Cross bracing denotes the bracing across excavations and trenches by horizontal or inclined struts that brace opposing shoring faces against each other. It is a central element of excavation support, particularly where space is tight, loads are high, and soil layers vary. In combination with infill panels, shoring panels, sheet pile walls or soldier pile walls, cross bracing provides structural stability, enables safe earthworks, and creates the framework for follow-on trades such as pipeline construction, foundation works or selective deconstruction. Where cross bracing ties into existing structures or requires its dismantling, interfaces arise to tools for concrete demolition and steel cutting—such as concrete crushers, hydraulic rock and concrete splitters, and steel shears by Darda GmbH—without the shoring itself being part of a demolition process.
Definition: What is meant by cross bracing
Cross bracing refers to the stiffening elements (struts) arranged perpendicular to the alignment of the structure or trench that connect two opposing shoring faces by compressive forces. These struts consist of steel tubes, H-beams, telescopic or hydraulic struts with head plates and bearing points. They transfer earth and traffic loads from the shoring wall into an opposing abutment and prevent deformations as well as subsequent soil collapse. Cross bracing differs from longitudinal bracing (stiffening in trench direction) and from tieback systems (e.g., ground anchors), since it acts as a compression system within the trench or excavation cross-section. In practice, people also refer to cross struts, spindle struts, or transverse beams; they are often combined with walers and beams to introduce loads along a line.
Configuration, components, and working principle of cross bracing
A typical cross bracing consists of one or more levels of struts clamped at defined elevations between opposing shoring elements. Load transfer takes place via head plates into the walers or directly into the shoring wall (e.g., shoring panels, sheet piles, soldier pile wall). The struts work in compression and are preloaded by spindles or hydraulic cylinders to limit settlements and movements at an early stage. Key components are: strut body system (tube, rolled H-section, telescopic), adjustment device (spindle, hydraulics), connection points (head plate, clevis), intermediate beams/walers as well as bearings and packings for load distribution. The operating principle is based on an equilibrium of forces from earth and traffic loads that is introduced in a controlled manner into the opposite shoring by the cross bracing; geometric stiffness, prestress, and frictional contact at the bearings largely govern the deformations. In deep excavations, several cross bracing levels are arranged vertically, often in combination with longitudinal walers, to form a spatially effective load-bearing system.
Fields of application and limits of use
Cross bracing is used in narrow trenches for utility installation, in medium to deep excavations of inner-city projects, and on constrained construction sites with high surcharge loads. In small to medium tunnel headings, temporary cross bracing can secure the face until the final lining (e.g., shotcrete, anchors, lattice girders) is installed. Limits of use arise from large excavation widths, lack of opposing abutments, highly heterogeneous soils, or constraints that require large clear openings (installation of cranes/equipment). In such cases, alternative systems (tiebacks, top-down/cover method) are evaluated.
Typical scenarios
- Trench shoring in utility and sewer construction with modular trench boxes and struts
- Excavations in inner-city locations with multiple levels of cross struts and longitudinal walers
- Temporary bracing for breakthroughs, underpinning, and alterations to existing structures
- Temporary cross bracing in tunnel and drift construction of small cross-sections
Planning: load assumptions, geometry and design
The design of the cross bracing takes into account geotechnical parameters, groundwater, traffic loads, construction stages and erection sequence. The objective is deformation control with sufficient reserve capacity. Geometry and grid (strut spacing, level elevations) are coordinated with the shoring system. In inner-city excavations, settlement limits increase the requirements for stiffness and prestress. For trenches, transport, rapid assembly and reusability are key. The design is the responsibility of qualified professionals; relevant standards are generally followed, without this text constituting a binding interpretation.
Influencing factors
- Soil parameters, groundwater level, and construction phases
- Excavation width, strut lengths, and buckling checks
- Prestressing forces and coefficients of friction at the bearing points
- Interfaces to embedded parts, utilities, and existing foundations
Installation, relocation and dismantling
The construction sequence follows the principle of incremental excavation with trailing shoring and timely cross bracing. Assembly-friendly, modular systems reduce downtime and ensure safe work in confined cross-sections. During relocation, the load path is shifted in a controlled manner before individual struts are released. Dismantling proceeds in reverse order to installation and requires careful safeguarding of the soil.
Recommended sequence
- Excavate a section, install or push down the shoring face
- Install walers, insert cross struts and pre-stress
- Continue excavation, add further levels, monitor deformations
- Adapt cross bracing section by section or temporarily relocate it for embedded parts/utilities
- Dismantling: redistribute loads, deliberately release prestress, loosen and recover struts
Interfaces to demolition and cutting
In existing structures, cross bracing can clash with concrete ribs, downstand beams, or steel girders. To make adjustments, concrete and steel components are selectively removed or cut. Depending on member thickness, accessibility, and sparking, concrete crushers, Steel Shears, combination shears, or multi cutters from Darda GmbH are used. Where impact and vibration must be avoided (e.g., near sensitive utilities), stone and concrete splitters or rock splitting cylinders enable low-vibration material removal. compact hydraulic power units provide the necessary power supply under confined site conditions.
Materials and construction methods
Cross bracing is predominantly fabricated from steel (tubes, rolled H-sections, telescopic struts), supplemented by prestressing elements (spindle/hydraulics). In trench shoring, modular boxes with integrated struts predominate. In excavations, free spans are bridged with auxiliary beams, bearing points are upgraded with packings, and contact areas are protected against point loads. In corrosive environments, coatings and maintenance are relevant. Aluminum is used in special cases where weight and handling dominate.
Occupational safety and monitoring
Occupational safety takes precedence: secure access routes, cordon off assembly areas, document load states, and record prestress values. Deformation and settlement measurements accompany critical construction stages. Releasing preloaded cross bracing requires controlled pressure relief. In sensitive areas, low-vibration methods—such as splitting instead of impact—reduce risks of sloughing and damage to adjacent existing structures.
Typical risks
- Insufficient prestress, delayed deformations
- Local overcompression at bearing points, crushing of shoring panels
- Uncontrolled load transfer during dismantling
- Surface water or groundwater influence, uplift
Typical failure patterns and their prevention
Failures often arise from unsuitable strut lengths (buckling), grids that are too coarse (deflecting walers), or insufficient bearing areas. Remedies include adjusted strut spacing, intermediate walers, sufficiently stiff walers, and verified prestress. Where clashes with embedded items occur, planned, selective removal with concrete crushers or low-vibration exposure using stone and concrete splitters from Darda GmbH has proven effective.
Use cases related to products and application areas of Darda GmbH
Cross bracing touches several application areas: In concrete demolition and special deconstruction, concrete crushers are used to create local openings, fit strut bearings, or remove temporary concrete beams in a controlled manner. In strip-out and cutting, steel shears and multi cutters enable cutting of steel cross struts without large-volume oxy-fuel cutting. In rock demolition and tunnel construction, rock splitting cylinders allow low-vibration widening of cross-sections for cross struts. In natural stone extraction, temporary cross bracing can assume safeguarding tasks in narrow benches and shafts; stone and concrete splitters support precise preparation of bearing surfaces. For special operations in sensitive facilities, cold, low-spark cutting methods are preferred to adapt cross bracing safely.
Quality assurance, documentation and reuse
Reusable systems require visual inspection, dimensional checks, and proof of load-bearing capacity. Assembly and prestress logs, measurement data, and photo documentation enhance traceability. A resource-conscious approach considers multiple reuse of struts and clean separation during dismantling. Low-vibration methods—such as splitting with hydraulic devices—reduce damage to shoring faces and facilitate recycling.
Practice-oriented guidance for planning and execution
Early coordination between geotechnics, structural engineering, and execution reduces risks. A digital construction-stage model with load states facilitates selection of strut levels and their accessibility. In proximity to existing structures, it is worth preparing alternative cutting methods: concrete crushers for reinforced concrete, steel shears for sections, and stone and concrete splitters for massive components without sparking. A tight cycle of inspection and re-tensioning keeps deformations low and secures the excavation edge—a prerequisite for on-schedule follow-on work.