古代磚砌體風化性能分析及風化程度評定

湯永凈++趙紅+葉真華+楊玉穎+邵振東

摘要：自然界中氣溫、降水的長期作用導致古代磚砌體風化，風化損傷材料和砌體力學性能。實驗采用大氣環境實驗艙實現自然風化作用人工模擬，根據不同飽水度和凍融次數，實驗艙設定了7種非飽水凍融工況，對7種工況影響下的磚、灰漿、砌體抗壓、砌體抗剪試件試件強度變化規律進行實驗分析。實驗表明，飽水度是反映材料凍融性能的重要指標；不同飽水度下的凍融試件強度呈現先升后降的趨勢；試件在飽水度為53%的凍融作用下，砌體構件具有最佳抗力；提出古代磚砌體構件風化程度評定標準。實驗對古磚砌體結構保護工作具有指導和應用價值，定期評定古塔砌體風化程度，時刻掌握古塔構件結構安全性能的變化規律，科學保護古塔。

關鍵詞：風化；風化系數；風化程；非飽水凍融；飽水度

中圖分類號：TU522文獻標志碼：A文章編號：16744764（2017）03006708

Abstract：During long action of temperature and precipitation， ancient brick masonries were weathered. The experiment employed an environmental chamber to simulate natural condition. seven unsaturated freezethaw cases were designed to treat various specimens which are brick units， mortar cube， triple masonry and prism masonry. We carried out saturation degree measurement， compressive test and shear test to the various specimens in laboratory. The resules show that the saturation degree is one key factor to effect on material freezethaw resistance. The strength of specimens increaseed firstly with saturation degree and decreases after a certain saturation degree. The best compressive resistance of brick， mortar， and prism masonry was when the saturation degree is about 53%. Based on the weathering coefficient and specimen mechanical behavior， we suggested the evaluation standard of weathering degree for ancient brick masonry structures.

Keywords：weathering； weathering coefficient； weathering degree； unsaturated freezethaw， saturation degree

以磚塔為代表的古代磚砌體常年裸露于大自然中，因氣溫、降雨及季風等自然營力作用，許多古塔砌體由表及里呈現龜裂、疏松、粉化、表面剝落等不同風化癥狀。風化癥狀的出現反映了砌體材料性能劣化，嚴重劣化可導致砌體結構局部塌落。自然營力對古塔不同部位的作用是不均勻的：日照不同，塔身南部溫度高于北部；風蝕不同，地理氣候決定最大風向頻率常常發生在塔身某固定側面；干濕不同，塔基及下部塔體因地下孔隙水作用其含水率高于上部。當強度衰減低于材料的允許強度，風化嚴重的部位會產生屈服破壞、塔基不均勻沉降或塔身呈現傾斜。……