During construction of new facilities where open cuts are not feasible, braced excavations support the ground around foundation excavations to control deformation of adjacent structures, utilities, and soil.
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Braced excavation is a method where deep excavations with straight vertical faces are laterally supported by a sheeting and bracing system until the structure is built.
In deep excavations creating a safe slope on the excavation face just for safety is generally not feasible due to high cost, inabundance of space and other structures present nearby. So, the excavation is temperorly supported by sheets/walls and struts, which are removed individually when their requirements cease. Relatively flexible sheets/walls are placed against excavation walls and supported by horizontal struts which in turn resist the earth pressure in compression.
Some methods are vertical timber sheeting, shoring, steel sheet piling, soldier beams and also tiebacks.
These structures might not be removed later but they may or may structurallynot be structurally important apart from offering temperorly lateral support. For example, tie backs support excavations and also replace permanent retaining walls.
Installation of the bracing struts is done by excavating soil locally around the strut and only continuing the excavation once preloading is complete. A typical sequence of excavation in cross-lot braced excavations is shown in Figure 1 is known as braced excavation.