Study On Mechanical Properties Of Expansive Mudstone Under Wetting Environment

With the gradual expansion of the field of national infrastructure construction and the continuous development of information media,all kinds of engineering problems are gradually exposed to people.The swelling and creep properties of mudstone have brought more and more trouble to the project.In order to minimize or even avoid engineering problems caused by expansive mudstone,in-depth study of the mechanical properties of expansive mudstone is our best choice at the moment.Most mudstones will swell when they encounter water,but in many cases they are often overlooked due to their small swelling deformation,which brings huge difficulties to the long-term use in the later period.Therefore,studying,understanding and mastering the swelling of mudstone is the primary task.The initial water content is one of the key factors affecting the swelling characteristics of mudstone.Therefore,in order to understand the swelling characteristics of mudstone,the initial water content must be considered..This article firstly starts from the mudstone disintegration test and free expansion rate test,and discusses the general methods for judging the swelling property of mudstone outdoors and indoors.Secondly,with the initial water content as the test variable,the mudstone free swelling rate test,the confined constrained swelling rate test and the loaded swelling rate test are carried out to analyze the effect of initial water content and load on the swelling deformation of mudstone,and compare and analyze the three types The relationship between the expansion rate.In addition,this article also focuses on analyzing the change of the expansion rate during the expansion process and fitting a mathematical model of the expansion process..Many engineering problems are often not destroyed by insufficient strength,but caused by long-term creep effects.Due to its low strength,mudstone is prone to creep deformation under loading and unloading conditions.Therefore,in order to understand the strength characteristics and creep characteristics of expansive mudstone,this article carried out indoor uniaxial loading test,loading-unloading cyclic test and uniaxial creep test,and analyzed the law of strain change and uniaxial creep deformation of mudstone under cyclic loading.And through analysis to obtain the creep model of mudstone.Finally,this paper takes the excavation of the soft rock roadbed as a case to carry out simulation.In-depth analysis of the stress,strain,displacement and other changes of the soft rock subgrade in the cutting process and the deformation of unloading rebound.And considering the water swelling characteristics of mudstone,the swelling deformation law of mudstone roadbed after absorbing water is simulated.For subgrades that strictly control post-construction deformation,subgrade creep and rebound deformation caused by cutting excavation and expansion induced deformation caused by changes in humidity should not be ignored.