| ABSTRACT:Tunnel lining structure health diagnosis is a subject to be carried out urgently. Based on widely reviewing related literatures both home and abroad, main causes for tunnel lining structure, common tunnel quality defects and damages laws, influences of voids behind lining and lining cracks on tunnel structure safety, and technical condition assessment for tunnel lining structure are deeply studied by combination method of theory analysis, numerical calculation, similarity model test and field testing. Main research work and research results are as follows:(1) According to present situation of the conception obscure between tunnel quality defect and tunnel damage in tunnel engineering, the common conception of tunnel quality defect and tunnel damage is given and the difference and connection are also analyzed in this paper.(2) According to the tunnel lining damage and cause survey data, the method for discovering the main causes of tunnel lining structure damage is put forward basgd on correspondence analysis model, which provides a new study method for the study of the main causes of tunnel lining structure damage. The analysis results show that the main causes are cavities behind the lining, insufficient lining thickness, misconduct of the surrounding rock and plastic ground pressure.(3) The general laws of common quality defects and damages, sunch as tunnel lining strength, carbonation depth, lining thickness, features of voids behind lining, features of lining cracks, etc, are obtained based on the statistical analysis of field test data of state road and provincial road tunnels in Ningbo.(4) Harm mechanism of voids behind lining are studied based on theory analysis, numerical calculation and similarity model test. The specific research contents are as follows:â‘ The stress status and displacement theoretical calculation formulae of surrounding rock influenced by voids behind lining are deduced based on planar elastic function of complex variable method.â‘¡Influence laws of voids behind lining on lining structure safety under different lateral pressure coefficients, different locations and different ranges are analyzed based on numerical calculation.â‘¢The deformation characteristics, mechanical characteristics and failure modes of plain concrete and reinforced concrete linings under different locations and different ranges are simulated based on indoor similarity model test. The test results can provide references for tunnel site detection and repair and reinforcement. (5) Be aimed at tunnel lining crack monitoring data, lining crack stability criterion and judgment process are established based on wavelet transform, gray theory and catastrophe theory, which provides a new method for the scientific analysis of the tunnel lining crack monitoring data. Lining crack stability criterion and judgment process for existing cracks in tunnel lining are established based on concrete fracture mechanics. And the effectiveness of the two study methods for tunnel lining crack stability is verified by case study.(6) According to the insufficiencies of existing tunnel lining technical condition assessment method in tunnel engineering circle, the scientific conception of tunnel health degree is put forward in this paper. The quantified relations between tunnel site detection data and assessment results is established by tunnel health degree function and A segmented and quantified tunnel lining technical condition assessment method based on field measurable parameters is also established.
|
PDF Full Text Request