Anchor Lattice Beam In The Working Mechanism Of Expansive Soil Slope Reinforcement And Design Methods

Landslide is a common geological disasters,such as the change of the geology,climate and human activity will produce certain effect to the occurrence of landslides.Study found that expansive soil slope landslide has obvious characteristics of shallow and tractional,and that the expansibility is the important reason of the slope occurs,in addition to crack,dry-wet circulation and over-consolidated all have influence to the stability of the slope.Anchor lattice beam lattice beams is the use of slope protection,at the same time the bolt use to be fixed a comprehensive protective measures,and had proved that the effect of reinforcement is good.Due to the positive and effective supporting effect,anchor lattice beam has been widely used in slope reinforcement engineering,especially for the expansive soil and other special soil slope.However,compare with actual application,the existing theoretical research for anchor lattice beam in the expansive soil is still very few,When the expansion of soil anchor solid axial force will change,how the trend,and if the stability of the slope will change when swelling,these are all important issues need to consider seriously.For the above,this paper studies the following content,and obtained the corresponding conclusions as follow:(1)According to the deformation coordination equations of elastic mechanics,the relationship between the expansion stress and strain is derived,it is concluded that the expansive soil expansion scope displacement at any depth in the soil,in order to provide calculation on the basis of considering the relative displacement between soil for later.(2)Take example by the mechanical characteristics of pile foundation,this paper aim to study the anchor stress in the expansive soil.According to the theory of elasticity,on the basis of considering the expansion of expansive soil,through the relative displacement between the anchor and the soil solid,to force analysis of structure,it is concluded that the expansion area and the expansion of anchor solid in the area of axial force and shear force analytic solution,use an example to analyze it,and also analyze such as the anchor length,diameter and solid expansion influence depth,and get the optimal anchorage length is 8 m,diameter is 110 mm,and verify its rationality.(3)According to the law of the expansion,based on the Swedish method,account for expansive soil slope stability coefficient of different expansion stage.Neutral point is an important theory in geotechnical anchoring,usually defined the biggest bolt axial force and friction is zero point is the neutral point.Based on the relationship of expanding depth and position of neutral point,expansion stage can be divided into early and slow period twostages.Through analysis the case,has verified that inflation in the early phase of swelling soil,with expansive soil in anchor solid interface can produce negative friction resistance,which can make the slope stability showed a trend of growth in a short time.But as growth slows the expansion of the soil interface friction resistance to increase,the slope stability gradually decreases.(4)Combined the Zhenjiang Xiangshan engineering cases,use the geotechnical analysis software MIDAS/GTS to build the three-dimensional slope model and comparing with the results of theoretical calculation analysis,prove the feasibility of the theoretical calculation,the rationality and economy,to ensure the safety of the construction of the project implementation.