| The retaining structure is an important research topic in the field of geotechnical engineering.Modern retaining structure has gradually developed from the traditional gravity type to the light type which adopts the thin wall,bending resistance,reinforcement,anchorage and other high strength materials.The ribbed slab retaining wall is a new type retaining structure composed of the retaining slab and the ribbed slab,keeping balance by the friction between ribbed slab and intercostal soil.The sheet-pile retaining wall with rib anchor is a composite retaining structure of ribbed slab retaining wall and traditional pile-slab wall.Its main components are anchor pile,retaining slab and ribbed slab.The earth pressure is balanced by the anti-overturning bending moment provided by anchor pile and the friction force provided by ribbed slab.At present,the research on the ribbed slab retaining wall and its composite structure is still in the initial stage,which lacks theoretical support and experimental evidence.Based on sand box model test,the influence of ribbed slab length,ribbed slab spacing and anchorage section length on the stability of ribbed slab retaining wall and sheet-pile retaining wall with rib anchor was analyzed,the reasonable construction method,failure mode and action mode were discussed.Centrifugal model test of the ribbed slab retaining wall was carried out with using self-made displacement control system,and the relationship between the earth pressure of retaining slab and ribbed slab and the wall displacement was studied.Combined with the existing research results of earth pressure,the difference of earth pressure distribution under different wall displacement modes was explored.The main understandings and conclusions are as follows:(1)The plexiglass retaining slab and cardboard ribbed slab was used to make the ribbed retaining wall model.In the model box with length 750mm×width 500mm×height 500 mm,aiming at layout method of retaining slab bisector and retaining slab mid line symmetry,the sand box model test of ribbed slab retaining wall with 80～240mm ribbed slab length,0～480mm ribbed slab spacing and 500 mm height was carried out.The stability and failure of the retaining wall under the combination of different length and spacing of the ribbed slab was observed and recorded.The influence law of the length and spacing of the ribbed slab on the stability of the retaining wall and the failure mode were analyzed.(2)The ribbed slab retaining wall can get the best stability by adopting the "equal panel midline layout method",which is distributing the retaining plate according to the number of ribbed slabs and placing the ribbed slabs at the center line of each equal segment.The constraint area and the constraint coefficient ξ=ribbed slab length l/ribbed slab spacing δwere introduced,the constraint effect of ribbed slab on the intercostal soil gradually increases with the increase of ξ,and the corresponding failure modes are friction anchoring type of ξ<0.64 and whole soil wall type of ξ>0.64,while 0.64≤ξ≤0.96 is transition zone.(3)The total ribbed slab area of the model retaining wall in the ultimate stable state increases with the increasing density of the ribbed slab arrangement.That is,the ribbed slab retaining wall using the "long rib sparsely distributed" friction anchorage design principle can get more stability of the rigid retaining wall,and the economy is better than the "short rib densely distributed" whole soil wall type.(4)For the sheet-pile retaining wall with rib anchor,the sand box model test under the conditions of ribbed slab length of 50～120mm,ribbed slab spacing of 167.7～250mm,anchoring section length of 0～100mm and wall height of 400 mm was carried out in an L-shaped plexiglass sand box with length 750mm×width 500mm×height 500 mm by using the model retaining wall composed of 2～3 units.The stability and failure of the retaining wall under the combination of different length and spacing of the ribbed slab and length of anchoring section was observed and recorded.The influence law of the corresponding factors on the stability of the retaining wall was studied,and the action mode of the sheet-pile retaining wall with rib anchor was discussed.(5)For the sheet-pile retaining wall with rib anchor,the buried depth of anchor pile can be reduced by lengthening the ribbed slab to enhance its friction anchoring effect.With the lengthening of ribbed slab and the shortening of anchoring section,the dominant factors for the stability of sheet-pile retaining wall with rib anchor are changed,and the action mode is transformed in the order of "pile anchor type","pile-rib anchor type","rib anchor type".(6)The reasonable construction method of sheet-pile retaining wall with rib anchor is related to the ratio a of the cost of anchoring section to rib plate per unit length.For the rib anchor dominant area of a>0.6375,the economy of retaining wall in "rib anchor type" that has the structure of long rib plate and short anchoring section is better,while for the pile anchor dominant area of a≤0.6375,"pile-rib anchor type" that has the structure of short rib plate and long anchoring section should be used.(7)By using the model box with length 800mm×width 600mm×height 600 mm and a self-made wall displacement control system,five groups of centrifugal model tests were carried out on the ribbed slab retaining wall with the ribbed slab length of 60～150mm,the ribbed slab spacing of 150～200mm and the wall height of 300 mm.And the laser displacement meter and earth pressure sensor were used to monitor the displacement of wall,the earth pressure of retaining slab and ribbed slab in real time.The relationship between ribbed slab arrangement and wall displacement mode was discussed,and the influence law of displacement mode on earth pressure of retaining slab and ribbed slab was analyzed.(8)The displacement mode of ribbed slab retaining wall is significantly affected by the layout of ribbed slab.With the change of rib ribbed slab layout from "long rib sparsely distributed" to "short rib densely distributed",the translational displacement of ribbed slab retaining wall decreases greatly,the displacement mode of wall gradually changes from the sliding translational mode to the overturning rotational mode,and the earth pressure of retaining slab and ribbed slab decreases by about 19% and 38% accordingly.(9)The earth pressure distribution characteristics of retaining slab and ribbed slab are closely related to the displacement mode of the wall.The wall of "long rib sparsely distributed" are translational mode and mixed mode,and the earth pressure of the retaining slab and ribbed slab increases first and then decreases along the depth,and the distance from the action point of earth pressure to the bottom is about 0.5 times the height of wall.While the distribution of earth pressure is approximately triangular for the wall of "short rib densely distributed",which is rotational displacement mode. |
PDF Full Text Request