Liquefaction Research Articles

Classification and Semiquantitative Evaluation of Paleoearthquake Identification From Trenches on Normal Faults: A Case Study of Holocene Paleoearthquake Events From the Northern Margin of the Hetao Basin, China

AbstractLong paleoearthquake series are crucial for understanding the recurrence patterns of active faults and evaluating the seismic hazards of faults. In this study, the first semiquantitative evaluation of paleoearthquake events from trenches was applied to normal faults, and classification criteria for identifying paleoearthquakes in trenches on normal faults are proposed to demonstrate the feasibility of semiquantitative evaluations of paleoearthquake events on normal faults. In this study, 72 paleoearthquake trench sites on normal faults around the world were analyzed, and the main indicators for identifying paleoearthquakes on normal faults include the presence of vertical offset (VO), collapse wedge (CW), fissure (FIS), buried paleosol (BP), angular unconformity (AU), upward termination (UT), and sand liquefaction (LF) features. To describe and apply this semiquantitative evaluation method for paleoearthquake events on normal faults, 33 trenches for paleoearthquakes on a fault system in the northern margin of the Hetao Basin were comprehensively analyzed to determine Holocene paleoearthquake events on the Sertengshan, Wulashan, and Daqingshan piedmont faults, and the reliability of paleoearthquake events is discussed. The integrity of the paleoearthquake events obtained was tested by the displacement limit method. The Holocene paleoearthquake recurrence on the three faults was quasiperiodic; the coefficients of variation (COVs) were 0.44, 0.58, and 0.4.

Numerical simulation of liquified natural gas droplet breakup in gas phase flow

Numerical simulation of liquified natural gas droplet breakup in gas phase flow

Research on the anti-seismic performance of composite precast utility tunnels based on the shaking table test and simulation analysis

In this paper, the parameters of haunch height, reinforcement ratio and site condition were evaluated for the influence on the seismic performance of a composite precast fabricated utility tunnel by shaking table test and numerical simulation. The dynamic response laws of acceleration, interlayer displacement and steel strain under unidirectional horizontal seismic excitation were analyzed through four specimens with a similarity ratio of 1:6 in the test. And a numerical model was established and analyzed by the finite element software ABAQUS based on the structure of utility tunnel. The results indicated that composite precast fabricated utility tunnel with the good anti-seismic performance. In a certain range, increasing the height of haunch or the ratio of reinforcement could reduce the influence of seismic wave on the utility tunnel structure, which was beneficial to the structure earthquake resistance. The clay field containing the interlayer of liquefied sandy soil has a certain damping effect on the structure of the utility tunnel, and the displacement response could be reduced by 14.1%. Under the excitation of strong earthquake, the reinforcement strain at the side wall upper end and haunches of the utility tunnel was the biggest, which is the key part of the structure. The experimental results were in good agreement with the fitting results, and the results could provide a reference value for the anti-seismic design and application of composite precast fabricated utility tunnel.

Corrigendum: Thermodynamic performance of ammonia in liquefied natural gas precooling cycle

Simeon Oka, Editor-in-Chief Emeritus of the journal Thermal Science request that it is necessary write correction in Table 6, p. 2012, in the paper THERMODYNAMIC PERFORMANCE OF AMMONIA IN LIQUEFIED NATURAL GAS PRECOOLING CYCLE by Ray SOUJOUDI* and Randall MANTEUFEL Department of Mechanical Engineering, University of Texas, San Antonio, Tex., USA Original scientific paper https://doi.org/10.2298/TSCI201227072S published in the journal Thermal Science, Year 2021, Vol. 25, No. 3A, pp. 2003-2016 <br><br><font color="red"><b> Link to the corrected article <u><a href="http://dx.doi.org/10.2298/TSCI201227072S">10.2298/TSCI201227072S</a></b></u>

Study on the Effect of Small Molecule Compounds on the Structure and Properties of Coal

In this research, small molecular compounds are extracted from Shenfu coal using solvent extraction method, then through analysis and comparison, the structure and properties of coal before and after extraction of coal in order to study small molecular compounds affect the structure and properties of coal. The results show that they have been affected to varying degrees and the core of the coal structural unit aromatic ring has not been reduced, the macromolecular structure of coal has not changed after the extraction of coal. And these studies surely help to study the reaction mechanism of coal liquefaction and guide the study of coal macromolecular.

Desarrollo de correlaciones para determinar el potencial a licuefacción mediante la aplicación del ensayo de penetración estática de piezocono (CPTu) en una cámara de calibración (CC).

El objetivo principal de este proyecto fue desarrollar correlaciones para determinar el potenciala licuefacción de depósitos de arenas sueltas empleando el ensayo de penetración estáticade piezocono CPTu; para ello fue necesario determinar el comportamiento de ensayos (CPTu)en la cámara de calibración (CC) del Laboratorio de Mecánica de Suelos y Rocas (IBF) en elInstituto Tecnológico de Karlruhe, además determinar la resistencia a licuefacción por mediode ensayos triaxiales cíclicos no drenados para muestras de arena, plantear una correlaciónentre la densidad relativa de almacenamiento (ID) de la muestra, la resistencia de punta(qc) del CPTu y la resistencia al flujo (CRR) de los ensayos triaxiales y por último compararla correlación experimental obtenida con correlaciones existentes de la literatura. Con esteproyecto se concluyó que en la región de bajas densidades de almacenamiento y bajasresistencias en punta una buena similitud, esto al comparar las correlaciones para los materialesexperimentales estudiados por el IBF con correlaciones provenientes de la literatura. Ahora bien,para densidades altas y, por lo tanto, mayores resistencias en punta, las curvas de correlaciónpara los materiales experimentales fueron más planas que en referencias bibliográficas; enotras palabras, la resistencia a licuefacción de los materiales experimentales en esta área esmenor de lo que habrían predicho las curvas de la literatura. Así pues, no es posible aplicardirectamente los resultados de este proyecto a otros sitios de estudio; ya que los materialesde las correlaciones realizadas (Kali4) y otros suelos difieren en aspectos como la mineralogía(criterios geológicos), la granulometría y la forma de partícula (criterios de composición); loscuales influyen sobre la susceptibilidad a la licuación.

Evaluation of Liquefaction Triggering for the Pohang Area Based on SPT and CPT Tests

Evaluation of Liquefaction Triggering for the Pohang Area Based on SPT and CPT Tests

Horizontal vibration response analysis of piles in liquefied soil under Winkler foundation model

Horizontal vibration response analysis of piles in liquefied soil under Winkler foundation model

Evaluation of Input Parameters in Constitutive Models Based on Liquefaction Resistance Curve and Laboratory Tests

Evaluation of Input Parameters in Constitutive Models Based on Liquefaction Resistance Curve and Laboratory Tests

Wave-induced liquefaction hazard assessment and liquefaction depth distribution: A case study in the Yellow River Estuary, China

Predicting the potential depth of wave-induced liquefaction is of vital importance of hazard assessment. Prevention and mitigation of liquefaction hazard can be carried out after predicting the liquefaction potential depth. Sediment geotechnical parameters were summarized from historical engineering projects and calculated liquefaction depth with data of actually measured water depth, sediment types and different wave recurrence periods. Then the study area was divided into different liquefaction zones. Results showed that both liquefaction range and depth increased with wave return period, which remained steady when increased to a certain extent. The calculated liquefaction depth was compared with the thickness of liquefied layers, which obtained by geophysical methods. Result shows that the average difference was about 1m, which means the method of liquefaction depth calculation was applicable in this study area. At last, in order to reduce harm of liquefaction, potential maximum liquefaction depth (PMLD) is put forward. PMLD is the smaller one between the thickness of seabed liquefiable sediment and the maximum calculated liquefaction depth. The calculation and partition of liquefaction depth can be more accurate after considering PMLD.

Techno-economic Feasibility of Thermochemical Conversion Pathways for Regional Agricultural Waste Biomass

This study examines four prominent thermochemical conversion technologies such as slow pyrolysis (SP), fast pyrolysis (FP), gasification (GA) and hydrothermal liquefaction (HTL), for treating poultry litter in New York State (NYS). Nine cases involving various combinations of the four technologies and different downstream processing options such as bio-oil upgrading, Fischer-Tropsch conversion and combined heat and power generation are chosen based on the product composition and distribution. High-fidelity process simulations for each technological platform are performed to derive the mass and energy balance information. Calculations and breakdown of the equipment costs, capital costs, operating and maintenance costs and utilities are provided and compared extensively for each of the nine cases. The economic performance is further analyzed by calculating and comparing the resultant net present values (NPV), ranging from $10 M to $170 M (SP), $89 M to $314.5 M (FP), $28 M to $196 M (HTL) and $25 M to $234 M (GA). The greenhouse gas emission inventories are also compiled to understand the corresponding impacts of different downstream processing choices (ranging from 217 to 494.5 kg CO2-eq/t feedstock with both the pyrolysis technologies outperforming the others in most cases) and to highlight the trade-off with economic performance. Through sensitivity analysis, the influential factors requiring further investigation are identified and it is found that plant capacity and bio-oil yield are the most important parameters for the fast pyrolysis systems, biochar price for SP is the single most important parameter.

Comparative study and multi-objective optimization of various configurations in natural gas liquefaction process

PRICO process is a promising method for liquefaction of the natural gas which is sometimes used with some optional equipment. Although the PRICO process is widely used in natural gas liquefaction, the configuration leading to the most desirable performance has not been determined. The liquefaction rate and the energy consumption are two important factors to evaluate the performance of the PRICO process. In this paper, the PRICO process with five different configurations were simulated and compared. By the means of the multi-objective optimization method, the liquefaction rate and the energy consumption were optimized, simultaneously, for the each of the procedures. The five different simulated configurations are simple PRICO process, simple process with third compressor, simple process with second heat exchanger, simple process with precooling heat exchanger and full-set process. The optimization results demonstrated that the three-compressor and the full-set processes achieved the maximum liquefaction rate (96.51) and the minimum energy consumption (1219.53 kW), respectively. The economic analysis has also presented and revealed that the three-compressor process had the highest net profit (730.9288 M$/25 years) among the configurations. In other words, three-compressor process outperformed other configurations with respect to the operation and economics (maximum liquefaction rate of 96.51 and net profit of 730.9288 M$/25 years).

Feasibility Study for Revision of Domestic Liquefaction Evaluation Criteria by Analyzing the Liquefaction Phenomenon Caused by the Pohang Earthquake

Feasibility Study for Revision of Domestic Liquefaction Evaluation Criteria by Analyzing the Liquefaction Phenomenon Caused by the Pohang Earthquake

An analysis of CT and MRI features of 16 patients with primary hepatic sarcomatoid carcinoma

Objective To analyze the CT and MRI features of primary hepatic sarcomatoid carcinoma. Methods A retrospective study was conducted on 16 patients with primary hepatic sarcomatoid carcinoma who presented to Wenzhou People's Hospital of Zhejiang Province and the Second Affiliated Hospital of Wenzhou Medical University from January 2009 to June 2019. There were 8 males and 8 females, with age ranging from 35 to 71 years (average 56.8 years). The site, size, shape, margin, density of signal, adjacent tissue changes and degree enhancement of tumor were analyzed. Results Tumors in the liver in the 16 patients were all solitary, with 11 in the right and 5 in the left liver. The maximum diameter of tumor ranged from 3 to 16cm (average 8.5cm). On plain CT scanning (n=16), the tumors were round or oval in 6, and lobulated or irregular in 10 patients. The margins of the tumors were clear in 10 and unclear in 6 patients. All tumors showed low density, with 15 tumors showing uneven density, with necrosis and liquefaction of different sizes in the center, while 1 tumor showing uniform density. On plain MRI scanning (n=4), four tumors had clear margins, with necrosis and liquefaction seen in the center of the tumors. The solid part showed a slightly lower signal on T1 weighted imaging and a slightly higher signal on T2 weighted imaging. The liquefaction focus of central necrosis showed higher signal intensity on T2 weighted imaging. Enhanced scanning (n=12 on CT enhancement and n=4 on MRI enhancement), the margins of the tumors were enhanced in the arterial phase. The enhancement was continued into the portal venous and delayed phases in 7 patients. Strip septate and margin enhancement in the tumor were enhanced in the arterial phase. The enhancement was continued into the portal venous and delayed phases in 7 patients. Inhomogeneous strengthening in the tumor was enhanced in the arterial phase. The enhancement was continued into the portal venous and delayed phases in 1 patient. Inhomogeneous strengthening in the tumor was enhanced in the arterial phase. The enhancement was continued into the portal venous phase. In the delayed phase, enhancement in the tumor decreased, but there was continuous enhancement of the margin and interval of the tumor in 1 patient. Conclusions Hepatic sarcomatoid carcinoma showed dual imaging characteristics of sarcoma and cancer. The imaging features of hepatic sarcomatoid carcinoma depended on the proportion of sarcomatoid components. Large intrahepatic tumors showed necrotic cystic degeneration, moderate or significant persistent enhancement in striped septum and margin of tumor. Key words: Liver neoplasms; Sarcomatoid carcinoma; Tomography, X-ray computers; Magnetic resonance imaging

VALIDAÇÃO DE MODELOS SIMPLIFICADOS DE PREVISÃO DO TEMPO DE LIQUEFAÇÃO ATRAVÉS DE ENSAIOS DE CENTRIFUGADORA

Os danos resultantes da ocorrência de sismos podem resultar da combinação da excitação sísmica e/ou de incrementos de pressão neutra no solo (liquefação). Estes dois efeitos estão interligados, uma vez que a redução da rigidez do solo por efeito da diminuição da tensão efetiva altera o comportamento mecânico do solo, nomeadamente a sua resposta sísmica. Assim, o nível e o tipo de danos são dependentes da velocidade de aumento da pressão neutra e do tempo para o qual a liquefação é desencadeada no solo, associada à energia sísmica libertada ao longo do tempo. No entanto, a maioria dos métodos simplificados de previsão da liquefação foca-se na identificação desse desencadeamento e não no tempo para o qual esta se desenvolve. Assim, é fundamental melhorar e desenvolver estes métodos para que possam fornecer estimativas confiáveis do efeito deste processo de aumento de pressão neutra e consequente progresso da liquefação nos horizontes sensíveis. Nesse sentido, os ensaios de centrifugadora são uma excelente oportunidade para validar esses métodos. Este artigo apresenta dois métodos simplificados de previsão da liquefação, e valida-os através da sua utilização para prever o aumento da pressão neutra numa série de ensaios de centrifugadora.

소용량 수소액화 파일럿 플랜트 구축을 위한 공정의 열역학 해석

소용량 수소액화 파일럿 플랜트 구축을 위한 공정의 열역학 해석

Optimal Sizing of Small Scale Liquefied Natural Gas Storage using Numerical Cascade Pinch Analysis

Increasing demand for liquefied natural gas (LNG) at the inaccessible area through pipeline has provided a solid platform for the emergence of new small scale LNG (ssLNG). The key challenges related to the ssLNG business are relatively expensive supply chain due to the diseconomy of small scale and meeting the security of supply and demand with limited supply alternatives available. Nevertheless, the market has increasingly become the preferred delivery method for natural gas (NG) because LNG can be produced at remote locations and distributed to end-users conveniently. To date, extensive works with a variety of objectives have been developed in an attempt to optimise the ssLNG supply chain in terms of conversion, transportation, and utilisation yet an optimal synthesis of LNG for small scale market has not been adequately investigated. The activity of loading and unloading of LNG in supply port terminals needs sufficient capacity of LNG storage tank. Designing an adequate capacity is necessary in order to secure reliable supplies of LNG as well as to offset fluctuations in the supply and demand of LNG. This work aims to ease industrial planner to design an optimal capacity of ssLNG storage by implementing a well established numerical cascade approach based on Pinch Analysis technique and proposed a new numerical approach of small scale LNG-Storage Cascade Analysis (ssLNG-SCA). Based on the proposed tool, the minimum amount of LNG supply for operation has been reduced from 2,100 m3 to 1,400 m3 due to the stored amount of excess LNG supply (700 m3) during start-up with the existence of ssLNG storage tank. The developed ssLNG-SCA in this work shows a significantly reduced storage capacity from 24,000 m3 to 6,300 m3 thus eliminate the need to provide for a larger and higher price of LNG storage tank. The storage offers delivery of NG to virtual trading hubs to meet end-user demand which inaccessible to the high-pressure pipeline.

Efficacy of open reduction and internal fixation in management of senile osteoporotic ankle fractures

Objective To explore the efficacy of open reduction and internal fixation in the treatment of senile osteoporotic ankle fractures. Methods A retrospective case series study was conducted to analyze the data of 26 elderly patients with osteoporotic ankle fractures which all caused by sprain from June 2012 to June 2018 in Changhai Hospital, including 10 male and 16 female patients aged from 60 to 93 years (mean, 69.72 years). In these 26 patients, three had medial malleolus fractures, four had lateral malleolus fractures, six had double ankle fractures and 13 had cotton's fractures. According to the Lauge-Hansen type, all 26 patients can be classified into four types: 5 with supination external rotation type, 4 supination adduction type, 16 with pronation-external rotation type and 1 with pronation abduction type. All the patients received open reduction and internal fixation. Plate fixation was used for lateral and posterior malleolus fractures, plate fixation and cannulated screws were applied to fix the comminuted posterior malleolus fracture while in the comminuted internal malleolus fracture, the steel plate was used only when needed. Early professional functional rehabilitation training and active anti-osteoporosis treatment were applied. All the operation time and bleeding volume were recorded, and the reduction of fracture plus the healing of wounds were observed. At last follow-up, American Orthopedic Foot & Ankle Society (AOFAS) Ankle Hindfoot Scale was used to evaluate the treatment effect and the Visual Analogue Scale (VAS)to evaluate the therapeutic effect and the subjective satisfaction of the patients. Complications were recorded as well. Results All patients were followed up for 12-48 months (mean, 23.6 months). Operation time ranged from 30 to 95 minutes (mean, 70 minutes) and bleeding volume ranged from 10 to 150 ml (mean, 70 ml). All patients got satisfied reduction of fracture within 25 patients' incision healing in first intention, although one has fat liquefaction. AOFAS Ankle Hindfoot Scale improved from preoperative (84.4±10.8)points to (31.9±11.4)points at last follow-up (P<0.01), and the results were excellent in five patients, good in 17, fair in three and poor in one, with the excellent and good rate of 85%. VAS improved from preoperative(1.85±0.73)points to (9.23±0.28)points at last follow-up (P<0.01). Among 26 patients, 5 with ankle stiffness of different degree recovered after rehabilitation care, and 2 with internal malleolus fractures had bone displacement when receiving rehabilitation care, with no side effect on basic function. No serious complications such as wound infection or skin necrosis were found. Conclusion For osteoporotic ankle fractures in the elderly, open reduction and internal fixation can promote functional recovery and relieve pain. Key words: Ankle injuries; Osteoporotic fractures; Fracture fixation, internal

Investigation of the effect of grain size on liquefaction potential of sands

Due to the permanent damage to structures during earthquakes, soil liquefaction is an important issue in geotechnical earthquake engineering that needs to be investigated. Typical examples of soil liquefaction have been observed in many earthquakes, particularly in Alaska, Niigata (1964), San Fernando (1971), Loma Prieta (1989), Kobe (1995) and Izmit (1999) earthquakes. In this study, liquefaction behavior of uniform sands of different grain sizes was investigated by using the energy-based method. For this purpose, a total of 36 deformation-controlled tests were conducted on water-saturated samples in undrained conditions by using the cyclic simple shear test method and considering the relative density, effective stress and mean grain size parameters that affect the cumulative liquefaction energy. The results showed that as the mean grain size decreases, the liquefaction potential of the sand increases. In addition, with increasing effective stress and relative density, the resistance of sand against liquefaction decreases. Multiple regression analysis was performed on the test results and separate correlations were proposed for the samples with mean grain size of 0.11-0.26 mm and for the ones with 0.45-0.85 mm. The recommended relationships were compared to the ones existing in the literature and compatible results were obtained.

Incorporating ground motion effects into Sasaki and Tamura prediction equations of liquefaction-induced uplift of underground structures

In metropolitan areas, the quantity and density of the underground structure increase rapidly in recent years. Even though most damage incidents of the underground structure were minor, there were still few incidents causing a great loss in lives and economy. Therefore, the safety evaluation of the underground structure becomes an important issue in the disaster prevention plan. Liquefaction induced uplift is one important factor damaging the underground structure. In order to perform a preliminary evaluation on the safety of the underground structure, simplified prediction equations were introduced to provide a first order estimation of the liquefaction induced uplift. From previous studies, the input motion is a major factor affecting the magnitude of the uplift. However, effects of the input motion were not studied and included in these equations in an appropriate and rational manner. In this article, a numerical simulation approach (FLAC program with UBCSAND model) is adopted to study effects of the input motion on the uplift. Numerical results show that the uplift and the Arias Intensity (Ia) are closely related. A simple modification procedure to include the input motion effects in the Sasaki and Tamura prediction equation is proposed in this article for engineering practices.