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一般来说,许多工程师都害怕大型地下洞室,因为它比小型洞室有更多的麻烦,但现有的许多力学计算却表明这种担心是多会的。尺度影响的三个方面为: 1)尺度对应力分布的影响。这里引入连续介质近似力学,用它可引入材料中微观不均匀的影响,并可以考虑到尺度对应力分布的影响; 2)尺度对岩石、岩体和支护构件强度的影响。脆性材料的强度根据最弱环节(Weakest link)理论变化,即强度随体积的增大而减小。由锚杆和喷混凝土支护的围岩已不全然是脆性材料,因此需要在理论上作某些修改; 3)根据隧道尺寸,尺度的影响依赖于不同的开挖顺序。开挖顺序会影响周围地层及支护构件的应力重新分布或集中。
In general, many engineers are afraid of large underground caverns because it is more troublesome than small caverns, but many of the existing mechanistic calculations show that such concerns can be met more often. Three aspects of scale impact are: 1) the impact of scale on stress distribution. The approximate mechanics of continuum is introduced here. It can be used to introduce the influence of microscopic heterogeneity in material and the influence of scale on stress distribution. 2) The influence of scale on the strength of rock, rock mass and supporting member. The strength of the brittle material changes according to the Weakest link theory that the strength decreases with increasing volume. Surrounding rock supported by rock bolts and shotcreting are not totally brittle materials and therefore require some modification in theory; 3) Depending on the tunnel size, the effect of scale depends on different excavation sequences. Excavation sequences can affect the stress redistribution or concentration in the surrounding strata and support members.