Study On The Soil Pressure And Stable Mechanism Of The Ribbed Slab Retaining Wall Based On The Centrifuge 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, developed into a variety of lightweight retaining structure as anchoring technology, reinforced soil technology, cantilever structure and composite structure, etc. The ribbed plate type of retaining wall 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 and soil and foundation to balance soil pressure. 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.Based on the studies of existing retaining wall, the effects of two main structural parameters as spacing and length of the ribbed-slab on the stability is discussed by the small-scale sand box model test. As the prototype of the 9-meter-high ribbed plate type of retaining wall, five groups centrifuge model tests are designed, including different rib spacing and different rib length. Study on the earth pressure size and distribution, displacement mode and stability mechanism of the panel of wall and the ribbed slab of side-wall by using displacement control device on the condition of different lateral displacement. Preliminary conclusions as below:(1)The ribbed plate type of retaining wall is a new type of lightweight retaining structure, using ribs as main anchorage, using panel as retaining soil, depending on the friction between the rib and the filling soil to balance soil pressure. The indoor test of scale model and centrifugal model indicate, the rib spacing and length are two key factors that influence the stability of stiffened plate retaining wall.(2) With the different rib spacing from sparse to dense, there are two kinds of typical mechanical modes of ribbed plate type of retaining wall:when the spacing is larger, it is the friction anchoring mode, witch balanced earth pressure on panel of wall, relying on the friction between the panel and stable area to provide anchoring forces, the destroyed surface mainly in intercostal soil at the limit state. When the spacing is smaller,the soil between adjacent ribs constraints strong friction, forms the whole wall type model, it is similar with gravity retaining wall which using the weight to keep stability, its’destroyed fracture surface is located in the soil outside the ribs.(3)The centrifugal model tests showed that the earth pressure on the panel and side-ribs of the ribs plate retaining wall change with ribs spacing from sparse to dense, Showed a tendency of gradually decreasing. The earth pressure on the M1, M2 wall panel of the friction and anchorage type has no significant difference with MO of no-ribs, it is about 1.55 times that of M3, M4 of the whole wall type. For the earth pressure of the ribs wall, M1, M2 is about 1.89 times for M3, M4.(4)The centrifugal model tests showed that the earth pressure on the panel and side-ribs of the ribs plate retaining wall distributed non-uniform characteristics along the wall, its distribution pattern has a good consistency. The earth pressure on the M1, M2 of friction and anchorage type showed a nonlinear distribution for first increase then decrease. The point of resultant force located at position with 0.51-0.56 times of height to the wall heel; the M3, M4 of whole wall type showed a approximately triangular distribution, its’point of resultant earth pressure is about 0.3-0.4 times of the wall height.(5) The earth pressure on the wall panel of rib plate retaining wall decreases gradually along with the increase of the wall displacement, while the earth pressure on the side-ribs has no obvious change, and it is greater than the corresponding wall panel. The ratio of earth pressure on the wall panel and side-ribs increases along with the decrease of the ribs space. The centrifugal model tests showed that the earth pressure on the wall panel of the friction anchorage type is 0.4-0.8 times of the earth pressure on the side-ribs, the earth pressure on the wall panel of the whole wall type is 0.58-0.9 times of the earth pressure on the ribs.