考虑水流侵入的海上风机基础灌浆连接段疲劳性能试验研究

海上风机基础中的灌浆连接段会在浪溅区或者水下工作,水流的侵入可能会对灌浆连接段的疲劳性能产生影响。本文设计了灌浆连接段局部性能试件,其中四个试件在空气中进行疲劳加载;同时,设计了一套水循环装置,让两个试件在水流侵入的条件下进行疲劳加载。试验结果表明,空气中疲劳荷载幅较大的试件A-3的灌浆材料出现了较宽的裂纹和剥落现象,试件加载的残余变形不断累积。同时,相同荷载幅条件下的两对试件相比,空气中的2个试件经过200万次疲劳循环总变形都在-0.7 mm以内;而水中的2个试件仅加载至26.4万次及6.4万次时,试验机位移便达到-10 mm,试验终止。由此可见,水流侵入会严重劣化灌浆连接段的疲劳性能。原因在于,水流会侵入灌浆材料裂纹内部,在荷载加载时,侵入的水分挤压灌浆材料局部的缝隙,加速裂纹的形成与开展;而在荷载卸载时,水流带走被压碎的灌浆材料,使得裂纹不稳定扩展,灌浆材料块体剥落。

Intrusions of Kuroshio and Shelf Waters on Northern Slope of South China Sea in Summer 2015

The northern slope region of the South China Sea(SCS) is a biological hot spot characterized by high primary productivity and biomasses transported by cross-shelf currents, which support the spawning and growth of commercially and ecologically important fish species. To understand the physical and biogeochemical processes that promote the high primary production of this region, we conducted a cruise from June 10 and July 2, 2015. In this study, we used fuzzy cluster analysis and optimum multiparameter analysis methods to analyze the hydrographic data collected during the cruise to determine the compositions of the upper 55-m water masses on the SCS northern slope and thereby elucidate the cross-slope transport of shelf water(SHW) and the intrusions of Kuroshio water(KW). We also analyzed the geostrophic currents derived from acoustic Doppler current profiler measurements and satellite data. The results reveal the surface waters on the northern slope of the SCS to be primarily composed of waters originating from South China Sea water(SCSW), KW, and SHW. The SCSW dominated a majority of the study region at percentages ranging between 60% and 100%. We found a strong cross-slope current with speeds greater than 50 cms^(-1) to have carried SHW into and through the surveyed slope area, and KW to have intruded onto the slope via mesoscale eddies, thereby dominating the southwestern section of the study area.

Seasonal variation of the Taiwan Warm Current Water and its underlying mechanism

Based on the historical observed data and the modeling results,this paper investigated the seasonal variations in the Taiwan Warm Current Water(TWCW)using a cluster analysis method and examined the contributions of the Kuroshio onshore intrusion and the Taiwan Strait Warm Current(TSWC)to the TWCW on seasonal time scales.The TWCW has obviously seasonal variation in its horizontal distribution,T-S characteristics and volume.The volume of TWCW is maximum(13746 km^3)in winter and minimum(11397 km^3)in autumn.As to the contributions to the TWCW,the TSWC is greatest in summer and smallest in winter,while the Kuroshio onshore intrusion northeast of Taiwan Island is strongest in winter and weakest in summer.By comparison,the Kuroshio onshore intrusion make greater contributions to the Taiwan Warm Current Surface Water(TWCSW)than the TSWC for most of the year,except for in the summertime(from June to August),while the Kuroshio Subsurface Water(KSSW)dominate the Taiwan Warm Current Deep Water(TWCDW).The analysis results demonstrate that the local monsoon winds is the dominant factor controlling the seasonal variation in the TWCW volume via Ekman dynamics,while the surface heat fl ux can play a secondary role via the joint ef fect of baroclinicity and relief.

Impact of seasonal tide variation on saltwater intrusion in the Changjiang River estuary

An improved 3-D ECOM-si model was used to study the impact of seasonal tide variation on saltwater intrusion into the Changjiang River estuary, especially at the bifurcation of the North Branch （NB） and the South Branch （SB）. The study assumes that the fiver discharge and wind are constant. The model successfully reproduced the saltwater intrusion. During spring tide, there is water and salt spillover （WSO and SSO） from the NB into the SB, and tidally averaged （net） water and salt fluxes are 985 m3/s and 24.8 ton/s, respectively. During neap tide, the WSO disappears and its net water flux is 122 m3/s. Meanwhile, the SSO continues, with net salt flux of 1.01 ton/s, much smaller than during spring tide. Because the tidal range during spring tide is smaller in June than in March, overall saltwater intrusion is weaker in June than in March during that tidal period. However, the WSO and SSO still exist in June. Net water and salt fluxes in that month are 622 m3/s and 15.35 ton/s, respectively, decreasing by 363 m3/s and 9.45 ton/s over those in March. Because tidal range during neap tide is greater in June than in March, saltwater intrusion in June is stronger than in March during that tidal period. The WSO and SSO appear in June, with net water and salt fluxes of 280 m3/s and 8.55 ton/s, respectively, increasing by 402 m3/s and 7.54 ton/s over those in March. Saltwater intrusion in the estuary is controlled by the fiver discharge, semi-diurnal flood-ebb tide, semi-monthly spring or neap tide, and seasonal tide variation.

Assessment of Saline Water Intrusion into Huong River in Dry Season

Most rivers in Vietnam flow directly to the sea where the interaction between fresh and salt water occurs. Because of uneven flow distribution through the year with only 20% annual flow in the dry season, while fresh water requirement for socio-economic activity in this season is much higher. With this situation, the simulation and finding out the mechanism of saline water intrusion into the estuary in general will help to suggest suitable solutions to control the situation. This paper presents results done at the Huong river estuary. Based on the data collected in current years and using MIKE11 softwave, number scenarios were simulated and found out the intruded process of saline water into the river. They will be very important parameters for which solutions to control negative effects to serve socio-economic development at the downstream of Huong river will be recommended and implemented in the later stage.