Experimental Study Of Active Earth Pressure Of Cohesionless Soil With Limited Width Behind The Retaining Wall And Numerical Simulation

Calculation of earth pressure behind the wall which is one of the basic issues in the field of geotechnical engineering has been calculated in most cases by the classical earth pressure theory of the Rankine or Coulomb up to now, the premise of which is that the soil behind the wall should be semi-infinite soil. However, the width of the soil behind the wall are limited in most situations in actual projects, the classical earth pressure theory is not applicable no longer at the moment. Therefore, to develop the failure mode of soil behind the wall and to calculate the distribution of earth pressure has become urgent problems. Based on former experiences this paper focuses on laboratory experiments, numerical analysis and theoretical research on active earth pressure of cohesionless soil with limited width behind the retaining wall, the main work is as follows:Firstly, an experiment was conducted to study the active earth pressure of cohesionless soil with limited width which was behind retaining wall in different modes, the failure mode of the soil and the distribution of the active earth pressure with different backfill width, and compared with the classical earth pressure theory. The results show that failure surface of limited-width soil behind the retaining wall is a continuous surface which will be continuously moving to outside with the increasing of backfill width and approaching to a fixed position. But the failure surface of soil is always located inside of the Coulomb failure surface. Furthermore, it has also been found that the actual active earth pressure is less than the one calculated by Coulomb theory, the difference of which will increase with the decrease of the backfill width. The monitoring of earth pressure indicates Coulomb theory is not applicable anymore for the backfilled soil with limited width. In addition, it is also found that the motion pattern of retaining wall has great effects on the distribution of the active earth pressure. The earth pressure will increase to a peak value firstly then decrease with the increase of depth when the motion of retaining wall is translated; the earth pressure will be increased linearly with the increase of depth when the retaining wall is rotating around the bottom; and a significant earth arch effect will be observed at the upper part of retaining wall when the wall is rotating around the top.Secondly, establish the plane model is establish by ABAQUS finite element software to simulate the active earth pressure of cohesionless soil with limited width behind retaining wall in three different modes. Filling aspect ratio, the wall friction angle, the soil friction angle and the displacement of the retaining wall were investigated for T mode, on this basis, distribution of the earth pressure on the corresponding fixed retaining wall was analyzed. The results showed that: In the T mode, the relative displacement which soil requires to be at active state increases with the increase of filling aspect ratio; the active earth pressure gradually increases when filling aspect ratio increases; and active earth pressure gradually decreases when the internal friction angle increases. It can be seen that the intensity distribution of the earth pressure are basically the same as the test results in three different modes at the same time.Thirdly, the specific form for cohesionless slip surface with limited width behind retaining wall was further studied based on laboratory tests and variational limit equilibrium method. The results showed that the actual shape of slip surface curve is always a logarithmic spiral curve when soil strength complies with the mohr-coulomb’s guidelines. On this basis, by using thin-layer element method and the area most value method, the specific expression of the active earth pressure of cohesionless soil with limited width behind retaining wall was gained. Then based on the value of earth pressure variation with filling aspect ratio, a new method, which was more reasonable compared to the Coulomb earth pressure theory, was proposed to define the limited width of the soil.