Study On Mechanical Behaviours Of Light Retaining Structures On Mountainous Expressway

In mountainous area, when constructing expressway, it is inclined to adopt light retaining system which is economical and adaptability rather than traditional gravity retaining wall. But the geology and topography of mountainous area is more complex, and the styles of the light retaining system are more changeable accordingly. Under this complex boundary condition, the mechanical behaviour of the light retaining system is very complex, and it is very difficult to decide the design parameters too. Nowadays, the study on theory of the light retaining system is far belower to that of the practice. Therefore, the value of the theory and engineering application is great to study the mechanism of the light retaining system. Based on Shuo-Hui expressway—the major project of the state and the opening fund project of the Hunan communication construction control laboratory, some researches had been studied as follows:1) Bury several kinds of testing cells carefully in four kinds light retaining systems (pre-stressed cable sheet-pile, cantilever sheet-pile, anchor post-panel retaining wall, pre-stressed cable post-panel retaining wall) of Shuo-Hui expressway and carry out on site testing systematically (including dynamic testing).2) Based on the unified strength theory, the ultimate equilibrium principle and the shape of rapture of surface, a formula, which takes into account the shape of rapture surface, dip angle of cable, strength of rocks, has been deduced.3) Based on the fundamental principle of defect theory, corresponding damage evolution equation and load transfer mechanism mechanics equation, an analytic solution of anchor cable axial stress and lateral friction stress has been deduced; with this analytic solution, Mindlin solution and Boussinesq solution, the normal stress, shear stress and the corresponding displacement which the cable may affect has been gained; and so do the displacement of grouting and wall; using the above theory achievement, the reasonable spacing optimization method of cable has been gained. At last, the reality projection was used to check the above theory achievements, which show good agreement.4) Choose pre-stressed cable sheet-pile as an example, use FLAC3D program to build the coupling numerical model of pile, soil, cable, and interfaces to calculate and analyze the stress and the strain of retaining wall in different influencing parameter, and offer the main calculating parameters which should be taken into account in design.5) According to the testing data of earth pressure, axial forces of cable, deformation of pile, the working situation of the four kinds of retaining walls has been analyzed; comparing the measured data with numerical computation data of each wall, inducing the features of stress and strain of each wall, and offer the design methods of each wall under static load.6) Based on ANASYS program, choose pre-stressed cable sheet-pile as an example to build FEM model, take velocity, load, unevenness, driving lane into account, the dynamic deformation and dynamic earth pressure of wall, and the dynamic pressure and dynamic deformation of road have been calculated and analyzed, and the mechanism of light retaining system has been discussed under traffic load.7) Take pre-stressed cable sheet-pile and anchor post-panel wall as an analysis object, carry out the dynamic measure of strain pressure cell of wall and roadbed, and comparing the measure data with calculation data. Appraise the effect of traffic load on retaining system, and offer the dynamic earth pressure calculation method under traffic load.