Study On The Drainage Pipe Blocking Mechanism Caused By Groundwater Crystallization And Its Influences On The High Slope Stability

A large number of engineering practices show that under the condition of short time heavy rainfall or abundant underground water,one of the important causes of slope engineering instability is the unreasonable design of drainage system or failure of drainage function,especially high slope engineering.Groundwater crystallization is an important factor in the failure of drainage system.To drain the crystallization of high slope project congestion,through theoretical analysis,laboratory test and numerical analysis method,analyzes the crystallization mechanism of drainage pipe wall,reveals the groundwater crystallization crystallization plugging pipe and the factors affecting the evolution law of degree of different drain plug on the stability of high slope stress and deformation of retaining structure and influence law,research contents and conclusions are as follows:(1)Based on the two typical high slope projects of the drainage pipe crystal blockage in the southwest mountain area,crystal and groundwater samples were taken to carry out the microscopic crystal electron microscope experiment and component XRD experiment of the crystals,as well as the groundwater ionic component and PH value experiment,to reveal the crystal blockage mechanism of the drainage pipe of the high slope.Microscopic tests and water quality analysis show that the crystalline minerals are mainly diamond-shaped or block-shaped in microscopic morphology,and the aggregation presents irregular poached crystal.The crystal composition is mainly carbonate,mainly calcite,with a small amount of viscous impurities.The concentration of Ca²⁺,and plasma will affect the crystallization of Ca CO₃ in the drainage pipe.The higher the PH value of groundwater,the easier it is to crystallize,the easier it is to plug the pipe.In addition,free CO₂ will affect the PH,which will affect the crystallization blocked tube.(2)Considering the influence of different water flowing areas,internal surface roughness of different pipe walls,different flow rates and air on crystallization in the process of water flow,an experimental device was developed and an indoor test was carried out.The experimental results show that the amount of crystallization in the tube wall of the solution from the outlet through air into the solution circulation test is larger than that from the outlet directly into the solution.When the flow rate is constant,the crystal mass of the tube wall is larger than that of the whole section.The crystalline mass of bellows was greater than that of smooth tube wall.The higher the flow rate,the smaller the crystallization mass of the test tube wall.The smaller the velocity,the greater the crystal mass.(3)The numerical model of high slope with frame lattice and bolt as supporting structure is established,and"plate with hole method"is put forward to simulate drainage hole,which provides a new idea for the study of drainage hole blockage.The mechanical response of slope water table and support structure under different blocking conditions of slope drainage hole is studied,and the slope stability under different working conditions is analyzed.The analysis shows that the groundwater level of the slope rises significantly after the drainage hole of the high slope is partially blocked.The exit position of slope toe shear has a large lateral displacement,and tends to extrude outwardly.After the drainage hole is completely blocked,this characteristic is more obvious.After the drainage hole is blocked,the lattice stress near the toe shear outlet changes greatly,and the bolt axial force increases significantly,among which the bolt segment located under the free water surface is more obvious.(4)Established with anchor pile retaining structure for high slope numerical model,by studying the different degree of drain plug conditions of ground water level change of retaining structure and mechanics,the following conclusion:after the drain plug,although the underground water level change significantly,but the rise of ground water level is not increased with increment and linear degree of drain plug,but congestion level reaches a critical value of underground water level rise sharply.With the increase of drainage hole blockage,the lateral displacement of anti-slide pile in slope toe position is larger,especially in the part below normal water level.The lateral displacement of pile top has no obvious change because it is restrained by anchor cable.In addition,the arch effect of rock and soil between piles is obvious,and the higher the water table is,the more obvious the effect is.Compared with normal drainage condition,anchor cable axial force increased by 70%.With the increase of drainage hole blockage,anchor cable axial force increased to the position of anti-slide pile.(5)Put forward the treatment method of crystallization blockage of high slope drainage pipe and applied for a patent,hoping to achieve good results in the design,construction and long-term operation of high slope drainage pipe.