Study On Soil Arching Effect And Active Earth Pressure For Cylindrical Wall

Soil arching effect is an phenomena commonly encountered in geotechnicalengineering, and has a significant effect on earth pressure. Experimental, numericalsimulation and theoretical analysis have been taken to study soil arching effect formany years, but the influence factors of gravity field and the soil arching effectaround cylindrical wall has never been studied. In this dissertation, experimental andnumerical simulation is carried out to investigate the effect of gravity field on soilarching effect, distinct element method is taken to analyze the soil arching effect andearth pressure on cylindrical wall. Based on the simulation results, theoreticalformulas for determining earth pressure on cylindrical is represented.Based on the electromagnetic field theory, the test system for uniform gradientmagnetic field is developed. Distribution of the magnetic field strength in the effectivespace,0.14m≤h≤0.30m，0≤r0≤0.04m, is uniform. The results show that withincreasing gravity field, the normalized earth pressure increase. The Particle FlowCode in2Dimensions is used to study soil arching effect by trapdoor experimentalunder normal gravity field. The linear variation along depth for lateral earth pressurecoefficient is obtained, which is introduce to correct Terzaghi’s theory. By thesimulation of trapdoor experimental under various gravity field, the variation law ofnormalized earth pressure, principal stress and contact force indicate that with theincreasing gravity field, the arching effect is less apparent.Earth pressure on cylindrical wall for uniform soil is simulated by PFC3D, theearth pressure and wall radial displacement variation laws are obtained. By analyzethe variation laws of principal and tangential stress, the results show thatcircumferential arching effect is more apparent than vertical arching effect. The effectof height-radial ratio, internal friction angle and gravity field on normalized earthpressure is analyzed. The results show that with increasing height-radial ratio, internalfriction angle and gravity field, normalized earth pressure decreases. By thesimulation of earth pressure on cylindrical wall for two layered soil, it is demonstratedthat circumferential arching effect affected by the layered soils with differentgeomechanical parameters.Based on the static equilibrium condition of the horizontal plane, theoreticalformulas for determining active earth pressure on cylindrical wall is representedconsidering vertical arching effect and circumferential arching effect by using horizontal slice method. The effect of internal frication angle, wall friction angle,height-radial ratio and tangential stress coefficient on active earth pressure is analyzed.Theoretical formula for active earth pressure with layered soils is presented byconsidering the equality of vertical force and shear force on the inteface. The activeearth pressure formula under non-limit state is obtained by considering the linearcorrelation of internal friction angle, wall friction angle and circumferential stresscoefficient with wall displacement. Calculation results by using the proposed formulasshow a better match with the simulation results.