Study On Fracture Propagation Of Synsedimentary Ground Fissures

Ground fissure is a band-like rupture phenomenon formed on the surface of the earth under the action of internal and external stress and human activities.Due to the rapid economic and social development and the intensification of human activities,the ground fissure disaster has become increasingly serious.Due to the existence of a large number of synsedimentary ground fissures,there are few studies on its activity characteristics and rupture propagation mechanism.In this paper,the same sedimentary ground fissures of sand are studied,and the study of rupture and extension of concealed ground fissures under the same sedimentation is carried out to summarize the sand.The same sedimentary rupture expansion law and evolution process determine the deformation zone width of the upper and lower plates of the ground fissure.The research results can provide theoretical basis and scientific basis for the avoidance distance and ground treatment plan involved in the prevention and control of ground fissure disasters,thus having important Theoretical significance and practical significance of engineering.The main research methods and main achievements of this paper are as follows:(1)Through the collection of field investigation data and the characteristics of ground fissure fracture revealed by on-site drilling and trenching,it is found that there is a significant difference in the error distance of the same sedimentary ground in different soil layers,and the amount of displacement increases from top to bottom,the same stratum.The thickness of the upper plate is larger than that of the lower plate;the same as the sedimentary ground crack also exhibits a reverse tendency to extend,and a crack that is connected to the main crack and close to the closed can be observed in the direction of the anti-dip crack.(2)Through the physical model test,the sand and the same amount of ground fissure activity(upper plate descent)of the same thickness are respectively carried out,and the fracture propagation and evolution process of the concealed ground fissure in the sand under the same sedimentation are summarized,and The fracture propagation characteristics of non-sedimentary ground fissures are compared and analyzed: 1)The fracture propagation process of each layer of sedimentary sand is similar to that of the non-sedimentary sedimentation process,which can be divided into the crack initiation activity stage,the crack end extension stage,and the near The upright crack tension and anti-propensity crack expansion stage,the crack penetration stage and the lower plate collapse stage are five stages;2)the fracture propagation characteristics of each sediment are similar,forming a “y” type fracture in the sand;3)After the secondary sedimentation,the early cracks before the deposition are closed or partially closed under the gravity of the overlying soil layer;4)During the ground fissure activity after each deposition,the new crack breaks along the main crack generated by the last activity.5)Under the condition of equal deposition thickness and equal ground fissure activity,the two fracture intervals of the top surface of each sedimentary sand are similar;6)the same sedimentary sand The cracks produced mainly include near-upright cracks and anti-tilting cracks(when the thickness of the deposit is large,there will also be a tendency to crack),mainly due to tensile cracking,and shearing may occur in the lower part of the vertical upright crack;7)The monitoring data of the earth pressure sensor and the optical fiber show that the maximum influence range of the lower plate is 0.4m,and the influence range of the upper plate is 1.2m at the maximum.(3)The theoretical analysis of the rupture angle in the same sedimentary process is carried out,and the width of the influence zone of the ground fissure is also estimated.