地球内部物理和演化的几个核心论题：Ⅲ微观地球物理概要

微地球物理是一正处酝酿阶段,以微物理学为基础,以地球内部及地质休和冉石物理特性搂研究对象,以理论、实验、数据和计算机模拟为手段的新兴学科。其研究内容涉及地球内部受多种微物理机制所制约的岩石圈和地幔流变,岩石动力摩擦与地壳脆－塑性转换,地震和断裂力学问题,流体－岩石相互作用,声发射／微震活动与声波／超声波理论和地质应用等。结合其动力学和相互耦合关系,是微地球物理学的一个重要研究方向。其应用结果将导致环境地球物理和环境地球化学并行发展。关于地球内部的认识存在相当的不确定性,有些问题如板块和地幔涌运动,以致微破裂和断层滑移运动等都可能涉及随机和无序理论的应用。微观与宏观方法的结合,并使两者相一致,是最终解决问题的必要途径和工作目标。     

雅鲁藏布江蛇绿岩中橄榄石的位错构造及上地幔流变状态

本文通过对雅鲁藏布江蛇绿岩中橄榄石的透射电子显微分析（TEM）和变形参数测算,划分出3个应变带,即强应变带、过渡型应变带和弱应变带,并详细地研究了它们的岩石结构、位错构造、变形机制和流变状态。镁铁质糜棱岩组成的强应变带中橄榄石发育亚颗粒和位错网络,具有低自由位错密度(10⁷～10⁸cm^-2),是在温度为850～950℃、压力10～13kbar、差异应力2～3MPa、应变速率为10^-16～10^-17s^-1、粘度10²²～10²³Pa.s,大致相当于35～40km的岩石圈深部由位错机制控制的深层剪切流变作用形成的。     

渗流场中岩石流变特性的数值模拟

渗流对岩石的流变特性有显著的影响,但限于试验条件,相关的试验成果较少。而数值计算技术已成为进行岩石力学研究的重要方法,因此,采用数值模拟方法对渗流场中岩石的流变特性进行了研究。对已有的岩石室内流变试验进行模拟来验证数值方法的有效性,在压缩流变试验的数值模拟中对试件分别施加单向、三向渗流场来模拟不同渗流条件对岩石流变特性的影响。模拟结果表明,在渗流方向上渗流产生的动水压力会导致试件的流变变形增大。此外,不同渗流场对流变的影响也有所差异,三向渗流场中试件受到的轴向渗透力小于单向渗流场,而侧向渗透力则大于单向渗流情况,这也导致三向渗流场中试件的轴向应变小于单向渗流场,而侧向应变大于单向渗流场。     

红矸石在锚喷支护巷道中的应用

通过对矿井锚索支护巷道喷浆骨料的各种配比试验研究，结合现场的实际应用，总结出比较适合巷道喷浆使用的采用红矸石做骨料的骨料配比方案。     

柔壁渗透仪的试验研究

针对防渗浆材结石体或灌浆固结体渗透性的测试及其对污染物阻滞性能测试的需要,研制了一种围压密封的柔壁渗透仪,并获得国家专利。采用S、N和Z型三类浆材结石体试样,通过在不同渗透压力、不同围压条件下的渗透系数测定,与南-55型变水头渗透仪的对比试验研究,以及垃圾渗沥液的渗滤试验,证明柔壁渗透仪对制样要求不高、密封好、测试误差＜119×10-7 cm/s,精度满足规范要求。该研究的创新点在于采用柔性乳胶膜作测试试样的侧壁,通过气压或水压施加围压实现试样的侧壁密封,渗透压力可在10～1000 kPa范围调节,围压可在10～1500 kPa范围调节,试样直径有618和101 mm两种规格可选,且精度要求不高,试样高度在20～150 mm范围内任意选用,可方便地用于测试浆材结石体或灌浆固结体的渗透系数,以及浆材结石体对污水中污染物的阻滞性能,有助于防渗浆材的研制。     

湘东北连云山杂岩流变学特征研究

出露于湘东北九岭—幕阜山岭之中的连云山杂岩属于古元古代结晶基底岩系。利用野外构造解析、岩组、石英分形理论等手段, 对湘东北连云山杂岩的变形表象和变形机制进行了详细的观察和研究。结果表明: 连云山杂岩至少遭受了早期韧性剪切和晚期韧性再造两个阶段, 石英塑性流变以菱面滑移系的作用为主; 从早期构造片(麻) 岩到晚期韧性再造形成条纹条带状混合岩, 其应变速率从早期的中应变速率(10-8. 8s-1 ) 到晚期的低应变速率(10-12s-1 ) 是逐渐降低的; 岩石的塑性流动变形机制不仅反映了角闪岩相的中、上地壳形成环境, 而且表明“雪峰古陆”基底中更深层次的物质尚未抬升出来。     

纤维水泥浆堵漏实验研究

钻孔漏失是煤田钻探常见的复杂问题之一,而水泥浆堵漏是现场使用最多的堵漏方法之一。但在裂缝性地层、洞穴或高渗地层中容易出现水泥浆漏失的难题。将特种纤维引入常规水泥浆体系中,通过室内实验研究纤维水泥浆的堵漏性能、触变性能、流动性能和水泥石的力学性能,并分析其堵漏作用机理,介绍了其在国内外油气钻井和固井领域的应用情况。研究表明,纤维水泥浆在此类地层中具有较好的堵漏效果,在煤田钻探领域将具有良好的应用前景。     

Rheological controls on extensional styles and the structural evolution of the Northern Carnarvon Basin,North West Shelf,Australia

The extensional architecture of the Northern Carnarvon Basin can be explained in terms of changes in lithospheric rheology during multiphase extension and lower crustal flow. Low‐angle detachments, while playing a minor role, are not considered to have been the primary mechanism for extension as suggested in previous models. Early extension (Cambrian‐Ordovician) in the Northern Carnarvon Basin is characterised by low‐angle detachment structures of limited regional extent. These structures have a spatial association with a Proterozoic mobile belt on the margin of the Pilbara Craton. Thermo‐mechanical conditions in the mobile belt may have predisposed the highly deformed crust to thin‐skinned extension and detachment development. Permo‐Carboniferous extension generated an extensive wide rift basin, suggesting ductile rheologies associated with intermediate lithospheric temperatures and crustal thickness. Thick Upper Permian to Upper Triassic post‐rift sequences and marked thinning of the lower crust occurred in association with only a small amount of extension in the upper crust. This observation can be reconciled by considering outward lower crustal flow, from beneath the basin towards the basin margin, following extension. Strong mid‐crustal reflectors, which occur over large areas of the Northern Carnarvon Basin, probably represent a boundary between flow and non‐flow regimes rather than detachment fault surfaces as in previous models. Crustal thinning and thermal decay following Permo‐Carboniferous extension contributed to the increased strength and brittle behaviour of the lithosphere. Consequently, Late Triassic to Early Cretaceous extension resulted in the development of far more localised narrow rift systems on the margins of the preceding wide rift basin. Diapiric intrusions are associated with the narrow rift basin development, resulting from either remobilisation of ductile lower crustal rock or the initial formation of sea‐floor spreading centres.     

Mechanical controls on collision-related compressional intraplate deformation

Intraplate compressional features, such as inverted extensional basins, upthrust basement blocks and whole lithospheric folds, play an important role in the structural framework of many cratons. Although compressional intraplate deformation can occur in a number of dynamic settings, stresses related to collisional plate coupling appear to be responsible for the development of the most important compressional intraplate structures. These can occur at distances of up to ±1600 km from a collision front, both in the fore-arc (foreland) and back-arc (hinterland) positions with respect to the subduction system controlling the evolution of the corresponding orogen. Back-arc compression associated with island arcs and Andean-type orogens occurs during periods of increased convergence rates between the subducting and overriding plates. For the build-up of intraplate compressional stresses in fore-arc and foreland domains, four collision-related scenarios are envisaged: (1) during the initiation of a subduction zone along a passive margin or within an oceanic basin; (2) during subduction impediment caused by the arrival of more buoyant crust, such as an oceanic plateau or a microcontinent at a subduction zone; (3) during the initial collision of an orogenic wedge with a passive margin, depending on the lithospheric and crustal configuration of the latter, the presence or absence of a thick passive margin sedimentary prism, and convergence rates and directions; (4) during post-collisional over-thickening and uplift of an orogenic wedge. The build-up of collision-related compressional intraplate stresses is indicative for mechanical coupling between an orogenic wedge and its fore- and/or hinterland. Crustal-scale intraplate deformation reflects mechanical coupling at crustal levels whereas lithosphere-scale deformation indicates mechanical coupling at the level of the mantle-lithosphere, probably in response to collisional lithospheric over-thickening of the orogen, slab detachment and the development of a mantle back-stop. The intensity of collisional coupling between an orogen and its fore- and hinterland is temporally and spatially variable. This can be a function of oblique collision. However, the build-up of high pore fluid pressures in subducted sediments may also account for mechanical decoupling of an orogen and its fore- and/or hinterland. Processes governing mechanical coupling/decoupling of orogens and fore- and hinterlands are still poorly understood and require further research. Localization of collision-related compressional intraplate deformations is controlled by spatial and temporal strength variations of the lithosphere in which the thermal regime, the crustal thickness, the pattern of pre-existing crustal and mantle discontinuities, as well as sedimentary loads and their thermal blanketing effect play an important role. The stratigraphic record of collision-related intraplate compressional deformation can contribute to dating of orogenic activity affecting the respective plate margin.     

基于黏弹性本构性能的隧道围岩变形预测研究

针对Ⅲ、Ⅳ级围岩,以江西高速公路隧道为背景,采用弹-黏塑性有限单元法分析预测不同类别隧道围岩变形。选取现场Ⅲ、Ⅳ级围岩进行室内剪切流变试验,分析得到Ⅲ、Ⅳ类岩样流变试验曲线与广义Kelvin 模型的流变曲线吻合较好。基于广义Kelvin模型,推导出黏弹性模型复杂应力状态下的应力-应变关系。采用施工过程的黏弹性动态反分析法计算围岩参数,结合反演参数对预测隧道围岩变形进行预测分析。研究成果已应用于实际隧道工程中,指导、修正设计和施工参数,可为安全施工提供合理依据。