Geotechnical Properties of Sandy Seafloors and the Consequences for Dynamic Penetrometer Interpretations: Quartz Sand Versus Carbonate Sand
Geotechnical Properties of Sandy Seafloors and the Consequences for Dynamic Penetrometer Interpretations: Quartz Sand Versus Carbonate Sand
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砂质海底的岩土工程特性以及动态贯入仪解释的后果：石英砂与碳酸盐砂
DOI：
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发表时间：
2012
影响因子：
1.7
通讯作者：
Achim J Kopf
中科院分区：
文献类型：
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作者：
Nina Stark;Roy H Wilkens;V. Ernstsen;M. Lambers;S. Stegmann;Achim J Kopf
海岸带的社会利用(包括海上风能发电厂、航道加宽、海滩保护和恢复)正变得越来越重要。由于强烈的潮汐和波浪作用，这些地区的沉积物动力学导致砂质沉积，这在实验室岩土试验中是很难模拟的。在这里，我们提供了使用轻质自由落体Nimrod渗透仪的现场渗透仪测试数据和补充的实验室实验，以表征以石英砂(德国北海)和钙质(美国夏威夷)矿物学为主的地区砂质海底的关键物理性质。与硅质砂岩相比，碳酸盐砂岩具有更高的摩擦角(碳酸盐：31-37°；石英：31-32°)和更高的孔隙率(碳酸盐：1.10-1.40；石英：0.81-0.93)，这在一定程度上是由于珊瑚来源的颗粒具有更高的角度。在现场测试中，我们始终发现碳酸盐砂岩(碳酸盐：68-210 mg；石英：25-85 mg)具有较高的沉积物强度(以减速和估计的准静态承载能力表示)，这也显示出更大的可压缩性。数值还受到海底倾角(例如，沿着水下沙丘或水道)或沉积物移动区域的分层(受潮汐、防岸或水流影响)的影响。研究表明，碳酸盐岩砂岩和石英砂在现场测量的渗透率剖面上的差异得到了实验室结果的支持，并提供了关于不同物性砂岩上覆的可动层的关键信息。
The societal usage of coastal zones (including offshore wind energy plants, waterway deepening, beach conservation and restoration) is of emerging importance. Sediment dynamics in these areas result in sandy deposits due to strong tidal and wave action, which is difficult to simulate in laboratory geotechnical tests. Here, we present data from in situ penetrometer tests using the lightweight, free-fall Nimrod penetrometer and complementary laboratory experiments to characterize the key physical properties of sandy seafloors in areas dominated by quartzose (North Sea, Germany) and calcareous (Hawaii, USA) mineralogy. The carbonate sands have higher friction angles (carbonate: 31–37°; quartz: 31–32°) and higher void ratios (carbonate: 1.10–1.40; quartz: 0.81–0.93) than their siliceous counterparts, which have partly been attributed to the higher angularity of the coral-derived particles. During the in situ tests, we consistently found higher sediment strength (expressed in deceleration as well as in estimated quasi-static bearing capacity) in the carbonate sand (carbonate: 68–210 g; quartz: 25–85 g), which also showed a greater compressibility. Values were additionally affected by seafloor inclination (e.g., along a sub-aqueous dune or a channel), or layering in areas of sediment mobilization (by tides, shorebreak or currents). The study shows that the differences in in situ measured penetration profiles between carbonate sands and quartz sands are supported by the laboratory results and provide crucial information on mobile layers overlying sands of various physical properties.