Research On Bearing Characteristics And Design Technology Of Prefabricated Reinforced Concrete Retaining Wall

Retaining wall is a common slope supporting structure.In view of the problem that there are few green and high prefabricated retaining walls,prefabricated reinforced concrete retaining wall with high construction efficiency and green arises at the historic moment.Relying on the science and technology planning project of Zhejiang Provincial Department of transportation(Project No.2019007),and with the cooperation of Zhejiang University City College,Shaoxing University of Arts and Sciences,Zhejiang Jiaogong Group Co.,Ltd.,Zhejiang Jiaogong Hongtu Construction Co.,Ltd.and Shaoxing Chengtou Industrial Manufacturing Co.,Ltd.,the design and construction of prefabricated retaining wall(excavation section retaining wall)for a project of 03 provincial road are studied Follow up and research with full cycle application;The design,prefabrication,assembly and destructive test of the retaining wall in the filling section of a project are followed up and studied.Aiming at the safety and applicability of retaining wall in excavation section in normal use,three-dimensional finite element analysis is carried out;Aiming at the filling section retaining wall,the traditional assembled retaining wall structure is split,parameter optimization and innovation,and the finite element software is verified;The full-scale destructive test of this kind of thinwalled retaining wall is carried out.The main work and conclusions are as follows:(1)In order to explore the characteristics and influencing factors of retaining wall in excavation section,ABAQUS finite element software is used to explore the mechanical characteristics of prefabricated retaining wall column and inclined shelf with different filling height and different filling types.The results show that the lateral displacement of retaining wall decreases with the increase of cohesion and the decrease of internal friction angle;When the retaining wall is embankment wall,the "equivalent internal friction angle method" is not suitable for calculating the force of inclined shelf;Due to its open structure,the stress distribution law of inclined shelf is a multi segment U-shaped curve,which is different from the traditional trend that the soil arching effect between piles increases first and then decreases.According to the structural particularity of retaining wall in excavation section,the key Prefabrication Technology and construction technology points are summarized(2)Based on the structure of pile sheet wall and cantilever wall,the retaining wall column of filling section is divided into upper and lower columns,upper and lower columns,ear block and inclined shelf.Each part is prefabricated independently,and the bottom plate is cast-in-place;At the same time,the interior of the column is hollowed out to form a thin-walled structure,and the thickness of the thin-walled wall is discussed.The structure of the cast-in-place floor is optimized to form a concave convex structure.Using ABAQUS finite element software,the common working conditions of this kind of retaining wall are simulated and analyzed.When it is used for shoulder wall,the maximum displacement trend of inclined shelf and column is closed bulging curve,while when it is used for embankment wall,the maximum displacement curve of inclined shelf and column is open bulging curve;Because the column is composed of upper and lower columns,the upper and lower columns will slide relatively when they are stressed;Under the action of vehicle load,the influence is small when the load is2.5m away from the retaining wall.In view of the structural novelty of the fill section retaining wall and the high requirements of its assembly accuracy,it is necessary to discuss the key technologies in the prefabrication period,and summarize the key technologies in the prefabrication period.(4)Because the mechanical mechanism and failure mode of the retaining wall in the filling section are unknown,it is necessary to carry out full-scale destructive test before it is applied to the test section.By using ABAQUS finite element software,the location of key nodes is obtained,and according to this,the embedding of vibrating wire strain gauge is guided.Through the test of steel strain gauge,it is found that due to the influence of hydration heat and concrete drying shrinkage,the solidification and hardening process of precast hollow column concrete presents the phenomenon of alternating tension and compression,and the change rule of each test point is consistent,and gradually tends to be stable in 35 days.1 and 2 vibrating wire strain gauges are arranged at the maximum stress position of 3M column steel bar.The stress of steel bar increases rapidly with the increase of load,and the stress increases rapidly with the increase of crack width.The stress of steel bar at the side of column is small,and its displacement increases linearly with the increase of load.When the load reaches 60 kn,the column begins to bend,and the displacement growth rate becomes larger;The stress of 2.5m column is similar to that of 3M column.The maximum position is 3 and 6vibrating wire strain gauges.The stress of the steel bar on the side of the column is small,and its displacement increases linearly with the increase of the load.When the load reaches 75 KN,the column begins to bend,and the displacement increases faster.The finite element simulation results are consistent with the measured results.After the loading of 3M column in the ultimate bearing state(about 100 k N),the combination of arc and "7" crack will be formed;When the load of the 2.5m column reaches the ultimate bearing state(about 335kn),the crack shape of the column is a V-shaped crack composed of bolt chamfer crack;XFEM method is used to simulate the column,and the simulation results are basically consistent with the test results.(5)As for the application of retaining wall in excavation section,it has been applied in the slope of a provincial road reconstruction project,which started in November 2018 and ended in April 2019.It is a factory standardized prefabricated composite component that can be quickly prefabricated and assembled,and can be afforested.The structure of retaining wall is reliable,safe,cost-effective,convenient and efficient.After vegetation greening,the slope presents a vigorous green landscape,which makes the retaining wall have good ecological and economic benefits.For the promotion of the retaining wall in the filling section,the concrete consumption of this retaining wall is less than that of the retaining wall in the excavation section,while retaining the greening function.The structural safety of this kind of retaining wall has been confirmed by full-scale test.Based on the economy and greening function of this kind of retaining wall,its promotion value is great.