7.5.1 According to requirements of economic factor and excavationschedule, tunnel boring machines (TBM) should be applied fortunneling where the surrounding rocks are of medium hardness.7.5.2 The normal excavation cross section by a TBM is of acircular sh...[继续阅读]

    7.3.1 For excavation of vertical shaft, mucking from the bottom ofshaft should be adopted. If conditions do not allow, full face tunnelingmethod from the top down shall be selected.7.3.2 For excavation of vertical shaft, mucking from the bottom ofshaft sh...[继续阅读]