquefaction and non-liquefaction cases as well as empirical equation between safety factor and liquefaction probability of saturated sands were given,then the empirical equation of cyclic resistance ratio CRR of saturated sands with different probability level was educedWhen liquefaction probability level was equal to 50%,the present method was consistent to traditional deterministic method of sand liquefaction estimation,and its reliability for liquefaction and non-liquefaction estimation of saturated sands was 904% and 812%,respectivelyThe method made the sand liquefaction probabilistic estimation of engineering site as easy and convenient as traditional deterministic method of sand liquefaction estimationSo it was possible that the method of sand liquefaction probability estimation would be applied in the engineering practice and adopted in codes for seismic design

Evaluation of modulus of subgrade reaction (K s ) in gravely soils based on SPT results

Abstract: The modulus of subgrade reaction is a conceptual relationship between soil pressure and deflection that is widely used in the structural analysis of foundation members. It is used for continues footings, mats and various types of piling. In practical and realistic terms, carrying out in-situ plate bearing tests or relating it in someway to intrinsic deformation characteristics of the soil can find 'Ks'. The plate load test is widely used and it fully described in ASTM D1194. Values of 'Ks' may also be assessed by relating them to the intrinsic parameters of the soil such as elastic modulus (E s ) and California bearing ratio (CBR) (Vesic, 1961, Bowels, 1997). 'E s ' can be derived from the results of triaxial tests. An approximate, empirical relationship between the modulus of subgrade reaction (K s ) and California bearing ratio (CBR) are presented. The standard penetration test is currently the most popular and economical means to obtain subsurface information. The SPT results have been used in correlations for unit weight (γ), relative density (Dr), angle of internal friction φ, and undrained compressive strength qu. It has also been used to estimate the bearing capacity of foundations and for estimating the stress-strain modulus 'Es'. In this paper the results of SPT and PLT tests on gravely soils of Tehran alluvium are evaluated. Due to the results obtained the correlation between SPT results (N1) 60 and modulus of subgrade reaction (Ks) are also presented for gravely soils. The complete data base including SPT and PLT test results and graphical correlations will be included in the main version of the paper.

Site amplification and liquefaction studies for bangalore city

Abstract: The objective of this paper is to find the response of soil overburden for Bangalore City for the Maximum Credible Earthquake (MCE) having a magnitude of 5.1 with a peak ground acceleration of 0.153g (Sitharam and Anbazhagan, 2006) and to ascertain its amplification and liquefaction potential. In order to determine the ground response using a one-dimensional approach, several input parameters including soil profile, bedrock level and other geotechnical properties of the subsurface and the design earthquake are required. Using the collected Standard Penetration Test (SPT) data along with the available geotechnical information and synthetically generated ground motion, equivalent linear analysis was performed using the computer program SHAKE-2000. For the selected bore holes, the soil profile fundamental period, peak acceleration, and ground response spectrum at the surface are reported. Liquefaction study was done using simplified Seed and Idriss approach by considering the amplified PGA at the ground surface. The result of the cyclic triaxial test conducted on undisturbed samples from some of the sites confirmed the results of Seed and Idriss approach. This procedure is repeated for other boreholes and an attempt is being made to develop seismic microzonation map for Bangalore City.

Determination of slity soil bearing capacity on modern yellow river delta in china

Abstract: The slity soil on the modern Yellow River Delta is the fine sediment which has been rapidly accumulated since the Yellow River divagated into Bohai Sea in 1855.The coverage area is about 5 000 km2.It almost covers Shengli Oil Field in Dongying City,Shandong Province.Four groups of site contrast tests are chosen to conduct the systematic site soil tests including the plate load test,spire plate load test,flat dilatometer test,standard penetration test and static cone penetration test.The characteristic values of the bearing capacity of the fine sediment that has been rapidly accumulated recently in entrance of Yellow River are studied according to the analysis of the site test and the laboratory test.The difference between the characteristic values of the bearing capacities that are confirmed by different methods is systematically contrasted.Moreover,the regression equations between specific penetration resistance Ps,blow counts of standard penetration test N,water content w and porosity ration e and the characteristic value of bearing capacity fk are built according to the bearing capacity that is confirmed by the plate load test.The research can provide scientific references to determine the characteristic value of the bearing capacity of the slity soil on the modern Yellow River Delta.

Experimental investigation of bearing capacity of highway loess foundations

Abstract: In the representative area of loess in the northwestern part of China, three typical highway foundation projects were selected to conduct experimental investigations on the bearing capacity of the subgrade soil. The three highway projects were the Can-Liu highway project in Gansu province, the Da-Yun highway project in Shanxi province, and the Yan-Yu highway project in Shanxi province. Each selected experimental site represented the properties of certain typical loess soils. According to in-situ tests (loading test, pressuremeter test and penetration test) conducted at the different test sites and related laboratory tests, the methods of determining bearing capacity for the subgrade soil in the loess area are discussed. Based on the investigation results and the property of the highway foundation engineering, this paper concludes that the bearing capacity of the subgrade soil in loess areas can be determined by pre-drilling pressuremeter tests instead of field loading tests under a restricted condition. On the other hand, the bearing capacities determined by penetration testing and laboratory testing can also be confirmed. With the development of northwestern part of China and construction of a national road net, more and more highway construction is to be made in the extensive areas of loess. With the effect of weathering, gulches are well developed in the loess area and many difficulties were encountered in excavation and filling (up to 70m) activities. Therefore it is important to evaluate the bearing capacity of subsoil in the area of loess. In some organisational divisions such as architecture and water conservancy, the engineers usually estimate the bearing capacity of subsoil by means of load test, cone penetration test (CPT), dynamic penetration test (DPT), standard penetration test (SPT), or pre-drilling pressuremeter test. Among the in situ tests, the load test is a fundamental method as its results are of high accuracy. But in linear construction, it is not convenient to estimate the bearing capacity of subsoil by means of load testing. So in road engineering, it is necessary to choose a practical in situ test to allow estimation of the bearing capacity of subsoil by comparing load test to other in situ tests. In the representative area of loess in the northwestern part of China, three typical highway foundation projects were selected to conduct experimental investigations on the bearing capacity of the subgrade soil in this paper. The three highway projects were the Can-Liu highway project in Gansu province, the Da-Yun highway project in Shanxi province, and the Yan-Yu highway project in Shanxi province. Among the three typical highway foundation projects, four test sites were selected. Four test sites were the Can-Liu test site (CL), the Da-Yun test site (DY), the Yan-Yu1 test site on the first-order terrace (YY1), and the Yan-Yu2 test site on the second-order terrace (YY2). At each test site, the evaluation of the bearing capacity of the subgrade soil was considered by means of in situ tests (load test, pre- drilling pressuremeter test, CPT, DPT and SPT) and related laboratory tests. SUMMARY

Multi-Method Strength Characterization for Soft Cretaceous Rocks in Texas

Abstract: Modern methods for designing drilled shafts, ACIP piles and similar foundations in soft rock require knowledge of the compressive strength and modulus of the rock. However, jointing at many sites prohibits the recovery of samples of sufficient length and integrity to test rock cores in either unconfined or triaxial compression. Since rational design procedures usually require values of compressive strength, surrogate methods must be employed to estimate the compressive strength of the rock. The surrogate methods considered here is the Texas cone penetrometer test (in which a 76-mm-diameter solid steel cone is driven into rock at the bottom of a borehole in much the same way as a split spoon is driven during the performance of a standard penetration test in cohesionless soil). An other issue during deep foundation construction is essential to locate the a rock stratum, especially when drilling with slurry, in which the bottom of the borehole cannot be observed and the cuttings may be so disturbed that overburden soil cuttings cannot be easily distinguished from cuttings in soft rock. Hence, a new static rock penetrometer was developed based on the concept of the pocket penetrometer, which has been used by field geotechnical boring loggers for many years. Soft rock formations typical of those for which such substitutions might be used are the upper Cretaceous formations of North central Texas, including the clay shale and limestone formations. The correlations between compressive strength and the Texas cone penetrometer test are formation-dependent, most likely through the degree of cementation present in the geomaterial. Also, the performance of the static penetrometer was verified in the field in boreholes that were drilled at the test sites in North central Texas. The readings at these sites, together with the values of q u measured using cores taken from the same elevation as the penetrometer test and Texas cone penetrometer resistance values at the same elevation in nearby boreholes. The readings were all made in open boreholes, not under slurry. Based on test results, a static rock penetrometer reading between score marks B and C (B-C) is indicative of soft, sound clay shale, and a reading of C or higher is indicative of sound limestone or sound, hard clay shale. Readings of B, A-B and A are indicative of overburden materials.

Correlation Analyses between Shear Wave Velocity and Ground Properties of Kunming Basin

Abstract: According to large amounts of in situ P-S logging data, the relationship between shear wave velocity and other physical properties of the clayey and sandy soils in the quaternary formation of Kunming Basin are summarized. With the aid of linear and non-linear correlation analyses, the regression equation of shear wave velocity and the standard penetration test N value (SPT-N value) are given here. The influence of ground depth to the shear wave velocity is discussed and the trend of shear wave velocity with the depth is also clarified.

Interpolation Methods and Neural Networks Applied to Geotechnical Mapping of a Brazilian Port Site

Abstract: Soil proprieties are typically determined from a limited number of in situ or laboratory tests performed at a specific site. The results of these tests may be used to estimate soil properties of the whole site by means interpolation techniques such as linear, polynomial, statistical or machine learning methods. In this paper, a Standard Penetration Test (SPT) database from the port of Navegantes, south Brazil, is used for analysis. Geotechnical mapping of SPT blow counts is made using classical interpolation methods and the neural networks technique, and their performance compared.