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1.
运用定量指标研究岩体风化问题的探讨 总被引：7，自引：0，他引：7
在分析国内外岩体风化问题研究现状的问题上，指出了目前岩体风化评价存在的主要问题。结合实际工程资料，从影响岩体风化的主要因素出发，选择了表征风化特征的代表性定量指标，并分析了指标间的相关性。这为风化岩体的量化评价提供了依据。 相似文献
2.
Norikazu Matsuoka 《Geomorphology》1995,12(4)
Field observations of weathering processes and the related landforms, combined with laboratory analyses of weathering products, permit a synthetic evaluation of Late Cenozoic weathering environments in the Sør Rondane Mountains, Antarctica, an arid upland characterized by low temperatures and strong winds. Rates and character of weathering depend mainly on moisture availability and the bedrock geology. Under the humid weathering regime that occurs only locally around the margin of the present sheet, frequent diurnal freeze-thaw cycles in summer cause relatively rapid rock fragmentation. Most of the mountains are situated in the arid weathering regime, under which rock breakdown is very slow unless the rock contains plenty of salts. Salt weathering becomes more intensive and extensive with exposure age, as a result of salt accumulation in rock, eventually producing soils as small as fine-silt size. Lack of clay mineralization even in weathered rocks having been exposed above the ice sheet prior to 4 Ma ago indicates that hydrolysis or carbonation of rock minerals has been insignificant during the past 4 Ma. The final products of weathering are due mainly to salt action and reflect the parent lithology. Resistant fine-grained granite forms strongly oxidized tors carved with tafoni, or fields of mushroom-like boulders overlying the fractured bedrock. Less resistant rocks, like biotite gneiss and amphibolite, produce stone pavements underlain by saline, silty soils up to 30–40 cm thick, the thickness of which corresponds to the maximum thaw depth. 相似文献
3.
《极地研究》1992,3(2):1-7
Some weathering observation sites were set up at different height and face in Great Wall Station area of King Geroge Island, Antarctica, since 1989. Baced on the data series obtained from 1987-1991, the relationship between physical weathering of rock and season, height, face are discussed in this paper. We also compare the results to that of other periglacial area in the world in order to know the special features of King George Island in physical weathering of rock. The rock weathering in south-east face of sea stack is higher than that of north-west face in same environment. Get rid of influence of elevation, rock type, weathering time and organisms, the main reason which caused physical weathering of this area is climate and orientation of rock. The King George Island of Antarctica belong to high latitude area. The temperature time of below zero is 6-8 months in a year, so the process of freeze-thow is restricted. Compared with other periglacial area in the world, the weathering rate of rock is midd 相似文献
4.
H S Goldie 《Area》2005,37(4):433-442
The re-interpretation of surface karst landforms in Northern England has led to a re-examination of well-known erratic-pedestal sites that were the origin for karst denudation rates applied extensively, on the supposition that erratics protect underlying limestone from rainwater solution. Height of the pedestal has been used to calculate long-term solutional-lowering, as much as 50 cm in 15 ka (33.3 mm/ka) from UK sites. The sites include Norber and Scar Close, Yorkshire, UK. This paper shows that the sites have been misinterpreted, in particular at Norber where the erratics lie on a pre-existing structurally stepped surface. Norber and several other sites also experience much mechanical weathering, in relatively weak, well-fractured limestones, a process which must be distinguished from solution. Sites in strong, less-fractured limestones demonstrate lower rates, which are sounder indications of land surface lowering. Some pedestals have been confirmed as partly resulting from solutional weathering in surrounding soil and vegetation. Re-evaluation reduces solution rates to 3–13 cm in 15 ka. Applying such rates has profound implications for understanding limestone landscapes, challenging orthodox views. 相似文献
5.
CHRISTINE ELLIOTT 《New Zealand geographer》2003,59(1):50-60
A review of some recent studies on rock weathering in Antarctica has revealed that Antarctic weathering research has a significant contribution to make to the ongoing debate about rock weathering in cold climates. Largely conducted in the field rather than the laboratory as in the Northern Hemisphere, it demonstrates that whilst all weathering processes can occur in Antarctica this is highly localised and dependent on the particular micro‐environment. Freeze‐thaw, for example, is not the most dominant process in many parts of Antarctica. The right combination of rock temperature and moisture can mean that salt, insolation, hydration or even chemical weathering can predominate. 相似文献
6.
7.
丹霞山顺层洞穴风化特征的试验研究 总被引：1，自引：1，他引：0
以丹霞盆地丹霞组2段顺层洞穴为研究对象,探讨不同岩性红层抗风化能力的差异,重点关注软岩夹层的风化特征及其对顺层洞穴发育的影响。在野外考察的基础上,选择3个典型顺层洞穴为案例,采集了洞穴剖面不同岩性红层的岩样及夹层水样品,进行一系列的岩矿理化测试和水样分析实验。结果表明：洞穴剖面岩性的不均一性及软岩夹层的风化凹进是形成丹霞山顺层洞穴的主要原因。顺层洞穴发育的软岩夹层一般是粉砂质泥岩,粘土矿物含量高,以泥质胶结为主,吸水性较强,开型空隙率较大,抗压强度小,易于风化破碎;上下岩层主要是砂岩和砂砾岩,以钙质和铁质胶结为主,吸水性较弱,开型孔隙率较小,抗压强度较大,风化速度较慢。在洞穴岩层风化过程中,粘土矿物的胀缩、钙质胶结物的溶解, 及铁质胶结物的水化作用等是导致岩体结构破坏的重要因素,但促使不同岩性红层风化的主导因素有所差别。粉砂质泥岩的风化以粘土矿物的胀缩作用为主,砂岩和砂砾岩的风化则以钙质胶结物的溶解作用为主。此外,酸性雨水渗入岩体后与各种矿物进行的一系列离子交换作用也促进了顺层洞穴岩层的风化。 相似文献
8.
Heather Viles 《Geomorphology》1995,13(1-4)
A wide range of information is now available on the ecology of rock surface microorganisms (including bacteria, fungi and algae) and lichens and their role in weathering in particular locations. External environmental conditions as well as rock characteristics determine the type of rock surface community, and thus the style of biological weathering. A simple, preliminary conceptual model can be drawn, which relates biological weathering activity to an environmental stress gradient and which is applicable at a range of scales. Further research needs carrying out to test and extend this model in order to make some progress towards the important goal of assessing the overall importance of biological weathering to geomorphology. 相似文献
9.
The endolithic lichen Lecidea auriculata is known to enhance rock surface weathering on the Little Ice Age moraines of the glacier Storbreen in Jotunheimen, central southern Norway. This study demonstrates the reduction in Schmidt hammer Rvalues that followed the rapid colonization by this lichen of pyroxene‐granulite boulders on terrain deglaciated over the last 88 years. In the absence of this lichen, the characteristic mean R‐value of boulder surfaces is 61.0 ± 0.3; where this lichen is present, R‐values are lower by at least 20 units on surfaces exposed for 30–40 years. A similar reduction in rock hardness on rock surfaces without a lichen cover requires about 10 ka. The rapid initial weakening of the rock surfaces is indicative of rates of biological weathering by endolithic lichens that may be two orders of magnitude (200–300 times) faster than rates of physico‐chemical weathering alone. If not avoided, the effects of this type of lichen are likely to negate the effectiveness of the Schmidt hammer and other methods for exposure‐age dating, including cosmogenic‐nuclide dating, in severe alpine and polar periglacial environments. The results also suggest a new method for dating rock surfaces exposed for <50 years. 相似文献
10.
Marie–Françoise André 《Geografiska Annaler: Series A, Physical Geography》2002,84(3&4):139-150
Ice–polished quartz veins, feldspar phenocrysts and quartzite layers were used as reference surfaces to assess the impact of Postglacial rock weathering in Lapland (68°N). Over 3200 measurements were carried out on roches moutonées and glaciofluvially scoured outcrops distributed within three study areas covering 8 km2 . Inferred weathering rates demonstrate that 10,000 years of Holocene weathering did not significantly modify the geometry of Weichselian rock surfaces. However, rates of general surface lowering range from 1 to 25, depending on the rock type, with average values at 0.2 mm ka−1 for homogeneous crystalline rocks (irrespective of their acidity and grain size), 1 mm ka−1 for biotite–rich crystalline rocks, and 5 mm ka−1 for carbonate sedimentary rocks. Accelerated rates were recorded in weathering pits and along joints with values up to ten times higher than on the rest of the rock surface. Comparisons with cold and temperate areas suggest that solution rates of carbonate rocks are highly dependent on climate conditions, whilst granular disintegration of crystalline rocks operates at the same rate whatever the environment. It probably means that microgelivation is not efficient on ice–polished crystalline outcrops even under harsh climate conditions, and that granular disintegration proceeds under various climates from the same ubiquitous combination of biochemical processes. Last, the weathering state of Late–Weichselian roches moutonées can be usefully compared to that of Preglacial tors of the nearby Kiruna area. 相似文献
11.
Marie–Françoise André 《Geografiska Annaler: Series A, Physical Geography》2002,84(3-4):139-150
Ice–polished quartz veins, feldspar phenocrysts and quartzite layers were used as reference surfaces to assess the impact of Postglacial rock weathering in Lapland (68°N). Over 3200 measurements were carried out on roches moutonées and glaciofluvially scoured outcrops distributed within three study areas covering 8 km2 . Inferred weathering rates demonstrate that 10,000 years of Holocene weathering did not significantly modify the geometry of Weichselian rock surfaces. However, rates of general surface lowering range from 1 to 25, depending on the rock type, with average values at 0.2 mm ka−1 for homogeneous crystalline rocks (irrespective of their acidity and grain size), 1 mm ka−1 for biotite–rich crystalline rocks, and 5 mm ka−1 for carbonate sedimentary rocks. Accelerated rates were recorded in weathering pits and along joints with values up to ten times higher than on the rest of the rock surface. Comparisons with cold and temperate areas suggest that solution rates of carbonate rocks are highly dependent on climate conditions, whilst granular disintegration of crystalline rocks operates at the same rate whatever the environment. It probably means that microgelivation is not efficient on ice–polished crystalline outcrops even under harsh climate conditions, and that granular disintegration proceeds under various climates from the same ubiquitous combination of biochemical processes. Last, the weathering state of Late–Weichselian roches moutonées can be usefully compared to that of Preglacial tors of the nearby Kiruna area. 相似文献
12.
Saxicolous species of lichens are able to induce and accelerate weathering of their rock substrate, and effects of lichens
on substrate can be attributed to both physical and chemical causes. This paper is focused on biotic weathering actions of
epilithic and endolithic species on the different rock types (sandstones and volcanogenic rocks) in Antarctica. The patterns,
mechanisms, processes and neoformations of rock-weathering resulting from lichen colonization are expounded in detail. Furthermore,
it is pointed out that, for a better understanding of the impacts of lichens on environments, the studies on the rate of biotic
weathering and the comprehensive involvement of the lichen effects on weathering of natural rocks remain to be carried out
in Antarctica. 相似文献
13.
Saxicolous species of lichens are able to induce and accelerate weathering of their rock substrate, and effects of lichens on substrate can be attributed to both physical and chemical causes. This paper is focused on biotic weathering actions of epilithic and endolithic species on the different rock types (sandstones and volcanogenic rocks) in Antarctica. The patterns, mechanisms, processes and neoformations of rock-weathering resulting from lichen colonization are expounded in detail. Furthermore, it is pointed out that, for a better understanding of the impacts of lichens on environments, the studies on the rate of biotic weathering and the comprehensive involvement of the lichen effects on weathering of natural rocks remain to be carried out in Antarctica. 相似文献
14.
阿尔泰山古风化壳研究结果表明，晚新生以来，至少存在两个风化期，形成了不同类型的风化壳，本文阐述这两个风化期的特征及相应形成的风化壳的类型及特点。 相似文献
15.
BY VIKRAM GUPTA RUCHIKA SHARMA MADHO PRASAD SAH 《Geografiska Annaler: Series A, Physical Geography》2009,91(3):179-188
Four rock types (quartz mica gneiss, schist, quartzite and calc-silicate) located in the Satluj and Alaknanda valleys were used to test whether a Schmidt hammer can be used to distinguish rock surfaces affected by various natural and man-induced processes like manual smoothing of rock surfaces by grindstone, surface weathering, deep weathering, fluvial polishing and blasting during road construction. Surfaces polished by fluvial process yielded the highest Schmidt hammer rebound (R-) values and the blast-affected surfaces yielded the lowest R-values for the same rock type. Variations in R-value also reflect the degree of weathering of the rock surfaces. It has been further observed that, for all the rock types, the strength of relationship between R-values for the treated surfaces (manual smoothing of rock surface by grindstone) and the unconfined compressive strength (UCS) is higher than for the fresh natural surfaces. 相似文献
16.
Effects of direct and indirect heating on the validity of rock weathering simulation studies and durability tests 总被引：2，自引：0，他引：2
Rock surface and subsurface temperature responses in samples exposed to direct heating (insolation) under natural hot desert conditions reveal considerable variability between lithologies related to differences in thermal properties, especially albedo and thermal conductivity. However, when the same samples are heated indirectly by air in an oven-based environmental cabinet, lithological differences in temperature response disappear and all samples attain temperatures similar to the air temperature within the cabinet. Rates and patterns of rock decay produced in such environmental cabinets may not, therefore, reflect those encountered under natural conditions, where breakdown is related to micro-environmental conditions at the rock/air interface and where rock temperature is one of the most important controlling factors. In addition to implications for assessment of weathering effectiveness, use of only indirect forms of heating affects the determination of comparative rock durability because all rock types are cycled through the same temperature regimes. Because temperature exerts such a major control on rock breakdown through its control on physical and chemical weathering processes, all significant factors influencing it must be included in the design of weathering simulations and durability tests. 相似文献
17.
Biancane badlands consisting of small domes dissected by rills and micropipes, with rough disordered microrehef, can be found along the Apennines in Italy. The dominant processes forming biancane differ from those of badlands formed on smectite-rich mudrocks, as micropipes associated with pseudokarstic enlargement of pores and cracks predominate and form the main routes for evacuation of eroded material.Biancana evolution is controlled by water infiltration into intact bedrock, producing an erodible weathering ‘rind’ which is more porous than intact rock. This rind is easily removed by rill or micropipe flow, and erosion is therefore ‘weathering-controlled’, depending on rind production by infiltrating water. Infiltration is initially slow and stepped, due to slow water movement through very small capillary pores in intact rock alternating with rapid filling of macropores and cracks. This occurs due to rapid matrix pore enlargement by dispersion and/or dissolution. The infiltration pattern is accurately reproduced by a model built on progressive development of weathering layers by moisture penetration. Model results are consistent with weathering rind depths and erosion observed in the field, and show that a pipe network can be generated on newly exposed rock by the rainfall of one year.Propagation of the pipe network diverts a progressively larger proportion of runoff into micropipes, expanding weathering rind production within the biancana as well as on the surface. Internal weathering and flow progressively dominate with few unweathered corestones, and the biancana gradually collapses into a penultimate “soufflé-like” form. 相似文献
18.
辽东半岛红色风化壳粒度分布特征浅析 总被引：1，自引：0，他引：1
运用贝克曼激光衍射粒度分析仪对辽东半岛大连市棋盘子村和龙王村的红色风化壳作粒度特征分析,粒度频率分布曲线的差异指示出两地风化壳风化程度较弱,风化不完全.结合X射线荧光光谱仪进行化学分析进一步探讨两地的风化特征,发现两地各自发育的母岩都具有不均一性,棋盘子村风化壳的发育与母岩具有同源关系,龙王村风化壳发育与母岩非同源.与南方红色风化壳比较,南方红色风化壳风化程度高于棋盘子村,且母岩具有均一性. 相似文献
19.
Influence of rock strength on the valley morphometry of Big Creek, central Idaho, USA 总被引：1，自引：0，他引：1
Zachery M. Lifton Glenn D. Thackray Robert Van Kirk Nancy F. Glenn 《Geomorphology》2009,111(3-4):173-181
Analysis of valley morphometry and bedrock strength along Big Creek, central Idaho, shows that valley floor width is strongly controlled by bedrock. We performed statistical analysis of Schmidt hammer rock strength as a function of lithology and aspect and of valley morphometry as a function of rock strength. Rock strength is significantly greater on the south side of the valley and in Eocene granodiorites. Rock strength is weakest in Eocene volcanic tuffs. Valley floor width depends negatively on weakest valley-side rock strength, and hillslope gradient on the north side of the valley depends positively on rock strength. Stream gradient does not depend on rock strength. Valley floor width appears to be controlled by bedrock strength on the weaker side of the valley, which was generally the north (south-facing) side. We speculate that a higher degree of weathering via freeze–thaw cycles contributes to lower strength on the north side. The positive dependence of hillslope gradient on rock strength on the north side provides evidence that differential weathering across lithologies determines the gradient that can be maintained as lateral migration of the stream erodes valley walls. These results suggest that in situ rock strength exerts strong influences on some measures of valley morphometry by modulating hillslope mass wasting processes and limiting lateral erosion. 相似文献
20.
福建长乐屏山风化坑与河流壶穴的成因及其证据 总被引：1，自引：0，他引：1
风化坑和壶穴是一种常见的岩石坑穴地形,其形成原因和形态完全不同,但容易被误解和混淆.结合对福建长乐三溪河地区这两种坑穴地形的实地考察,本文从地貌学,沉积学,岩石化学和矿物学等各个方面对两者的形成过程、影响因素进行了论证和对比.研究表明：风化坑形成于岩石面积水的风化作用,壶穴则是由河流的旋转水流对河床产生的侵蚀作用形成;山顶风化坑的发育与河流流水作用没有关系,河流壶穴的形成与河谷的发育过程有关,河谷中的风化坑只能在河流深切后,流水不再作用到的河床部位发育;只要条件合适,风化坑或壶穴随时可以生成;风化坑与河流壶穴的形态,坑内沉积物的磨圆度、粒度特征等反映出各自不同的形成过程.风化坑内碎屑与周边岩石的化学蚀变指数CIA 值的差异反映了风化坑的化学风化成因;风化坑内碎屑与周边岩石石英长石比例的差异说明风化坑是矿物差异风化的结果;用CIA 值和英长比均无法区分河流壶穴和风化坑中的碎屑颗粒,但两者化学元素迁移特征的差别反映了风化坑的风化作用和河流壶穴的流水搬运作用的成因差别;风化坑的风化程度达不到当地风化壳的风化程度,但不同气候带风化坑碎屑的CIA 值能反映不同气候带风化作用的强度差异. 相似文献