固化剂加固黄土研究综述

黄土由于特殊的成土环境、粒径分布和矿物成分而具有不良工程特性,比如高压缩性和强湿陷性。这种不良特性导致黄土地区灾害频发,需要对黄土进行加固才能满足工程建设的需求。利用固化剂加固黄土与传统方法相比具有省时省力、代价低效果好的优点,因而得到广泛关注。本文总结了目前被发现能有效改善黄土工程性质的多种固化剂,包括了纳米材料、无机硬化剂、有机高分子材料、生物酶以及生物矿化几大类。对各固化剂的物质组成、加固机理、加固效果和应用现状进行了详细阐述。纳米材料由于尺寸小、比表面积大,能够包裹土颗粒形成尺寸较小的集粒,填充粒间孔隙,从而增加土体密实度和均匀性。无机硬化剂在土中起胶结和填充作用。有机高分子材料通过离子交换作用破坏土颗粒表面的弱结合水膜,增大粒间引力,提高土体密实度。此外,有机高分子材料还具有胶结和填充作用。生物酶通过催化作用提高土中有机大分子活性,生成具有胶结和填充作用的有机质。生物矿化中微生物的代谢物（碳酸钙）均有填充孔隙和胶结土颗粒的作用。通过分析已有研究成果,我们认为黄土固化剂研究后期应注重以下方面：（1）固化剂加固效果的时效性;（2）固化剂在黄土工程中的应用,包括考虑工程条件差异性的施工工艺;（3）环境因素和固化剂加固黄土的相互作用。     

岩石力学性质的影响因素分析

室内岩石力学实验作为岩石力学性质分析的有效手段之一,已逐渐被国内外学者广泛使用。但是,由于岩石力学试验仪器、微裂隙、孔隙等各因素的影响,同组岩石样品力学参数数据结果相差较大。如何排除或减少各类影响因素造成的结果偏差,以合理的确定岩石力学性质,是岩石力学实验研究的重要内容。本文根据胶西北山东黄金4000m深钻岩石样品获得的室内劈裂、单轴和三轴试验结果,结合岩样破裂方位、方式及强度特征,分析了微裂隙、孔隙率（孔隙）、围压、岩样实验时所受摩擦力4类因素对室内岩石力学性质的影响,研究结果可为室内岩石力学试验数据的选取工作提供参考。     

Al2O3改良红黏土的力学试验研究

广西是我国铝业的生产大省,在生产金属铝的时候会产生污染物赤泥,由于赤泥结合的化学碱难以脱除,对地下水污染严重,大量的赤泥堆放,不仅占用了大片的土地,干燥的赤泥还会造成粉尘污染,有效地对赤泥进行回收利用已经成为当前迫在眉睫的任务。本次研究尝试使用作为赤泥主要成分之一的Al2O3的掺入,研究其对红黏土的物理力学性质的影响,本次试验采用掺入率分别为0、1%、2%、3%、4%,5个不同掺入比例Al2O3后的红黏土。对其进行液塑性试验,分析不同掺入率的红黏土的液塑性变化情况。通过击实试验,得出不同掺入率下红黏土的最大干密度、最优含水率。最后对红黏土重塑样进行三轴不固结不排水剪切试验,获得在同一含水率,不同掺入率、不同围压下的应力-应变关系曲线、弹性模量、抗剪强度参数的变化规律。试验结果表明：改良后的红黏土还是具有高液、塑限的特性,其状态为坚硬。随着掺入的Al2O3的量增加,其液限、塑限、塑性指数、含水率、最大干密度都降低;同等Al2O3掺入量的情况下,随着围压的增大抗剪强度增强,在同等围压下,随着Al2O3掺入量的增加抗剪强度呈先降低后增高的状态。     

Micrometer-sized ice particles for planetary-science experiments - I. Preparation, critical rolling friction force, and specific surface energy

Coagulation models assume a higher sticking threshold for micrometer-sized ice particles than for micrometer-sized silicate particles. However, in contrast to silicates, laboratory investigations of the collision properties of micrometer-sized ice particles (in particular, of the most abundant H₂O-ice) have not been conducted yet. Thus, we used two different experimental methods to produce micrometer-sized H₂O-ice particles, i.e. by spraying H₂O droplets into liquid nitrogen and by spraying H₂O droplets into a cold nitrogen atmosphere. The mean particle radii of the ice particles produced with these experimental methods are (1.49 ± 0.79) μm and (1.45 ± 0.65) μm. Ice aggregates composed of the micrometer-sized ice particles are highly porous (volume filling factor: ? = 0.11 ± 0.01) or rather compact (volume filling factor: ? = 0.72 ± 0.04), depending on the method of production. Furthermore, the critical rolling friction force of F_Roll,ice = (114.8 ± 23.8) × 10⁻¹⁰ N was measured for micrometer-sized ice particles, which exceeds the critical rolling friction force of micrometer-sized SiO₂ particles . This result implies that the adhesive bonding between micrometer-sized ice particles is stronger than the bonding strength between SiO₂ particles. An estimation of the specific surface energy of micrometer-sized ice particles, derived from the measured critical rolling friction forces and the surface energy of micrometer-sized SiO₂ particles, results in γ_ice = 0.190 J m⁻².     

基于力学模式的动态大地测量数据反演研究

本文在文献（１）的基础上，进一步研究了基于力学模式动态大地测量反演理论。首先提出了力学模式下动态大地测量反问题的六种形式，导出了第一，二类动态大地测量反问题的线性最小的二乘解，研究了动态大地测量反问题的妥；最后，结合数值例子，讨论了利用地壳垂直形变数据反演地壳断层错动的一种方法。     

深基坑围护结构力学变形监测技术

主要介绍了北京地铁五号线和平西桥车站施工期间的力学变形监测技术,阐述了力学变形监测工作在城市松散含水地层深基坑围护桩施工时的一些技术要求和措施,文章系统地总结了本工程中的力学变形监测技术,为今后类似工程变形监测工作积累了宝贵的经验。     

Regional variation of mechanical and chemical denudation,upper Colorado River Basin,U.S.A.

The variation of mechanical and chemical denudation is investigated using discharge and sediment yield data from the Upper Colorado River System. Annual precipitation ranges from approximately 150 mm to 1500 mm. Mean specific yield ranges from 0-2 1/s km² ( = 6 mm p a) to 151/s km² ( = 475 mm p a). The hydrological-geomorphological system adjusts itself to these varying climatic conditions; in some areas, however, the effects of lithology or land use seem to override the climatic controls. It is demonstrated that the increase in the absolute and particularly the relative amount of suspended sediment is closely related to a decrease in annual runoff and to an increase in the importance of high magnitude/low frequency events. This indicates that in areas of low annual runoff and high runoff variability, soluble rocks are more resistant than in more humid areas. During high magnitude/low frequency events, suspended sediment concentrations and loads are very high in semiarid areas due to sparse vegetation cover and dominance of direct runoff. Events of moderate magnitude and frequency, which in more humid areas transport most of the dissolved load, seldom occur. The trend towards increasing mechanical denudation is even observed in areas of very low runoff (0-221/s km² = 7 mm p a). The peak of sediment yield in dry areas seems to approximate the point of no runoff very closely. Mechanical and chemical denudation are of equal importance at a runoff of about 300 mm per year.     

青藏高原的热力和动力作用对亚洲季风区环流的影响

利用NCEP/NCAR再分析资料,研究了青藏高原热状况的季节变化、动力和热力作用对周围环流,特别是对亚洲热带季风环流的影响。高原对西风带的机械作用在冬季最强,春季次之。冬季的机械作用形成以高原为主,南侧气旋性、北侧反气旋性的"偶极子"偏差环流,它比传统认识的爬坡、绕流的影响范围大得多,遍及东亚的高、低纬度。随着西风带的北移和高原总加热在4月由负变正,南侧气旋性偏差环流增强并逐渐北移,6月形成气旋盘踞整个高原的夏季型。在高原南侧,高原冬季偶极型、夏季加热的作用导致孟加拉湾地区常年存在印缅槽,使得印度半岛的感热加热始终强于中南半岛,而中南半岛上空的潜热加热大于印度半岛。印缅槽的演变存在明显的半年周期,证明2月初和8月初的较强低压槽分别对应冬季高原最强的动力强迫和夏季高原最强的热力强迫。对低纬经向风场的分析还表明,季风爆发前高原的热力作用尤为重要,是导致江南春雨的形成,亚洲季风最早在孟加拉湾东部爆发,最后在印度半岛爆发的原因。     

岩石的脆性-延性转变及塑性流动网络

实验变形研究表明.随着矿物组成.粒度、温度、围压、应变率、液体介质等因素的变化岩石由脆性,半脆性,向半延性.延性转变,其中包括力学行为.微观机制和宏观结构的变化,而决定岩石脆性-延性转变的基本因素在于所含的粘塑性成分及其粘滞性.半延性流动具有共轭网络状的结构特征;延性流动则包括网络状流动和均匀流动两种宏观结构;半延性-延性流动网络以其近似正交性和非牛顿流动特性分别与半脆性破裂网络和均匀延性流动相区别.基于上述研究,可将地壳、上地幔划分为脆性-半脆性的中上地壳,半延性-延性网络状流动的岩石圈下层(含下地壳和岩石圈地幔)和均匀延性流动的软流圈.地壳多震层内的大型地震带及网络是岩石圈下层塑性流动网络的一种响应.     

Hydro-climatic analysis of mechanical breakups reconstructed from tree-rings, Necopastic watershed, northern Québec, Canada

We used a 54-year (1950–2003) ice scar chronology constructed from damaged trees to investigate relationships between large scale hydro-climatic conditions and mechanical breakup magnitude in the Necopastic River watershed (James Bay, northern Québec). Our objectives were: (1) to identify hydrologic and climatic variables that explain variations in mechanical breakup magnitude at the watershed scale, (2) to organize these variables in terms of importance and (3) to construct a predictive model for ice-floods in the Necopastic watershed. We used parametric correlation analysis to measure the degree of linear association between variables and classification trees (CT) coupled with a cross-validation approach to construct the predictive model and to organize variables according to their importance. In the Necopastic watershed, the type and magnitude of breakups are determined by an interaction between forces that maintain the ice cover in place and forces that tend to dislodge it. In contrast with lakes, early and rapidly rising floods, rather than abnormally high flood discharge, create conditions that favour intense mechanical breakups. Moreover, cold and snowy spring conditions during high positive Arctic Oscillation (AO) indices delay the thermal degradation of the ice cover and preserve its mechanical properties over longer time periods.