The Effects Of Sand And Soil Interlayers On Propagation Of Buried Ground Fissures

Ground fissures are ground surface ruptures that have a certain length and width on the ground under the influence of natural and human factors.They have an important impact on urban construction,land use,and engineering facilities,while some hidden ground fissures have potential.The harm is even more inestimable.The purpose of this paper is to study the development law of the cracks in the sand and soil interbedded strata.It provides a basis and an important reference for the further prevention of ground fissures and the effective use of land,which has important theoretical and practical significance.The main results of this paper are as follows:?1?According to the field investigation data and trench exploration,the development characteristics of ground fissures in sand and soil interlayers were summarized.Through physical model tests,the fracture propagation process,surface displacement,fracture morphology,and soil stress of buried ground fissures in sand and soil layers were studied.The characteristics of ground fissures in sand and soil interlayers were compared with ground fissures in pure silty clay and pure sand.?2?On the basis of the above,an indoor physical model test was carried out.The results are as follows:1)The process of fracture crack propagation in sand and soil interlayers can be divided into five stages:the beginning of the hidden fracture,the crack initiation stage,the anti-tide crack expansion stage,the fracture perforation stage and the bottom plate collapse stage.2)The angle of hidden ground fissures will suddenly change in sand and soil interlayers.3)There are certain rules in the influence range of the ground fissures.Generally speaking,the range of impact on the hanging wall is larger than the influence range of the foot walll,which is about 1.5 times of the foot wall.When the sand and soil are interbedded,the influence range is between the homogeneous soil and the homogeneous sand.?3?Using the PFC^2D discrete element software,the crack propagation process of ground fissures is simulated and compared with the results of the physical model test.The results show that the fracture propagation of ground fissures is closely related to the change of the displacement,which leads directly to the change of stress state and the occurrence of cracks.