Intensity And Stability Study Of The Xiaoqi Village Glacial Till Slope Based On SWCC

There are numerous large and ultra-large glacial tills in areas of dry-warm valleyin the upper reaches of the Minjiang River, forming a large number of natural high andsteep slopes with obvious progressive deformation. As the region has many towns and amain road built along the river, the stability of slopes has a significant impact on them.The impact of rainfall on this type of deposits is very important, specifically Under theimpact of rainfall, the stability of large glacial tills will be reduced. On the basis of sitesurvey, the study selected the representative deposit samples from Xiaoqi Village.The Xiaoqi Village glacial till is located in the Xiaoqi village of Xue town, LiCounty, the right bank of the Zagunao river, which the317State Road through itsleading edge. Its mainly composition is moraine deposits, flat shape looks liketongue-shaped, vertical length is465m, average width is210m, its area is7.3×104m2, and volume is about250×104m3, belong to large accumulation. Its frontelevation is within the range of1595~1600m, the trailing edge elevation is1842m,relative elevation is242m. The leading edge is straight to the Zagunao River,somethin thickness residual talus has developed at the trailing edge; the right boundary is abedrock cliff; and exposed bedrock can be found at the left boundary.In order to study the strength and stability of the glacial till slope underunsaturated strength theory, this paper carried out following works:1) It carried out field reconnaissance and site investigation. On the basis ofunderstanding and fully awaring of the formation conditions, deformationcharacteristics and the factors that affect slope stability of this landslide. we haveanalyzed the formation mechanism of the landslide, and thought that the generaldamage characteristics of this landslide belong to the sliding crack model, also knownas traction slpoe.2) Completed a series of medium shear tests under different saturation of glacialtills. Combining the Coulomb formula and test results, we found that with the increaseof saturation Sr, the C, and shear strengthfhave showed a index decrease.According to the test results fit the curve’s trend, we have got three function formulasof saturation. 3) Carried out the pressure plate test to get soil water characteristic curve (SWCC)of glacial till And By formulating the SWCC, we have found a relationship betweenthe matrix suction and saturation. On this basis, by applying existed non-saturationintensity formulas and summarizing a new formula,this paper has found t a kind of hestrength express which is suitable to the soil.4) Use limit equilibrium method to analysis the slope stability of glacial till.Calculating slope stability by using different C,, and bulk density values underdifferent saturation to study the relationship between saturation and stability, we havefound that with the increasing of saturation, the stability decresed exponentially. Andwhen the stability coefficient F=1.15, content (16.61%) of the slope was very closeto the optimum water content (16.53%), which can be used as a slope monitoring andwarning value.5) Combineing weather conditions of this area and SWCC research, this paper hasanalysised the slope stability of glacial till under different rainfall intensities anddifferent rainfall sustained time.6) According to the stability changes of two conditions, this paper has proposed amoraine slope monitoring and warning advice of glacial till, which would divided alertlevels into three:yellow, orange and red.