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101.
Storm deposits and storm-generated coarse carbonate breccias on a pelagic outer shelf (South-East Basin, France) 总被引:2,自引:0,他引:2
Michel Seguret Alexis Moussine-Pouchkine Guilherme Raja Gabaglia & Frederic Bouchette 《Sedimentology》2001,48(2):231-254
Uppermost Jurassic limestones of the South‐East Basin (France) are organized into four facies associations that were deposited in four distinct zones: (1) peritidal lagoonal limestones; (2) bioclastic and reefal limestones; (3) pelagic lime mudstones; (4) lime mudstones/calcarenites/coarse breccias. Calcarenite deposits of zone 4 exhibit sedimentary structures that are diagnostic of deposition under wave‐induced combined flow. In subzone 4a, both vertical and lateral transitions from lime mudstone/calcarenite to breccia indicate in situ brecciation under wave‐cyclic loading. Breccias were produced by heterogeneous liquefaction of material previously deposited on the sea floor. Deposits in subzone 4a record relatively long periods (>400 kyr) of sedimentation below wave base, alternating with periods of deposition under wave‐induced currents and periods of in situ deformation. In this zone, storm waves were attenuated by wave–sediment interaction, and wave energy was absorbed by the deformation of soft sediment. With reference to present‐day wave attenuation, water depths in this zone ranged between 50 and 80 m. Landwards of the attenuation zone, in zone 3, storm waves were reduced to fair‐weather wave heights. Storm wave base was not horizontal and became shallower landwards. As a consequence, water depth and wave energy were not linearly related. On a small area of the seaward edge of subzone 4a, cobbles were removed by traction currents and redeposited in subzone 4b. There, they formed a 100‐m‐thick wedge, which prograded over 3 km and was built up by the stacking of 5‐ to 20‐m‐thick cross‐stratified sets of coarse breccia. This wedge records the transport and redeposition of cobbles by a high‐velocity unidirectional component of a combined flow. The increase in flow velocity in a restricted area is proposed to result from flow concentration in a channel‐like structure of the downwelling in the gulf formed by the basin. In more distal subzone 4c, the hydrodynamic effect of wave‐induced currents was quasi‐permanent, and brecciation by wave–sediment interaction occurred only episodically. This indicates that, seawards of the attenuation zone, hydrodynamic storm wave base was deeper than mechanical storm wave base. Uppermost Jurassic carbonates were deposited and soft‐sediment deformed on a hurricane‐dominated ramp of very gentle slope and characterized by a zone of storm wave degeneration, located seawards of a zone of sedimentation below wave base. 相似文献
102.
注浆法在填土地基加固处理中的应用实例 总被引:3,自引:0,他引:3
泸溪县武溪110kv变电站场地地基为人工开挖山坡堆填而成,填土厚薄不均,由块石、碎石及粉土构成。变电站建成后,建筑物及地面发生不均匀沉降,建设方要求进行加固处理,经过反复对比和投资验算,确定采用充填、渗透注浆法对填土地基注入浓水泥浆进行加固处理。施工前,先要进行注浆试验,选择合理的注浆方式和技术参数。注浆加固后,通过一年多的观察,建筑物及地面不均匀沉隆均得到控制,达到了提高地基承载力,稳定建筑的目的。 相似文献
103.
系统介绍了泥浆材料的现状及发展趋势,重点叙述了水基泥浆、油基泥浆及合成基泥浆这3大类泥浆材料的现状及发展趋势。 相似文献
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目前,省内各地调单位在编制1∶5万区域地质图编稿原图时采用的方法、程序和依据的技术要求等方面尚不完全一致,直接且不同程度地影响了地质图件的质量。本文就上述问题,依据国家、部颁布的有关规程、规范及局的有关文件精神作了较全面系统的说明与论述,可望今后逐步走上统一标准。 相似文献
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Min-Zheng Zhang 《地震学报(英文版)》1993,6(3):761-768
This paper summarizes the origin and idea of the control of civil engineering structures and reviews the state-of-the art
of recent advances in structural control both theoretically and technologically. The prospects for structural control and
key research objects to remain to be solved are put forward at last.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 375–380, 1993. 相似文献