PURPOSE: To easily and surely achieve timbering by enabling a receiving joint secured to a wale to be connected at a desired angle to a main joint which is secured to a beam member.

CONSTITUTION: Large-aperture pin holes are bored through the pressure receiving plate of a receiving joint 2 which is secured to a wale H constitution timbering and through approximately the center of each of the pair of supporting plates for a main joint 3 which is secured to a beam member A via a jack J. A number of small-diameter connecting holes are bored on concentric circles surrounding the large-aperture pin holes. Joint pins 4 are fitted into the respective large-aperture pin holes of the receiving joint 2 and the main joint 3 and locked in place by means of dividing pins so that the wale H is temporarily joined to the beam member A. A bolt B is fitted into a small-diameter connecting hole at a predetermined angle corresponding to the configuration of the ground to be drilled and to the rigidity of the timbering, and is held in position by a nut N. To connect the beam member A to the wale H, the gap between the wale H and the beam member A is adjusted by the jack J.