Hydraulic breakthrough of clay smears due to technical and natural actions

IF 5.6 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Acta Geotechnica Pub Date : 2024-04-25 DOI:10.1007/s11440-024-02261-8

Gerd Gudehus, Christian Karcher

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Abstract

We outlined earlier in this journal by means of finite element simulations how patterns of normal faults arise by a synsedimentary tectonic extension, and how clay smears evolve therein. In the present paper, we show how hydraulic breakthroughs of clay smears can arise so that water, gas and mud rise in faults. Mechanical properties of sand and clay are introduced first for the stable range and then for rupture and internal erosion. Our numerical simulations for the evolution of normal faults and clay smears are discussed in light of critical phenomena. Water assembled in an open-cast mine about 20 years ago as the critical hydraulic gradient in a clay smear dropped to the actual one due to the rapid excavation-induced deformation. The latter led to a critical point under an excavation the slope of which was parallel to a nearby normal fault. Clay smears can also break by earthquakes so that the critical hydraulic gradient drops to the actual one caused by methane with an excess pressure. This can lead to hydraulic breakthroughs and cold eruptions at outcrops of faults.

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技术和自然作用导致的粘土层水力破坏

我们在本刊早先的文章中通过有限元模拟概述了正断层的形态是如何通过合成沉积构造延伸而产生的，以及粘土层是如何在其中演变的。在本文中，我们将展示粘土层的水力突破是如何产生的，从而使断层中的水、气体和泥浆上升。本文首先介绍了砂和粘土在稳定范围内的力学性质，然后介绍了断裂和内部侵蚀的力学性质。我们根据临界现象讨论了正常断层和粘土层演变的数值模拟。大约 20 年前，由于快速挖掘引起的变形，粘土岩层中的临界水力梯度下降到实际梯度，水在露天矿中聚集。后者导致在挖掘机下出现临界点，而挖掘机的斜坡与附近的正断层平行。粘土层也会因地震而破裂，从而使临界水力坡度下降到实际坡度，这是由于甲烷压力过大造成的。这可能导致断层露头处的水力突破和冷喷发。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Acta Geotechnica ENGINEERING, GEOLOGICAL-

CiteScore

9.90

自引率

17.50%

发文量

297

审稿时长

4 months

期刊介绍： Acta Geotechnica is an international journal devoted to the publication and dissemination of basic and applied research in geoengineering – an interdisciplinary field dealing with geomaterials such as soils and rocks. Coverage emphasizes the interplay between geomechanical models and their engineering applications. The journal presents original research papers on fundamental concepts in geomechanics and their novel applications in geoengineering based on experimental, analytical and/or numerical approaches. The main purpose of the journal is to foster understanding of the fundamental mechanisms behind the phenomena and processes in geomaterials, from kilometer-scale problems as they occur in geoscience, and down to the nano-scale, with their potential impact on geoengineering. The journal strives to report and archive progress in the field in a timely manner, presenting research papers, review articles, short notes and letters to the editors.