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浅谈工程地质选线对山区高速(高等级)公路工程造价的影响 总被引：1，自引：0，他引：1
陈国照 《地质灾害与环境保护》2006,17(1):101-103
近年来,高速(高等级)公路建设发展迅速,降低公路工程造价是公路建设决策、设计、施工、管理等环节所必须考虑的问题。山区地质条件复杂,重视公路工程地质选线工作,深入现场调查,充分发挥遥感、物探、钻探等勘察手段在公路上的应用,是降低山区高速(高等级)公路工程造价最有效的途径。 相似文献
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山岭重丘区修建高等级公路,由于山区自然条件复杂,地形多变、公路设计应按交通学要求,采用与自然地形相协调的几何线形,以提高行车速度,节省工程费用,增加经济效益。 相似文献
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岩溶山区聚落格局演变等级效应及其与交通条件的关系——以贵州省后寨河、王家寨、茂兰地区为例 总被引：7，自引：4，他引：3
运用1963年、80年代2004年三期高分辩率影像数据源和GIS分析方法,以贵州省后寨河、王家寨、茂兰地区为例,按空间规模将聚落分为五级,并探讨其分布格局演变规律与交通条件的关系。结果表明:(1)1963年,高等级聚落个数较少,低等级聚落较多;高等级聚落多分布在水源条件好、耕地资源多而优的峰林-平原地带;(2)1963年到80年代期间,岩溶山区聚落发展主要集中于中等级聚落,高、低等级聚落变化不大;(3)到2004年,各等级聚落的数量和规模均得到了较大发展,但发展的强度主要出现在两极(1级、5级);(4)岩溶山区聚落等级变化受交通条件影响较大,同时也受制于区域经济发展水平、自然地理因素影响;(5)今后聚落优化建设、交通条件改善应以4级聚落作为重点对象,5级聚落的重构应重点考虑空间迁移,方向为公路两侧,以改善对外通达度。 相似文献
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山岭重丘区高速公路——百罗高速公路景观绿化设计,运用景观绿化设计手段和方法充分体现了百色当地"革命老区、红色政权、多少数民族"等的地域特色。通过景观绿化设计,对公路沿线景观有较大的改善,在有限的投资范围内力争恢复沿线原生植被,恢复环境,恢复自然,把百罗高速公路建成高规格的具有南亚热带地域特色的景观大道。整个设计自始至终贯穿自然、生态、发展的"绿色廊道"和坚持"以人为本、和谐共生、功能互补、生态效应"的原则。 相似文献
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在岩溶地区公路建设中，受复杂地形地貌的影响，将不可避免地产生占用耕地、破坏植被等环境问题，使得岩溶地区本来就脆弱的生态环境日趋恶化。因此，合理利用土地资源，维护生态平衡，将成为岩溶地区公路建设必须考虑的重要议题。在文中结合岩溶地区公路建设的实际情况，利用先进的GIS技术，针对公路建设的不同阶段，分别提出了各种不同的技术手段和工程措施，既指导了岩溶地区的公路建设．也保护了有限的土地资源。 相似文献
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高等级长大公路隧道的设计是一个系统工程,涉及内容较多,包括土建工程设计和设备系统工程设计,给设计工作增加了很大难度。本文结合合芜高速公路试刀山隧道,对高等级长大公路隧道的设计体系进行了有益的探讨,并对设计中采用的新技术、新工艺进行了详细介绍。 相似文献
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山岭重丘区高速公路—百罗高速公路景观绿化设计,运用景观绿化设计手段和方法充分体现了百色当地“革命老区、红色政权、多少数民族”等的地域特色。通过景观绿化设计,对公路沿线景观有一个较大的改善,在有限的投资范围内力争恢复沿线原生植被,恢复环境,恢复自然,把百罗高速公路建成高规格的具有南亚热带地域特色的景观大道。整个设计自始至终贯穿“自然、生态、发展的‘绿色廊道’和坚持‘以人为本、和谐共生、功能互补、生态效应’的原则”的设计理念。 相似文献
9.
滇藏公路类乌齐-俄洛桥段地质灾害发生频繁,长期以来一直严重影响了该段公路的正常通行。经实地调查研究发现,沿线存在崩塌、滑坡和泥石流等7类地质灾害,共有各类灾害点48处。为使该段公路改建工程的顺利进行,减少地质灾害对改建后公路的危害,文章结合地质环境条件和灾害特征等对全段地质灾害进行了危险性现状评估和预测评估,运用灾损率法和风险性区划法将评估区划分为7个区,并对这7个区进行了地质灾害危险性综合评估、建设场地适宜性和防治工程重要性分级。经综合评估发现,地质灾害危险性大的地区主要分布在地质条件差的高山峡谷地带,危险性小的地区主要分布在地质条件好的宽谷和山岭地带。最后提出了目前青藏高原地区公路地质灾害危险性评估中存在的问题。 相似文献
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邓穗芬 《地质灾害与环境保护》2005,16(1):63-65
高速公路建设的迅猛发展将会极大地促进社会经济发展和改善人们生活质量,但也对环境造成了一定的影响。本文以广东省新(会)台(山)高速公路环境保护工程设计的实践经验,提出了一些设计思路,为今后在公路设计、施工中重视环境保护提供借鉴。 相似文献
11.
Liu Qingsheng 《中国地质大学学报(英文版)》1998,9(1):3
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Ductile shear zones are important in tectonic reconstructions as a source of information on the relative motion of large crustal blocks or plates in the geological past. Methods to interpret fabric in ductile shear zones were mostly developed for low grade rocks where overprinting relations are usually well preserved. However, high grade shear zones are common and dominate in many Precambrian terrains. High grade shear zones should be analysed in a different way from low grade zones. The plane on which shear sense markers should be observed, the vorticity profile plane, is more difficult to find than in low grade shear zones. The most reliable shear sense markers in high grade shear zones are shear bands, mineral fish, mantled porphyroclasts, sigmoids and asymmetric boudins. 相似文献
13.
Alteration zones (more commonly foot wall alteration zones) are related to volcanic-hosted massive sulfide (VMS) deposits and represent unique features that may be targeted during exploration. Of these, the chloritic foot wall alteration pipe is the most extensive and characteristic of VMS deposits. This feature is geochemically identified by a strong relative enrichment in aluminium and magnesium and a coupled depletion in calcium and sodium, giving rise to chloritic rocks in the primary environment of formation. During high grade regional metamorphism such chloritic precursor rock types are replaced by an unusual mineral paragenesis, typically containing magnesium rich cordierite, phlogopite, orthoamphiboles or orthopyroxenes and aluminium rich minerals such as sillimanite and corundum. This suggests that the unusual geochemical features of the alteration zone, retained during the deformation and metamorphism, should be recognisable in lithogeochemical exploration.The massive sulfide deposit in the eastern part of the metamorphic Namaqua Province, South Africa, at Areachap, Kantienpan and the defunct Prieska Cu–Zn Mine are hosted by a Mid-Proterozoic volcano sedimentary succession known as the Areachap Group. These deposits were affected by a complex deformation and metamorphic history and represent examples of upper amphibolite to granulite grade metamorphosed VMS deposits.The application of the known lithogeochemical methods is especially complicated where the geology is not well understood, due to the poor rock exposure of complexly deformed and metamorphosed areas, such as in the eastern part of the Namaqua Province.The box plot presents a more readily applicable lithogeochemical method to characterize and identify the alteration process, but it was designed for relatively un-metamorphosed environments. It is demonstrated here that the box plot may also be applied to high-grade metamorphic terrains and that the mineral phases used in defining the boxplot in low grade metamorphic environments may be replaced by their equivalents in high grade metamorphic terrains. The compositional trends of the metamorphic minerals themselves may be used in defining the boxplot for high grade metamorphic terrains. These include the transition of: annite to phlogopite; grossular to almandine or pyrope, augite to enstatite or clinoenstatite, and hornblende to gedrite or cummingtonite. Close to the ore zone, the relative Mg content of pyroxene, cordierite and biotite are higher than further away from this zone. It could be demonstrated that the changes in the mineral compositions are gradational when comparing unaffected rocks with progressively more altered wall rocks.Conclusions based on an application of the isocon method demonstrate that primary footwall alteration zones in the Areachap Group's VMS deposits are characterized by elemental depletion of Na2O, CaO, Sr, Ni, V and La and enrichment of MgO, Fe2O3(total), S, Zn, SiO2, Co and F. It is shown that the whole rock compositions of rocks that were independently identified as the metamorphic equivalents of altered rocks, using the isocon method, plot in the correct place in the box plot for high grade regionally metamorphosed terrains. This establishes the box plot as an effective and practical tool for lithogeochemical exploration for VMS deposits in complexly deformed high grade metamorphosed terrains. 相似文献
14.
中国太古宙地质体组成、阶段划分和演化 总被引：21，自引：0，他引：21
我国太古宇陆壳主要见于华北克拉通区内，由高级变质的麻粒岩相带、角闪宕相区和低、中级变质的绿岩－花岗岩区组成。按地质时序可划分为始、古、中、新太古４个阶段。麻粒岩相带的组成主要由英云闪长质片麻岩为主和少量表壳岩或主要由表壳岩含一些花岗质岩石。绿岩－花岗岩区时代主要属新太古代，绿岩属基性火山－沉积建造，基性岩的原岩物质来自相对亏损的上地幔，形成于大陆边缘的裂谷环境。太古宙末，板块体制已经形成，麻粒岩相带是板块体制的俯冲碰撞机制的产物。对克拉通古陆块能长期成为大陆的解释，应认为是下地壳的挤压环境，促使陆壳以板底垫托叠置、垂直增生所致。 相似文献
15.
试论华北地台中生代超变质作用与地幔热柱作用 总被引：7，自引：2，他引：5
本文通过冀西北、胶东等金矿富集区“太古宙”高级变质地体中生代金矿化、变质核杂岩构造、花岗岩、碱性岩等问题的讨论,认为中生代强烈而广泛的混合岩化、花岗岩化、流变“片麻岩”化等超变质作用,是华北地台太古宙高级变质地体变质程度深、同一地质体同位素年龄数据相差悬殊、中生代强烈岩浆活动等异常地质现象的重要原因之一。它既是华北地台活化的重要深部地质作用,亦是深部“去根作用”的具体体现。而中生代地幔热柱作用又是用变质作用、变质核杂岩构造、金矿成矿作用的深部机制,也是华北地台中生代活化的根本原因所在。 相似文献
16.
H. J. Dalstra J. R. Ridley E. J. M. Bloem D. I. Groves 《Australian Journal of Earth Sciences》2013,60(5):765-784
Two contrasting styles of metamorphism are preserved in the central Southern Cross Province. An early, low‐grade and low‐strain event prevailed in the central parts of the Marda greenstone belt and was broadly synchronous with the first major folding event (D1) in the region. Mineral assemblages similar to those encountered in sea‐floor alteration are indicative of mostly prehnite‐pumpellyite facies conditions, but locally actinolite‐bearing assemblages suggest conditions up to mid‐greenschist facies. Geothermobarometry indicates that peak metamorphic conditions were of the order of 250–300°C at pressures below 180 MPa in the prehnite‐pumpellyite facies, but may have been as high as 400°C at 220 MPa in the greenschist facies. A later, higher grade, high‐strain metamorphic event was largely confined to the margins of the greenstone belts. Mineral assemblages and geothermobarometry suggest conditions from upper greenschist facies at P–T conditions of about 500°C and 220 MPa to upper amphibolite facies at 670°C and 400 MPa. Critical mineral reactions in metapelitic rocks suggest clockwise P–T paths. Metamorphism was diachronous across the metamorphic domains. Peak metamorphic conditions were reached relatively early in the low‐grade terrains, but outlasted most of the deformation in the higher grade terrains. Early metamorphism is interpreted to be a low‐strain, ocean‐floor‐style alteration event in a basin with high heat flow. In contrast, differential uplift of the granitoids and greenstones, with conductive heat input from the granitoids into the greenstones, is the preferred explanation for the distribution and timing of the high‐strain metamorphism in this region. 相似文献
17.
Early Precambrian tonalite-trondhjemite sialic nuclei 总被引：1，自引：0，他引：1
A.Y. Glikson 《Earth》1979,15(1):1-73
Early Precambrian batholiths evolved by diapiric intrusion of near-liquidus to superheated tonalitic and trondhjemitic magmas into an early greenstones crust. Distribution patterns of enclaves and xenolith screens derived from the latter provide reference markers which define the internal geometry and detailed structure of the “gregarious batholiths” (Macgregor) as polydomal multi-lobal bodies. Near-liquidus temperatures are suggested by the digestion of vast volumes of ultramafic—mafic crust by the acid magmas. Tracing of xenolith trains between low and high grade metamorphic terrains provide key evidence for coeval relations between granite—greenstone type terrains and amphibolite to granulite facies infracrustal root zones of the latter. The formation of the plutonic tonalite—trondhjemite suite was accompanied by dacitic to rhyolitic extrusions, the acid volcanic lenses being located above early greenstone units intruded by the batholiths and below upper greenstone sequences which postdate these intrusions. The geochemical characteristics of high-level and deep-level tonalites and trondhjemites are compared. Both suites display very wide compositional spectra, but data from high-grade terrains tend to define a more basic field than data from granite—greenstone terrains. Effects of source compositions on the geochemistry of the acid plutonic rocks are pointed out. Tonalites dominate in South African terrains whereas trondhjemites dominate in Western Australian terrains — a difference conceivably related to the more ultramafic composition of source rocks represented by early greenstone units in southern Africa. Granodiorites and potassic granites form a comparatively minor component of Archaean batholiths, and may occur in the following forms: (1) bands of augen gneiss in high-grade terrains; (2) components of trondhjemitic to granitic gneisses in high-level plutons; and (3) discrete post-tectonic intrusions typically emplaced at high levels of the batholiths and along older tonalite—greenstone contacts. Migmatites characteristically form in close spatial association with xenolith-rich zones, probably due to depression of the solidus consequent on water addition related to dehydration of the xenoliths. A derivation of the acid sodic magmas by anatexis of sialic materials is inconsistent with geochemical evidence and petrological theory. In contrast, the commonly low to very low LIL element levels and REE evidence indicate derivation by about 30–50% melting of basic rocks. Marked trace element anomalies are characteristic of some Archaean plutonic suites, e.g. very high Sr in some Western Australian rocks, low Rb in some Lewisian (Scotland) and South African rocks, U depletion in South African and southwestern Greenland suites, high Li in some Pilbara rocks and high Zr in some southwestern Greenland rocks. However, the only consistent anomaly observed to date is a well-pronounced depletion in Y and heavy REE, suggesting extensive equilibration of the acid melts with eclogite and/or amphibolite. Uniformitarian interpretations of the Archaean are questioned in the light of the evidence for high temperature and pressure, the unique tectonic style of diapirism and the low initial87Sr/86Sr as compared to Proterozoic plutonic suites. The diachronous nucleation of tonalite—trondhjemite plutons during the Archaean is seen as the major process effecting a transformation of an early Archaean sima into sial. 相似文献
18.
Colin M. Graham 《Contributions to Mineralogy and Petrology》1974,47(3):165-185
Blue-green hornblendes are observed in metabasite assemblages throughout the chlorite, biotite and garnet zones of the southwest Scottish Highlands. Actinolites are common in more Mg-rich metabasites in these zones. At low grade, hornblendes are relatively edenite-rich, and may sometimes occur together with a more Mg-rich, Al-poor actinolite. Within the garnet zone, hornblendes are pargasitic, showing extensive tschermakite substitution. Textural and chemical evidence do not indicate the presence of any miscibility gap between hornblende and actinolite within the chlorite to garnet zones in the southwest Highlands. The occurrence of hornblende-actinolite pairs in metabasites of the Scottish Dalradian, and perhaps also in other metamorphic terrains, is considered to reflect the incomplete chemical equilibration of lower grade actinolitic amphibole during prograde metamorphism, rather than a miscibility gap. The paucity of amphibole compositions intermediate between hornblende and actinolite in many metamorphic terrains is thought to reflect the rapid but continuous change of stable amphibole compositions in metabasites over a small range of increased metamorphic grade. 相似文献
19.
《Applied Geochemistry》2005,20(8):1489-1495
Trace element data for stream sediment samples collected from 6 river basins situated in geomorphologically and climatologically different terrains of Sri Lanka were analyzed to identify a suitable geochemical ratio to delineate potential areas for gems. All the areas are located in high grade metamorphic terrains with different lithologies. Correlations between different elements were studied using Spearman rank correlation and elements showing consistent high correlations were selected to calculate element ratios that can be used to discriminate areas with different potentials for gems. It was noted that the Rb, Ba, Sr, and the Ti, Nb, Zr element groups have high correlations between them. From the calculated ratios Ba/Sr, Rb/Sr and RbxBa/Sr2 were identified as being useful. The best ratio was determined considering the discrimination %, and representation of within category gem potential variation.Results show that RbxBa/Sr2 is the best ratio and a value greater than 4 represents gem potential areas while a ratio less than 1 represents low/no potential areas. Application of these results to the locations where test gem pits were validated this empirical rule. 相似文献
20.
太古宙高级变质杂岩的近水平顺层剪切构造变形及岩石深熔作用-以内蒙古大青山地区为例 总被引：2，自引：0，他引：2
内蒙古大青山地区是华北地台北缘以富含麻粒岩系和孔兹岩系为特征的高级变质地层发育的地区之一，其中太古宙的岩石普遍经历了麻粒岩相变质与变形作用。在高级变质杂岩中变形构造复杂，其中近南北向和近东西向构造构成了本区的基本构造格局。研究发现，在高级变质地层中还存在着一期近水平顺层剪切构造变形形迹，其形成于下地壳麻粒岩相。近水平顺层剪切构造变形不仅导致麻粒岩系与孔兹岩系以近水平构造面相接触。同时还导致麻粒岩系及孔兹岩系不同程度的熔融。 相似文献