Arrangement method of tunnel upper step steel arch

The invention discloses a tunnel upper step steel arch arrangement method, and relates to the technical field of tunnel steel arch construction, and the method comprises the following steps: constructing according to a step method, when an upper step is excavated, excavating one more step on each of the left and right side surfaces of the excavated contour; and then an upper step steel arch frame is arranged, the step of arranging the upper step steel arch frame comprises the steps of arranging an arc steel arch frame, and arranging an inclined supporting leg on each of the two sides of the arc steel arch frame to be supported on the step. The pressure borne by the foot-lock anchor rod through the upper step arch frame is reduced by half, and the safety coefficient is doubled. 本发明公开了一种隧道上台阶钢拱架布置方法，涉及隧道钢拱架施工技术领域，包括按台阶法施工，在上台阶开挖时，开挖的轮廓在左右侧面分别多挖一个台阶；之后布置上台阶钢拱架，布置上台阶钢拱架时包括布置圆弧钢拱架，并在圆弧钢拱架的两侧分别布置一条斜向支腿支撑于台阶上。本发明通过上台阶拱架锁脚锚杆承受的压力减半，安全系数加倍。