Experimental Study On Active Earth Pressure Of Cohesionless Soil With Limited Width

In recent years,China's waterway volume has gradually increased,the navigable capacity of the water transport hub has been gradually saturated,a large number of new or expansion of the construction or construction project is in the preparatory stage.Due to the tight construction of the project,the second-tier shiplock construction needs to be close to the first-line shiplock.It is unavoidable to study the influence of excavation on the adjacent shiplock,and the distribution of soil pressure and its distribution.In the traditional theory of earth pressure Rankie or Coulomb theory,it is assumed that the back of the retaining wall is semi-infinite,not satisfied with the above situation.In this paper,the geotechnical model test,the centrifugal model test and the finite element numerical simulation analysis are carried out for the deformation characteristics of the finite width soil and the earth pressure.Considering the influence of the soil width and the friction of the wall and soil,the main work and conclusions are as follows:(1)Independent research and development of conventional geotechnical model test equipment,combined with GeoPIV to explore the finite soil damage model and the difference between traditional soil pressure theory,and delineation of finite soil and semi-infinite soil boundaries.The results show that with the reduction of soil depth ratio,limited soil damage to the sliding surface of the form will go through three processes:the sliding surface is the plane of the movable retaining wall to the surface of the earth table;the sliding surface produces the angle of the sliding surface.The sliding surface is cut off by the wall of the retaining wall.According to the angle of the sliding surface of the finite width of the soil,it can be deduced that the boundary between the semi-infinite soil and the finite soil should be between the width and depth ratio of the soil 0.75 to 1.(2)Based on the characteristics of finite soil damage,the damage deformation model of three finite soils is proposed by using the limit equilibrium theory and the assumption of the sliding wedge body,and the corresponding active earth pressure expression is deduced.Mechanism 1:When the soil depth ratio k>0.5,the sliding wedge was triangular;Mechanism 2:When the soil depth ratio 0.25 ?k<0.5,the sliding wedge was irregular quadrilateral;Mechanism 3:when the soil depth to depth ratio k<0.25,the wedge is trapezoidal.(3)The centrifugal model test was carried out and the damage of the finite soil and its active earth pressure were observed by using GeoPIV.The rationality was verified by comparing with the three finite soil failure modes proposed in this paper.According to the results of the centrifugal model test,when the soil depth ratio is reduced or the friction angle of the wall is increased,the active soil pressure of the finite soil decreases gradually,and the active earth pressure coefficient decreases gradually along the depth direction.The distribution trend of earth pressure measured under different width and depth ratio and different wall soil friction angle is basically consistent with the calculated value.(4)The finite element numerical simulation method is used to verify the results of the centrifugal model test,and the number of test groups is supplemented,and the influence of the soil width and the friction factors of soil and soil on the damage pattern of finite soil is explored.It can be seen from the simulation data that when the finite soil reaches the equilibrium state,the horizontal earth pressure on the side of the fixed retaining wall can not be neglected.The decrease of the width of the soil will increase the contact area between the wedge and the fixed wall,and the stability of the soil will be improved.When the friction angle of the wall on both sides of the finite soil is increased,the active earth pressure of the finite soil is gradually reduced,and the friction resistance of the fixed retaining wall is increasing,which makes the stability of the soil be improved.Near the fixed retaining wall side of the soil should be displaced,due to the role of wall friction remains fixed,finite soil plastic area area will be relatively reduced.