Standard Penetration Test Blow Counts Research Articles

CORRELATION BETWEEN SPT AND PMT RESULTS FOR SANDY AND CLAYEY SOILS

Determination of soil deformation and strength properties is of great importance in geotechnical design. The disturbance that occurred during the sampling from the field affects the results obtained by the laboratory tests. Therefore, the lack of representation of the field conditions and in-situ soil features with laboratory tests leads the designers to carry out field tests. Standard penetration test (SPT) and the Menard pressuremeter test (PMT) are the most widely used geotechnical field tests in which the results are utilized to investigate soil properties and lateral deformation characteristics at a specified depth. In this study, a total of 102 data of sandy and clayey soils belonging to the geotechnical investigations carried out in Istanbul were compiled. The regression analysis between the corrected SPT blow count N60, pressuremeter modulus EPMT, limit pressure PL and EPMT/PL ratio is performed. Empirical equations were separately developed for sandy and clayey soils between the considered parameters. The developed equations showed that there are acceptable relationships between the parameters examined in the particular dataset. Moreover, a neural network (NN) based prediction model was developed to predict EPMT and PL using the available soil data. The highly accurate prediction performance of the proposed model demonstrated the availability of modern methods for the estimation of soil parameters.

A Simple and Sustainable Prediction Method of Liquefaction-Induced Settlement at Pohang Using an Artificial Neural Network

Conventionally, liquefaction-induced settlements have been predicted through numerical or analytical methods. In this study, a machine learning approach for predicting the liquefaction-induced settlement at Pohang was investigated. In particular, we examined the potential of an artificial neural network (ANN) algorithm to predict the earthquake-induced settlement at Pohang on the basis of standard penetration test (SPT) data. The performance of two ANN models for settlement prediction was studied and compared in terms of the R2 correlation. Model 1 (input parameters: unit weight, corrected SPT blow count, and cyclic stress ratio (CSR)) showed higher prediction accuracy than model 2 (input parameters: depth of the soil layer, corrected SPT blow count, and the CSR), and the difference in the R2 correlation between the models was about 0.12. Subsequently, an optimal ANN model was used to develop a simple predictive model equation, which was implemented using a matrix formulation. Finally, the liquefaction-induced settlement chart based on the predictive model equation was proposed, and the applicability of the chart was verified by comparing it with the interferometric synthetic aperture radar (InSAR) image.

Prediction of Pile Axial Bearing Capacity Using Artificial Neural Network and Random Forest

Axial bearing capacity of piles is the most important parameter in pile foundation design. In this paper, artificial neural network (ANN) and random forest (RF) algorithms were utilized to predict the ultimate axial bearing capacity of driven piles. An unprecedented database containing 2314 driven pile static load test reports were gathered, including the pile diameter, length of pile segments, natural ground elevation, pile top elevation, guide pile segment stop driving elevation, pile tip elevation, average standard penetration test (SPT) value along the embedded length of pile, and average SPT blow counts at the tip of pile as input variables, whereas the ultimate load on pile top was considered as output variable. The dataset was divided into the training (70%) and testing (30%) parts for the construction and validation phases, respectively. Various error criteria, namely mean absolute error (MAE), root mean squared error (RMSE), and the coefficient of determination (R2) were used to evaluate the performance of RF and ANN algorithms. In addition, the predicted results of pile load tests were compared with five empirical equations derived from the literature and with classical multi-variable regression. The results showed that RF outperformed ANN and other methods. Sensitivity analysis was conducted to reveal that the average SPT value and pile tip elevation were the most important factors in predicting the axial bearing capacity of piles.

Evaluation of Liquefaction Potential of Soil at a Power Plant Site in Chittagong, Bangladesh

This study presents an evaluation of liquefaction potential for combined cycle power plant site located in the Chittagong district, Bangladesh, using standard penetration test blow counts (SPT-N values). The peak ground acceleration (PGA) values at a bedrock level were estimated deterministically using both linear and point source models as well as different ground motion prediction equations (GMPEs). The surface level hazard was estimated using amplification factors for the soil conditions present and the response spectrum at the center of the plant site was plotted. The liquefaction potential for the site was arrived at by using the SPT-N values of 33 boreholes in the site and at every 3-meter interval from the ground level to a depth of 30 meters. The results from the LPI contours at successive depths indicate that in the majority of the borehole locations, the soil up to 15 meters depth had a significant hazard of liquefaction. These findings from the present study can prove to be crucial from the structural point of view, for any future construction activities in the area.

Effects of grain shape on the standard penetration test and particle packing

Coarse soils can contain flaky grains in addition to rounded or angular grains, along with a varying fines content. Depending on the regional geology, however, the mica grain content can be remarkable, reaching 30 % or higher. Therefore, it is reasonable to expect that mica grains would affect the soil behaviour. In this study, soils of a delta deposit that are known to involve mica grains were examined. The river sand was considered as the host material and the mica grain contents were determined by means of the flotation technique. A correlation between the mica content as found using the flotation technique and XRD count numbers obtained using an X-ray diffraction test method for each soil sample was established. The standard penetration test (SPT) blow counts from various boreholes were interpreted from the mica content’s influence point of view. The results showed that the mica grains would reduce the SPT resistance at certain fines-content, host-sand, mica-grain combinations. The reduction in the SPT resistance as a result of the presence of mica grains might reach eight units at depths close to the ground surface. This influence is expressed by means of a dimensionless parameter (MCef); however, it diminished with an increasing effective stress and fines content. The findings of the present study show that the influence of particle shape on the overall soil behaviour deserves further study.

Unified correlation between SPT–N and shear wave velocity for a wide range of soil types considering strain-dependent behavior

The shear wave velocity (Vs) of sediments plays a key role in seismic wave amplification and is required in site response analysis. Such information is usually lacking during field exploration, but standard penetration test blow count (N) is typically available. Therefore, several studies have established empirical correlations between N and Vs for engineering use. However, these empirical correlations significantly vary in terms of model form and are only applicable to specific soil types, such as sand or clay. A unified empirical correlation for a wide range of soil types, which contains several soil properties (e.g., liquid limit and plasticity index (PI)) in addition to the Vs and N of strata, is developed in this study using the Engineering Geological Database for the Taiwan Strong Motion Instrumentation Program. Influences of confining stress, fines content (FC), PI, and soil types on small-strain properties (i.e., Vs) and large-strain measurements (i.e., N) are first evaluated through the developed correlations with these parameters. The unified correlation between Vs and N that is dependent on confining stress, FC, and PI is then proposed through the conditional prediction approach. The model successfully applies to different regions in Taiwan that includes various types of soil deposits and, thus, is potentially used for the other regions.

Evaluation of strength distribution at cut slope of decomposed granite with the use of sounding method and geophysical exploration method

Natural slopes and cut slopes frequently collapse due to heavy rain and earthquakes, causing disasters. Countermeasures must be applied to mitigate such disasters. There is an especially high risk of a collapse at the surface layer of slopes, and thus, evaluating the strength distribution in the surface layer in detail is important to mitigating and preventing disasters. As simple investigation methods for these purposes, there are sounding methods and geophysical exploration methods. In the present study, dynamic cone penetration (DCP) is selected as the sounding method, and the surface wave method (SWM) is selected as the geophysical exploration method. The strength parameters are generally assumed based on standard penetration tests (SPTs), but DCP tests are simpler than SPTs and can be applied to narrow spaces. On the other hand, the SWM can be used to investigate wide spaces in a short time. We developed a synthesized approach to the geophysical exploration method and the sounding method. The two results obtained from the SWM and the DCP tests—namely the shear velocity and the DCP blow count, respectively—need to be converted to the standard penetration test blow count in order to be synthesized. An indicator simulation, one of the geostatistical methods, is employed to simulate the random field of N values by synthesizing the two results. The proposed procedure is applied to evaluate the strength of the weak surface layer of a cut slope composed of weathered granite, and its applicability for practical use is verified.

Estimating shear wave velocity of soil using standard penetration test (SPT) blow counts in Mashhad city

This study investigates the correlation between shear wave velocity ( $$V_{\mathrm{S}}$$ ) and standard penetration test blow counts (SPT-N value) in all soil types, gravelly soil, sandy soil and clayey soil for Mashhad city in the north eastern region of Iran. The $$V_{\mathrm{S}}$$ data used were measured through downhole method in 84 construction projects (in 88 boreholes). From among collected data, 424 pairs of $$V_{\mathrm{S}}$$ -SPT recorded in one depth were used for regression analysis. The obtained results showed that the N-value had a critical role in estimating $$V_{\mathrm{S}}$$ and soil type was less effective in this regard. These findings are in line with the findings of the previous studies. Regression equations obtained in this study were compared with correlations from previous studies. There was a relative similarity between the previously published and the new regression equations for Iranian soils. Although almost all correlations follow a similar trend, there are significant differences between new equations and correlations reported for other countries. The regression coefficients of the new equations show the acceptable capability of the suggested correlations in estimating $$V_{\mathrm{S}}$$ through SPT-N value. Therefore, these equations can be used to estimate $$V_{\mathrm{S}}$$ for the soils of the current study area and for other similar areas. Moreover, $$V_{\mathrm{S30}}$$ was used for site classification of the study area as per National Earthquake Hazard Reduction Program (NEHRP) guidelines and it was shown that a major portion of the city comes under site class C and other locations are categorised as site class D.

Seismically induced settlement of ground experiencing undrained shaking and laterally constrained compression

A method is proposed for estimating seismically induced settlement of saturated sands experiencing undrained shaking and laterally constrained compression. An empirical relationship is developed between the seismic coefficient of vertical compression, mvs, and standard penetration test blow count, N60, as a function of factor of safety against liquefaction, Fℓ, based on data interpreted from 18 sets of laboratory cyclic direct simple shear tests and 23 cases of field observations of seismic liquefaction. The proposed method is compared with seismic settlement observed at 78 sites subjected to 7.1–8.0 magnitude earthquakes, and with predictions by the previous well-known methods of settlement analysis for undrained shaking. For silty–clayey sands, the significant effect of the plasticity of fines on seismic settlement is illustrated. The use of pre- or post-earthquake penetration resistance for back-analyses of field seismic settlement observations is examined. A tentative correction factor is suggested for seismic settlement estimated based on the assumption of undrained shaking and laterally constrained compression for liquefied saturated sublayers at small distances from drainage boundaries or under buildings with small breadths, which may experience volumetric compression during ground shaking.

Interpretive Structural Modeling and MICMAC Analysis for Identifying and Benchmarking Significant Factors of Seismic Soil Liquefaction

Seismic soil liquefaction is considered as one of the most complex geotechnical earthquake engineering problems owing to the uncertainty and complexity involved in soil parameters, seismic parameters, and site condition factors. Each one of these parameters contains a variety of factors that trigger liquefaction and have varying degrees of importance. However, estimating accurate and reliable liquefaction-induced hazards requires identification and benchmarking of the most influential factors that control soil liquefaction. Seismic soil liquefaction factors were identified by Systematic Literature Review (SLR) approach and analyzed through Interpretive Structural Modeling (ISM) and the Cross-Impact Matrix Multiplication Applied to Classification (MICMAC) methodologies. The ISM model presented the relationships between fifteen seismic soil liquefaction factors and their benchmarking position from higher to lower-level significant factors in hierarchy. MICMAC is used to examine the strength of the relationship between seismic soil liquefaction significant factors based on their driving and dependence power. This research characterizes the identification and benchmarking of the seismic soil liquefaction factors and their relationships. The results show that the factors—duration of earthquake, peak ground acceleration, drainage condition, and standard penetration test (SPT) blow counts—influence seismic soil liquefaction directly and soil type is the governing factor that forms the base of the ISM hierarchy and consequently triggers seismic soil liquefaction. The results provide a more accurate way of selecting significant factors for establishment of seismic soil liquefaction potential and liquefaction-induced hazards risk assessment models.

Assessment of Soil Liquefaction Potential in Kamra, Pakistan

In seismically active regions, soil liquefaction is a serious geotechnical engineering problem that mainly occurs in saturated granular soils with a shallow groundwater table. Significant seismic hazards are present in Kamra, Pakistan. With the rapid increase in construction in recent years, the evaluation of liquefaction is now considered to be more important for land use planning and development. The intent of this study is to highlight soil liquefaction susceptibility that will eventually support the national authorities in developing guidelines for sustainable development and the mitigation of liquefaction. The typical subsoil profile of Kamra consists of silty gravel (GM) overlain by silty sand (SM), poorly graded sand (SP), and fill layers. Kamra is close to the active Ranja–Khairabad fault with a peak ground acceleration of 0.24g. The river Sehat and the Ghazi Brotha canal pass through the study area. In this study, the soil liquefaction potential in Kamra was assessed at 10 different sites (50 boreholes) by using a stress-based procedure for calculating the factor of safety against soil liquefaction. The results revealed that the middle layers, i.e., poorly graded sand and silty sand in the subsoil profile, are extremely susceptible to liquefaction during earthquakes with magnitudes between 7.5 and 8.0 in Kamra. The correlation between the factor of safety and the equivalent clean-sand-corrected standard penetration test (SPT) blow counts according to the earthquake magnitudes was developed and can also be utilized for areas adjoining Kamra that have the same subsoil profile.

Empirical SPT-CPT correlation for soils from Lahore, Pakistan

Standard Penetration Test (SPT) and cone penetration test (CPT) are the most widely used in situ tests to depict the soil stratigraphy and determine the geotechnical engineering of the subsurface soils. The CPT leaps out because of its capability to trace the resistance continuously and due to its accuracy, it is considered to be reliable than the SPT. The outcome of these tests is very important for the design procedures to be implemented for various geotechnical purposes. To effectively utilize all the available data, there is a need of updating the correlation between these two widely used in situ tests. This study implements the statistical linear regression model using a 107 SPT and 49 CPT measurements across the city of Lahore, Pakistan to develop correlations between the the uncorrected SPT blow counts (N) and cone resistance (qc) for various soils. The developed correlation is compared in terms of qc/N ratios with the previous published studies.

Near-surface shear wave velocity estimation and V s 30 mapping for Dhaka City, Bangladesh

Dhaka, the capital city of Bangladesh, is one of the seismically vulnerable cities in the world due to its location close to the convergent boundary between the Eurasian and Indian Plates, unplanned urbanization, non-engineered construction practice, high population density, and weak emergency response system. The city is developed on an elevated Pleistocene terrace with surrounding Holocene floodplains. The terrace consists of the Pleistocene clayey soils, and the floodplains are composed of alluvial sandy and clayey soils. The average shear wave velocity of the near-surface soils up to a depth of 30 m (V s 30 ) is required for Dhaka City to estimate the amplification factors of seismic waves for site-specific seismic hazard analysis. Therefore, the V s 30 has been estimated in the city using downhole seismic (DS), multichannel analysis of surface waves (MASW), and small-scale microtremor measurement (SSMM) methods, and empirical correlation between the shear wave velocity (Vs) and standard penetration test blow count (SPT-N). The V s 30 has also been predicted using the relationship between the V s 30 and Holocene soil thickness. The V s 30 results of the DS, MASW, SSMM, and SPT-N vary from 127 to 320 m/s. The V s 30 values that are predicted based on the Holocene soil thickness vary from 145 to 260 m/s. Then, a V s 30 map has been prepared for Dhaka City using the V s 30 values that are predicted from the Holocene soil thickness at a grid of 30 m. The near-surface soils of the city are classified based on the V s 30 as site classes D (stiff soils) and E (soft soils) according to the NEHRP (National Earthquake Hazards Reduction Program, the USA) and as subsoil classes C and D according to the Eurocode 8.

Deterministic and Probabilistic Analysis of Liquefaction for Different Regions in Bihar

The built environment and human life have been regularly affected by earthquakes. One of the most catastrophic earthquake hazards is liquefaction causing failure of embankment, earth structures, foundations, natural slopes and superstructures. In this paper, three methods have been used to predict the liquefaction susceptibility of some of high seismically active regions of Bihar such as Darbhanga, Samastipur, West-Champaran and Araria Sangram. The first method is based on semi-empirical approach, given by Idriss and Boulanger (in: Proceedings of 11th International conference on soil dynamics and earthquake engineering and 3rd International conference on earthquake geotechnical engineering vol 1, pp 32–56, 2006). The stress reduction factor (rd), overburden correction factor for cyclic stress ratios Kσ, earthquake magnitude scaling factor for cyclic stress ratios (MSF) and recently modified relations has been considered in this approach. The result is obtained in form of factor of safety at particular depth beneath the ground surface. The second approach is based on Muduli’s probabilistic method (2013) and third is on relevance vector machine (RVM) method developed by Karthikeyan et al. (Eur J Environ Civ Eng 17(4):248–262, 2013). RVM model has been used to determine the liquefaction potential of soil based on standard penetration test (SPT) blow count. The SPT data has been used as input parameter for the analysis. Site coming under high seismic zone is more susceptible to liquefaction during earthquake. This concludes that earthquake magnitude plays very important role for the assessment of liquefaction, irrespective of soil type and water table of the site. This paper contains the deterministic and probabilistic analysis of liquefaction behavior of soil.

Side-by-Side Correlation of Texas Cone Penetration and Standard Penetration Test Blowcount Values

This paper presents side-by-side comparisons of blowcount values for the Texas cone penetration (TCP) test and the standard penetration test (SPT). The comparisons yielded statistically-significant regression models for both coarse-grained soils and fine-grained soils. Consistent with expected trends and published data, the TCP–SPT relationship is nonlinear, with weak to fair correlation strength (R2 = 23–44%). For TCP blowcounts (N60, TCP) varying from 25 to 200 blows/30 cm (1 ft), corresponding SPT blowcounts (N60, SPT) are typically 30–60% lower than N60, TCP in fine-grained soils. Likewise, corresponding N60, SPT blowcounts are 10–70% lower than N60, TCP in coarse-grained soils, all other things being equal. Comparative data were obtained from published sources and from project-specific field research sites used for full-scale deep foundation load tests. The final dataset consisted of 225 test pairs obtained in similar soils and geomaterials, at equivalent depths, with all blowcounts normalized to 30 cm (12 in.) penetration (i.e., blows/30 cm or blows/ft) within the bounds of typical test precision, and corrected to 60% hammer efficiency. The generally weak correlations do not support conversion of N60, TCP to N60, SPT (or vice versa) to compute foundation capacity for final design. But, engineers can certainly get an intuitive feel about site conditions and preliminary foundation capacity by using the correlation equations to translate their knowledge of one test to the other. This study extends previous work by formally comparing and contrasting the similar yet different SPT and TCP test methods in such a way as to make the results useful to users of both tests and to the broader geotechnical engineering community.

Predicting Shear Wave Velocity of Soil Using Multiple Linear Regression Analysis and Artificial Neural Networks

In this paper, the correlation between shear wave velocity and some of the index parameters of soils including standard penetration test blow counts (SPT), fine-content (FC), soil moisture (W), liquid limit (LL) and depth (D) is investigated. The study attempts to show the application of artificial neural networks and multiple regression analysis in the prediction of the shear wave velocity (VS) value of soils. New predicting equations are suggested to correlate VS and mentioned parameters based on a dataset collected from Mashhad city in the north east of Iran. The results suggest that better and more exact correlations in the estimation of VS are acquired when ANN method is used. The predicted values using ANN method are checked against the real values of VS to evaluate the performance of this method. The minimum correlation coefficient obtained in ANN method is higher than the maximum correlation coefficient obtained from the MLR. In addition, the value of estimation error in the ANN method is much less than the MLR method indicating the higher confidence coefficient of the ANN in estimating the VS of soil.

Evaluation of liquefaction potential and post-liquefaction settlements in a coastal region in Atakum

Soil liquefaction is one of the most momentous causes of damages induced by earthquakes. It can be described as a sudden decrease in the strength of saturated, cohesionless soil layers, remaining effectual for a length of time under transient and cyclic loading due to excess pore water pressure generation. Consequently, the most appropriate and typical soil condition which brings the potential out to liquefy is loose sand with a groundwater table close to ground surface. This study is pertinent to determine the liquefaction potential in a coastal region in Atakum County of Samsun Province, Turkey. Therefore, empirical equations were used to determine the peak ground accelerations for three scenario earthquakes with the magnitudes of 6.5, 7.0, and 7.2 in order to consider in the simplified procedure context proposed by Seed and Idriss (J. Soil Mech. Found. Div. ASCE 97:1249–1273 1971). Liquefaction potential evaluations were performed using standard penetration test blow counts for four boreholes for sandy portions of the soil profile which exist in the first 20 m below ground surface. In addition to analytical evaluations, two-dimensional nonlinear analyses were ran with Towhata-Iai constitutive model suitable for liquefaction analysis available in DIANA finite element software to clarify excess pore pressure generation that leads to liquefaction. It is also well-known that sands tend to densify when subjected to seismic shaking. Densification of undersoil causes settlement at the ground surface. Liquefaction induced settlements usually cause damages on both superstructures and infrastructures. On the basis of this fact, the method proposed by Ishihara and Yoshimine (Soils Found. 32:173–188 1992) was used to determine the settlements for scenario earthquakes.

Seismic site effects in the central zone of Monterrey Metropolitan Area (northeast Mexico) from a geotechnical multidisciplinary assessment

Prediction of the ground shaking response requires data expressed in terms of soil dynamic properties. Based on the analysis of surficial geology, geotechnical borehole data, seismic refraction (VS) and microtremors (H/V) surveys, we have developed a qualitative evaluation of local ground response to earthquakes in the Monterrey Metropolitan Area (MMA), the main urban and economic hub in northern Mexico. The results provide a detailed geotechnical model for the central zone of the MMA. Although such information is not yet complete for the MMA region, an initial approach has been developed in order to estimate the distribution of damage associated with expected moderate earthquakes. An empirical correlation is introduced to obtain VS as a function of standard penetration test blow counts (SPTN). According to the results, the central-southern part of the study area might experience higher amplifications of ground shaking produced by moderate seismicity because the larger thicknesses of alluvial sediments are deposited there. The 2D geotechnical model proposed would be very useful in making decisions regarding planning or land use, deployment of protocols of rapid response and for producing detailed microzonation maps for those zones with similar geological features as the MMA in northeast Mexico.

Full waveform tomography to resolve desert alluvium

This paper presents shear wave velocity distribution developed from full waveform tomography on a seismic dataset recorded in the northwest Las Vegas Valley, Nevada. The setting is a deep and variable alluvial sequence, encompassing gravel, sand, silt and clay, with some carbonate cementation. Seismic data were collected along a ~144-m long array using 72 equally spaced geophones, with an accelerated drop-weight source applied at 6-m intervals. The dataset was interpreted using an advanced 2-D full waveform tomography method. The same dataset was also analyzed using Rayleigh wave dispersion, following the multichannel analysis of surface waves (MASW) method, to develop a single, 1-D velocity profile. Results from the MASW method indicated a mild velocity inversion. The waveform tomography method was able to characterize vertical and lateral velocity variations along the array length to 25m depth. Results showed significantly contrasting high- and low-velocity layers. While depth-averaged shear wave velocities from the two methods were similar, the degree of variability indicated using FWI is supported by strong variation in Standard Penetration Test (SPT) blow counts from a nearby drillhole and by expectations from sediment lithology.

Evaluation of liquefaction-resistance of soils using standard penetration test, cone penetration test, and shear-wave velocity data for Dhaka, Chittagong, and Sylhet cities in Bangladesh

The evaluation of liquefaction-resistance for saturated loose sandy and silty soils up to a depth of 20 m is an important component of geotechnical site characterization in an earthquake-prone region. In the present study, the standard penetration-test blow count (SPT-N), cone penetration test (CPT) tip resistance (qc), and shear-wave velocity (Vs) data of near-surface soils from Dhaka, Chittagong, and Sylhet cities were used to evaluate the liquefaction-resistance by a simplified procedure. At each site in the cities, the liquefaction-resistance is evaluated using a peak horizontal ground acceleration of 0.15, 0.20, and 0.25 g for a scenario earthquake of magnitude 7.5 (Mw). Then, the liquefaction potential index (LPI) is calculated for each site using the safety factors of liquefaction-resistance and thickness of liquefiable soil layers to predict the severity of liquefaction. The results indicate that sand boils (LPI > 5) and lateral spreading (LPI > 12) will be generated due to liquefaction in the Holocene saturated sandy and silty soils in Dhaka, Chittagong, and Sylhet cities. The evaluation of liquefaction-resistance using the SPT-N, qc, and Vs data shows considerable variation in the prediction of safety factor and LPI. Therefore, it is necessary to use two or more in situ test data to properly evaluate the liquefaction-resistance of soils for an area; and the simplified procedure needs to be used carefully. The results of the liquefaction-resistance of soils can be used to improve the ground condition in Dhaka, Chittagong and Sylhet cities for the construction of earthquake-resilient structures and future urban development.