| Composite geomembranes have been extensively utilized as horizontal seepage control systems at the bottom of reservoirs,artificial lakes,solid waste landfills and so on.For the surrounding dam plain reservoirs that use anti-seepage of reservoir basin,the leakage of reservoirs water,the rise in groundwater table and other reasons lead to the pore gas in unsaturated soil under the composite geomembrane gather,rise and change into pressure,which can cause composite geomembrane bulging deformation,even the bulging damage,those phenomenons are called composite geomembranes air expansion phenomenon.the composite geomembrane bulging deformation will further exacerbate water leakage,and the influence of the reservoir seepage safety.Study on mechanical characteristics of composite geomembrane bulging deformation,to ensure the safety and reliability of the plain reservoir which use composite geomembrane anti-seepage of reservoir basin has important practical significance.This paper su mmarizes the characteristics of composite geomembrane bulging deformation,a set of test equipment for studying on composite geomembrane bulging deformation,the experimental study on influence factors of composite geomembrane bulging deformation was carried out,and the influence factors,bulging deformation and burst pressure of composite geomembrane bulging deformation were su mmed up.The main research contents and results are as follows:(1)The main influencing factors of composite geomembrane bulging deformation were the diameter of apparatus,loading rate and combination mode.(2)The morphological characteristics of the composite geomembrane bulging deformation was studied,the characteristics of composite geomembrane air expansion deformation in ring-restrained conditions was analysed,the corresponding formulas of stress and strain are derived.By bulging geomembrane geomembrane deformation,and under the same conditions and placed below the geotextile expansion rupture analysis test data,the geotextile bears no mechanical effect,plays a major role in protecting thegeomembrane piercing,prolong composite geomembrane service life,and the main load is above the middle of the geotextile and geomembrane.The mechanical properties of materials should be independent of the stress and strain is derived and the formula itself,so the formula is applicable to all geosynthetic materials inflatable deformation stress and strain calculation.The stress and strain formula is deduced that strain is relatedto the diameter of apparatus,the center point deflection of the specimen,the thickness and the bursting pressure,and stress only relatedto the diameter of apparatus and the center point deflection of the specimen.(3)Through the bulge deformation geomembrane,and under the condition of the same geomembrane and placed the geotextile under the burst test data analysis can be concluded that the geotextile don’t stress the mechanics function,main protection geomembrane pierced,prolong the service life of the composite geomembrane,and bear the main load is above the geotextile and the middle of the geomembrane.(4)The composite geomembrane swelling area is smaller,the rate of the faster,the bursting pressure is greater,and center point deflection of the specimen is reduce,the limit value of composite geomembrane crown height was related to the ultimate elongation of composite geomembrane,the Change trend of the bursting pressure is opposite to center point deflection of the specime and stress-strain.(5)The stress strain curve of composite geomembrane air expansion deformation could be divided into four stages:elastic stage,the yield stage,strengthen stage and bursting break stage.(6)When geomembrane closely combining with geotextile and geomembrane,geotextile interaction,the integrity of a stronger,better mechanical properties,thus make the composite geomembrane can withstand stress and strain is Greater than the sum of the geomembrane and geotextile. |
