Soil investigations, offshore mid Norway: A case study of glacial influence on geotechnical properties
Soil investigations, offshore mid Norway: A case study of glacial influence on geotechnical properties
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挪威中部近海土壤调查：冰川对岩土特性影响的案例研究
DOI：
10.1016/0921-8181(95)00024-0
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发表时间：
1996
影响因子：
3.9
通讯作者：
T. By
中科院分区：
文献类型：
--
作者：
J. Sættem;L. Rise;K. Rokoengen;T. By
挪威中部大陆架外部的细粒冰川海洋和冰川沉积物在剪切强度和固结程度方面表现出复杂的变化。在 Smørbukk Sør 油田（约 65°N，7°E），在正常或可能欠固结的冰川和海洋沉积物顶部发现了约 80 m 的不同程度的超固结粘土碴。 60 m 以下发现含气量较高，钻孔下部较软沉积物中的孔隙水可能在上覆硬碓沉积时部分被天然气水合物截留。 80 m 厚的冰碛部分的岩土特性的变化主要是由于末次冰期期间地冰下方的压实造成的，我们解释了冰碛的强度变化，以反映沉积物孔隙水冻结到冰基上导致高度超固结区间，以及冰底处的热平衡或融化导致软碛区间的变化。斯莫尔布克 (Skjoldryggen) 西北部的一个大山脊可能部分是由冰流振荡期间的冰推挤形成的，同时所描述的斯莫尔布克的冰碛沉积的同时。该脊阻碍了冰流，从而阻碍了浪涌结束时的摩擦加热，从而产生了净冻结基底冰的脉冲和基底的固结。所描述的过程可能影响了 Skjoldryggen 的大面积冰层，并且在具有复杂冰川历史和细粒底层的地区可能很常见。
Fine-grained glaciomarine and glacial deposits on the outer Mid Norwegian continental shelf show complex variations in shear strength and degree of consolidation. At the Smørbukk Sør field (approx. 65°N, 7°E) about 80 m of variably overconsolidated clayey till is found on top of normally- or possibly underconsolidated glaciomarine and marine sediments. A high gas content is found below 60 m, and the porewater in the rather soft sediments in the lower part of the borehole may have been partly trapped by gas hydrates when the overlying hard till was deposited. The variations in geotechnical properties of the 80 m thick till section are suggested to result mainly from compaction below grounded ice during the last glaciation, and we interpret the strength variations in the till to reflect shifts between freeze of sediment porewater onto the base of the ice causing highly overconsolidated intervals, and thermal equilibrium or melting at the ice sole resulting in intervals of softer till. A large ridge northwest of Smørbukk (Skjoldryggen) is probably partly formed by ice push during ice flow oscillations at the same time as the described till at Smørbukk was deposited. This ridge retarded the ice flow and hence the frictional heating at the end of surges, creating pulses of net freezing base ice and consolidation of the substratum. The described process has possibly affected a wide area up-ice of Skjoldryggen, and may be common in areas with a complex glacial history and a fine-grained substratum.