| Taking a sand-loess tower foundation slope of northern Shaanxi as the research object,combining of field investigation and engineering geological analysis,the basic characteristics and damage types of typical sand loess slopes are studied.Using laboratory test and microscopic analysis,the physico-mechanical properties and microstructure of sand loess were studied.The macroscopic and microscopic differences between the sandy loess in Dingbian County of northern Shaanxi and the clayey loess in Chang'an District of Xi'an are analyzed and compared.On this basis,stress-strain characteristics of tower foundation slope under different working conditions are simulated by using finite element software MIDAS.Furthermore,the failure mechanism of tower foundation slope in sandy loess area is revealed and the corresponding protective measures are put forward.The main conclusions are as follows:(1)Sand-loess slope can be divided into broken line and near-straight lines according to the shape of slope profile,and can be divided into single structure and double structure according to material composition.The failure types can be divided into three types: falling water tunnel,gully and slump,among which slump is the main form of sand loess slope failure.(2)Sampling was carried out in Dingbian County of northern Shaanxi and Chang'an District of Xi'an.Conventional tests,triaxial shear tests and microscopic tests were carried out on soil samples from the two areas.By comparing and analyzing the test results,the differences of physical properties,mechanical properties and micro-characteristics between sand loess and Xi'an clay loess in the study area are summarized.(3)With the help of finite element software,the slope stability and stress-strain can be calculated.With the increase of influencing factors,the slope stability gradually decreases,and the stress and strain of the tower foundation slope are obviously different.Wind load and rainfall are the main factors affecting slope stability and stress-strain.(4)Based on the numerical simulation results,the failure mechanism of sandy loess tower foundation slope is summarized.The failure mechanism of the sandy loess tower foundation slope is that the tension stress of the shoulder of the slope increases due to the load of the electric tower,resulting in tension cracks;in addition,rainfall weakens the strength of soil and erodes the foot of slope,which increases the tensile stress of shoulder and concentrates the shear stress of foot of slope,The potential sliding surface is formed and eventually destroyed.(5)Based on the existing loess slope protection measures and the failure mechanism of the tower foundation slope,the protection engineering design of the tower foundation slope in the study area is carried out. |
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