{"id":20017,"date":"2026-01-10T12:58:37","date_gmt":"2026-01-10T11:58:37","guid":{"rendered":"https:\/\/www.darda.de\/?page_id=20017"},"modified":"2026-01-10T12:58:37","modified_gmt":"2026-01-10T11:58:37","slug":"tunnel-lamella","status":"publish","type":"page","link":"https:\/\/www.darda.de\/en\/knowledge\/tunnel-lamella","title":{"rendered":"Tunnel lamella"},"content":{"rendered":"
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In German-speaking engineering, the term tunnel lamella<\/strong> is used as a practice-oriented umbrella term for lamella-shaped components and sectionally constructed elements in tunnel construction. Depending on the context, this may refer to individual lamellae<\/em> of a diaphragm wall in cut-and-cover and diaphragm-wall construction, lamella-like sections in shotcrete construction (NATM\/SEM), or lamellae in the area of portals and ventilation structures. In planning, construction, maintenance, and deconstruction, the tunnel lamella is particularly important because it directly influences excavation pit and tunnel statics, construction sequencing, and topics such as sealing, ventilation, and maintenance. For modifications, controlled concrete demolition, and special demolition, low-vibration methods are often used; in combination with hydraulic power packs, this includes the use of concrete pulverizer<\/strong> as well as hydraulic wedge splitter<\/strong>.<\/p>\n

Definition: What is meant by tunnel lamella<\/h2>\n

A tunnel lamella<\/strong> is a lamella-shaped, self-contained partial structure or a sectionally constructed component area that fulfills structural, sealing, guiding, or ventilation functions in tunnel construction. Typical examples are diaphragm wall lamellae of excavation pits and tunnel exterior walls, lamella-wise applied shotcrete panels for face stabilization, lamellae for noise and light control at portals, and ventilation lamellae in shafts and cross passages. The term does not describe a single standardized component type, but rather the lamella-like execution: as a panel, field, segment section, or air-guiding lamella. For maintenance or deconstruction of such lamellae, controlled methods with low vibration, low dust, and high precision are required, such as splitting massive concrete areas or clamp-like removal of reinforced concrete components.<\/p>\n

Construction types, materials, and installation locations of tunnel lamellae<\/h2>\n

Tunnel lamellae occur in several practical variants. They differ in material, thickness, dimensions, and connection details, but always fulfill a clearly assigned function in the construction sequence and later operation. The following outlines the most important construction types, explains their typical applications, and shows the impacts on production, inspection, maintenance, and deconstruction.<\/p>\n

Diaphragm wall lamellae in cut-and-cover and diaphragm-wall methods<\/h3>\n

Diaphragm walls are constructed in lamella-wise separated sections. Each lamella is excavated in a support fluid, fitted with reinforcement cages, and concreted. In tunnel construction (especially in cut-and-cover), these lamellae take significant earth and traffic loads, provide groundwater protection, and often form the future exterior wall of the structure. Waterstops, swelling profiles, and interlocking solutions ensure sealing between lamellae. When opening, retrofitting, or deconstructing individual lamella fields, controlled removal of heavily reinforced concrete is required; here, concrete pulverizer<\/strong> and\u2014for massive zones\u2014hydraulic wedge splitter<\/strong> are preferred to minimize vibrations.<\/p>\n

Shotcrete lamellae in NATM\/SEM<\/h3>\n

In conventional tunneling, the tunnel face and top heading are secured section by section with shotcrete. These panels are often installed alternately in a lamella-like pattern to limit settlements and control load behavior. The lamellae consist of shotcrete with reinforcement meshes, anchor<\/strong>, and possibly fibers. For local reinforcements, openings, or repairs: thinner shotcrete lamellae can be removed precisely with a concrete pulverizer<\/strong>; for thicker areas or rock-laden zones, hydraulic wedge splitter<\/strong> as well as rock wedge splitter<\/strong> have proven effective to release the rock\u2013concrete bond without impact.<\/p>\n

Ventilation and portal lamellae<\/h3>\n

At tunnel portals and in ventilation structures, lamellae made of steel, aluminum, or GFRP are used for air guidance, weather and noise protection, and light control. These ventilation lamellae<\/em> are corrosion-protected and designed for flow performance. For replacement and deconstruction, separation of metal sections and disassembly of frames are key. For mechanical cutting, steel shear<\/strong> can be used; load-bearing concrete frames of lamella fields are reduced in a controlled manner with a concrete pulverizer<\/strong>. Smaller metal profiles or installations can be cut with an attachment shear<\/strong>.<\/p>\n

Materials and typical dimensions<\/h3>\n