Research Of Bearing Capacity Of New Complex Anchorage Of Sheet Piles

With the development of the transportation industry,suspension bridges have been widely used due to their superior spanning performance,and the anchorage as the main load-bearing structure of suspension bridges has also been continuously developed.The traditional gravity anchorage has a long construction period and high construction cost due to the large amount of excavation of the foundation pit and the large amount of materials.So it is necessary to innovate the anchorage structure.The paper takes the south anchorage of the G3 Tongling Yangtze River Highway-Rail Bridge as the subject background.The main research contents and conclusions are as follows:(1)In view of the shortcomings of the current suspension bridge anchorage,a new type of anchorage structure-complex anchorage of sheet piles is proposed.The interaction mechanism between the anchorage and the soil is analyzed,and the formula for calculating the safety factor of the anti-sliding stability of the complex anchorage of sheet piles is proposed.The anti-sliding stability of the anchorage is checked and the anti-slip stability safety factor K=2.35 was obtained,which meets the requirements of the specification.(2)Numerical simulation of the complex anchorage of sheet piles by using FLAC3 D finite difference software,the displacement characteristics of the anchorage foundation under grading vertical loading,grading horizontal loading,completion of the anchorage construction,operating status,and equal-scale application of the main cable tension are analyzed,and the simulation results were compared with the characteristics of the stepped gravity anchorage.The results show that in the complex anchorage foundation of sheet piles,the sheet-pile foundation gives full play to its embedded effect,mobilizes the frictional resistance and end resistance of the surrounding rock mass to resist the anchorage displacement,and has good bearing performance.The anchorage resists the pulling force of the main cable through the shear friction force between sheet piles and rock mass and the self-weight effect of the gravity foundation.The force is relatively reasonable,and its vertical and horizontal displacements meet the limits of relevant domestic and foreign codes.The failure mode is generally slip failure,and the anti-slip stability safety factor is 2.58;in addition,through comparison with the simulation results of the stepped gravity anchorage,there is a difference in the force mechanism between the two under the same main cable force,and the displacement is not much different.(3)By changing the rock mass parameters of a single rock layer,compare the displacement of the complex anchorage of sheet piles under different rock mass parameters,it can be seen that the deformation modulus of rock mass has a greater impact on the displacement of the complex anchorage of sheet piles.With the increase of the rock mass deformation modulus,the horizontal and vertical displacement of the anchorage decrease significantly.When the deformation modulus of rock mass is small,the change of the deformation modulus has a great influence on the anchorage displacement.When the deformation modulus increases to a certain degree,the influence on the anchorage displacement decreases significantly;as the cohesion and internal friction angle of the rock mass increase,the displacement of the anchorage is also reduced correspondingly,but the influence of the cohesion and internal friction angle of the rock mass on the displacement of the anchorage is significantly smaller than the influence of the deformation modulus of the rock mass.By changing the height of the sheet piles,it is found that as the height increases,the anchorage displacement decreases correspondingly,but when the height of the sheet piles increases to a certain extent,the anchorage displacement tends to be stable.(4)The construction technology of the new complex anchorage of sheet piles was studied,the overall construction technology of the sheet pile composite anchorage was designed,and the construction method of the sheet pile foundation was proposed;by combining the complex anchorage of sheet piles and the stepped gravity anchorage in comparison with the material cost and construction period,the economic analysis of the anchorage is carried out.The results show that: compared with traditional stepped gravity anchors,the new complex anchorage of sheet piles save 21.1% of material costs and 1/3 of the construction period,which is in line with economic principles and green development concepts.