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压力隧洞钢筋混凝土衬砌的裂缝间距直接影响裂缝宽度,是限裂设计重要参数之一。4个现场水压试验的结果和实际经验表明:与建筑构件相比,衬砌初次开裂的特点是裂缝间距较大、条数较少。提供一个确定“初裂间距”的钢筋混凝土曲梁法,它能考虑配筋量、衬砌曲率、内水压力、围岩的法向及切向反力的作用,且计算较为简易。比较了本法和“弹性地基曲梁理论”的优缺点并进行了讨论。算例表明,两法计算结果大体一致,都能反映衬砌的初裂特点,较为符合实际。也可利用所提供的方法判断随着内水压的升高是否发生第二次开裂。
The pressure tunnel reinforced concrete lining crack spacing directly affect the crack width is one of the important parameters of crack design. The results of the four on-site hydrostatic tests and practical experience show that compared with the building components, the initial cracking of the lining is characterized by a large crack spacing and a small number of strips. It provides a reinforced concrete curved beam method to determine the “initial crack spacing”, which can consider the effect of the amount of reinforcement, lining curvature, internal water pressure, surrounding rock normal and tangential reaction force, and the calculation is relatively simple. The advantages and disadvantages of this law and “elastic foundation curved beam theory ” are compared and discussed. The example shows that the results of the two methods are generally consistent, which can reflect the characteristics of the initial cracking of the lining and is more realistic. The method provided can also be used to determine if a second cracking has occurred with increasing internal pressure.