Limit Analysis And Test Verification Of Pull-out Bearing Capacity Of Strip Anchor Plate Near The Slope

Anchor plate is considered as one of the most important fou ndations providing uplift capacity,because of the characteristic of flexible form,quick construction,low cost,and less influence on the existing surroundings,anchor plates can be widely used in modern hanging bridges,large signal towers and transmission towers,slope protecting walls,floating marine structure projects.Because of the complex terrain in the mountainous areas and the uneven topography of the ocean floor,anchor plates are often used in nearby slope structures,for example mountain semaphore and offshore oil extraction platforms.The pull-out bearing capacity of the anchor plate depends on the fracture mechanism of the soil,but the existing theories are mostly based on artificially assumed fracture surfaces,there is a difference from the actual,which have certain limitations.Based on the upper limit theory of limit analysis,the theoretical calculation formulas for the pull-out bearing capacity of the anchorage plate and the soil fracture surface are obtained in this paper,meanwhile,the pull-up bearing test of the anchorage plate on the slope is carried out,the pull-out test process of the anchorage plate are measured and observed with the help of the DIC picture processing technology,which verifies the theoretical method of the paper.The ground research work of this paper is as follows:Firstly,based on upper bound theory of limit analysis,the p ermissible velocity field of the soil above the anchorage plate is constructed,and the pull-out bearing model of the anchor facing the slope is established.The nonlinear characteristics of rock and soil materials are considered,and the nonlinear strengt h criterion and associated flow rules are applied.Calculate the internal energy di ssipation and external force work of the ancho plate on the slope under the limit damage state.Based on the principle of virtual work and the principle of variational extre mes,the theoretical calculation expression of ultimate pull-out carrying resistance and soil fracture surface of the anchor at slope and ground with the corresponding ultimate damage state are derived.Secondly,in order to verify the validity of the theo retical solution,the mock up test of the strip anchor plate embedded in adjacent sandy slope and ground were carried out.The test picture collection of the pull-up process is performed using DIC picture processing technology.The load-displacement curves and test images under the various conditions are acquired by changing the slope angle and the horizontal distance of anchor plate from the slope(the edge-distance ratio).According to the load-displacement curve,the ultimate pull-out carrying resistance of the anchor plate is obtained,and the deformation displacement field of the the observation area during the pull-out process is obtained by post-processing the images collected by DIC industrial camera.The test results show that the pull-out carrying resistance of the anchor plate decreases with the increase of the slope angle,and increases with the increase of the edge-distance ratio;The soil rupture surface on both sides of the ground anchor plate is symmetrically distributed,while the rupture surface of the soil on both sides of the adjacent slope anchor plate is asymmetric.There is a slope effect on the adjacent solpe anchor plate,which increases the edge-distance ratio,the failure surface of the soil body becomes asymmetric from asymmetric.The theoretical solution is compared with experimental results to verify the reasonableness and validity of the theoretical solution in this paper.In the next place,the influencing factors of the anti-uplift bearing capacity of anchor plate facing the slope were analyzed,and the results show that the ran ge of the soil rupture surface corresponds tightly to the size of the anti-uplift carrying resistance of anchor plate.The wider the range of soil fracture surface,the higher the pullout capacity of anchor plate,and in the meantime the narrower range of soil fracture surface bring the lower pullout capacity.The pull-out bearing resistance of the anchor plate increases with the increase of the anchor plate depth ratio and the initial cohesion of the soil,and the range of the soil fracture surface also in creases with the increase of anchor plate depth ratio and the initial cohesion of the soil which expands to both sides of the anchor;The pull-out bearing capacity decreases with the increase of the slope angle,the nonlinear parameters of the soil and the uniaxial tensile strength,and the range of the soil fracture surface also shrinks toward the center of the anchor plate with the increase of,the nonlinear parameters of the soil,and uniaxial tensile strength,however,with the increase of slope angle,the range of soil rupture surface expanded.Finally,the impact of the edge-distance ratio on the bearing capacity of the st rip anchor plate was analyzed,and the concept of critical slope-to-slope ratio was given and its determination method was proposed for engineering design reference.