大别山北部蛇绿岩的地球化学制约

常量元素,微量元素,稀土元素,Ｎｄ同位素及氧同位素地球化学特征表明,太别山北部变质镁铁－超镁铁质岩带中存在变质的蛇绿岩,它主要由变质橄榄岩,辉长岩（－辉绿岩？）和基性熔岩三部分组成,其中,变质的基性熔岩的亏损地幔模式年龄ｔＤＭ／Ｍａ＝１０３６．８～１２９３．８,εＮｄ（ｔ）＝７．２～７．７,表明它可能代表１０００Ｍａ左右形成于中等扩张速率（２ｃｍ／ａｄ左右）洋盆条件下的洋壳残片。     

中国黄渤海沉积物声速与物理性质研究

In order to investigate the correlation between a sound velocity and sediment bulk properties and explore the influence of frequency dependence of the sound velocity on the prediction of the sediment properties by the sound velocity,a compressional wave velocity is measured at frequencies of 25–250 k Hz on marine sediment samples collected from the Bohai Sea and the Yellow Sea in laboratory,together with the geotechnical parameters of sediments.The results indicate that the sound velocity ranges from 1.232 to 1.721 km/s for the collected sediment samples with a significant dispersion within the series measuring frequency.Poorly sorted sediments are highly dispersive nearly with a positive linear relationship.The porosity shows a better negative logarithmic correlation with the sound velocity compared with other geotechnical parameters.Generally,the sound velocity increases with the increasing of the average particle size,sand content,wet and dry bulk densities,and decreasing of the clay content,and water content.An important point should be demonstrated that the higher correlation can be obtained when the measuring frequency is low within the frequency ranges from 25 to 250 k Hz since the inhomogeneity of sediment properties has a more remarkably influence on the laboratory sound velocity measurement at the high frequency.     

高速公路软基处理方案模糊评价因素

模糊评价方法是高速公路软基处理方案优化设计中经常采用的一种方法 ,这种评价方法的影响因素很多。介绍影响评价结果的评价因素 ,举出工程实例来说明各个评价因素的影响。     

大别山北部镁铁-超镁铁质岩带的研究新进展

报道了大别山北部镁铁－ 超镁铁质岩带研究的一些最新进展,其中特别重要的是两种产状新鲜榴辉岩露头的发现、超高压变质线索及变质蛇绿岩的地球化学证据等。讨论了该带需进一步研究的若干问题。     

A probe heat flow value of the East China Sea shelf

Bottom temperature variation (BTV) is a serious problem in determining the thermal gradient and heart flow of the sediments in shallow seas. The water depth of the East China Sea shelf is mostly below 150m, and the heat flow measurement is strongly affected by BTV. Following a statistical algorithm, we rechecked the temperature and thermal conductivity data of the cruises KX90-1 and KX91-1, carried out by a cooperation program of China and Japan, and calculate the heat flow in a site without long-term temperature record. The calculated heat flow in the site was 58.6±3.6 mW/m², being just within the range of the drill heat flow value of East China Sea shelf. The inversed amplitude spectrum of BTV has a peak in frequency of 1/10 per year, and the annual component is also an important part. Comparison with two lakes of Lake Greifensee and Lac Leman (i.e. Lake Geneva), which are in different water depth, revealed that with increasing water depth, the peak of amplitude spectrum moved towards low frequency components. The heat flow values calculated in this paper and from petroleum bore hole in East China Sea shelf are much more close to that in southeast China than in Okinawa Trough. Supported by the National High Technology R&D Program of China (2004 AA616060)     

南黄海海底沉积物声学特性及其影响因素试验研究

利用自南黄海中西部海底取回的沉积物样品,对其声学特性及其影响因素进行了试验研究,结果显示,研究区海底沉积物的压缩波速为1.359 ~1.695 km/s,剪切波速为12.5 ~70.9 m/s;颗粒较细的沉积物与较低的压缩波速、剪切波速对应,主要集中在研究区东侧水深较深处;沉积物的物理力学性质对其压缩波速、剪切波速的影响较显著,沉积物的温度和换能器的频率对上述声学两参数也具有一定的影响,而沉积物的包含物及薄夹层等影响声波传播的理论计算结果。给出了研究区海底沉积物物理力学各参数与压缩波速、剪切波速之间的回归方程,以期为国防、工程提供基础资料。     

南黄海中部海底沉积物原位声速与物理性质相关关系

基于在南黄海中部获得的海底沉积物原位声速数据,分析讨论了原位声速与密度、含水量、孔隙比、孔隙度等沉积物物理性质参数的相关关系。通过回归分析建立了海底沉积物原位声速预测方程。结果表明,原位声速与上述物理参数之间具有良好的相关性,相关系数r均大于0.93。对比分析了原位声速预测方程与甲板声速预测方程的差异,两者最小相差15.8 m/s,最大相差31.3 m/s,平均差值约为22.6 m/s。将原位声速预测方程与其他研究者建立的声速预测方程进行了对比,结果表明不同声速预测方程存在明显差异,初步分析了存在差异的原因。     

Correction for effects of temperature and pressure on sound speed in shallow seafloor sediments

Abstract

Three types of sediments were selected to measure their sound speed under changing temperature and pressure conditions in laboratory. The effects of temperature and pressure on sound speed in sediments and their trends were analyzed. The results showed that, with increasing temperature and pressure, the sound speed exhibits an increasing trend in all selected sediments. For each sample, the ratio of the sound speed in sediments to that in seawater almost remained unchanged at different pressures and temperatures, with a maximum fluctuation of 1.09% for temperature dependence and 0.68% pressure dependence. Combining the analysis of experimental results and sound speed correction procedure given by Hamilton, specific correction formulas of sound speed for temperature and pressure were presented. The laboratory-measured sound speed in the experiment and the sound speed obtained in the South Yellow Sea were corrected to reduce the effects of temperature and pressure using the correction formulas. The results show that the correction formulas with constant sound speed ratio are effective for correcting the sound speed measurement errors caused by changes in temperature and pressure. As a further consideration, the effects of the fluctuation of sound speed ratio on sound speed correction were analyzed.     

Strength characteristics and mechanisms of salt-rich soil–cement

Salt-rich soft soils have not only general characteristics of common soft soils, but also contain high contents of Mg²⁺, Cl^?, and SO₄^2?, which have negative effects on deep mixing method using cement to treat soft soils. Laboratory and field tests were conducted to investigate the effects of changing cement incorporating ratio, water content, cement mixing ratio, and contents of Mg²⁺, Cl^?, and SO₄^2? on the unconfined compressive strength of the salt-rich soil–cement. The microstructure of soil–cement and the mechanism for the strength change of salt-rich soil–cement were investigated using X-ray diffraction, scanning electronic microscopy (SEM), and backscattered diffraction technology. It was found that an increase of cement incorporating ratio enhanced the strength of soil–cement but reduced its strength when water is added. Different amounts of Mg²⁺, Cl^?, and SO₄^2? not only caused the difference in the microstructures of salt-rich soil–cement but also influenced the soil–cement strength.     

由CPT确定灌注桩极限承载力的可靠性分析

利用随机场理论,研究了灌注桩的Ｐｓ,ｆｉ和Ｐｓｂ统计特性的统计原则,对相关距离、桩截面尺寸、端阻力计算范围等在程序编制中的协调问题进行了探讨;对上海地区１７个场地的４６条ＣＰＴ曲线进行了电算,进而求出了由ＣＰＴ确定灌注桩极限承载力的可靠度指标的统计特性。