孤石爆破预处理技术在盾构隧道中的应用

以某地铁盾构区间为例,介绍盾构穿越风化岩地层时遇到孤石的处理经过,着重论述网格法进行孤石探测、由地面实施点对点孤石爆破处理施工技术,为盾构穿越孤石群打出一条绿色通道,降低开舱换刀风险,保障盾构顺利掘进。

Application of Boulder Blasting Pretreatment Technology in Shield Tunnel

In order to study the shear strength of different plastic subgrade soil subjected to freeze-thaw cycles, three kinds of plastic indexes of soil samples are studied through the laboratory triaxial test and freeze-thaw cycle test. The results show that when the number of freeze-thaw cycles increases, the shear strength increases with the increase of plastic indexes. When the plasticity index is the same, the shear strength changes differently with the increase of freeze-thaw cycles and confining pressure, in which the shear strength is inversely proportional to the times of freeze-thaw cycle and directly proportional to the confining pressure. After 6~7 times of freeze-thaw cycles, the changes of shear strength of the three kinds of plastic index soil samples tend to be gentle.