本文關鍵詞：碾壓混凝土重力壩施工期溫控措施及溫度應力優(yōu)化研究　出處：《西北農林科技大學》2015年碩士論文　論文類型：學位論文

  更多相關文章： 碾壓混凝土重力壩 溫度場 溫度應力 溫控措施 方案優(yōu)化

【摘要】：混凝土有別于普通混凝土,具有干硬性且沒有坍落度,在施工過程中采用通倉澆筑,薄層鋪料,震動碾壓的方法,因此具有施工快、用料省的優(yōu)點。經過我國廣大科研工作者的不懈努力,碾壓混凝土壩施工已具備了相當成熟的技術,并在擁有高粉煤灰摻量、少水泥用量的特點。由于碾壓混凝土壩中摻入了大量的粉煤灰,水化熱速率要明顯降低,同時,壩體的上升速度較快,致使倉面與空氣接觸時間較短,散熱不足,容易在壩體內部形成溫度集中,導致很大的溫度應力,使壩體更容易產生裂縫,影響大壩安全。論文利用有限元分析軟件ANSYS對碾壓混凝土重力壩施工期的溫度場和應力場進行仿真分析,綜合考慮了外界氣溫變化、水泥水化熱隨齡期變化、不同的澆筑溫度及分層的實際影響,以及混凝土彈性模量、徐變度隨齡期變化等特性,提出了仿真實現(xiàn)過程。在模擬施工過程中,通過改變水管通水冷卻方案、澆筑倉面保溫、改變混凝土澆筑溫度等溫控措施對壩體溫度應力進行分析,從而對施工期的施工方案進行優(yōu)化,對不同方案下壩體的溫度應力進行對比,并在最后提出碾壓混凝土施工期溫度控制的最佳方案。經分析可得到以下結論:(1)水管冷卻能夠在一定程度上降低壩體溫度,應根據實際需要選取水管冷卻方案,可適當增大水管間距和提高通水溫度以節(jié)約成本。(2)壩體澆筑盡量減少間歇時間,特別是高氣溫時段,澆筑時可選擇去掉間歇時間,從而使混凝土的預冷措施得到最大利用。(3)壩體表面保溫措施可以防止表面裂縫產生,但對整個大壩溫度場的影響較小。
[Abstract]:Concrete is different from ordinary concrete. It is dry and hard and has no slump. In the process of construction, it adopts the methods of storehouse pouring, thin layer laying and vibration rolling, so it has fast construction. Through the unremitting efforts of the vast number of scientific research workers in our country, the RCC dam construction has already possessed quite mature technology, and has the high fly ash content. Because a large amount of fly ash is added into the RCC dam, the hydration heat rate will be obviously reduced, and the rising speed of the dam body will be faster, resulting in a shorter contact time between the silo surface and the air. Because of insufficient heat dissipation, it is easy to form temperature concentration inside the dam body, which leads to great temperature stress and makes the dam body easier to produce cracks. The finite element analysis software ANSYS is used to simulate the temperature field and stress field of RCC gravity dam during the construction period. The cement hydration heat varies with age, the actual influence of different pouring temperature and delamination, as well as the characteristics of concrete elastic modulus and creep with age, etc. The temperature stress of the dam body is analyzed by changing the water cooling scheme of the water pipe, the heat preservation of the pouring silo surface and changing the pouring temperature of the concrete, so as to optimize the construction plan during the construction period. The temperature stress of dam body under different schemes is compared. Finally, the optimal scheme of temperature control during the construction period of RCC is put forward. The following conclusion can be obtained by analysis) the cooling of water pipe can reduce the temperature of dam to a certain extent. The cooling scheme of water pipe should be selected according to the actual needs, which can increase the spacing of water pipes and increase the water temperature to save cost. 2) the intermittent time, especially the period of high temperature, can be reduced as much as possible. When pouring, the intermittent time can be removed, so that the precooling measures of concrete can be used to the maximum extent. The surface heat preservation measures of dam body can prevent surface cracks, but have little effect on the temperature field of the whole dam.
【學位授予單位】：西北農林科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TV642;TV544

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