Optimization Analysis And Study On Mechanism Of Anti-slide Measure In Deeply Excavated Expansive Soil Slope Of South To North Water Diversion Project

During the construction period and the used period of South-North Water Diversion Project,the heavy cutting expansive soil canal maybe frequently landslide.Therefore the canal stability and the security should be considered to in both periods.For overcoming the shortage of this situation,Yangtze River Survey Planning and Design Institute offered two anti-sliding reinforcement measures for the heavy cutting expansive soil slide slope.Using FEA methods to simulate,contrast and analyze the landslide mechanism,optimize the anti-sliding measures of the canal and obtain the best pile diameter,not only do great contribution to the South-North Water Diversion Project,but also offer the practical and engineering values for the expansive soil engineering management project.The detail contents are given as follows:Firstly,by analyzing the soil parameter test in lab,the basic physical and geo-technical parameters of weak,medium and strong expansive soil were obtained in Nanyang section in the South-North Water Diversion Project.At the same time,by using the FEM numerical simulation(Geostudio)to analyze the dry-wet circulation of expansive soil,the worst situation of the engineering project was obtained under the impact of dry-wet cyclic on canal slop landslide.Secondly,based on the location of the weak structural surface from the site conditions.the influence of weak structural surface extension in the condition of dry-wet cycle to the stability of canal and the mechanism of the landslide has been studied.The mechanism showed that the worst landslide situation appearing in the canal due to more than 34 meters of the weak structural surface in between the medium and strong expansive soil junction.Thirdly,the anti-slide mechanism of the pile diameter of 35 centimeter and the pile spacing of 1.2 meter of the square and circular of anti-slide piles were analyzed by the horizontal displacement of soil,plastic strain,pile stress,safety factor and soil arching effect.The results showed that the safety and durability of the square anti-slide pile is better than the circular anti-slide pile.Next,based on the comparison among 25 kinds of schemes in different pile diameters and pile space sizes of anti-slide reinforcement measures,the results showed that the scheme of 35 centimeters for the pile diameter and 1.2 meters for the pile spacing size was the best program in all the schemes.Finally,by comparing three kinds of pile-space size of anti-slide supporting system of slide-resistant piles and slope beams with the tiny square anti-slide pile of the pile diameter 35 centimeters and the pile spacing 1.2 meters,the results showed that the slope combinationbeam supporting system method not only have better for canal slope safety factor than the tiny square pile methods,but also do a good job in diminishing the horizontal displacement of soil,plastic strain,pile stress.It is important for ensuring the safety and stability of surface soil of canal to use slope beams be able to decrease the horizontal displacement in the surface expansive soil of canal.