Study On Ground Surface Settlement Caused By Shallow Mining Method And The Control Standard

It is predicted that a great deal of urban metro engineering will be constructed at early-middle period in the 21st century based on flourish metro engineering foreground nowadays,and at one time many geotechnical problems will also come forth.Large land subsidence value induced by metro tunneling can lead to that road surface,buried pipelines and buildings and so on are damaged.Furthermore,bad economic loss and social effect can be brought about.As a result,it is an urgent realistic problem that land subsidence induced by urban underground engineering is forecasted and controlled so as to ensure the safety of close-by building and buried pipeline.By the method of probability statistical analysis and numerical calculation about. Beijin metro engineering:â‘ Base on the typical formation conditions of Beijng,the mechanism and the law of strata deformation caused by Shallow Mining Method are summarized.At the same time,the whole process of ground deformation is described in detail.The Principle of Shallow Mining Method is concluded,and the feathers and the method of support design are described in this paper;â‘¡By the probability statistical analysis on field monitoring measurement data of Beijin metro line 5 and line 10 in detail,the reasonable control standards of the ground settlement are given,which changes the situation of the single contol standards 30mm in Beijin metro engineering in the past.At the same time,based on the site construction monitor data of running tunnels and subway stations constructed by Mining Method, the curves of surface settlement troughs are fitted and the feather of formation loss rate and trough width parameter are deeply researched,which gives some relevant conclusions;â‘¢By the measure of regression analysis and numerical simulation,the influence of the buried depth for the related parameters of surface settlement troughs are studied. The changing law of the surface maximum settlement value,the formation loss rate and the trough width parameter with increasing buried depth is given.Find the critical depth below which the influence for the ground surface caused by the construction of standard section interval tunnel by Shallow Mining Method is negligibly small.At the same time,the effect of primary support structure stress with increasing buried depth is researched and some important laws are found,then the range of buried depth below which it is considered that the formation can form the stable arch structure by itself is given.Finally,the positions of the formation arch structure in different buried depths and the changing rules of the position with increasing buried depth are given by the further study of the characteristics of formation settlement curves below different burid depths;â‘£Based on the new ground surface settlement control standards,optimization analysis for the excavation methods of complex group tunnels in Huangzhuang metro station's construction is maken by numerical simulation method.First classify the various group tunnels according to the excavation space position and establish the thinks system of optimization analysis for the excavation methods of complex group tunnels.Then respectively study the laws of ground deformation caused by excavation of all kinds group tunnels and emphatically optimize the excavation methods of group tunnels in the plans based on the view of controlling the ground deformation and making the primary support safety.At last,the best optimization excavation methods are given by numerical simulation method combining practical projects.At the same time,the safety of the primary support in the construction of group tunnels is be verified,which supports the establishment of new ground surface settlement control standards.