Experiment On Stability And Failure Mode Of Ribbed Slab Retaining Wall Based On Sand Box Model Test

Retaining structure is an important part of geotechnical engineering.With the rapid development of retaining structure,the types of structure have evolved from gravity retaining wall which relying on the weight of gravity to balance the earth pressure,developing into a variety of lightweight retaining structure as anchoring technology,reinforced soil technology,cantilever structure and composite structure,etc.The ribbed slad retaining wall(RSRW)is a new type of lightweight retaining structure,composed of a wall panel,ribs and intercostal soil,depending on the friction between the ribs and the soil in stable region to balance soil pressure on the panel.There are many characteristics of the ribbed slab retaining wall,such as making full use of the self-stability of the soil,small disturbance to soil on slope,low bearing capacity of foundation and simple structure,etc.At present,they are unclear that the force and deformation characteristics,stability mechanism and distruction mode of the ribbed slab retaining wall,no perfect design and calculate methods were established.On the summary and analysis of research results of retaining wall,we conduct small sand box indoor model test to explore the factors influent the stability of two different types of RSRW--flexible panel(paper)retaining wall and rigid panel(organic glass slad)retaining wall.Focusing on the analysis how the two main factors(rib spacing and rib length)influent the structural stability of RSRW.And to find out the reasonable layout of them.In addition,the centrifugal model test of ribbed plate retaining wall model,artificial pushing wall test in centrifugal after unloading,observing and exploring different failure modes of rib arrangement of ribbed plate retaining wall and rupture location,verify the theoretical assumptions,we obtained the following conclusions:(1)RSRW is made of the ribbed slad as the main anchor and the panel for retaining soil,relied on the friction between ribbed slads and the soil fill in them to balance the earth pressure as a new type of retaining structure.It shows that rib spacing and length are two key factors that influent the stability of RSRW by the indoor sand box model test.(2)The sand box of the model test is a plywood model box(length 750mm,width 500mm,high 500mm).The flexible panel RSRW model is made of white cardboard(350g/m2)as wall panels,grey cardboard(800gim2)as ribbed slad.The wall packing is quartz sand.It shows that the influence of panel stiffness is low,soil pressure acting on the wall panel to the wall panel has local deformation,with the increase of the distance between floors is more obvious,the retaining wall stability unfavorable.The ultimate steady state long rib arrangement sparsely distributed required floor area is large,the minimum floor length limit,short rib required floor area is covered with the rib spacing becomes smaller and increases,therefore,in the long thin cloth and rib rib short rib with arrangement of transition zone mode required floor area small,for the optimal layout.(3)The model box is made of organic glass plate which length is 750mm,width is 500mm,and higth is 500mm.Using organic glass plate as the wall panel,800g/m2 double rib and grey paper as fine sand as filling out rigid panel sand box model test.The test shows that the sand box effect of the side wall is not significant,can be regarded as the plane of symmetry,the lateral rib to rib spacing sand box wall two times the distance between the space layout and rational arrangement,i.e.the symmetry plane layout method,a space arrangement method is more reasonable.The stability of rigid retaining wall panel floor panel's stiffness has little effect,can give full play to friction between the rib and the soil,in the limit of the steady state,the long rib sparsely distributed required minimum area of ribbed slad.(4)The model box is made of steel,which length is 800mm.width is 600mm,high is 600mm.The model retainng wall is made of organic glass which the height is 300 mm ribbed slad wall ribbed plate type retaining wall model with standard sand as the wall after packing was carried out in 4 groups of sand box model test.After centrifugal loading,given the ribbed slab retaining wall displacement of the retaining wall enough damage,rupture location and morphology observation of internal surface.The ribbed slab retaining wall horizontal displacement is large,push the wall test of ribbed plate retaining wall failure is equivalent to no external force under the influence of its retaining wall failure,verified with rib spacing from sparse to dense changes,in the limit of the steady state,there are two kinds of typical mechanical action mode of ribbed plate type retaining wall:spacing is large,rely on the effect of soil friction rib and the stable region provide the anchoring force of earth pressure balance wall panel,friction type long rib anchoring sparsely distributed failure modes.The rupture limit state of the surface is located in the intercostal space is small,the soil;soil by friction constraint adjacent rib intercostal strong,forming a whole wall,similar to the the wall weight reached stable gravity retaining wall,the whole wall type with short rib failure mode,failure of fracture face at imaginary wall behind the lateral soil.