澳门土壤剪切波速的相关性分析

土壤的剪切波速(VS),是抗震设计的一个重要参数,但有关澳门土层的相关资料则十分稀少。研究的主要目的是根据近期野外测试的结果,探讨澳门土层的VS与标准贯入试验的打击锤数(N)的关系,并以简单之幂函数建立VS与N值的关系式。作为澳门轻轨交通系统之勘察计划,研究进行了五组下孔法(DH),地震波圆锥触探试验(S-CPT)以及标准贯入试验(SPT)的测试。根据试验结果所得的关系式估算剪切波速高于较澳门轻轨设计大纲的建议值,而使用另一有关澳门土层的数据库来验证新的关系式,亦可获得合理的决定系数。     

地下水位循环变化时隧道开挖对群桩的长期影响研究

为解决地下水位随季节升降变化时隧道开挖对邻近桩基的长期影响难题,通过三维离心模型试验,研究了地下水位循环变化时隧道对群桩的长期影响。主要分析水位循环变化时地表长期沉降、桩顶长期附加沉降、桩身长期附加弯矩和附加轴力的变化规律。试验结果表明：在隧道附近,地下水位循环变化尤其是降水对地表长期沉降影响更为明显。地表长期附加沉降随着地下水位循环次数增加而增大,且呈衰减式变形,即使经过3次水位升降循环也不能稳定;桩基长期附加沉降显著,其附加沉降量占总沉降量的50%以上;前、后桩的长期附加轴力基本为正值,桩总轴力增加,对既有受压桩极为不利,附加轴力拐点位置及最大值有所区别;经过3次地下水位循环变化后,前、后桩桩身弯矩反弯点个数减少,但桩身最大附加弯矩均明显变大,当达到极限弯矩,桩身出现塑性铰,这对穿越厚软弱层地基中的既有受压柔性桩极为危险。     

Wave power statistics for individual waves

The paper provides a bivariate distribution of wave power and wave height, as well as a bivariate distribution of wave power and wave period; both bivariate distributions are for individual waves within a sea state. This is relevant for e.g. making assessments of wave power devices and their potential for converting energy from waves. The results can be applied to compare systematically the wave power potential for individual waves in a given sea state at different locations.     

胶东晚中生代金矿成矿的硫同位素组成及热动力源

胶东地区晚中生代金矿床均有一个与岛弧玄武质、安山质岩浆相一致的δ^34(6．5‰-7.0‰)硫源，而全铜矿床的δ^34为4．5‰-5．0‰，与岛弧玄武质岩浆的δ^34接近。可初步认为该区全(铜)成矿流体的热源来自地慢或俯冲地慢楔产生的玄武岩浆。成矿流体的产生与岛弧玄武质岩浆底侵／内侵作用密切相关，形成于被加热的地壳。     

Near-source particulate emissions and plume dynamics from agricultural field operations

Particulate matter emissions generated by agricultural field preparation and harvesting operations were measured remotely via aerosol lidar and sampled simultaneously with a variety of aerosol point samplers in order to quantify dust plume space and time dynamics and particulate mass and number concentrations. Data for two cotton operations (disking, harvesting) in a flood-irrigated field in New Mexico are presented. Dust plume dynamics varied with boundary layer meteorological conditions, especially atmospheric stability, with plume maximum height significantly lower under stable conditions. Plume tracking indicated little change in plume area with height under unstable conditions and plume movement depended on wind speed and direction. Particle mass distributions indicate approximately 50% of the measured PM₁₀ mass was PM_2.5, significantly higher than previously reported values, possibly due to the near-source nature of the samples collected here. Variability in plume movement matched the variability in short-term wind fluctuations and this variability helps explain why models that utilize long-term averages perform poorly when trying to capture plume dynamics for nonsteady sources such as tractor operations.     

Lessons Learned from the Tragedy during the 100 km Ultramarathon Race in Baiyin,Gansu Province on 22 May 2021

Twenty-one runners died of hypothermia during the 100 km Ultramarathon Mountain race in Baiyin, Gansu Province on 22 May 2021. The hypothermia was caused by a combination of low temperatures, precipitation, and high winds associated with a typical large-scale cold front passing by the race site that morning. Based on historical hourly records of13 meteorological surface stations over the past six years, temperature(3.0°C) and apparent temperature(-5.1°C) at 1200 LST as well as gust wind speed(11.2 m s-1) at 1100 LST on the day of the tragedy were found to be within the top or bottom 5 th percentile for the month of May. The precipitation was only moderate at this time, but when temperature lower than 3.0°C,gust wind speed greater than 11.2 m s-1, and precipitation greater than 0.1 mm for any adjacent three hours were combined together, 1200 LST 22 May fell within the top 0.1% of cases. The European Centre for Medium-range Weather Forecasting model produced reasonably good forecasts of the low temperature and high wind one day and seven days before the event,respectfully. Based on this study, lessons that can be learned from this tragedy are summarized from an academic perspective: Hazard and impact forecasts of high-impact weather events should be developed to increase the value of weather forecasts. Probability forecasts should be issued by government weather agencies and communicated well to the public. And more importantly, knowledge of how to evaluate the impact of weather should be delivered to the public in the future.We would like to extend our deepest condolences to the families and loved ones of the people who lost their lives in this tragedy, including 21 runners and one officer. May our efforts honor those who lost their lives by highlighting the value of weather forecasting and calling for greater action in the future.     

中国香港大型酸性火山岩六方柱状节理构造景观及其地质成因意义

在简单介绍中国香港地质概况的基础上,对发育在香港境内酸性火山岩中的大型六方柱状节理构造景观进行了介绍,并对其形成的地质基础和过程进行了探讨.对世界上著名的十多个柱状节理构造景观进行对比后指出,香港酸性火山凝灰岩大型六方柱状节理景观是世界上同类岩石中罕见的地质现象,分布面积大,露头完整,具有稀缺性、独特性和典型性,对西太...     

Origin of the acidic volcanics of the Tolfa district,Tuscan Province,central Italy: an elemental and Sr-isotopic study

Volcanic rocks from the southern part of the Tuscan Province, the Tolfa district, range in composition from dacites to rhyolites. They have relatively high contents of many incompatible elements and their ⁸⁷Sr/⁸⁶Sr ratios vary between 0.7129 and 0.7148 (28 analyses) with one analysis of 0.7112. The four major eruption centres of the district can be distinguished geochemically. It is shown that the variation of major and trace elements within each area can be explained by fractional crystallization without significant crustal assimilation. The geochemical patterns of the incompatible elements of the investigated volcanics have a close similarity to the alkaline undersaturated volcanics from the nearby Roman Province. The geochemical and isotopic similarity between the Tolfa volcanics and those of the Roman Province suggests a common origin for these components of the magmas. It is suggested that, while the origin of the LIL-element enrichment of the Roman Province magmas is a mantle which was metasomatised by fluids or melts derived from upper crustal material of sedimentary origin recycled into the mantle by subduction, the Tolfa volcanics were derived directly from the subducted material by melting.     

Oxygen Transfer Through Flexible Tubing and Its Effects on Ground Water Sampling Results

A model for the diffusion of gases through polymeric tubing was derived which predicts that the amount of gas transferred is proportional to the tubing length and inversely proportional to the pumping rate. The model was experimentally tested and confirmed for oxygen transfer through fluorinated ethylene-propylene copolymer (FEP) tubing using tubing lengths and flow rates typical of ground water sampling. Diffusion can introduce measurable concentrations of oxygen into initially anoxic water. Diffusive loss of carbon dioxide from water that is oversaturated with respect to atmospheric CO₂ does not measurably affect pH under similar usage conditions.