The Mechanical Properties And Damage Laws Of Constrained Argillaceous Dolomite Under Freezing And Thawing Conditions

Guizhou is a mountainous province,with abundant rainfall and groundwater,and intricate underground rivers.This means that civil construction is difficult.Multiple engineering,include slope engineering,tunnel engineering,foundation pit engineering,etc,excavate large areas in mountainous.Rocks are exposed to the air with frequent rain and accidental rainstorm.Disasters such as slope collapse,foundation pit collapse,and tunnel collapse often occur.Argillaceous dolomite has a high clay mineral content and strong water sensitivity.Limestone and dolomite are widely distributed in Guizhou.The article simulates the rock mass in the anchorage engineering,and studies the degradation of argillaceous dolomite in the freeze-thaw environment.The article conducts freeze-thaw tests on different grades of prestressed rock samples.By tracing the changing characteristics of the rock test,the physical and mechanical laws of constrained rock freezing and thawing were obtained,and the mechanism of the influence of prestress on the freeze-thaw rock was revealed.The article research content is as follows:(1)The basic parameter test before the freeze-thaw test,design restraint devices to facilitate the application of different levels of prestress,the device is simple,easy to operate,and can be used in both water and ice environments,and it can track the changes of prestress in real time with high accuracy,which is suitable for the research in this paper..(2)The pre-stressed grades are 0%,20%,40%,and 60% of the drying strength of the rock.The test was performed in 5 freeze-thaw batches,with 5 freeze-thaw cycles as 1 batch,and 5 batches in each batch.The cycle is gradually increasing.Rock mass and P-wave velocity tests are performed before and after freezing and thawing.The apparent phenomena of different periods are compared to reflect the degree of rock freeze-thaw damage.(3)Monitor the change of prestress loss during the freeze-thaw test through the principle of the prestress device.Under the water environment of the freeze-thaw test,the prestress loss is large and the freeze environment loss is small.The relationshipbetween the prestress loss and the freeze-thaw environment is revealed.Further analysis The mechanism of prestress loss is also reflected,and the freeze-thaw characteristics of prestressed rock are also reflected.Studies show that the prestress loss of 60% constrained rock is the smallest.(4)After the freeze-thaw test of the rock sample,a uniaxial compression test is performed.The uniaxial test process is used in conjunction with the DIC technology to analyze the rock mechanical characteristics and failure process,and obtain the relationship between the prestressed rock and the failure mechanism in the freeze-thaw environment.It shows that 20% prestressed rock has the best resistance to freeze-thaw degradation.