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巴顿等(1974)建议的岩体质量与支护压力之间的相关关系式除对挤压地层外已被证 明是有用的。从20个隧道断面上系统收集的现场资料表明:覆盖层高度与隧道收敛闭合的关系,显 然需要用一个修正系数来考虑,如果用应力折减系数来考虑似乎不适当。如所预期,支护压力随着 隧道收敛闭合而迅速减小,然后超过一个限制的闭合量后就增大。事实上,观测的侧墙支护压力始 终接近于零,除了在挤压地层情况已经通过对Q-wall稍微修改侧墙系数来认真对待,从现场资料 导得的标准表明,在覆盖层高度超过350Q~(1/3)时会遇到挤压的地层情况。这里报告的资料也证实巴 顿等较早发现的支护压力与隧道尺寸的大小无关。
The correlation between the mass of rock mass and the supporting pressure proposed by Barton et al. (1974) has proved to be useful except for the extrusion of formations. Field data collected from 20 tunnel sections show that the relationship between the height of the overburden and the closure of the tunnel apparently needs to be considered with a correction factor which does not seem to be appropriate if considering the stress reduction factor. As expected, the support pressure rapidly decreases as the tunnel converges and then increases beyond a limited amount of closure. In fact, the observed sidewall support pressure is always close to zero, except that in the case of pinched formations, the sidewall coefficients have been taken lightly by slightly modifying the Q-wall. Criteria derived from the field data indicate that when the overburden height exceeds 350Q ~ (1/3) will encounter the extrusion of the formation. The data reported here also confirm that the earlier found support pressure by Patton et al. Has nothing to do with the size of the tunnel.