Research On The Influence Of Water And Heat On The Mechanical Properties Of Soil

In recent years,as climate change has become more and more significant,various natural geological disasters have occurred frequently,causing serious impacts on the country and society.In order to better cope with the geological disasters induced by climate change and reduce the risks and losses of disasters,this paper analyzes the characteristics of climate change in Chongqing in recent years based on the measured meteorological data in the past 69 years in Chongqing area,and uses this as the water and heat in the indoor test.Refer to the value of the effect;then through direct shear test and screening experiment and other indoor test methods to explore the influence of hydrothermal effect on soil shear strength and particle size gradation,the main conclusions are as follows:1.Based on the measured meteorological data in the past 69 years in Chongqing area,the characteristics of climate change in Chongqing area were obtained,and the response analysis of climate change and geological disasters in Chongqing area was carried out:(1)The annual average temperature and annual maximum temperature in Chongqing in the past 69 years have shown a trend of falling first and then rising,while the number of high temperature days has shown an upward trend,and extreme high temperature and drought events have occurred frequently.In the recent 69 years,the annual rainfall in Chongqing has shown a steady and rising trend,while the number of rainy days has shown a trend of first decline and then rise.In addition,the rainfall intensity in the past 69 years has also shown a significant increase trend.(2)There is a good synchronization between climate change in Chongqing and the occurrence of geological disasters.In recent years,disasters have occurred more and more frequently under the coupling effect of multi-hazard factors in Chongqing.The superposition of extreme high temperature and drought events and extreme rainfall events forms a disaster chain,which has played a role in promoting the occurrence of geological disasters.2.Through research and analysis of the influence of temperature and dry-wet cycle conditions on the structure of rock and soil,it is found that:(1)After the soil is heated,the content of granules will decrease in large particles and increase in small particles.The higher the temperature,the longer the heating time,and the greater the degree of soil fragmentation.(2)The effect of dry-wet cycles can also cause soil particles to break up,and the degree of fragmentation increases with the increase in the number of dry-wet cycles.3.After studying the influence of gradation,rainfall and temperature on the shear strength of soil,it is found that:(1)The curvature coefficient mainly affects the internal friction angle of the soil,while the uneven coefficient mainly affects the cohesion of the soil.(2)The shear strength of the soil body decreases continuously with the increase of rainfall duration.The changes in shear strength under different rainfall intensities are also different: when the rainfall intensity is small,it decays in a nearly linear manner with the progress of the rainfall;when the rainfall intensity is large,the shear strength index decays quickly in the early stage of the rainfall.Then slowly slow down until it stabilizes.(3)As the heating continues,the soil moisture content continues to decrease and the shear strength continues to increase.At the same time,for soils with low moisture content,the higher the temperature,the greater the shear strength.4.On the basis of the previous research,the orthogonal test is used to explore the influence of the coupling effect of water and heat on the shear strength of the soil:(1)The shear strength of the soil body decays continuously with the increase of the number of dry and wet cycles.The attenuation amplitude after the first and second cycles is the largest,and the shear strength index is basically stable after 5 cycles of dry and wet.(2)Compared with the gradation,rainfall and temperature,the amplitude of the dry and wet cycle has a greater impact on the shear strength.(3)For soils with relatively uniform particle distribution,after a relatively small amount of dry-wet cycles occur in a low temperature and low-intensity rainfall environment,the shear strength of the soil is attenuated to a small extent;for poorly graded soils,at high temperatures,After a large range of dry-wet cycles occur in a highintensity rainfall environment,the shear strength of the soil is attenuated to a greater degree.