Electrical resistivity change of saturated sand during reliquefaction under hammering loading

The electrical resistivity method was verified as an optional technique to monitor the change of mesostructure of saturated soils.To investigate the change laws of resistivity and analyze the reliquefaction meso-mechanism during the consecutive liquefaction process,five successive impact liquefaction tests were performed in a one-dimensional cubical chamber.The resistivity variation and excess pore water pressure(EPWP)were measured.The results indicate that the excess pore water pressure experienced four stages:quick increase stage,slow dissipation stage,rapid dissipation stage,and stability stage.Meanwhile,a swift decrease of resistivity emerged before the start of the rapid dissipation stage of EPWP,and then an increasing trend of resistivity is demonstrated with the densification of soil.It is proved that the vertical pore connectivity of liquefied sand is better than its random deposit state,based on a comparative study of porosity calculated from the settlement and resistivity of sand after each test.

Experimental studies on liquefaction and reliquefaction potential of saturated ground subjected to repeated incremental acceleration loading with varying shaking duration

Past research has focused on the factors that influence liquefaction under normal shaking conditions.However,studies on parameters that influence the reliquefaction potential of saturated deposits during repeated shaking events are limited.In this study,an attempt has been made to examine the influence of acceleration amplitude and shaking duration on liquefaction and reliquefaction potential under repeated shaking conditions is conducted.1-g uni-axial shaking table experiments were performed on saturated ground prepared with 40%and 60%relative density.The prepared ground was subjected to alternate longer and shorter shaking durations(40 and 20 s)of repeated incremental 0.1 g,0.2 g,0.3 g and 0.4 g acceleration loading,respectively.The variation in density,excess pore water pressure(EPWP),cyclic resistance ratio(CRR)and surface settlement were estimated.The results showed that due to repeated incremental shaking events,reliquefaction was observed on the prepared ground.During longer shaking duration,the post-liquefied soil showed density improvement with improved soil resistance.However,the application of shorter duration loading followed by longer shaking reduced the beneficial effect of density improvement by disturbing the densified ground.Due to this,the ground was found to be more susceptible to reliquefaction in the subsequent incremental longer shaking event.

国内外LNG船再液化系统及其关键设备发展现状

为了实现LNG船再液化系统及其关键设备的国产化和自主可控发展,调研了国内外再液化系统厂家。根据处理对象将系统分为Reliquefaction和Subcooler,分析不同厂家的工艺特点、设备组成,并对比不同厂家的市场、成本优劣。

Large-scale liquefied natural gas ships

Design Unit and Construction Shipyard:Hudong-Zhonghua Shipbuilding(Group)Co.,Ltd.Ship Classification Society:China Classification Society,Lloyd's Register of Shipping,American Bureau of Shipping,etc.1 Overview of liquefied natural gas(LNG)ships Compared with other fossil fuels,such as coal and oil,natural gas emits less carbon dioxide and no sulfide and dust;therefore,it is considered cleaner and an important direction for China’s implementation of its energy strategy adjustment.Natural gas accounts for over 20%of primary energy worldwide.