Liquefaction Hazard Assessment Research Articles

Applicability of Pseudoprobabilistic Method of Liquefaction Hazard Assessment for Nuclear Power Plants at Diffuse Seismicity Sites

For the new nuclear power plants, the hazard of liquefaction due to earthquakes should be excluded by appropriate site selection or eliminated by engineering measures. An important question is how to define a quantitative criterion for negligibility of the liquefaction hazard. In the case of operating plants, liquefaction can be revealed as a beyond-design-basis event. It is important to learn whether the liquefaction hazard has a safety relevance and whether there is a sufficient margin to the onset of liquefaction. The use of pseudoprobabilistic method would be practicable for the definition of probability of liquefaction, but it could result in overconservative results. In this paper, the applicability of the pseudoprobabilistic procedure is demonstrated for the sites in diffuse seismicity environment and for low hazard levels that are typical for nuclear safety considerations. Use of the procedure is demonstrated in a case study with realistic site-plant parameters.

Using High Performance Computing for Liquefaction Hazard Assessment with Statistical Soil Models

Conventional methods for liquefaction assessment using engineering indices such as Factor of safety against Liquefaction (FL) tend to overestimate liquefaction hazards. The soil dynamics analysis-based assessment with automatic modeling is more rational and robust. Soil properties are known for large uncertainties. Rather than deterministic soil models, statistical models for soil parameters should be considered. With automatic modeling, a large number of statistic models can be generated without difficulty. The problem becomes how to assess liquefaction hazard with statistic models in an efficient way. Using high performance computing, we develop an efficient liquefaction assessment method for statistical modeling of soils. A high parallel efficiency can be achieved and a large number of statical models of the order of 104 can be simulated within a reasonable time span. The method developed in this paper can be used as an efficient tool for unravelling critical parameters of soil liquefaction.

Toward a numerical-simulation-based liquefaction hazard assessment for urban regions using high-performance computing

Effective and efficient liquefaction hazard assessment is critical in making disaster mitigation plans for urban regions. In this paper, we present a numerical-simulation (NS)-based method for assessing urban-wide liquefaction hazard. The method includes an automatic modelling for individual sites and an application of high-performance computing (HPC) for efficient assessment. The feasibility of the method is demonstrated by conducting simulations for more than 10,000 individual sites in an urban region. The urban-wide assessment results depend on a pressure threshold of liquefaction occurrence and the dependence increases as the ground motion increases. A comparison with a conventional method using engineering indices (EI) shows a tendency of the EI-based method to predict a considerably greater number of liquefied sites than the proposed method. With the continuing improvement on numerical simulations and on computer efficiency, NS-based assessments can be regarded as promising alternatives to conventional EI-based methods for urban-wide liquefaction assessment.

Addressing limitations in existing ‘simplified’ liquefaction triggering evaluation procedures: application to induced seismicity in the Groningen gas field

The Groningen gas field is one of the largest in the world and has produced over 2000 billion m3 of natural gas since the start of production in 1963. The first earthquakes linked to gas production in the Groningen field occurred in 1991, with the largest event to date being a local magnitude (ML) 3.6. As a result, the field operator is leading an effort to quantify the seismic hazard and risk resulting from the gas production operations, including the assessment of liquefaction hazard. However, due to the unique characteristics of both the seismic hazard and the geological subsurface, particularly the unconsolidated sediments, direct application of existing liquefaction evaluation procedures is deemed inappropriate in Groningen. Specifically, the depth-stress reduction factor (rd) and the magnitude scaling factor relationships inherent to existing variants of the simplified liquefaction evaluation procedure are considered unsuitable for use. Accordingly, efforts have first focused on developing a framework for evaluating the liquefaction potential of the region for moment magnitudes (M) ranging from 3.5 to 7.0. The limitations of existing liquefaction procedures for use in Groningen and the path being followed to overcome these shortcomings are presented in detail herein.

In‐situ and laboratory methods for liquefaction hazard assessment

AbstractConsidering liquefaction as one of the geotechnical instabilities (problems), which increase damages during strong earthquakes, there are different approaches available for assessment of its potential. The study presents the investigations and results on the evaluation of the potential of liquefiable soil layers at location where new business ‐ residential complex is planned to be built. Results from the performed in situ investigations (SPT, CPT) and laboratory experiments provide valuable contribution regarding the evaluation of liquefaction hazard at the location with medium to high seismicity and non‐homogenous soil condition. Furthermore, recommendations are given for the proper depth as a foundation level of the structures that are planned to be built on this site. Methodology applied in this study points out the necessity of attention and precaution to deliver conclusions for potential of liquefaction in urban areas.

Zonation liquefaction hazard assessment by GIS and Geotechnical data in southern coasts of the Caspian Sea (Beach Amirabad)

Zonation liquefaction hazard assessment by GIS and Geotechnical data in southern coasts of the Caspian Sea (Beach Amirabad)

Seismic Liquefaction Potential in Muscat, Sultanate of Oman

Seismic liquefaction is a serious geotechnical engineering problem that takes place in saturated cohesion less soils during earthquakes due to the increase of pore-pressure so that the soil shear strength is decreased to zero. Muscat is situated in the north-eastern part of Oman close to Oman Mountains, which witnessed four earthquakes of order of 5.2 magnitude in the last 1300 years. The surface geology of Muscat reveals great variety of hard rocks in the eastern, southern and western parts to dense and lose sediments in the middle and northern parts. Muscat Municipality provided 1082 borehole data to be examined for their liquefaction susceptibility based on the soil characteristics. Susceptible soils only are further considered to liquefaction hazard assessment. Liquefaction occurs during an earthquake if the cyclic stress ratio (CSR) caused by the earthquake is higher than the cyclic resistance ratio (CRR) of the soil. CSR values were evaluated using probabilistic peak ground acceleration (PGA) values for return period of 2475 years at the surface given by detailed hazard and micro zonation studies. CRR for Muscat region is conducted based on the borehole data with N values of SPT tests, and shear wave velocity results from 99 MASW surveys over the entire region. All the required corrections to get standardized (N1) 60 values, to correct shear-wave velocity, and scale the results for Mw 6.0 instead of the proposed 7.5 are conducted. Liquefaction hazard maps were created using the minimum factor of safety (FS) at each site as a representative of the FS against liquefaction at that location. Results indicate that under the current level of seismic hazard, liquefaction potential is possible at some sites along the northern coast, where alluvial soils, shallow ground water table, and relatively high ground motion are present. The expected settlement of the soft soil at each liquefiable site is also evaluated.

Ground response analysis and liquefaction hazard assessment for Vishakhapatnam city

Liquefaction is a complex phenomenon where the soil is subjected to high strain levels due to dynamic loading at the time of seismic events, contributing to severe damage and collapse of the structures. The effect of liquefaction can be predicted in three stages, i.e., evaluation of susceptibility, hazard and deformations. Soil susceptibility to liquefaction can be assessed using the geotechnical properties such as grain size, age of the soil deposit, penetration resistance of the soil, whereas hazard can be assessed in terms of factor of safety estimated against liquefaction. In the present study, one-dimensional equivalent linear ground response analysis has been carried in the study area Vishakhapatnam, Andhra Pradesh (India) and the surface peak ground acceleration (PGA) has been estimated using DEEPSOIL. The surface PGA values obtained have been used in liquefaction hazard assessment using stress-based method (SBM) and energy-based method (EBM). Hazard maps were generated from the estimated values of PGA and factor of safety against liquefaction (F L). The surface PGA values obtained are in the range of 0.09–0.14 g which are higher than 0.1 g (limiting value provided by Seismic code of India (IS: 1893-2002)). It is observed that the locations in the central part of the city are prone to higher accelerations comparatively. From liquefaction potential assessment, it is evident that most of the locations in northern and central parts of the city are prone to liquefaction. As the study area has two operational ports and is highly industrialized, findings from the present study will be helpful in retrofitting, analysis and design of structures, therefore, solving practical challenges in structural and geotechnical engineering.

Seismic Site Classification and Liquefaction Hazard Assessment of Jaipur City, India

Multichannel Analysis of Surface Wave (MASW) is one of the latest geophysical methods used for determining the shear wave velocity of the soil. A series of MASW tests were carried out in this study using a multi channel seismograph with 24 numbers of 4.5 Hz vertical geophones. Collected data were analysed using Surface Plus software. One-dimensional shear wave velocity models were developed from the analyses of the collected data for the Jaipur city. The average shear wave velocity (VS30) for the top 30 m of soil deposit was estimated for the Jaipur city. Based on this VS30 value, the Jaipur city was finally divided into various sub-zones as per the NEHRP guidelines. From the study it has been observed that all the studied areas are falling either in site class C or D. In top 15 m depth, almost all studied area is having average shear wave velocity less than 360 m/s. The estimated shear wave velocity data were used in the assessment of liquefaction potential of soil at various locations in the city. From the liquefaction potential results it can be concluded that most of the city area is not susceptible to liquefaction.

Assessment of earthquake-induced liquefaction hazard in urban areas of Hanoi city using LPI-based method

Assessment of earthquake-induced liquefaction hazard in urban areas of Hanoi city using LPI-based method

Assessment of liquefaction hazard along shoreline areas of Peninsular Malaysia

ABSTRACTUsing a collection of 2074 boreholes extracted from soil investigation reports utilized by standard penetration test, this study examines the susceptibility of soil liquefaction hazard along the shoreline of Peninsular Malaysia. Data collection and site visit were conducted to gather all the basic information related to soil liquefaction hazard. Three types of results are presented in the form of photos (recent shoreline condition), graphical illustrations (soil composition, SPT-N distribution and zone of saturation) and liquefaction susceptibility plots. The findings indicate there is obviously a critical need to adapt further liquefaction analysis in the shoreline region of Peninsular Malaysia to better understand liquefaction hazard and produced beneficial information on the matter. A risk assessment matrix is also introduced in classifying the severity and recommended mitigation measures of the studied areas.

A hybrid geotechnical and geological data-based framework for multiscale regional liquefaction hazard mapping

Regional assessment of liquefaction hazard necessitates not only models for evaluating liquefaction potentials and their spatial extent, but also the means to account for heterogeneous sources of i...

Earthquake induced liquefaction hazard, probability and risk assessment in the city of Kolkata, India: its historical perspective and deterministic scenario

Liquefaction-induced ground failure is one amongst the leading causes of infrastructure damage due to the impact of large earthquakes in unconsolidated, non-cohesive, water saturated alluvial terrains. The city of Kolkata is located on the potentially liquefiable alluvial fan deposits of Ganga-Bramhaputra-Meghna Delta system with subsurface litho-stratigraphic sequence comprising of varying percentages of clay, cohesionless silt, sand, and gravel interbedded with decomposed wood and peat. Additionally, the region has moderately shallow groundwater condition especially in the post-monsoon seasons. In view of burgeoning population, there had been unplanned expansion of settlements in the hazardous geological, geomorphological, and hydrological conditions exposing the city to severe liquefaction hazard. The 1897 Shillong and 1934 Bihar-Nepal earthquakes both of M w 8.1 reportedly induced Modified Mercalli Intensity of IV–V and VI–VII respectively in the city reportedly triggering widespread to sporadic liquefaction condition with surface manifestation of sand boils, lateral spreading, ground subsidence, etc., thus posing a strong case for liquefaction potential analysis in the terrain. With the motivation of assessing seismic hazard, vulnerability, and risk of the city of Kolkata through a consorted federal funding stipulated for all the metros and upstart urban centers in India located in BIS seismic zones III, IV, and V with population more than one million, an attempt has been made here to understand the liquefaction susceptibility condition of Kolkata under the impact of earthquake loading employing modern multivariate techniques and also to predict deterministic liquefaction scenario of the city in the event of a probabilistic seismic hazard condition with 10% probability of exceedance in 50 years and a return period of 475 years. We conducted in-depth geophysical and geotechnical investigations in the city encompassing 435 km2 area. The stochastically synthesized bedrock ground motion for both the 1897 and 1934 earthquakes on non-linear analysis of local site conditions through DEEPSOIL Geotechnical analysis package present surface level peak ground acceleration of the order of 0.05–0.14 g for the 1934 Bihar-Nepal earthquake while for the 1897 Shillong earthquake it is found to be in the range of 0.03–0.11 g. The factor of safety (FOS) against liquefaction, the probability of liquefaction (P L), the liquefaction potential index (LPI), and the liquefaction risk index are estimated under the influence of these two earthquakes wherein the city is classified into severe (LPI > 15), high (5 < LPI ≤ 15), moderate (0 < LPI ≤ 5), and non-liquefiable (LPI = 0) susceptibility zones. While the 1934 Bihar-Nepal earthquake induced moderate to severe liquefaction hazard condition in the city in mostly the deltaic plain and interdistributary marsh geomorphologic units with 13.5% sites exhibiting moderate hazard with a median LPI of 1.8, 8.5% sites depicting high with a median LPI of 9.1 and 4% sites with a median LPI of 18.9 exhibiting severe hazard condition, 1897 Shillong earthquake induced mostly non-liquefaction condition with very few sites depicting moderate and high liquefaction hazard. A conservative liquefaction hazard scenario of the city on the other hand estimated through deterministic approach for 10% probability of exceedance in 50 years predicts a high hazard zone in the 3.5–19 m depth region with FOS < 1 and P L > 65% comprising of coarse-grained sediments of sand, silty sand, and clayey silty sand in mostly the deltaic plain geomorphologic unit with 39.1% sites depicting severe liquefaction hazard with a median LPI of 28.3. A non-linear regression analysis on both the historical and deterministic liquefaction scenarios in P L versus LPI domain with ± 1 standard deviation confidence bound generated a cubic polynomial relationship between the two liquefaction hazard proxies. This study considered a bench mark for other cities in the country and elsewhere forms an integral part of the mega-seismic microzonation endeavors undertaken in all the earthquake-prone counties in the world.

Liquefaction hazard mapping in the city of Boumerd\xe8s, Northern Algeria

The city of Boumerdès, located in Northern Algeria, was badly affected during the May 21, 2003 Zemmouri (Mw = 6.8) earthquake where extensive liquefaction has been reported. The aim of this paper is to assess and to map the liquefaction potential for Boumerdès. We collected and used data from 154 boreholes, 10 down-hole tests, 56 standard penetrations tests (SPT), and inventory of 35 water level points. This data has been analyzed in the framework of geographical information systems (GIS). We assessed the liquefaction potential index (LPI) by considering a seismic hazard scenario corresponding to amax = 0.48 g calculated, using a probabilistic approach, for a return period of 500 years. LPI values have been correlated to compile the liquefaction hazard map that indicates the quantitative characteristics of the liquefiable layers and the induced disruption probability area. Results show that the main part of the city of Boumerdès belongs to a low liquefaction potential area except for a narrow corridor along the Corso waterway, where the liquefaction potential is moderate to high. The obtained results are compatible with the geological, geotechnical and hydrogeological susceptibility to liquefaction of the area. The results also show a good agreement with the observations made after the May 21, 2003 Zemmouri earthquake. The obtained liquefaction hazard maps may serve as useful tools for land management and planning in the city of Boumerdès and as an example of liquefaction hazard assessment that may be applied in other populated cities in northern Algeria’s seismic prone areas.

Generation of Liquefaction Potential Map for Kanpur City and Allahabad City of Northern India: An Attempt for Liquefaction Hazard Assessment

Kanpur City and Allahabad City are the most populous city and the largest urban agglomeration among other north Indian cities. Both the cities are situated along Ganga and Yamuna River. The study areas are one of the growing urban centers in Northern India. Two large Himalayan earthquakes experienced by this area during 1803 A.D. and 1934, and large-scale liquefaction was reported in and around the area along with the recent 2015 Gorkha earthquake which caused severe shaking. As per the IS-1893–2002, the study area lies in seismic zone III and the soils from the above cities are prone to liquefaction. However, no such attempt has been made so far for the detailed liquefaction potential map for the study area. The present study is an approach towards evaluation and preparation of spatial distribution map of liquefaction potential for the Kanpur City and Allahabad City using several bore hole data collected from the study area. The PGA used for the liquefaction potential analysis was taken from the ground response analysis of Kanpur soil and Allahabad soil. The PGA values are 0.25 and 0.18 g for Kanpur soil and Allahabad soil respectively. The results are presented in the form of factor of safety contour map at a depth of 7, 15, 24 and 30 m below the ground surface. The map indicates that most of the sites in Kanpur City and Allahabad City area are susceptible to liquefaction and hence this aspect has to be considered in earthquake-resistant design of foundations/structures in Kanpur City and Allahabad City.

Clarifying the differences between traditional liquefaction hazard maps and probabilistic liquefaction reference parameter maps

Traditional liquefaction hazard maps are useful tools for preliminary engineering site assessment and policy development. However, these maps should not be used for site-specific liquefaction hazard assessment. Simplified probabilistic liquefaction analysis procedures can be used instead to perform site-specific liquefaction hazard assessment, but these procedures rely on probabilistic reference parameter maps that are not yet familiar to most engineering and geological practitioners. As a result, some professionals are questioning the differences between traditional liquefaction hazard maps and the new probabilistic reference parameter maps. This paper clarifies the differences between these two types of maps, and shows how each of these maps complements the other. New probabilistic reference parameter maps for liquefaction triggering and lateral spread displacement are developed and presented for San Diego, California, and simplified probabilistic equations necessary to use the reference parameter maps are summarized. An example map-based liquefaction triggering and lateral spread displacement analysis is performed for a representative site near San Diego Bay. Results of the analysis demonstrate that the probabilistic assessment confirms and augments the information conveyed by the traditional liquefaction hazard map.

Real-time assessment framework of spatial liquefaction hazard in port areas considering site-specific seismic response

This paper proposes a systematic framework for real-time assessment of spatial liquefaction hazard of port areas considering local seismic response characteristics based on a geographic information system (GIS) platform. The framework is integrated and embedded with sequential, interrelated subprocedures and a database for liquefaction-induced damage evaluation that standardizes and both individually and collectively quantifies analytical results. To integrate the current in situ condition of a selected port area, the framework functions as a spatial database system for geotechnical and structural data and as a recipient of automatic transmission of seismic monitoring data. The geotechnical profile correlated with liquefaction potential is compiled into a geotechnical spatial grid built by geostatistical methods. Linked with the geotechnical spatial grid, the processing of site-specific responses is automatically interpreted from previously derived correlations between rock acceleration and maximum acceleration of each soil layer. As a result, the liquefaction severity is determined based on a combined geotechnical spatial grid with seismic load correlation in real-time according to a simplified procedure, allowing calculation of the liquefaction potential index (LPI). To demonstrate practical applications of the framework in estimating the liquefaction hazard in real-time, liquefaction-hazard maps were visualized for two earthquake scenarios, verifying the applicability of the proposed framework.

Liquefaction Hazard Assessment Using SPT and VS for Two Cities in India

The seismic behavior of a saturated soil depends on the potential for significant strains or strength loss that can contribute to ground deformations or instability during an earthquake. Historic large earthquakes throughout the world explain that the liquefaction related ground failure commonly causes extensive structural and lifeline damage in urban areas. Detailed assessment of liquefaction hazard is important for evaluating and reducing the risk through appropriate mitigation techniques. Soil liquefaction generally occurs in areas underlain by low density, saturated granular sediments. The liquefaction susceptibility can be mapped using specific, well established geologic and geotechnical criteria. Damages caused by liquefaction of saturated soil revealed that after liquefaction the ground failed, sand boiling occurred and the structure subsided unevenly causing tilting, cracking or even collapse. After the devastating 2001 Gujarat earthquake, the Government of India has paid serious attention to carry out the detailed site characterization and ground response studies which are very crucial in seismic microzonation and it is also accepted as a guiding tool in land use planning and safe construction practices to avoid the loss from the future earthquakes. Very preliminary process of reducing the effects of earthquake is by assessing the hazard itself. As part of the national level microzonation program, Department of Science and Technology, Govt. of India has initiated microzonation of 63 cities in India. In this research paper two urban centers Delhi and Vijayawada city which falls in seismic zones IV and III respectively are considered for liquefaction hazard assessment. Since these two cities are falling in the areas with high and moderate seismic probability, there is a great need for the assessment of liquefaction potential. An attempt has been made estimate the liquefaction hazard for these two cities considered using the measured shear wave velocities and SPT borehole data. From the detailed liquefaction assessment, it is observed that the possibility is severe in the north and north eastern side of Delhi and is very less in the western side of the city. In the south and central part of the area where shear wave velocities of the soil strata is ≥180 m/s the possibility of liquefaction is unlikely and in Vijayawada city, the occurrence of liquefaction is likely at several locations especially in Patamata, Autonagar and Kanuru.

Assessment of Liquefaction Potential Index Using Deterministic and Probabilistic Approaches

Liquefaction is a devastating effect of earthquakes resulting in sudden decrease in shear strength due to excess pore water pressure generation, resulting in differential settlement of structure, inducing severe damages. Assessment of liquefaction hazard for a given site is important for planning out mitigation works. In this paper the liquefaction susceptibility using deterministic and probabilistic methodologies was assessed and results are presented in terms of liquefaction potential index (LPI) for a nuclear power plant site. The results of this study are explored further in the article.

Probabilistic seismic hazard assessment for the sliding displacement and liquefaction potential of offshore sites

This research is intended to present probabilistic sliding displacement and liquefaction hazard assessment procedures where expected sliding displacement of offshore slopes and factor of safety against liquefaction potential of subsoils are derived for extreme level earthquake and abnormal level earthquake conditions, as defined in the ISO 19901-2 guideline. These probabilistic approaches rigorously account for the variability in the intensity measure (e.g. ground acceleration), the variability in the engineering demand parameters (EDP) (e.g. sliding displacement and factor of safety against liquefaction), and the variability in the soil input parameters required to compute the EDP. The procedures are applied to a hypothetical site in the vicinity of oil and gas platforms located in the Santa Barbara Channel in Southern California.