滑带土粘土矿物定向性的x射线衍射及其对滑坡的作用

本文首先论述了粘土矿物颗粒定向排列测定的基本原理并提出粘土矿物定向性定量评价方法,然后根据实例—庙上北滑坡的滑带土粘土矿物的X射线衍射结果,进行定向性定量分析计算,得出滑带土粘土矿物颗粒的定向度为弱到中等定向,并以中等定向为主。因而在水的往返作用下,滑带土具一定的胀缩性及胀缩的不均匀性,再加上粘土矿物本身亦具有的胀缩性及胀缩的可逆性和循环性,故导致滑带土抗剪强度和结构强度不断降低,大大影响斜坡的稳定性。     

A simple test and predictive models for assessing swell potential of Ankara (Turkey) Clay

During the past three decades, damage due to swelling action of Ankara Clay has been observed more clearly in some parts of Ankara where rapid expansion of the city led to the construction of various kinds of structures. In this study, a comprehensive research program has been conducted (i) to investigate the effect of remoulding and desiccation on the swelling behavior of Ankara Clay and its swelling anisotropy, (ii) to estimate depth of active zone, (iii) to develop a simple technique in determining the magnitude of swelling based on water content of the soaked specimen after 24 and 72 h (w_max24,72), and (iv) to produce predictive models which could be used to estimate the swelling potential of Ankara Clay from its mineralogical and simply measured engineering characteristics. A laboratory testing program was carried out using both undisturbed, and remoulded and desiccated samples selected from 20 different locations. Montmorillonite was identified as being the main clay mineral present. Based on the moisture content variation with depth, the active expansive zone was considered to be about 2 m. The test results suggest that swelling pressure of the clay considerably decreases and/or dies out when the water content is greater than 30%. It is also noted that the measured lateral swelling is significantly in excess of the vertical equivalent indicating an anisotropy with respect to swelling. Statistical assessments indicate that a new parameter (w_max24,72) from a simple test, suggested in this study, is a very strong parameter for predicting swelling parameters of Ankara Clay. Based on 60 empirical predictive equations with coefficients of correlation between 0.96 and 0.66 from multiple regression analyses, w_max24,72, methylene blue value, liquid limit, dry unit weight and smectite content are the most important index and mineralogical properties to predict the swelling parameters of Ankara clay with small deviations from the measured values.     

Measuring the k–S–p relations on DNAPLs migration

Migration characteristics of dense non-aqueous phase liquids (DNAPLs) in the subsurface can be expressed as a water–DNAPL two-phase system based on mainly the k–S–p relations, which describe the relations among relative permeability (k), degree of water saturation (S), and capillary pressure head (p). The aims of this research are to develop an experimental system with new type of probes, such as the electrical conductivity probe for measuring the degree of water saturation and the hydrophilic and hydrophobic tensiometer for measuring the pore water and DNAPL pressures, and also to estimate the results obtained from the developed experimental system. From these tests, the excellent k–S–p relations were obtained and the efficiency and validity of this developed experimental system have been confirmed in terms of the concept of the scaling coefficient calculated by interfacial tensions.     

Numerical models of tectonic deformation at the Baltica–Avalonia transition zone during the Paleocene phase of inversion

Predictions from dynamic modelling of the lithospheric deformation are presented for Northern Europe, where several basins underwent inversion during the Late Cretaceous and Early Cenozoic and contemporary uplift and erosion of sediments occurred. In order to analyse the evolution of the continental lithosphere, the equations for the deformation of a continuum are solved numerically under thin sheet assumption for the lithosphere. The most important stress sources are assumed to be the Late Cretaceous Alpine tectonics; localized rheological heterogeneities can also affect local deformation and stress patterns. Present-day observations available in the studied region and coming from seismic structural interpretations and stress measurements have been used to constrain the model. Our modelling results show that lateral variation in lithospheric strength below the basin systems in Central Europe strongly controls the regional deformation and the stress regime. Furthermore, we have demonstrated that the geometry of the boundary between Baltica and Avalonia, together with different rheological characteristics of the two plates, had a crucial role on local crustal deformation and faulting regime resulting in the Baltica–Avalonia transition zone from the S–N Alpine convergence.     

新疆盐渍土分散性研究

通过研究分析盐渍土及改变盐渍含量对分散性试验的影响,认为土块试验、针孔试验对受高钠离子影响的盐渍土分散性评价是较为有效的方法。新疆土料石膏发育,环境水中Ca2+离子丰富,分散性评价最好在工程实际情况下进行。     

Global thermal and dynamical perturbations due to Cretaceous mantle avalanche

The numerical models of mantle convection agree to depict avalanches behaviour according to the level of endothermicity of the spinel → perovskite phase change. Their potential effects on the global thermal and dynamical states of the mantle have been computed thanks to a numerical code, which takes into account both the 400-km exothermic and the 660-km endothermic phase changes. The cycle followed by the avalanches is: local layering, destabilization of the 660-km thermal layer, travelling and spreading on the core, and reappearing of the local layering. Therefore, mantle convection is characterized by quiet periods of partial layering embedded in catastrophic events. During the avalanche, the amplitude of the surface velocity is multiplied by two, which would imply an enhanced plate tectonic and ridge activities. The global thermal effects of the avalanche are compatible with a high mantle temperature and an acceleration of Earth's rotation during the Cretaceous. They also offer a coherent explanation to locate the origin of mantle plumes both within the CMB and just below the transition zone.     

水稻低温冷害遥感监测技术与方法进展

根据国内外水稻低温冷害遥感监测和遥感灾损评估研究进展情况，分析了水稻低温冷害遥感监测的可行性和各种方法的优缺点，提出了低温冷害遥感监测方面需要开展的相关研究领域和需要解决的几个问题。     

日光温室低温寡照灾害指标

文章根据1965～2000年河北省日光温室试验观测资料及各地历年低温寡照对蔬菜的影响程度，确定了低温寡照灾害等级指标，分析了低温寡照的时空分布规律，20世纪80年代以后，河北省各市低温寡照发生次数比60、70年代明显增多；随着纬度增高，河北省低温寡照发生次数明显减少，危害程度明显减轻。     

对地观测小卫星的相位噪声分析与控制

结合传输型对地观测小卫星一体化设计的特点，介绍了一种用于对地观测小卫星系统的锁相接收机的-构成及原理，并对系统的相位噪声性能进行了详尽的分析，提出了对其相位噪声进行技术控制的方法。通过文中的分析与研究，消除了由于对地观测小卫星相位噪声所引起的系统误码率的恶化，提高了系统的可靠性，为下一步对地观测小卫星的发展与应用打下了良好的技术基础。     

中国西南低空急流活动的统计分析

参照北美研究低空急流气候特征的方法，对中国低空急流进行重新定义，实现了低空急流定义的统一，并在此基础上对低空急流活动特征进行了分析。结果表明：中国低空急流主要有两个活动中心，分别位于江南地区和东北地区；江南地区的低空急流活动主要有两个活跃期，分别为1-4月和6-7月；东北地区的低空急流活动主要表现为2月、8-9月两个活动较弱期；江南地区的低空急流主要在6-8月表现出独立的急流轴，东北地区则主要在8月份；汛期低空急流活动与长江流域区域性暴雨有伴随性，多雨年急流次数很多，少雨年则很少；长江中下游及两湖盆地附近急流活动有明显的日变化。