Mechanism Of Disaster Reduction Of Ground Fissure Based On Isolation Wall And Design Method Research

Ground fissures are a type of macroscopic geological phenomenon characterized by ground rupture and deformation.They are widespread,densely clustered,and frequently active,making them one of the most serious geological hazards.As the most widely developed type of ground fissure,structural fissures have the typical characteristics of slow disaster-causing and sustained damage,posing a serious threat to buildings in ground fissure development zones.Currently,"evacuation" and "passive" prevention and control methods are generally used to prevent and control structural ground fissure disasters.However,the "evacuation" prevention and control method requires avoiding the fissure spatially,resulting in significant waste of land resources.The "passive" prevention and control method cannot effectively ensure the safety of buildings crossing or approaching the fissure under continuous fault activity due to its specific application conditions.The "active guidance" prevention and control method based on isolation walls is a new and effective way to solve the above problems,but the mechanism and design method of this method are not yet clear.Based on the collection and organization of relevant materials and literature,this paper takes the ground fissure at Beijing Capital International Airport as the research object.Firstly,combined with the characteristics of reverse fault and normal fault-type ground fissure movements,the isolation effect of isolation walls on reverse fault and normal fault-type ground fissures is analyzed.Secondly,through theoretical analysis,the formulas for calculating the soil pressure and internal force of the isolation wall are derived,revealing the distribution laws of soil pressure and internal force,as well as lateral displacement changes.Through numerical analysis,the applicability of the soil pressure calculation formula of the isolation wall is verified,and the mechanical action mechanism of the isolation wall in preventing structural ground fissure disasters is revealed.On this basis,the soil pressure and deformation laws of isolation walls under different influencing factors are analyzed.Finally,based on the mechanical action mechanism of isolation walls,the design method of isolation walls is discussed.The study shows that:(1)Flexible isolation walls can effectively guide the direction of reverse fault rupture and coordinate its reverse thrust-overturn deformation;rigid isolation walls can effectively reduce differential settlement deformations of normal fault-type ground fissures and isolate the propagation path of ground fissures.(2)Above the intersection of the isolation wall and the ground fissure,the soil pressure gradually increases with the wall height and is distributed in a triangular shape.At the intersection,the direction of the soil pressure on the isolation wall changes.Below the intersection,the soil pressure on the isolation wall increases and is distributed in a trapezoidal shape as the wall height increases.(3)With the increase of the isolation wall thickness,the soil pressure on the isolation wall gradually increases,while the lateral displacement gradually decreases.After the isolation wall thickness reaches 1.5m,the variations in soil pressure and lateral displacement tend to stabilize.The elastic modulus of the wall hardly affects the soil pressure and lateral displacement of the isolation wall.As the Poisson’s ratio and elastic modulus of the soil gradually increase,the soil pressure and lateral displacement of the isolation wall decrease.(4)The design method of the separation wall is to establish the geomechanical model of the separation wall according to the ground fissure parameters and considering the partition effect of the separation wall.The preliminary calculation of the structure is carried out through the theoretical derivation formula,and the distribution of the earth pressure,internal force and lateral displacement of the separation wall is obtained.Then,the stability of the isolation wall is checked,including the overall stability,anti-overturning stability and anti-uplift stability.Finally,the separation wall structure design,including the wall body concrete and reinforcement calculation.