The Effects Of Soil Property On Propagation Of Buried Ground Fissures

Earth fissures is an main environment geological disaster that has accompanied human society for a long time. It is also a scientific problem urgently needed to be solved. Rapid development during the past few centuries of human civilization, human activities on the earth’s environment is becoming more and more far-reaching. The large-scale exploitation of resources and the transformation of geological bodies make the ecological environment worse, and natural disasters occur frequently. Earth fissures is widespread in many countries, the intensity and scale of its development is increasing year by year.The main contents are:1.Based on the investigation into the typical earth fissure of Weihe-basin, we have come to some conclusion as follows. Firstly, earth fissure may be initiated by tensile stresses at shallow and shear stresses at depth. Secondly, earth fissures are approximately vertical cracks in the ground, dip-slip fissure surfaces are typically concave toward the down-thrown block. Moreover, field observations indicate that differential movement across the fault rupture dissipates as the fault rupture propagates upwards toward the surface.2.Discrete element model simulations are performed to investigate the progressive deformation of a soil cover overlying a pre-existing, blind, normal fault as it propagates to the surface. The internal angle of friction and the cohesion are assessed through the use of biaxial numerical tests. A large number of numerical simulations show that the effect of material properties is robust. The main conclusions are as follows. Firstly, the shear strength of the soil is not completely equal to the friction and the cohesion, and the function of the adhesive force will weaken or even disappear under the condition of large confining pressure and high strain. Secondly, the friction angle of the soil will cause the fissure angle increase, and the increase of the cohesion will cause the surface tension crack, and anti dip crack is prone to appear at the hanging wall. Moreover, the friction angle of the soil determines the total angle, and the cohesion force will cause the fissure angle increase as it propagates upwards.3.According to the field observation and discrete element model simulations, a new theory is proposed for earth fissure formation and propagation based on basic soil mechanisms principles. The theory indicate that fissure is forming and propagating with the increasing of differential movement. At the same time, the relationship between rupture angle and state of stress is studied.