This apparatus relates to shoring of deep excavations such as pits or trenches. It includes vertical rail posts arranged symmetrically in pairs that are spaced from each other along the excavation, articulated trusses and/or spreaders holding opposite rail posts against each other and large shoring panels sliding between adjacent rail posts on either side of the excavation. Each rail post has on either side one channel of a stepped or non-stepped cross section guiding vertically two or more shoring panels. In one variation, the inner and outer panel guides on one side of the vertical rail post reside in the same vertical plane. The connections between the rail post and the wall panels are partially or completely open. The open connections may be performed by magnetic forces arising from thin magnetic flat bars incorporated in the posts or the panels in the area of their contact. The articulated truss may be of a scissoring type and may be composed of triangular cells only and their members may have pinned connections. The cross members of the truss are pinned together in their mid-length enabling their relative rotation while their extremities are pinned into vertical members which have several rows of pinning holes in order to adjust the width of the trench without the need for additional spreaders. The vertical members of the truss slide formlockingly between a pair of opposite posts and could be adjusted at any level from the bottom of excavation. The truss may also include one or more rollers that facilitate its vertical mobility.