Study On The Design Method Of Double-shielded TBM Drinage Segment Structure In High Water Pressure

At present,with the rapid development of tunnel construction in China,the double shield TBM has been used more and more because of its environmental protection,high efficiency and safety characteristics.With the wide application of this method,more and more challenges have been encountered.Among them,the problem of high water pressure is the typical problem often faced by double shield TBM.As a result,the diseases such as water inrush,water inrush,cracking,leakage of segment joints and insufficient safety of segment under high water pressure are common.It is well known that in the process of tunnel construction,if there is high water pressure,the usual way is to strengthen the lining support strength or adopt corresponding waterproof and drainage measures to deal with it.However,due to the self-construction method of TBM with double shields and the characteristics of segment support,the traditional waterproof and drainage measures can not be applied,and the relevant research at home and abroad is still lacking,resulting in the existing single type of segment waterproof and drainage,segment installation.Waste and other issues.In view of the damage caused by high water pressure to the structure of double shield TBM tunnel and the existing problems,this paper uses data investigation,numerical simulation,field investigation and laboratory test and other research methods to study the drainaged segment lining and water load calculation method of double shield TBM tunnel.The main achievements are as follows:1.By means of data investigation,four factors affecting the adaptability of segment water head are identified:segment thickness,segment reinforcement ratio,concrete strength grade and segment joint opening.For different influencing factors,numerical simulation was used to calculate the head bearing capacity of segments under different design parameters and the maximum opening of j oints at different head heights.2.Through model test and numerical simulation method,the distribution and evolution law of seepage field around double shield TBM tunnel under different types of waterproof and drainage are explored,the concept of influence the range of seepage field is put forward,and the influence range coefficient of surrounding rock seepage related to permeability coefficient of surrounding rock and drainage rate of segment is fitted.Based on this,the relationship between the water pressure behind the segments under different types of tunnel waterproof and drainage,the influence range of surrounding rock permeability and the drainage rate of the segments is deeply analyzed,and the calculation method of the design water load for the segments of TBM tunnel with double shields is proposed.3.Based on the numerical simulation method and the characteristics of double shield TBM construction method and segment,a waterproof and drainage scheme suitable for double shield TBM tunnel is proposed.A three-dimensional fluid-solid coupling model is established to calculate the conditions of inverted arch central drainage,symmetrical drainage on both sides of inverted arch,circumferential drainage and deep hole drainage.The advantages and disadvantages of different drainage schemes are compared comprehensively.For the deep hole drainage scheme,the recommended value of the hole depth of surrounding rock is given.Finally,the recommended value of segment drainage rate under different drainage schemes is proposed.The above results can provide a reference for the design of the drainaged segment lining of double shield TBM tunnel and the calculation of the design water load of the segment.