Based on analysis of grouted tubular rock bolts used in improving the mechanical property of fractured and weak surrounding rock and enhancing the anchoring force of rock bolts,the mechanical model of tunnel with shotcrete and tubular rock bolt support is created.

The unstable measuring system of raw material,the jam of granulator entry trough,return material of off-gas pipeline,water balance in drying system and so on in urea-based compound fertilizer process designed by Wuhuan Science & Technology Co.

Through the analysis of the structure of the off-gas pipe and the loads acting on it,it is indicated that the improper structure is the main source to cause the buckling of the inner pipe in off-gas pipe.