SPT-N Value Research Articles

Overview on Standards for Liquefaction Triggering Evaluation using the Simplified Method

Evidence of liquefaction during the 2017 Pohang earthquake has highlighted the urgent need to evaluate the current seismic design standard for liquefaction in Korea, particularly the liquefaction triggering standard. With the simplified method, which is the most popular method for evaluating liquefaction triggering, the factor of safety for liquefaction triggering is calculated via the cyclic stress ratio (CSR) and the cyclic resistance ratio (CRR). The parameters in the CSR and CRR have undergone changes over time based on new research findings and lessons learned from liquefaction case-histories. Hence, the current design standard for liquefaction triggering evaluation in Korea should also reflect these changes to achieve seismic safety during future earthquakes. In this study, liquefaction susceptibility criteria were discussed initially and this was followed by a review of the current liquefaction triggering codes/guidelines in other countries and Korea. Next, the parameters associated with the CSR such as the maximum ground acceleration, stress reduction factor, magnitude scaling factor, and overburden correction factor were discussed in detail. Then, the evaluation of the CRR using the SPT N-value and CPT qc-value was elaborated along with overburden and clean-sand correction factors. Based on this review of liquefaction triggering evaluation standards, recommendations are made for improving the current seismic design standard related to liquefaction triggering in Korea.

New horizons in practical liquefaction prediction and mitigation measures for existing structures

The paper presents some recent research advances on practical liquefaction prediction and mitigation measures for existing structures. A new simplified generalized liquefaction prediction and assessment method that is capable of considering the influence of the waveforms and durations of earthquakes has been developed. The validity of this method adopting the effective number of waves concept has been comprehensively verified using the case histories of past major earthquakes for the cases of liquefaction and no liquefaction. A unique feature of the new simplified method is its universality, allowing it to be applied to all types of liquefaction charts based on SPT N-values, CPT q-values, and shear-wave velocities. The paper also presents a new compaction grouting that can reduce the ground upheaval quantity, which has remained an issue for more than 50 years, by 80–90%. The new compaction grouting, up-and-down method, has substantially higher efficiency of upheaval/uplift control and higher efficacy as liquefaction countermeasures around existing structures.

Settlement and Capacity Analysis of Land Support Development on Flyover in Large City; Pekanbaru, Indonesia

The study area located on the street of Soebrantas to Soekarno Hatta Street, with the coordinate position of 0 ° 30 ' 0.79 "N 101 ° 24 ' 57.88 "E - 0 ° 30 ' 0.16 "N 101 ° 24 ' 53.17 "E in Pekanbaru City, Indonesia. The development that will Conduct flyovers in this area became the basis of this research. The main study of this research is to find out how an Atterberg's boundaries, compressibility, and the likelihood of a ground decline in drill 1 use the value of N SPT to match with the purpose of this study. Which is (1) to know the large grain size of soil samples, (2) Knowing the value of the liquid limit, the plastic boundary, and the plastic index of the soil samples, (3) Knowing the possibility of land degradation in the research area, (4) Power capacity analysis of ground support (5) Knowing the decline of modeling using the Plaxis 2D method (6) knows the relationship of decreasing values based on NSPT and Plaxis (7) Knowing the relationship of sieve analysis and Attaberg limit with decreased results. Methods of data retrieval have done with soil testing in the field and soil testing in the laboratories. A comprehensive analysis of the grain has done with sieve analysis. Plastic boundary, liquid, and plastic boundary indices with method Attaberg limit. Decreased analysis and Power capacity analysis of ground support with NSPT value tests.

Prediction of the California bearing ratio from some field measurements of soils

In this study, the fast and safe predictability of the California bearing ratio (CBR) from some important soil parameters that can be obtained easily and cheaply was investigated. Within the scope of this study, the CBR values of 21 different soils in different regions of Sivas province (Turkey) were determined in situ by CBR tests. Then, standard penetration tests (SPT) and ground vibration measurements were conducted on the same soils. At the same time, some physical properties of the soils were determined as a result of field and laboratory studies. Regression analyses were carried out in order to develop correlations between the CBR, and field and laboratory study results. Significant and highly correlated relations between the CBR and peak particle velocity, blow number (SPT-N value), water content (w) and dry unit weight(γd), were obtained. Prediction performance of all proposed equations were tested by using the root mean square error (RMSE) and variance account for (VAF) indices, and particularly, correlations obtained between the CBR – ground vibration and CBR – standard penetration values were observed to have high prediction performance. Good performance indices (correlation coefficients, RMSE, VAF) indicate that the CBR values of soils can be used for initial assessment.

Subsurface void mapping using geophysical and geotechnical techniques with uncertainties estimation: case study of Kinta Valley, Perak, Malaysia

In this study, an assessment of the subsurface conditions was carried out using both the geophysical and geotechnical methods for delineating lithology units and mapping cavities in the subsurface. In light of this, geo-electrical vertical electrical soundings (VES) technique and drilling tests from which in situ standard penetration tests (SPT-N) and particle size distribution (PSD) analysis on some selected samples were carried out. Additionally, accuracy assessment of the field measurements was carried out statistically using coverage factor and uncertainty analysis at 95% confidence level in justification of the relationship between the estimated depth of the cavity and the resistivity values. The results of VES and 2D resistivity imaging show that three layers are delineated. The weathered bedrock with resistivity of about 500 Ωm hosts the cavity which is air-filled at shallow depth and saturated with fluid or clay with low resistivity of about 127 Ωm at deeper depth. The SPT N-values obtained ranges between 0–5 and 10–20 corresponding to weak/unconsolidated zone and consolidated sediments, respectively. The SPT N-values from the boreholes drilled agreed with the inferred lithology units from electrical resistivity survey. The results of the PSD suggest that sand/gravel sediments with grain sizes more than 0.075 mm dominated the study area. A combination of both the geophysical and geotechnical data shows good agreement and their relevance in addressing subsurface problems.

Efficient surface wave method for investigation of the seabed

In the design and construction of structures, information on the SPT N-values and the undrained shear strength is very important for investigating problems related to stability, deformation, etc. Since the shear wave velocity (S-wave velocity) is correlated with these properties, geophysical exploration methods, such as surface wave methods, which can estimate the properties densely over a wide area, are effective for creating better geotechnical designs and building better structures. In terms of investigating the seabed using a surface wave method, the method of arranging hydrophones on the seabed and dropping a weight from a boat to generate surface waves was proposed in previous studies. The present study proposes a new method using a distinctive weight-dropping source, which causes the weight to fall vertically with little resistance from the fluid region and to generate a desirable surface wave efficiently at the impact of landing. Underwater dropping tests were carried out at two field sites to find the desirable shape for the weight-dropping source. In a fundamental field test at a tideland, the effectiveness and applicability of the proposed weight-dropping method were demonstrated through a comparison with reliable on-land survey methods using geophones. Moreover, the accuracy of the proposed method was demonstrated through a practical field test conducted at sea by comparing the SPT N-values converted from the S-wave velocity, obtained by the proposed method, with those measured by standard penetration tests. Recognizing that calm conditions are required for the waves and the currents in order to apply the proposed method, the method is expected to be an effective tool for geotechnical investigations of the seabed, and to be applicable for creating better designs and constructing better coastal and marine structures.

Assessment of soil liquefaction potential: a case study for Moulvibazar town, Sylhet, Bangladesh

Liquefaction can intensify the destruction caused by an earthquake; thus, a region with high liquefaction potential could be more disastrous. Bangladesh is surrounded by the Indo-Burma Folded Belt in the east, the Dauki Fault and Himalayan Syntaxis in the north that are known to have occurred high magnitude earthquakes (e.g., Mw > 7) in the past. Therefore, assessing seismic hazards in the regions that are economically growing fast is of great interest. Among many other hazard assessment parameters, soil liquefaction potential index (LPI) can be used to assess seismic hazards. In this study, we have assessed the seismic hazard potential for a small town (Moulvibazar) in the northeast Bangladesh documenting liquefaction potential indices for different surface geological units using an earthquake of moment magnitude Mw 8 having a peak horizontal ground acceleration (PGA) of 0.36 g. Twenty-five standard penetration test (SPT) boreholes were completed within the study area to obtain SPT-N values for two surface geological units: (1) Holo–Pleistocene low elevated terrace deposits (Zone 1) and (2) Holocene flood plain deposits (Zone 2). Using the SPT-N values, the LPI values have been calculated for the soil profile of each borehole. The LPI values in the town vary from 0 to 42.33, whereas values from 1.42 to 7.52 are in Zone 1 and values from 0 to 42.34 are in Zone 2. It has been predicted that 42% and 78% areas of Zone 1 and Zone 2, respectively, might exhibit surface manifestation of liquefaction. The results of this study can be used for seismic risk management of Moulvibazar town.

Estimated Empirical Correlations Between Shear Wave Velocity and SPT-N Value for Indore City Using NLR and ANN

In this paper, an attempt has been made to propose a generalized correlation between shear wave velocity (Vs) and SPT-N values for all soil types for generalized depth using the concepts of regression. Around 40 correlations have been compiled and applied for estimating the shear wave velocity (Vs) correlation for the region and also to address the uncertainty issue. The generated correlation is then used for the computation of Vs for one-dimensional (1D) ground response analysis at two different site locations in Indore region. 1D ground response analysis is performed using DEEPSOILv6.1. Soil profiles at site taken as input for analysis were collected from 245 boreholes at 26 different locations in the Madhya Pradesh region (one of the central states in India), and it can be concluded that Vs–N correlations estimated after reducing the errors applying the multilinear perceptron and generalized regression neural network models using MATLAB coding gave better results over the linear regression analysis applied for the site-specific ground response analysis.

Three-Dimensional Response of the Supported-Deep Excavation System: Case Study of a Large Scale Underground Metro Station

The complexities and the economic computational infeasibility associated in some cases, with three-dimensional finite element models, has imposed a motive for many investigators to accept numerical modeling simplification solutions such as assuming two-dimensional (2D) plane strain conditions in simulation of several supported-deep excavation problems, especially for cases with a relatively high aspect ratio in plan dimensions. In this research, a two-dimensional finite element model was established to simulate the behavior of the supporting system of a large-scale deep excavation utilized in the construction of an underground metro station Rod El Farrag project (Egypt). The essential geotechnical engineering properties of soil layers were calculated using results of in-situ and laboratory tests and empirical correlations with SPT-N values. On the other hand, a three-dimensional finite element model was established with the same parameters adopted in the two-dimensional model. Sufficient sensitivity numerical analyses were performed to make the three-dimensional finite element model economically feasible. Results of the two-dimensional model were compared with those obtained from the field measurements and the three-dimensional numerical model. The comparison results showed that 3D high stiffening at the primary walls’ corners and also at the locations of cross walls has a significant effect on both the lateral wall deformations and the neighboring soil vertical settlement.

A Three-Dimensional Geotechnical Spatial Modeling Method for Borehole Dataset Using Optimization of Geostatistical Approaches

A large amount of geotechnical investigation data is essential for the highly reliable design of geotechnical structure at a construction site. The number of geotechnical investigations, however, has been generally insufficient and spatially biased owing to economic and spatial-temporal limitations. In this study, a geotechnical three-dimensional spatial modeling was implemented using an optimized geostatistical interpolation approach at a bridge construction site in the south-central part of the Korean peninsula. The geotechnical investigation data were collected and standardized for the construction of a geo-database. For the site-specific stratification, a kriging-based integration of the geo-layers and the seismic velocity from a seismic refraction survey were applied. The value from a standard penetration test (SPT)-N of an uninvestigated location was predicted using parametric and nonparametric geostatistical methods. We accomplished three-dimensional spatial interpolations using ordinary kriging, a sequential Gaussian simulation with a normal score transformed dataset, and a sequential indicator simulation using the geodatabase. A leave-one-out cross validation was carried out to quantitatively evaluate the reliability of the three-dimensional modeling. Finally, a three-dimensional geotechnical spatial model assigned with subsurface stratification and SPT-N values was constructed using the sequential Gaussian simulation.

Site Response Study and Amplification Factor for Shallow Bedrock Sites

Amplification is a key paramter considered to account modifcation of seimic wave in the soil for earthquake resistance design of structure placed on soil. Initially, earthquake wave amplifications are related with shear wave velocity (Vs) ratio of soil and foundation layer, and then it was related to average value of Vs up to 30 m (Vs30 ). Application of Vs30 concept to represent amplification in shallow bedrock sites is questionable and has rock velocity added to soil velocity. In this study, shallow bedrock sites in Bengaluru, Chennai, Coimbatore and Vishakhapatnam has been analyzed to understand amplifications and its proximity to Vs30 . The site response calculations are done using one-dimensional nonlinear approach. Intraplate recordings from around the world suitable for the study area are selected. For comparison with known data, the amplification factors are evaluated considering the period ranges similar to international codes. Then, considering spectral signatures from response spectra for all site rock and surface motions, the factors are calculated for period range 0.01–0.06 s and 0.05–1.0 s. Based on the study, only one mid-period amplification factor has been proposed. This amplification factor represents the significant amplification of the site. Acceleration spectra show similar trends for different site classes irrespective of the fact that profiles are selected based on Vs values or SPT-N values. This is observed over a wide range of results and indicates shear modulus as an influencing parameter. Comparison of spectral signatures for different site classes suggests that amplification reduces as the modulus of the soil column increases. Thus, it may be appropriate to classify sites based on shear modulus of soil column.

Assessment on liquefaction potential of seabed soil in Chang-Bin Offshore wind farm considering parametric uncertainty of standard penetration tests

Liquefaction potential analysis is a required task in the foundation design process of offshore wind turbine in Taiwan. The standard penetration test (SPT) is mostly used in the preliminary soil investigation of the pilot offshore wind farm in Chang-Bin, Taiwan. Due to the different experimental conditions and operating conditions, the N value (SPT-N) of SPT varies greatly. This study applies statistical methods in conjunction with the New Japan Road Association simplified-empirical method (NJRA method) to incorporate the uncertainty of SPT-N values into the offshore liquefaction potential assessment to quantify the risk of seabed liquefaction. The study statistics the field experimental geotechnical parameters SPT-N and determines the probability density function of the SPT-N distribution of each layer of soil in the offshore wind farm. In order to quantify the risk of seabed soil liquefaction potential, the Monte Carlo random sampling method is used, and by the NJRA method to carry out the seabed liquefaction potential in Changhua, Taiwan. After comparing, the results obtained by the current SPT-based soil liquefaction potential assessment by deterministic approach are conservative. In the ground investigation of offshore wind farm development, the method proposed in this paper can access the thickness of liquefiable soil layers under any given probability for optimizing offshore wind turbine foundation design.

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.

Geotechnical Characterization of the Soil along the Banks of the Sagumayon River in the Province of Albay, Philippines

The effects of pollution, weather and climate, and societal pressures had changed drastically thephysical characteristics and use of the Sagumayon River, an important river network in the city of Legazpi.This study aimed to obtain relevant geotechnical engineering properties of the soil along the river banks,which could provide an indication of its vulnerability to erosion, settlement, and slope failure. In-situ andex-situ tests conducted in four areas of the river along an 800-m stretch within the Bicol University–MainCampus revealed a granular type of soil, poorly graded sand with silt (SP-SM) of low SPT N-value (from2–20 blows/ ft), friction angle of 27° to 33° and Soil Bearing Capacity of 74 ~ 217 kPa. The riverbank soilsare susceptible to certain modes of erosion, settlement, and slope failure. The soil is comprised of 82% sandand 18% silt. Borehole sites with shallow groundwater table have been found to exhibit high soil moisturecontent values. Structures that will be built on the area should be designed to allow a tolerable, evensettlement of 25 mm and up to 37.5 mm of maximum differential settlement. The study recommends thatthe index properties obtained be used in conjunction with cross-sectional survey data of the river banks toanalyse the stability of the slopes. Remedial measures should be provided to secure against further surfaceerosion. In the design of structures to be built on the area, there is a need to validate the soil properties bydrilling more bore holes to ensure stability of structures.

CORE LOG AND CONE PENETRATION TEST APPROACH FOR BEARING CAPACITY ANALYSIS OF QUATERNARY DEPOSIT AND ITS CORRELATION TO FACIES DISTRIBUTION IN SOUTHERN BALI

Area development deals with optimal land use and the reduction of the risk of geological disasters. The coastal area of South Bali is prone to land settlement hazards. In order to mitigate the risk, it is important to understand the depositional environment of the area related to its bearing capacity and geological hazard risks. The aim of this research is to understand the subsurface depositional environment and quantifying its bearing capacity. Quantitative modeling was carried out to obtain the sediment-bearing capacity of the Pendungan area in Bali, Indonesia. The methods used in this research were the observation of borehole cores, the identification of the cone penetration test (CPTu) curves pattern, the sediment index property test, the soil strength laboratory, and bearing capacity analysis. Based on lithologic association, the CPTu curve pattern, and grain size analysis, there are three facies developing in the study area with different bearing capacity values. Generally, beach ridge sand has a higher bearing capacity (N-SPT value of 8 – 52) for shallow foundation than fluvial clay. Meanwhile, floodplain facies has the lowest bearing capacity (N-SPT value of 2 – 20).

Liquefaction Potential Analysis of Reusep Prestress Bridge in Pidie Jaya due to 6.4 Mw Earthquake

Pidie Jaya is one of the districts in Aceh Province – Indonesia. On December 7, 2016, Pidie Jaya experienced a shallow 6.4 Mw earthquake which destroyed some vital buildings and also human loss. Based on preliminary field investigation, some geological damages like soil movement, soil cracks, and liquefactions occur because of the earthquake. Some liquefaction phenomena scattered in the area of Ulim, Panteraja, Meunasah Balek, Manohara Beach and Sagoe Trienggadeng. An evidence of liquefaction in Pidie Jaya area was displayed in this research based on several literature review. Furthermore, these paper aims to identify liquefaction possibilities in Trienggadeng Reusep Prestress Bridge based on a geotechnical investigation of N-SPT and some seismic data by using Kishida method. The surrounded area of the bridge was first evaluated in terms of geological setting, tectonics and seismic activity related to 6.4Mw of the previous earthquake. Furthermore, it was found from the soil profile that the studied area has a potency of liquefaction because of several saturated sand layers and high groundwater level. Effective overburden pressure of sand layers was calculated and plotted with N-SPT value to determine the possibility of liquefaction. The result shows that liquefaction potential shows high possibility for sand dominant layers both from bor-log 1 in 17.5 m and 25 m depths, and bor-log 2 in the depth of 17 m and 26.5 m.

Identification of Possible Liquefaction Zones Across Guwahati and Targets for Future Ground Improvement Ascertaining no Further Liquefaction of Such Zones

Liquefaction is associated with the loss of shear strength of soil, causing considerable damages. The Northeast Indian region has experienced many major (M ≥ 7.0) to great earthquakes (EQs) such as 1869 Cachar EQ and 1897 Shillong EQ. As a consequence, Guwahati city had faced large scale damage and significant induced effects such as liquefaction during past EQs. At present, Guwahati is the largest business hub of the northeast India. Further, Guwahati is also amongst the list of cities, Government of India has shortlisted to be developed as “smart city”. For these reasons, the city attracts lots of infrastructural growth in the times to come. In the present work, the liquefaction potential of Guwahati subsoil is evaluated. For the purpose, seismic scenarios experiences during 1869 Cachar EQ (Mw = 7.5), 1897 Shillong EQ (Mw = 8.1), average horizontal seismic coefficient given by IS 1893 (Part 1): 2016 (seismic zone V) and maximum amplified peak ground acceleration (PGA) values obtained based on site-specific subsoil data are considered separately. In-situ subsoil properties are obtained from 244 boreholes (BHs) till 30 m depth and maps showing possible liquefiable zones across Guwahati are developed. In addition, maps showing target SPT-N value ($$N^{improved}$$), to be obtained at above liquefiable zones after ground improvement, ensuring no further liquefaction, are also developed. Thus, the present study collectively identify zones which may undergo liquefaction during future EQs and further, how much improvement in the subsoil strength properties are required so that the above found liquefaction can be avoided, is also estimated. Obtained results and proposed values will provide very useful information to field engineers regarding where and how much ground improvement is required for avoiding future liquefaction. In addition, the present study is very helpful for city planning and microzonation studies.

Case Study of Correlation between the SPT-N Value and PMT Results Performed on Weathered Granite Zone in Korea

Case Study of Correlation between the SPT-N Value and PMT Results Performed on Weathered Granite Zone in Korea

Probable intensity of Sylhet city from an event like 1918 Srimangal earthquake

An intensity map plays an important role and is required for construction, so in this study, we presented a map of intensity for every ward of the city of Sylhet. Another objective of this research is to create a methodology to develop the intensity map for Sylhet with the equation readily available. Sylhet is Bangladesh’s most seismically susceptible region owing to its location in the southeast portion of Dauki fault. In the last 101 years, almost 184 massive earthquakes in the Sylhet area have taken place between the magnitude of 4 and 7.2. Among these earthquakes, the 1918 earthquake of Srimangal was selected as it was the first one to be felt and recorded in Bangladesh as a destructive earthquake. The probable intensity map for the Sylhet city of Bangladesh using Geographic Information Technology has been made considering the 1918 Srimangal earthquake as a scenario case. For this purpose, 157 boreholes data were collected to calculate the shear wave velocity. The SPT-N value of most of the borehole data is as deep as 15 m. Then it was converted to the required amount at a depth of 30 m. In addition, Shear wave velocity was also converted to the Peak Ground Acceleration using McGuire equation. The highest Amplification Factor was used among the three equations for converting the Peak Ground Acceleration into the Surface Acceleration. Finally, the Surface Acceleration has been converted into the Modified Mercalli Intensity scale to make it simple to comprehend. The findings show that the minimum and maximum Peak Ground Acceleration are both 0.164 g and 0.175 g, and the Amplification Factors vary between minimum and maximum from 2.027 to 3.40. Also, surface acceleration ranges from 0.347 to 0.578 g. The intensity is estimated at 27 wards in the city of Sylhet. This demonstrates that 81.48% of the intensity IX areas are impacted and 18.52% of the intensity VIII areas as a scenario case for the Srimangals 1918’s earthquake. Since the town of Sylhet does not have an intensity map, this research aims to prepare a map for all Sylhet wards.

Determination of relationship between standard penetration test and geotechnical parameters in Ahwaz soil

ABSTRACT The present study is the result of more than 150 geotechnical investigations that were conducted over 2 years (from 2015 to 2016) on the Ahwaz soil (which is mainly composed of clay with low plasticity in different regions). The standard penetration test was performed at all the boring locations, and after preparing the undisturbed Shelby tube samples from different depths, the unconsolidated undrained triaxial (UU), Atterberg limits, in situ moisture content and grading tests were performed on all samples. All of the abovementioned parameters are presented for the Ahvaz soil, and the range of values of each of the parameters were investigated, and finally, the relationship between the modulus of elasticity and the standard penetration test was studied. The effect of different soil parameters and their contribution to the determination of soil elasticity modulus is another important result of this study. The most important result of this study could be the different classifications of soil elasticity moduli by using the sample Nspt values to estimate the elasticity moduli because the standard penetration test value has the highest correlation and the most significant relationship with elasticity moduli.