目前,我国在农村推广的沼气池大多是采用普通混凝土结构或钢筋混凝土结构。由于混凝土内部存在连通或不连通的孔隙,这些孔隙是渗水的途径。当混凝土处于饱水状态并遇到温度低于零度时,内部水分冻结,造成结构体积膨胀。各种孔隙的周壁上产生相当大的内压力,引起孔壁的胀大并产生拉应力。当温度升至零度以上时,冰虽融化, At present, most biogas digesters popularized in rural areas in China are ordinary concrete structures or reinforced concrete structures. Due to the existence of concrete inside the communication or non-connectivity of the pores, these pores are water seepage. When the concrete is saturated with water and encounters temperatures below zero, the internal moisture is frozen, causing the structural volume to expand. A large amount of internal pressure is generated on the peripheral walls of various pores, causing the expansion of the cell walls and the generation of tensile stress. When the temperature rose above zero, the ice melted,