Abstract:

During TBM boring under buildings in shallowburied composite strata, pea gravel filling and grouting and the interface location of soft and hard rock both have great influence on building settlement. In order to find out those influence laws, numerical simulation and field monitoring methods are used. The following conclusions can be drawn: (1) After excavation and before pea gravel filling completed, the settlement of buildings, accounting for about 70% of the total settlement, is the fastest since the surrounding rock is in nonsupport state; (2) With the strong compressibility of pea gravels, settlement still existis when the pea gravel filling is finished, which accounts for about 30% of the total settlement; (3) The interface location of soft and hard rocks has significant influence on building settlement during tunneling of single shield TBM. According to the extent of influence, it can be classified into three categories and then control measures are given correspondingly. Both onsite monitoring and date analysis show that surface grouting and timely pea gravel filling and grouting are of great importance for settlement controlling of building.

Key words: tunnel construction, composite stratum, single shield TBM, pea gravel, building settlement, interface of soft and hard rock