| This paper takes the temporary slope support project of water pump house in Liangjiang Gas Power Plant of Huaneng Chongqing as the research object,demonstrates the supporting scheme under the current building slope code system,refers to the underground engineering such as vertical well and tunnel,discusses the stability state and the stress state of the supporting structure and the stress state of supporting structure by means of theoretical analysis and numerical simulation,and proves the rationality and superiority of bolting and shotcreting support structure in circular foundation pit with inclined rock stratum combined with arch effect principle in combination with actual engineering monitoring data and implementation effect,and consummates the theoretical analysis content of such supporting structure,To provide reference experience,ideas and data for the design and construction of similar projects in the future.The results of the study are as follows:①The excavation of foundation pit causes the change of rock stress,changes the transfer path of the original stress,causes the uneven displacement of the rock body,forms the wedge-tightening effect,and thus produces the arch effect in a certain range of surrounding rock.This phenomenon is common in tunnel engineering and shaft engineering and has corresponding theoretical support.This phenomenon is beneficial to the self-stability of circular rock foundation pit.The stability of inclined rock foundation pit can not be evaluated simply from two-dimensional plane model.②The analysis method of surrounding rock stability of circular foundation pit with inclined rock stratum is more complicated,which is influenced by physical and mechanical parameters of rock mass,dip angle of rock formation,fracture,distribution of weak intercalation and thickness of weak intercalation.③By using FLAC3 D,the excavation and support of circular foundation pit with inclined rock layer are simulated and calculated.By simulation and analysis,the arch effect of circular foundation pit along the foundation pit wall after excavation is obvious,and the arch ring is circular with 25 m diameter circular rock foundation pit.The arch effect formed by rock mass itself can ensure the stability of foundation pit,the whole strain is small,and no support is needed.④The cutting of the structural plane has great influence on the integrity of the circular foundation pit.If the structural plane is too developed,the arch ring formed by the circular foundation pit will be cut into fragments,and the rock mass will change from integral shape to block shape.⑤If the diameter of circular foundation pit of inclined rock layer reaches about150 m,the plastic zone will pass through,and the arch effect may fail and need to be protected.⑥Based on the theory of arch effect and numerical simulation results,a design scheme bedding slip under the condition of two-dimensional plane model is proposed.The actual stability effect of monitoring data and macro inspection feedback foundation pit is good during the implementation of the project,and the optimization of supporting structure plays a positive role in saving the construction period and cost. |
PDF Full Text Request