The Research On The Collapse Mechanism And Treatment Method Of Subsea Tunnel During Construction

In the tunnel construction,the landslide is a common accident,the influence factor of the tunnel collapse is many,the control is more difficult,is the tunnel construction process is very common hazard accident.Once the landslide accident occurred,not only delay the duration of the project,improve the cost of the project,damage the construction machinery,and even cause casualties.The subject of a power plant is located in the sea water tunnel project as an example,a comprehensive analysis of the causes of tunnel collapse accident,the treatment scheme of vhul's collapse,and using the method of numerical simulation,the disposal process of tunnel collapse were analyzed on the mechanical property of supporting structure simulation,safety of the disposal scheme was evaluated,and the optimization is carried out on the analysis,after a similar treatment of tunnel collapse has practical guidance and reference significance.The following main conclusions are obtained through the analysis:(1)the main factors affecting the landslide of the submarine tunnel are bad geological conditions,underground water,design factors,construction and management factors,etc..In these factors,resulting in poor geological conditions is one of the most important factors of tunnel collapse,but the underground(table)occasions,factors of tunnel collapse second impact.Of course,some of the factors in the tunnel design,construction and management of tunnel construction can not be ignored,which are related factors of tunnel collapse.(2)in a power plant water supply and drainage tunnel collapse examples,can the general geological conditions of tunnel portal are poor,broken surrounding rock,poor bearing capacity of surrounding rock is often IV ~ V grade,once the collapse accident treatment,basic steps: the collapse of control-surface treatment-body collapse collapse-slope reinforcement the collapse body treatment vault upper cavity collapse treatment of tunnel excavation and support-landslide two excavation,monitoring and measurement.(3)in a power plant water supply and drainage tunnel collapse stress numerical simulation of displacement field and plastic zone in the field,as follows: 1)the excavation steps can reduce the working face of the tensile stress level;2)tensilemaximum horizontal displacement force of maximum principal stress is mainly concentrated in the arch foot;3)the maximum displacement of vault is mainly distributed in the vault within 60 degrees,the maximum displacement of floor heave are mainly distributed in the central 1/3 at the bottom;collapse treatment of arch and vault60 degrees of key support;4)two lining support,reduce the scope of the lining sinking trend,bottom plate uplift phenomenon is suppressed that pipe,grouting,cavity collapse shed advance support and lining plays an important role in supporting measures,effective treatment of landslide.(4)according to the "tunnel collapse once the first flood,after reinforcement,anti expansion,then the treatment principle of treatment," sooner rather than later,"according to the excavation methods for the actual engineering situation and supporting methods,adhere to guide the construction of informatization,and constantly improve the construction management level.The construction should always follow the excavation of the principle of minimum energy,avoid the impact on the stability of surrounding rock,the subsea tunnel collapse treatment optimization design of the basic way.