关键词: PCCP;内压;外压;断丝比例;塑性;

Abstract: In order to study the internal or external pressure bearing capacities of prestressed concrete cylinder pipes(PCCPs)after wire breakage, based on the large diameter PCCP of a water diversion project in working, the calculation models under internal or external pressure were established, and the influences of different ratios of broken wires in the middle of pipe body on failure of mortar protective cover, concrete core, cylinder and prestressed steel wires were analyzed.The main conclusions are as follows: under internal pressure, the mortar protective cover, concrete core and cylinder of PCCPs with broken wires all show a stress concentration in the broken wire areas, and with the increase of the ratio, the corresponding internal pressures of the concrete core, cylinder and prestressed steel wires gradually decrease when entering plasticity.As the ratio of broken wires exceeds 10%,the internal pressures of mortar protective cover tend to be stable when it enters plasticity.When the ratio exceeds 35%,the internal pressures of concrete core tend to be stable when entering plasticity.Under external pressure, the pressure values of mortar protective cover in intact pipe and broken pipes are basically the same.The pressure values of concrete core in broken pipes change little with the change ratio of broken wires, but they are obviously lower than that of the intact pipe.When the ratio is less than 20%,the external pressures of cylinder are basically decrease linearly with the increase of the ratio, and when it exceeds 20%,the value is constant.For the prestressed steel wires, when the ratio is less than 40%,the external pressures change linearly.After the ratio increases up to 40%,the external pressure value is basically constant, and is consistent with those of the cylinder entering plasticity.The research results can provide a basis for safety assessment and reinforcement of PCCPs after wire breakage.

Key words: PCCP; internal pressure; external pressure; ratio of broken wires; plasticity;