Study On The Influence Of Lining Thickness On Technical Condition Evaluation For Tunnel Lining Structure

In recent years,with the rapid development of road infrastructure construction in China,a large number of highway tunnels have been built.With the increasing operation time of highway tunnels,most of tunnels operating under ill condition,which has become increasingly common.And the problem of tunnel diseases is being given increasing amount of attention.Tunnel lining is the last line of defense to ensure the safety of tunnel operation,the internal force and stiffness of the tunnel structure will change,when the lining thickness is insufficient,which will lead to a series of diseases or catastrophic accidents.Therefore,it is necessary to study the influence of insufficient tunnel lining thickness on tunnel structure.Meanwhile,how to assess the technical condition of tunnel lining structure accurately which can ensure the normal operation and safety of tunnels,has become a top priority in tunnel management.The main research contents and conclusions are as follows:①Stratum structure method has been used to establish the three-dimensional model of lining thickness insufficiency.The element analysis by factors including lining thickness,occurrence location and the range of disease lining.To examine the safety of the lining structure,section strength calculation and strength reduction method have been used.The numerical results are as follows:1)With the increase of insufficient lining thickness,the safety factor of lining structure decreases linearly.2)The safety factor drops most obviously,when the thickness is insufficient at the vault.3)With the thinning of the lining,the safety factor of the tunnel changes in two stages.As the thickness ratio is exceeds 1/2,the safety factor decreases significantly.4)When the thickness of the lining is insufficient,the damage of the multiple diseases is greater than the single disease.②Establishing evaluation model by fuzzy comprehensive evaluation method.Meanwhile determining evaluation index of lining thickness.Moreover,the evaluation indexes of lining thickness are ensured.In addition,index weight was calculated through Delphi method and entropy value method.③In order to ensure the fuzziness and randomness in the evaluation process,the cloud model theory is introduced to construct the membership cloud of the evaluation index of lining thickness.And the membership grade functions be used to calculate evaluating index sign.Finally,the feasibility of the evaluation method is verified by an engineering case,which has proved that the evaluation method constructed in this paper is more practical and accurate.