Mechanical Response of Composite Structure in Shield Working Shafts Under Very Heavy Ground Loads
To solve the problem of lack of verification for effects of very heavy ground loads in current design of shield working shafts,an indoor scale model test was carried out to research mechanical response of composite structure in shield working shafts composed of underground diaphragm walls and main structure inner walls under very heavy ground loads from constructing period to service period.Considering effects of ground water in soil around shield working shafts,impacts of soil shear strength loss on the maximum very heavy ground load was discussed.The results show that under the very heavy ground loads,the middle wall in the shield working shaft has a large compressive stiffness and bears a large amount of load effect in the form of compression.An integral horizontal displacement at a low stress level is therefore prone to occur at upper composite structure,and an integral collapse due to instability occurs at lower supporting struc-ture.The underground diaphragm wall in the composite structure bears most of the internal force due to the initial deflec-tion of main structure inner walls during constructing period and the integral horizontal displacement of composite structure.By observing the deformation of composite structure in the indoor scale model,the ultimate overload at the top of the shield working shaft conversed from model data is 445.5 kPa,which is much greater than the subsoil bearing capacity characteristic value of 130 kPa of soil around the shield working shaft.Safety and reliability of ground hardening design under very heavy ground loads according to subsoil bearing capacity are therefore verified.
shield working shaftcomposite structurevery heavy ground loadmodel testsubsoil bearing capacity
NETL
NSTL
万方数据
维普
