Showing papers on "Standard penetration test published in 2008"

In Situ Testing in Geomechanics: The Main Tests

Abstract: Foreword Preface Acknowledgements List of symbols Introduction General considerations Codes of practice Interpretation methods Scope and purposes Standard penetration test (SPT) General considerations Standards and procedures Wave propagation analysis Measurements and corrections Characterization and classification Soil properties in granular materials Soil properties in cohesive materials Soil properties in bonded soils Soil properties in weak rock Direct design methods Soil liquefaction Concluding remarks Notes Piezocone penetration test (CPTU) Equipment and procedures New developments Specifications and standards Test results Soil classification Interpretation methods Soil properties in cohesive materials Granular soils Properties in silty soils Properties in bonded geomaterials Pile bearing capacity Liquefaction Notes Vane test General considerations Equipment and procedures Interpretation Shear strength Stress history Notes Pressuremeter tests General considerations Types of instruments Calibration procedures Experimental results Analysis of pressuremeter tests Pressuremeter tests in sand Cone pressuremeter tests in clay and sand Pressuremeter tests in cohesive-frictional soils Pressuremeter tests in unsaturated soil conditions Design rules Flat dilatometer test (DMT) General considerations Equipment and procedures Intermediate DMT parameters Interpretation of test results Soil characterization Geotechnical parameters in clay Geotechnical parameters in sand Direct applications Design parameters: guidelines Clay Sand 282 Residual soils Stiffness References and further reading Index

Mapping of Average Shear Wave Velocity for Bangalore Region: A Case Study

Abstract: Mapping the shear wave velocity profile is an important part in seismic hazard and microzonation studies. The shear wave velocity of soil in the city of Bangalore was mapped using the Multichannel Analysis of Surface Wave (MASW) technique. An empirical relationship was found between the Standard Penetration Test (SPT) corrected N value ((N1)60cs) and measured shear wave velocity (Vs). The survey points were selected in such a way that the results represent the entire Bangalore region, covering an area of 220 km2. Fifty-eight 1-D and 20 2-D MASW surveys were performed and their velocity profiles determined. The average shear wave velocity of Bangalore soils was evaluated for depths of 5 m, 10 m, 15 m, 20 m, 25 m and 30 m. The sub-soil classification was made for seismic local site effect evaluation based on average shear wave velocity of 30-m depth (Vs30) of sites using the National Earthquake Hazards Reduction Program (NEHRP) and International Building Code (IBC) classification. Mapping clearly indicates that the depth of soil obtained from MASW closely matches with the soil layers identified in SPT bore holes. Estimation of local site effects for an earthquake requires knowledge of the dynamic properties of soil, which is usually expressed in terms of shear wave velocity. Hence, to make use of abundant SPT data available on many geotechnical projects in Bangalore, an attempt was made to develop a relationship between Vs (m/s) and (N1)60cs. The measured shear wave velocity at 38 locations close to SPT boreholes was used to generate the correlation between the corrected N values and shear wave velocity. A power fit model correlation was developed with a regression coefficient (R2) of 0.84. This relationship between shear wave velocity and corrected SPT N values correlates well with the Japan Road Association equations.

Seismic microzonation of Bangalore, India

Abstract: In the present study, an attempt has been made to evaluate the seismic hazard considering local site effects by carrying out detailed geotechnical and geophysical site characterization in Bangalore, India to develop microzonation maps. An area of 220 km2, encompassing Bangalore Mahanagara Palike (BMP) has been chosen as the study area. Seismic hazard analysis and microzonation of Bangalore are addressed in three parts: in the first part, estimation of seismic hazard is done using seismotectonic and geological information. Second part deals with site characterization using geotechnical and shallow geophysical techniques. In the last part, local site effects are assessed by carrying out one-dimensional (1-D) ground response analysis (using the program SHAKE2000) using both standard penetration test (SPT) data and shear wave velocity data from multichannel analysis of surface wave (MASW) survey. Further, field experiments using microtremor studies have also been carried out for evaluation of predominant frequency of the soil columns. The same has been assessed using 1-D ground response analysis and compared with microtremor results. Further, the Seed and Idriss simplified approach has been adopted to evaluate the soil liquefaction susceptibility and liquefaction resistance assessment. Microzonation maps have been prepared with a scale of 1:20,000. The detailed methodology, along with experimental details, collated data, results and maps are presented in this paper.

Seismic Microzonation: Principles,Practices and Experiments

Abstract: This paper presents an overview of the seismic microzonation and the grade/level based study along with methods used for estimating hazard. The principles of seismic microzonation along with some current practices are discussed. Summary of seismic microzonation experiments carried out in India is presented. A detailed work of seismic microzonation of Bangalore has been presented as a case study. In this case study, a seismotectonic map for microzonation area has been developed covering 350 km radius around Bangalore, India using seismicity and seismotectonic parameters of the region. For seismic microzonation Bangalore Mahanagar Palike (BMP) area of 220 km2 has been selected as the study area. Seismic hazard analysis has been carried out using deterministic as well as probabilistic approaches. Synthetic ground motion at 653 locations, recurrence relation and peak ground acceleration maps at rock level have been generated. A detailed site characterization has been carried out using borehole with standard penetration test (SPT) ―N‖ values and geophysical data. The base map and 3-dimensional sub surface borehole model has been generated for study area using geographical information system (GIS). Multichannel analysis of surface wave (MASW)method has been used to generate one-dimensional shear wave velocity profile at 58 locations and two- dimensional profile at 20 locations. These shear wave velocities are used to estimate equivalent shear wave velocity in the study area at every 5m intervals up to a depth of 30m. Because of wider variation in the rock depth, equivalent shear for the soil overburden thickness alone has been estimated and mapped using ArcGIS 9.2. Based on equivalent shear wave velocity of soil overburden thickness, the study area is classified as ―site class D‖. Site response study has been carried out using geotechnical properties and synthetic ground motions with program SHAKE2000.The soil in the study area is classified as soil with moderate amplification potential. Site response results obtained using standard penetration test (SPT) ―N‖ values and shear wave velocity are compared, it is found that the results based on shear wave velocity is lower than the results based on SPT ―N‖ values. Further, predominant frequency of soil column has been estimated based on ambient noise survey measurements using instruments of L4-3D short period sensors equipped with Reftek 24 bit digital acquisition systems. Predominant frequency obtained from site response study is compared with ambient noise survey. In general, predominant frequencies in the study area vary from 3Hz to 12Hz. Due to flat terrain in the study area, the induced effect of land slide possibility is considered to be remote. However, induced effect of liquefaction hazard has been estimated and mapped. Finally, by integrating the above hazard parameters two hazard index maps have been developed using Analytic Hierarchy Process (AHP) on GIS platform. One map is based on deterministic hazard analysis and other map is based on probabilistic hazard analysis. Finally, a general guideline is proposed by bringing out the advantages and disadvantages of different approaches.

Relationship between the standard penetration test and the pressuremeter test on sandy silty clays: a case study from Denizli

Abstract: The standard penetration test (SPT) is the in situ test most commonly used to investigate the properties of silt, clay, sand and fine gravel. The Menard pressuremeter test (PMT) can be utilized to obtain the strength and deformation properties of any soil or weak rock. The study investigated the relationship between the corrected SPT blow count (N cor) and the PMT parameters of elastic modulus (E m) and limit pressure (p L). It is concluded that for the soils tested, E m and p L can be estimated as a function of N cor values, with r = 0.91 and 0.97, respectively.

Bearing capacity of driven piles in sands from spt–applied to 60 case histories

Abstract: In recent years determining bearing capacity of piles from in-situ testing data as a complement of static and dynamic analysis has been used by geotechnical engineers. In this paper, different approaches for estimating the bearing capacity of piles from SPT data have been explained and compared. A new method based on the N-value from SPT is presented and calibrated. Data averaging, failure zone extension, and plunging failure of piles has been noticed in the proposed approach. A data base has been compiled including 43 full scale static pile load tests and 17 dynamic testings which were analyzed with the signal matching technique by CAPWAP. The SPT data were performed close to pile locations are also included in the data base. A comparison of current methods by error investigation with cumulative probability and Log-Normal approaches demonstrates that the proposed method predicts pile capacity with more accuracy and less scatter than other methods. Results of prediction with good agreement to measured capacities indicate that the proposed method can be used as an alternative for determining the bearing capacity of piles in geotechnical practice. Keywords– Pile, bearing capacity, standard penetration test, SPT, static and dynamic load tests

Stochastic modeling of spt n-value and evaluation of probability of liquefaction at guwahati city

Abstract: Standard penetration test (SPT) reveals the spatial complexity of standard penetration resistance (N-value) with depth. In this paper, a 1D stochastic characterization of spatial complexity of N-values is developed by considering data obtained from sixty two boreholes in Guwahati City. The N-value profile is modeled as the sum of deterministic part and a stochastic component. The deterministic part which characterizes the non-stationary mean of the data is determined by linear regression analysis. The remaining error is modeled as a spatial random field. The characterization of error heterogeneity as a homogeneous Gaussian random field successfully captures the observed auto-correlation function. The proposed stochastic model is used to compute the probability of factor of safety against liquefaction by Monte-Carlo simulation. The results obtained are presented in form of fragility surfaces, expressing the probability of liquefaction as a function of magnitude of the earthquake and epicentral distance. It is observed that the probability of liquefaction at Guwahati city due to strong earthquakes occurring even at large distances is very high.

Estimating Shear Strength Properties of Soils Using SPT Blow Counts: An Energy Balance Approach

Abstract: The subsurface exploration of a site is often the aspect of a project that gets overlooked during the design process. Many clients will get standard soil borings, but do not want to pay for a full laboratory analysis. Lack of data forces the designer to estimate important engineering properties of the soil. Very often the Standard Penetration Test (SPT) blow counts are used to estimate the shear strength properties of soil in foundation designs. Few correlations are widely used. However, no clear explanation is found to justify the selection most of these mathematical equations. This manuscript describes a new approach to estimate the shear strength parameters based on the SPT blow counts. In this method, the standard penetration test is treated analogous to driving a miniature pipe pile. The energy input to the soil is used to correlate the SPT blow count to the shear strength parameters of the soil at the depth of testing. Soil boring records from few different sites were analyzed and a statistical analysis revealed that the proposed method can provide a better estimation than the widely used existing correlations.

Tangent modulus correcting method for non-linear sedimentation computation of foundation

Abstract: A revised equation for tangent modulus of the foundation soil of a certain soil layer is obtained by making use of load test result which is subject to hyperbolic curve fitting. The equation is as follows: EI equals to (1-Beta bpz) E0/Beta or EI equals to (1-Beta Rf/pzpu) E0/Beta. Next, the revised tangent modulus of each stratified soil in different depth of the soil layer is determined according to a standard penetration test or other in situ testing the test parameters of which are assumed according to linear dependence relation; finally, the results of the nonlinearity sedimentation of large-area foundation or the base are obtained according to a layerwise summation method. The method is characterized in that the invention can make analysis of the whole process of the nonlinearity sedimentation to the limit state, the calculation principle is simple, calculation parameter source is reliable, subsidiary stress is revised according to the test result of plate loading test and the calculating result is accurate; the invention can be widely used in the design of various foundation engineering with the aim of settlement control in civil engineering field.

Characterization and Geotechnical Properties of Piedmont Residual Soils

Abstract: In this paper, characterization and geotechnical properties of Piedmont residual soils are presented for two research sites located at the Carolina slate and Charlotte belts of North Carolina. Similar to most other residual soils, the index and geotechnical properties of the Piedmont residual soils are highly variable. Site investigations were conducted at the test sites using standard penetration test (SPT) and borehole shear test (BST). Also, a series of laboratory tests were performed to obtain consolidated undrained (CU) triaxial strengths and index properties of the soils. By comparing the CU strength of the soils to the borehole shear data at known moisture contents, the strength properties attributable to degree of saturation or suction were estimated.

The Analysis of Composite Foundation with CFG and Gravel Piles to Resist Soil Liquefaction

Abstract: Based on a practical engineering project (in Inner Mongolia), which uses composite foundation with CFG & gravel piles to deal with the soil liquefaction, the composite foundation’s capacity and function mechanism are analyzed in the paper. And the design, construction effect and test results of the composite foundation are also discussed. The test results presented in the paper can be applied to the similar projects in the region of Inner Mongolia. These include the experimental parameters of the composite foundation, the test results of the carrying capacity of single pile vertical static load and heavy dynamic touch test, the test results of the pile’s quality affected by low stain dynamic test and the test results of standard penetration experiment. The following conclusions can be reached from the analysis of the test results mentioned above: (1) That the engineering project involved in the paper has gotten good reinforcement effect shows that the application of the composite foundation to resisting soil liquefaction is successful, which sets an example for widely application of the composite foundation with CFG and gravel piles to treating the soil liquefaction of foundations; (2) The composite foundation with CFG and gravel piles has the functions of quickening up the soil’s drainage and consolidation; and (3) During the construction of the composite foundation, the dynamical load and the shock absorption function of the piles can increase soil’s density, and thereby abate or clear up soil liquefaction.

Soil Improvement for Damage Mitigation Along Izmit Bay During the 1999 Kocaeli Earthquake

Abstract: Ground treatment has been widely used to mitigate earthquake damages at poor soil sites. Following the 1999 Kocaeli Earthquake in Turkey (MW=7.4), we studied the performance of industrial and commercial sites along Izmit Bay that had been improved. Soil conditions along the Bay consist of soft, weak soils that increase damage potential. Four sites presented here showed that soil treatment was effective in mitigating damage.

Evaluation of liquefaction of sandy soils based on cone penetration test

Abstract: Soil liquefaction is a major concern for structures constructed on sandy and silty sites.Soil liquefaction is also a major design issue for large structures such as mine tailings impoundments and earth dams.Therefore,liquefaction evaluation plays an important role in seismic investigation and design of buildings.It is important to determine the soil stratigraphy and in-situ soil state for soil liquefaction.Because of the difficulty and cost constraint of obtaining high-quality undisturbed sand samples,the in-situ test is a perfect method to evaluate the potential for soil liquefaction.At present,numerous methods based on the cone penetration test(CPT) data have been developed for evaluating the potential of soil liquefaction,but the validity is still confused.As a new kind of in-situ test,the piezocone penetration test(CPTU),is receiving increasing attention for assessing the soil liquefaction potential because of its repeatability,reliability,continuous data tracing and cost effectiveness.The methods for evaluating liquefaction potential of soils using in-situ tests are reviewed based on the precious works.Two comprehensive CPTU-based methods for assessing liquefaction resistance of sandy soils are evaluated and compared on the basis of data collected on nine sites in Jining—Xuzhou Expressway,where the actual field performances against liquefaction from CPT data are used as referenced data.It is shown that Robertson method and Olsen method are considered to be fairly accurate in predicting liquefaction resistance of sandy soils.The Robertson method is slightly more accurate than the Olsen method.

Intepretation of CPTU results in terms of soil design parameters at Satnica Djakovacka, Croatia

Abstract: A well-documented case history on the use of CPTU and SPT data is summarised. Over 2000m length of soil was interpreted using cone penetration tests with pore pressure measurement (CPTU) during extensive geotechnical investigations as performed for the design of the Corridor Vc motorway which, on its section through Slavonia, connects the Republic of Croatia with Hungary in the north, and with Bosnia and Herzegovina in the south. An attempt to correlate cone penetration test (CPTU) and standard penetration test (SPT) results is presented herein.The testingwas performed in overconsolidated silty clay formation in order to estimate physical and mechanical properties of the soil. In a specific site near Djakovo in Slavonia (Croatia) the CPTU and SPT were performed. CPTU results were interpreted based on results obtained by laboratory testing of undisturbed samples extracted from the borehole drilled 2m away from the CPTU test location. The properties are estimated using appropriate empirical CPTU correlations which have been successfully adapted to local conditions.

Liquefaction Potential of Inorganic and Organic Silts

Abstract: Although Rhode Island is not considered to be a region of high seismicity, by code the liquefaction potential of soil during an earthquake must still be considered in the design of certain highway structures. There is some debate in local engineering practice whether the silty soils that are commonly encountered in Rhode Island are susceptible to liquefaction. These soils are typically characterized as either inorganic silts or organic silts and are sometimes found in a loose condition in the field. The current standard of practice for evaluating liquefaction potential uses in situ tests such as the standard penetration test and engineering correlations, which were developed primarily from tests in sands. Because of this, there is still considerable uncertainty about the dynamic behavior of the Rhode Island silts. This report presents a laboratory study on the liquefaction potential of silts from Rhode Island. This study included a field sampling program consisting of piston and block sampling and an assessment of sample disturbance. It was not possible to obtain high quality samples of either the inorganic or organic silts using either commonly used drilling and sampling techniques or a state-of-the-art piston sampler. A modified moist tamping method was developed to reconstitute samples of inorganic silt for cyclic triaxial testing, and it is shown that the results of the reconstituted samples compare well to the block samples and samples prepared from a slurry. It is believed that the modified moist tamping method captures the in situ fabric of the silt and can be used in place of undisturbed samples for estimating the onset of liquefaction of these soils. Cyclic resistance curves are presented for inorganic silts from the Olneyville neighborhood of Providence and Wellington Avenue in Cranston, and for organic silt from Quonset Point. The relationship between the cyclic resistance of these soils and in situ test results are presented in a subsequent report.

Shear Wave Velocity Profiling and Liquefaction Hazard Analysis

Abstract: Only a few states in the nation have areas with higher earthquake design acceleration coefficients than Northeast Arkansas. The area is prone to damage from earthquakes in the New Madrid seismic zone (NMSZ). The American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specification indicates the “liquefaction of foundation soil (has) contributed to much of the damage” to bridges in earthquakes. The code suggests that site-specific studies be performed at bridge locations to evaluate liquefaction hazards. It is well established that in-situ shear wave velocity (Vs) profiles of the subsurface, to a depth of at least 30-meters, are necessary for a site-specific seismic ground response analysis. Furthermore, site-specific Vs profiles can be used as a screening tool to evaluate the depth and thickness of potentially liquefiable soil layers. The objective of this research, as set forth by the State of Arkansas Highway and Transportation Department (AHTD), was to obtain site-specific Vs profiles to depths of at least 30-meters at selected bridge locations in Northeast Arkansas. These bridges shall be considered as either “critical” or “essential” according to AASHTO, and were to be chosen in consultation with the AHTD. The Vs profiles were to be used to determine the soil liquefaction potential at each bridge location using a “Simplified Shear Wave Velocity Procedure”. These Vs liquefaction evaluations were then to be compared with Standard Penetration Test (SPT) liquefaction evaluation procedures using blow count (N) and grain size distribution data already available from the AHTD.

A Comparison Of Shear Wave Velocities Obtained From The Crosshole Seismic, Spectral Analysis Of Surface Waves And Multiple Impacts Of Surface Waves Methods

Abstract: Presented herein is the comparison of the shear wave velocity results, with respect to depth, obtained from three separate test methods at a soil test site. The Crosshole Seismic (CS) test was performed utilizing three cased boreholes nominally 10 feet apart. The direct shear wave velocity was obtained from the results of the CS test. The Spectral Analysis of Surface Waves (SASW) test method and Multiple Impact of Surface Waves (MISW) test method were also performed at the same test site for comparison purposes. Neither the SASW nor MISW test methods require the installation of boreholes, thus reducing the cost of the test. SASW and MISW differ slightly from one another in the equipment used, method of data collection, and differ significantly in data processing. This paper includes a comparison and discussion of the test results, as well as backgrounds of each test method. Introduction Construction of foundation systems for civil structures often requires detailed information of the site soil properties. Bore logs provide soil samples for soil type classification and laboratory testing to determine strength and consolidation parameters among other properties with respect to depth. A number of soil-boring related in-situ tests have also been correlated with soil strength (e.g. standard penetration test, cone penetration test), however in the interest of accuracy it is certainly advantageous to measure a in-situ soil property directly related to soil modulus. Shear wave velocity (Vs) has become the standard property from which in-situ soil modulus is determined due to its direct relationship with modulus via the soil mass density (which can be assumed with little error or easily measured from soil samples) as well as it’s relative ease of measurement, due to the advancement of seismic techniques. A number of in-situ test methods have been developed to measure Vs with respect to depth; within this paper, three methods, Crosshole Seismic (CS), Spectral Analysis of Surface Waves (SASW), and Multiple Impact of Surface Waves (MISW), will be described and compared. Traditionally, CS testing has been considered the most accurate method in determining Vs, because it is a direct measurement of the wave speed. SASW and MISW however, can be employed much more rapidly and economically because the methods are performed on the ground surface (unlike CS where at least two boreholes are required to perform the testing). Yet, no known research has been performed to directly compare the accuracy of the latter two methods to equivalent CS results. With this objective, all three tests were performed at the same soil site for direct data comparison.

Discussion of The Standard Penetration Test

Abstract: (Originally published in Proc. of the Fourth Panamerican Conference on Soil Mechanics and Foundation Engineering , ASCE, San Juan, Puerto Rico,1971. 90-99.)

Study on Correlation Between Shear Wave Velocity and Ground Properties for Ground Liquefaction Investigation of Silts

Abstract: Shear wave velocity (Vs) of soil is one of the key parameters used in assessment of liquefaction potential of saturated soils in the base with leveled ground surface; determination of shear module of soils used in seismic response analyses. Such parameter can be experimentally obtained from laboratory soil tests and field measurements. Statistical relation of shear wave velocity with soil properties based on the surface wave survey investigation, and resonant column triaxial tests, which are taken from more than 14 sites within the depth of 10 m under ground surface, is obtained in Tianjin (China) area. The relationship between shear wave velocity and the standard penetration test N value (SPT-N value) of silt and clay in the quaternary formation are summarized. It is an important problem to research the effect of shear wave velocity on liquefaction resistance of saturated silts (sandy loams) for evaluating liquefaction resistance. According the results of cyclic triaxial tests, a correlation between liquefaction resistance and shear wave velocity is presented. The results are useful for ground liquefaction investigation and the evaluation of liquefaction resistance.

Penetration-type Bender Element Probe for Stiffness Measurements of Soft Soils

Abstract: Ground stiffness(shear wave velocity) is one of the key parameters in geotechnical earthquake engineering. An In-situ seismic technique has its own advantages and disadvantages over the others in stiffness measurements. By combining the crosshole and seismic cone techniques and utilizing favourable features of bender elements, a new hybrid probe has been developed in order to enhance data quality and easiness of testing. The basic structure of the probe, called "MudFork" is a fork composed of two blades, on each of which source and receiver bender elements were mounted respectively. To evaluate the disturbance caused by the penetration of the probe, shear wave velocity measurements were carried out in the Kaolinite slurry in the laboratory. Finally, the probe was penetrated in coastal mud near Incheon, Korea, using SPT(standard penetration test)rods pushed with a routine boring machine and shear wave velocity measurements were carried out. The results were verified with data from laboratory and cone testing. The performance of the probe turns out to be excellent in terms of data quality and testing convenience.

Seismic and Geotechnical Site Characterizations at Four Earthquake Strong Motion Sites in Washington State

Abstract: As part of on going program for generating maps addressing geologic site effects in Washington, the Washington State Department of Natural Resources (DNR), Division of Geology and Earth Resources (DGER) drilled 30-meter-deep geotechnical boreholes at four strong-motion sites operated by the Pacific Northwest Seismic Network (PNSN). Invasive (soil sampling, Standard Penetration Test (SPT) and downhole seismic) and noninvasive (Multichannel Analysis of Surface Waves, (MASW)) methods were used to determine shear-wave velocity profiles, specifically for the top 100 feet of soil column, at each of these strong motion sites. The boreholes were logged for visual soil classification and SPTs, and selected soil samples were tested in the laboratory to obtain plasticity and gradation values. In addition, S-and P-waves generated at the surface were received by a 3-component geophone placed at 1-m intervals in each borehole. Then the borehole sites were later surveyed by using MASW method to estimate the Vs profiles at each borehole site. The MASW survey shows a very good correlation with the downhole S-velocity profiles. SPT blow counts are consistent with soil conditions in the Puget Sound area. Site classes E, D-E, D, C-D and C, as described in the International Building Codes (IBC 2006), were determined by using average shear-wave velocities and SPT blow count values to 30 meters (~100 feet) of soil column of the four boreholes. An updateable geospatial database incorporating shear-wave data and velocities, borehole geotechnical information (soil samples and their laboratory tests, SPT blow counts, etc.) will be generated and periodically updated. This database will directly be available through the DGER‘s interactive mapping service for end users such as federal and local government agencies, urban planning and emergency response groups and seismic networks, such as PNSN.