溪洛渡水电站无压泄洪洞衬砌混凝土秋季施工温控方案优选

为研究溪洛渡水电站无压泄洪洞秋季施工的温控防裂问题,运用三维有限元法模拟施工过程与温控措施,通过改变混凝土表面的热对流系数来模拟洒水、流水养护的影响,采用直接法模拟冷却水管的作用。运用ANSYS软件对1.0m厚衬砌混凝土秋季施工的5种工况,包括基本工况、基本工况加洒水养护、恒温流水养护、加洒水及恒温流水养护、无通水冷却,进行了仿真计算。通过比较相应工况中特定断面的表面点在不同时间的温度应力值和抗裂安全系数,得出结论:洒水能够有效降低拉应力;常温流水会加大内表温差;通水冷却有效降低最高温度,但应力改善效果不明显。秋季浇筑混凝土,早期宜洒水和通水冷却,后期恒温流水养护,这样能够有效避免温度裂缝的产生。

Autumn Construction Project Optimization for Concrete Lining of the Non-pressure Spillway Tunnel in Xiluodu Hydropower Station

In order to study the problem of preventing cracks in the construction of the flow regime non-pressure spillway tunnel in Xiluodu Power Station,a 3-D finite element analysis is made to simulate the construction process and the temperature controlling measures.It simulates the effects of sprinkler,water conservation by changing the surface heat convection coefficient of concrete and simulates the effect of cooling pipe by taking the direct method.Five working conditions of the 1.0-meter thick concrete lining in construction in autumn,including the basic condition,basic condition with sprinkler,with thermostatic water conservation,with sprinkler and thermostatic water conservation,without water cooling,are simulated and calculated by software ANSYS.By comparing the thermal stress value and crack security coefficient of the surface points in specific sections at different times of relevant conditions,it can be concluded that:Sprinklers can effectively reduce tensile stress.Room temperature water conservation can increase the temperature difference between the internal and table concrete.Water cooling reduces effectively the early maximum temperature,but the effect of reducing stress is not obvious.Pouring concrete in autumn,early sprinkler maintenance should be adopted together with water cooling.Later on,thermostatic water conservation should be adopted.Thus,it can effectively avoid temperature cracks.