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ABSTRACT A site investigation is needed prior to any civil engineering construction. The results of this site investigation must lead to recognition of problems related to geology. If the problems related to the geology-structure interaction cannot be handled economically, the structure has to be relocated into more suitable terrains. In some cases, as for line infrastructures (e. g. highways, railroads etc.) this relocation is not always possible. In these cases the problems related to the implementation of the structure into the geology have to be overcome. In this light, karstified areas belong to the most difficult engineering terrains. Although the presence of karst in a certain region can be identified during a site investigation, the exact location of karst voids cannot be predicted with a precision accurate enough for construction. In this contribution, an inventory is made of the possible presence of karst in Belgium. Then 2 case studies are presented in which the particularities of karst of different age (Palaeokarst, Mesozoic karst and Caenozoic karst) are presented. 1 WHERE CAN WE FIND KARST IN BELGIUM One method to analyse the extent of karst in a region consists in mapping outcrops of the lithologies prone to dissolution. In Belgium the areas that could be affected by karst are restricted predominantly toWallonia. In Wallonia the karst is restricted predominantly to Palaeozoic rocks1. In these Palaeozoic rocks the karst is restricted to those that consist of limestone and dolomite, most karst can be found in the limestone (Ek 1996). The occurrence of the outcrops2 of these formations is shown in figure 1. Our contribution will, on the basis of the karst features in Belgium, discuss only the carbonate karst. Brussels the largest city in Belgium, Antwerp the largest city in Flanders and Liège the largest city inWallonia: in fact 94% of the population of Belgium is fenced in by the karst belt, shown in figure 2, which starts in the west near Tournai and continues via Mons and Charleroi to the German border, then it turns north between Liège and the Netherlands border but here in the subsurface. If one wants to connect Belgian cities to Germany or France one has unavoidably to pass this Belgian karst belt. 2 KARST FORMED DURING THREE DIFFERENT GEOLOGICAL ERAS Karst encountered in Belgium was formed either during the Palaeozoic (Visean), Mesozoic (Lias) or during the Caenozoic. 3 CASE I: TUNNEL DE SOUMAGNE Introduction A major achievement of the Belgian railway was the recent construction of a high-speed railroad from Brussels via Liège and Aachen to Cologne. The track Brussels – Liège has been inaugurated 2003. Thereafter construction focused on the section Liège – Aachen. To be able to maintain a high travel velocity the path of the former, rather curved railroad, was not be followed. Unavoidably a tunnel needed to be constructed to pass through some hills on theway from Liège to the plateau de Herve. This tunnel is the Soumagne tunnel (the breakthrough occurred in October 2004).
- Phanerozoic > Paleozoic > Carboniferous > Pennsylvanian > Lower Pennsylvanian > Bashkirian (0.68)
- Phanerozoic > Paleozoic > Carboniferous > Mississippian (0.46)
Influence of Deep Coal Mines on the Stability of Shallow Cavities
Georgieva, Temenuga (University of Mons, Belgium) | Descamps, Fanny (University of Mons, Belgium) | Ajdanlijsky, George (Bulgarian Academy of Sciences, Bulgaria) | Vandycke, Sara (University of Mons, Belgium) | Gonze, Nicolas (University of Mons, Belgium) | Tshibangu, Jean-Pierre (University of Mons, Belgium)
ABSTRACT: Wallonia and Hauts-de-France regions encounter complex developments of multi-level mining cavities that may affect the stability of shallower ones. This work focusses on an abandoned room-and-pillar quarry that extracted phosphatic chalk. On the same site, coal was mined out at depths from 200 to 750 m. To evaluate the influence of deep coal mines on the stability of shallow cavities, the geometry of created voids was modelled, integrating the mining sequence. In addition, detailed topographic and structural surveys of the chalk quarry were completed by rock mass quality assessment. Then a finite element geomechanical model combining the room-and-pillar quarry and the longwall mining was created. Specific vertical cross sections were investigated. The model revealed the progressive influence of coal mining on the room-and-pillar quarry as the surface mined out increased. These large models finally provide boundary conditions for local models in which the influence of specific parameters can be investigated. INTRODUCTION Numerous underground cavities, either man-made or natural, occur in Wallonia (Belgium) and Hauts-de-France regions. Both territories exhibit a comparable geological context and, hence, similarities in the typology of underground cavities. In particular, chalk, limestone, sand and clay were extracted by underground quarries. About 900 abandoned underground quarries are identified in each region. Their size varies from a couple of galleries around an access shaft to a well-structured network of rooms and pillars on areas covering several dozens of hectares. Beside the quarries, other cavities are also known. Some of them are particular to a region: karsts are mainly a concern in Wallonia, whereas military works are specific to Hauts-de-France. This variety of shallow depth cavities represent an issue for the authorities and the communities in terms of land management and planning and economic development of the territories. Also in relation with a common geology, both regions have a similar industrial history, closely related to coal mining. The coal fields extend from the Nord-Pas-de-Calais basin towards Liège area, and even further northwards. They are characterized by numerous thin coal seams with a limited thickness (0.5 to 1 m in Wallonia, 0.8 to 2.9 m in Nord-Pas-de-Calais), separated by quite thick sandstone-claystone interburden. Most seams cover large areas, up to several dozen km, and are influenced by complex geological processes (folding, faulting, underthrust). Mining generally started at shallow depth but reached 1000 m or more in some areas. During the 19th-20th centuries, coal was mined out quite intensively by the longwall technique. Cumulated production reached about 2 billion tons in each region.
- Europe > Belgium > Wallonia (0.87)
- Europe > France > Hauts-de-France > Pas-de-Calais (0.45)
- Europe > France > Paris Basin (0.99)
- Europe > Belgium > Mons Basin (0.99)
ABSTRACT: Chalk has long been used as a strong building material. The shallow underground room-and-pillar quarries where the chalk was extracted now lie abandoned and endure the effects of time and weathering, increasing their risk of collapse. The risk of instability is an issue for more than 10 000 towns in France. We have studied the physico-mechanical behaviour and ageing of two types of chalk in underground quarries in the Parisian Basin, France. The dolomitic chalk (Saint-Martin-Le-Nœud) exhibits variations in mechanical and physical properties with horizontal pillar depth, and both density and compressive strength appear to increase outwards from the core to the wall of the pillar. SEM analysis reveals progressive degradation and increasing homogeneity of the grains from the edge to the inside of the pillar. In contrast, in physico-mechanical tests and SEM analyses performed on the Estreux glauconitic chalk, no significant variation was observed between the pillar wall and pillar core. 1 INTRODUCTION Alteration can be defined as a modification of the physico-chemical properties of minerals and therefore rocks, by atmospheric agents, groundwater or thermal waters (Foucault & Raoult 1995). The process is dependent on climate, water and temperature, as well as on the nature and degree of fissuring of the rock. Alteration generally leads to less-coherent rocks, promoting their deterioration and eventual failure (Gupta & Seshagiri Rao 2000, Massuda 2001). Macroscopic signs of alteration include the appearance of cracks, microfractures and macroporosity, as well as the presence of hard deposits that result from chemical transformations (Oyama & Chigira 2000). The alteration of rocks by dissolution (limestones, tuffs, sandstones, crystalline rocks), with or without mineral neoformation, has been studied by numerous authors (Gupta & Seshagiri Rao 2000). The term "ageing" refers to weathering of a rock within a medium influenced by human activity. In the context of underground structures, the term is used to describe the range of mineralogical and physical modifications of the rock over time. These modifications then lead to a deterioration of the hydraulic or mechanical properties.
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.34)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.34)
- Materials > Metals & Mining (0.68)
- Energy > Oil & Gas > Upstream (0.68)
Abstract The Trou Loulou is an old underground soft carbonate quarry located in Eastern Belgium. This shallow depth room-and-pillar quarry was mined out from the 16th century for building stone. Now, it is considered as a cultural heritage. In the same area, an open-pit quarry is currently mining carbonated rocks for cement production. The Trou Loulou is located in the extension of this open-pit quarry. Therefore, a stability study was required for determining the security distance between both sites in order to preserve this heritage when the open-pit comes closer to it. In this paper, we first describe the geological context. A conceptual model is derived from 2D and 3D surveying of the site. In situ and laboratory mechanical characterizations are performed and a stability analysis is proposed using 2D finite element modelling. Progressive simulation of the open-pit quarry shows the occurrence of localized roof failure. 1 Introduction Carbonated rocks have been mined out in Eastern Belgium for several centuries. In this study, we focus on two sites: an underground quarry and an open-pit one. First, tuffeau was used since the 16 or 17 century as a building stone. For this purpose, a shallow depth room-and-pillar quarry was developed, following an irregular pattern, using peaks and saws for cutting the rock. This activity led to 12km of galleries, containing many historical traces (drawings, engravings, etc.) and which later also served as a refuge during the war. This site is named "Trou Loulou" and is now considered as a cultural heritage. In the last decades, open-pit quarries developed in the same area for cement production and are still expanding. Particularly, this study deals with the extension of one quarry in the direction of the Trou Loulou underground cavity (Figure. 1, left). In order to plan its future activities and guarantee the preservation of the historical site, the cement producer wanted to determine the security distance to keep between the current open-pit quarry and the Trou Loulou.
Relost and refound: Detection of a paleontologically, historically, cinematically(?), and environmentally important solution feature in the carbonate belt of southeastern Pennsylvania
Bechtel, Timothy D. (University of Pennsylvania) | Hojdila, Jaime L. (University of Pennsylvania) | Baughman, Samuel H. (University of Pennsylvania) | DeMayo, Toni (University of Pennsylvania) | Doheny, Edward (University of Pennsylvania)
The following article describes a recent geophysical survey whose purpose was to locate a solution cavity known as the “Port Kennedy Bone Cave” beneath Valley Forge National Historical Park, in the carbonate belt of South-eastern Pennsylvania. The authors must apologize at the outset for presenting an article that leaves out such important details as the actual site location and coordinates or north arrows on the figures. This “if-we-tell-you-we-have-to-kill-you” approach is necessary because the bone cave contains one of the most important middle Pleistocene (Irvingtonian, or ∼750,000 year-old) fossil deposits in North America. It contains plants, insects, turtles, snakes, birds, and mammals—including giant tapirs, ground sloths, sabre-tooth cats, cheetahs, bears, and mammoths. Some of these fossils were new to science when the cave was discovered by quarry workers in the late 1800s, and were studied by the most famous paleontologists of that time (e.g. Edwin Drinker Cope, Henry C. Mercer, and Charles Wheatley). Some of the fossils from the bone cave are still found nowhere else. This makes the cave a possible target for modern looters if they are foolish enough to face the National Park Service Rangers, and the hazardous materials, and the rumored 150-ton locomotive, which protect its entrance…. But perhaps we should start at the beginning.
- Phanerozoic > Paleozoic (0.69)
- Phanerozoic > Cenozoic > Quaternary > Pleistocene > Middle Pleistocene (0.34)
- Geophysics > Magnetic Surveying (0.69)
- Geophysics > Gravity Surveying (0.69)
- Energy > Oil & Gas > Upstream (1.00)
- Media > Film (0.69)
- Materials > Chemicals (0.63)
- Government > Regional Government > North America Government > United States Government (0.50)
- North America > United States > Pennsylvania > Newark Basin (0.99)
- North America > United States > New Jersey > Newark Basin (0.99)