Study On Characteristics Of Frost Heaving And Thaw Settlement Of Huainan Weak Expansive Soil

The artificial freezing method is widely used in various underground engineering constructions,which ensures that the construction can be carried out safely and efficiently under various complicated geological conditions,but the freezing method brings convenience to the construction while it is generated during the freezing process.The frost heaving and the melting and sinking after melting will affect the surrounding buildings and other facilities.Therefore,it is very important to study the factors affecting the frost heaving and sinking during construction.Through previous studies,it is found that the research on the characteristics of soil frost heave and sinking is basically conventional soil,and the research on the frost heave and sinking characteristics of weak expansive soil is less.There are few research data on frost heaving and sedimentation that can be referenced,which cannot fully meet the requirements of these areas when performing underground artificial freezing method.Therefore,the freezing test of the typical weak expansive soil in Huainan is carried out under the indoor closed system,and the factors affecting the frost heaving and sinking of the soil are studied in detail.The main work is as follows:(1)The selected soil samples were subjected to conventional geotechnical tests,including free expansion rate test,liquid plastic limit test,etc.The test results showed that the selected soil samples were weak expansive soil.(2)A set of devices capable of performing the heave-sinking test was carried out.The frost-swelling test of the weakly expansive soil in the Huainan area was carried out under the indoor closed system.The water content,dry density and freezing temperature were considered in the test.The effect of salt content on the frost heaving characteristics,it is found that the water content,freezing temperature and dry density have a great influence on the frost heave of the soil,and the salt content has little effect.In addition,in the study of the sinking property,the influence of the load on the soil is also considered.It is found that the water content,the dry density,the load and the cold end temperature have a greater degree of melting and sinking to the soil,and the salt content has less influence on it.(3)The temperature change trend and water migration during the freezing process were studied.The experimental results showed that the initial temperature drop rate of the sample was faster and gradually slowed down later.After stabilization,the temperature was approximately linear with the height of the soil.The moisture content of the frozen soil is higher than the initial water content,the moisture content of the unfrozen soil is lower than the initial water content,and the maximum moisture content appears at the last stable frozen front.The data obtained from the test has certain reference and guiding value for the construction of the area rich in weak expansive soil during the artificial freezing method.Figure[48]table[21]reference[56].