Abstract:The counterforces applied under beams are tested on the site,which is carried out on a granite eluvium slope reinforced with prestressed cable beams along the expressway from Shantou to Jieyang. The data of the counterforces are obtained from the earth-pressure cells under the bottom of beams. It is put forward that under a definite prestressed force,the distribution discipline of the counterforce along the length of beam is quadratic parabola rather than linear or uniform one. The axial force of the main reinforcement in the beams is also tested at the same time,which leads to the conclusion that the distribution discipline along the length of a beam is also quadratic parabola. The distribution discipline obtained from the test confirms that the distortions of the beams are objective. Considering the distortions of the beams,the bending moment along the vertical beam is calculated based on differential equation of beams. The results indicate that the distribution discipline of bending moment along the length of beam is cubical parabola. Both the cubical parabola distribution of the bending moment and the quadratic parabola distribution of the counterforce are accord with the stress-strain and deformation of the beams.