底孔坝段温度应力场仿真研究

Simulative study on temperature stress field in dam section of bottom outlet

针对坝身开孔后削弱了混凝土坝结构的整体性、孔口周围易产生应力集中并可能导致产生温度裂缝的问题,采用三维有限单元法对底孔坝段施工全过程进行温度应力场仿真研究,计算考虑了通水冷却、混凝土的水化热温升以及弹性模量等对底孔坝段温度和应力的影响,并对比分析了不同方案下坝体温度应力。结果表明:方案4(约束区Tp=18℃,非约束区Tp=22℃,通水冷却)在采取通水冷却和控制混凝土浇筑温度措施后,高程1 624.5~1 631.5 m范围内垫层常态混凝土最高温度为33.8℃,最大温度应力为1.50 MPa;高程1 626.5~1 646.5 m范围内碾压混凝土最高温度为26.8℃,最大温度应力为1.32 MPa;高程1 646.5~1 692.0 m范围内闸室以上常态混凝土最高温度为36.5℃,最大温度应力为1.45 MPa,从而坝段各区域的最高温度均小于允许最高温度,最大应力小于该工程的允许拉应力。研究成果为混凝土坝底孔坝段施工温度控制提供借鉴。

Aiming at the problem of that the structural integrity of concrete dam is to be weakened after arranging outlet, and then stress concentration is prone to occur around the outlet and temperature cracks are possibly caused therein as well, a simula- tive study is made on the whole construction process of the dam section of bottom outlet with 3 - D finite element method, in which the impacts from water cooling, hydration heat temperature rise of concrete, elastic modulus, etc. on both the temperature and stress of the dam section are considered in the calculation, and then the temperature stress of the dam body under different schemes are comparatively analyzed. The result shows that under the condition of the scheme 4 （ the constraint zone Tp = 18 ℃, unconstraint zone Tp = 22 ℃, with water cooling）, the highest temperature is 33.8 ℃ and the maximum temperature stress is 1.50 MPa within the elevation range of 1 646. 5 m to 1 692.0 m, the highest temperature is 26. 8 ℃ and the maximum tem- perature stress is 1.32 MPa within the elevation range of 1 626. 5 m to 1646. 5 m and the highest temperature is 36. 5 ℃ and the maximum temperature stress is 1.45 MPa within the elevation range of 1 646. 5 m to 1 692. 0 m after adopting the measures of wa- ter cooling and control of concrete placing temperature, thus the highest temperatures in all the zones of the dam section are less than the allowable highest temperature concerned, and the maximum stress is less than the allowable tensile stress of the project. The study result can provide a reference for the temperature control of the construction of concrete dam section of bottom outlet.