Schmidt‐hammer exposure‐age dating (SHD) of snow‐avalanche impact ramparts in southern Norway: approaches,results and implications for landform age,dynamics and development          下载免费PDF全文

John A. Matthews  Lindsey J. McEwen  Geraint Owen 《地球表面变化过程与地形》2015,40(13):1705-1718

Schmidt‐hammer exposure‐age dating (SHD) was applied to the problem of dating the diachronous surfaces of five distal river‐bank boulder ramparts deposited by snow avalanches plunging into the Jostedøla and Sprongdøla rivers in the Jostedalsbreen region of southern Norway. Approaches to local high‐precision linear age calibration, which controlled in different ways for boulder roundness, were developed. The mean age (SHD_mean) and the maximum age (SHD_max) of surface boulders were estimated for whole ramparts, crests and distal fringes. Interpretation was further assisted by reference to R‐value distributions. SHD_mean ages (with 95% confidence intervals) ranged from 520 ± 270 years to 5375 ± 965 years, whereas SHD_max ages (expected to be exceeded by <5% of surface boulders) ranged from 675 to 9065 years. SHD ages from the Jostedøla ramparts tended to be older than those associated with the Sprongdøla, rampart crests were younger than the respective distal fringes, and use of relatively rounded boulders yielded more consistent SHD ages than angular boulders. The SHD_mean ages indicate differences in recent levels of snow‐avalanche activity between ramparts and provide insights into rampart dynamics as boulders are deposited on rampart crests and, in smaller numbers, on the distal fringes. SHD_max ages provide minimum age estimates of rampart age (i.e. the time elapsed since the ramparts began to form) and suggest that at least some of the ramparts have been developing since the early Holocene. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

填土地基强夯加固效果研究          下载免费PDF全文

张北战  姚仰平  方雨菲 《地震工程学报》2015,37(S1):30-34

针对回填土地基,通过量纲分析得到强夯加固深度和累积夯沉量的计算公式,结合已有工程资料对所提出的计算公式进行验证。结果表明:该公式能够较为精确地预测填土地基的加固深度与累积夯沉量;分析表明:累积夯沉量与加固深度比值随着诸多要素而变化,仅在确定的落距和夯锤半径范围内的才可以作为常数进行推广;最后分析夯锤半径及厚度对强夯效果的影响。  相似文献   

ENDOLITHIC LICHENS,RAPID BIOLOGICAL WEATHERING AND SCHMIDT HAMMER R‐VALUES ON RECENTLY EXPOSED ROCK SURFACES: STORBREEN GLACIER FORELAND,JOTUNHEIMEN, NORWAY     

JOHN A. MATTHEWS  GERAINT OWEN 《Geografiska Annaler: Series A, Physical Geography》2008,90(4):287-297

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   

Air flow calculation of reverse circulation drilling technique with air DTH hammer     

HUANG Yong  ZHU Lihong  YIN Kun  BO Kun 《世界地质(英文版)》2010,13(3)

Air DTH hammer has been successfully applied in minor-caliber solid mineral exploration,water-well drilling and other drilling areas.In order to expand the applications of the technology,the authors further studied the principle and analyzed the mechanism of reverse circulation drilling technique with air DTH hammer to get the perfect assembles of equipments by optimizing working parameters.No parameter seemed more important than the air volume because it could maintain the working performance stability.The minimum air volume is related to the parameters such as depth and pressure,which was calculated under the actual conditions.It was solved for the air injection flow tables of the air DTH Hammer working at the different pressures.According to the data tables,operators could adjust the air volume to meet the demand on this technique,which had a realistic guiding significance.So it could build up a set of systematic and complete hi-technique.  相似文献   

AN EVALUATION OF SURFACE HARDNESS OF NATURAL AND MODIFIED ROCKS USING SCHMIDT HAMMER: STUDY FROM NORTHWESTERN HIMALAYA, INDIA     

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   

高能射流式液动锤在花岗岩中的钻进研究          下载免费PDF全文

孙强  杨冬冬  彭枧明  纪天坤  张鑫鑫 《探矿工程》2016,43(8):39-43

由于干热岩地层通常为火成岩,研磨性强、可钻性差,现有常规工艺方法钻进效率低,为此专门研制了用于干热岩钻进用的SC-86H型高能射流式液动锤,并对该高能射流式液动锤样机进行了地面钻进试验。试验采用可钻性等级为10级的完整花岗岩作为钻进对象,观测了冲锤质量、活塞行程和泵量对机械钻速的影响。试验结果表明：增大冲锤质量、活塞行程和泵量有利于提高机械钻速。试验过程中获得的最大机械钻速为5.19 m/h,较常规回转钻进机械钻速提升显著。  相似文献   

山西中村煤矿抢险救援快速钻井施工技术          下载免费PDF全文

徐培远  曹伟  王立峰  张晓昂 《探矿工程》2016,43(10):278-280

2016年7月2日,山西中村煤矿发生突水事故,12名矿工被困井下。采用CMD100型车载钻机、空气潜孔锤钻井技术准确钻孔至离地面114 m的巷道中心,快速建立了生命通道,给井下被困矿工送去急需的给养,为进一步抢险救援赢得了宝贵时间,最终8名被困矿工成功获救。本文介绍了该次矿山抢险救援中2号食物补给井的快速钻井施工技术,并对矿山应急救援钻井专业队伍建设和装备配套提出了建议。  相似文献   

新型射流式元件结构设计与试验研究          下载免费PDF全文

纪天坤  孙强  杨冬冬  彭枧明 《探矿工程》2016,43(6):52-55

射流式液动锤由于其具有钻进效率高、钻进深度不受限制等优点被成功应用于油气钻井领域。然而由于射流元件在复杂受力条件下极易破损,严重制约了射流式液动锤的使用寿命。为解决此问题,对射流式液动锤射流元件受力情况进行了数值模拟分析,通过分析射流元件内部应力场分布情况,得出了射流元件破损机理,并设计了新型两体式射流元件。模拟分析研究表明,采用新型两体式射流元件可将元件内最大应力值降低一个数量级,使射流元件受力情况明显改善,可有效地提高其使用寿命。  相似文献   

空气潜孔锤钻进技术在乌蒙山地下水探采结合工程中的应用          下载免费PDF全文

张统得  严君凤  房勇  许蛟 《探矿工程》2016,43(10):238-241

乌蒙山地下水探采结合工程是将水文地质调查中的水文地质勘探与供水井施工相结合的一项国家重点扶贫项目,该项目50余口探采结合井的施工解决了超过5万人的生活饮用水问题,取得了良好的社会经济效益。空气潜孔锤钻进技术在该项目中发挥了重要作用。文章介绍了空气潜孔锤在水文水井钻探中的技术优势,重点阐述了该项技术的施工工艺、设备选型以及典型复杂情况的处理,并提出了该项技术在水文水井施工方面的下一步研究方向。  相似文献   

空气潜孔锤钻进典型事故原因分析及处理措施          下载免费PDF全文

宋继伟  赵华宣  苏宁  李奇龙 《探矿工程》2018,45(5):22-28

贵州省地质矿产勘查开发局就“贵州复杂地层深井钻探工艺应用研究”科研项目中“空气潜孔锤钻进技术” 部分进行了试验研究,在试验过程中曾出现了锤头断裂、硬质合金齿折断、冲击器堵塞并阻卡、泥环包裹、卡埋钻、井眼弯曲等典型事故。详细分析了出现这些典型事故的原因,形成了避免和解决这些典型事故的系统技术措施。该成果经现场检验效果良好。本文对该成果进行了全面阐述,以期为同类施工提供借鉴。  相似文献