A two-dimensional singular integral equation with 1／r singularity is discussed in this pa-per，and the closed-form solution of this equation is obtained．The result obtained showsthat the pressure distribution of Hertzian contact problem is unique，and can applied to con-tact problems and crack problems.

This paper states dry and crack problems of timber in drying.

Analysis of three aseismic questions and review on seismic response for new type of retaining walls;