| With the rapid increase of inland waterway traffic volume,the navigation capacity of ship locks of waterway hubs is gradually becoming saturated,and a large number of new or extended lock projects have started or are in the stage of preparation and demonstration.In order to reduce the expropriation area and improve the utilization ratio of soil,a large number of multi-line locks need to be built close to the existing lock.In order to study the influence of foundation pit excavation on the adjacent lock,first of all,the deformation and failure characteristics of finite soil are studied.In this paper,model test and numerical simulation are carried out on the basis of "the first phase of the reconstruction and expansion of the third-class waterway from Yongzhou to Hengyang on the Xiangjiang River".In practical engineering,the traditional calculation method of earth pressure theory is still in use,but the traditional theory assumes that the backfill behind the retaining wall is semi-infinite soil,which is obviously different from the actual situation.Aiming at the deformation and failure characteristics of finite soil mass,physical model test and finite element numerical simulation analysis are carried out.The main work and conclusions are as follows:(1)Aiming at the problems of long test period and difficult observation of large-scale geotechnical test equipment,the failure characteristics of soil were analyzed by self-made model test equipment and particle image velocimetry(PIV).The advantages of test equipment and observation methods are short test period,automatic control,experimental research,microscopic and procedural observation of various displacement modes.In the later stage of the test,a new method of judging the slip surface is adopted by PIV technique,that is,the shear strain line in the shear strain nephogram of the soil behind the wall reaches the moment of continuity and penetration,and the ultimate failure state of the soil is considered.(2)Physical model tests of deformation and failure characteristics of soils with different filling widths under three active and passive displacement modes(translation,rotation around the top of the wall and rotation around the bottom of the wall)are carried out to analyze the shape and variation of slip surface of soils with different filling widths,and determine the limit of width-depth ratio of finite soils.(3)The experimental results of active displacement of retaining wall rotating around the bottom of the wall are quite different from those obtained by predecessors.There are few model tests of passive displacement of retaining wall rotating around the top of the wall and around the bottom of the wall.Therefore,a new method is used to determine the sliding surface first,and then the soil is determined by particle image velocimetry(PIV).The failure characteristics of the retaining wall are analyzed in the process and final state.The following conclusions are drawn:the sliding surface of active displacement around the bottom of the retaining wall develops from the soil surface to the movable retaining wall surface,and the sliding surface is located about 1/3～1/2 of the height of the wall from the bottom of the retaining wall;When the retaining wall moves around the top of the wall,the slip surface develops from the lower part of the retaining wall about 1/4 of the height of the bottom to the surface of the soil.When the retaining wall rotates passively around the top of the wall,the slip surface develops from the heel of the movable retaining wall to the fixed retaining wall.Surface or upper soil surface.(4)The PLAXIS finite element numerical simulation is used to analyze the deformation and failure characteristics of the soil when the retaining wall rotates around the bottom of the wall. |
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