海铺立交软土路基工程地质特性及稳定性数值分析研究

发布时间：2018-05-28 06:16

本文选题：山区软土 + 工程地质特性　；参考：《西南交通大学》2015年硕士论文

【摘要】：贵州大部分地区为山地,碳酸盐岩广泛分布,年降雨量大,地下水动力条件好,岩溶发育地势低洼处多分布软土。软土性质特殊且复杂,尤其是山区软土随机零星分布,组成具有自身范围和厚度变化大,地形和地质条件复杂等特点。针对上述问题,本文对山区软土的工程地质特性进行了一系列的试验研究,并在试验结果和已有病害基础上进行了软土路基的稳定性数值模拟分析。获得了以下认识：(1)由室内试验分析得到研究区上覆土层粘土矿物含量高,具有较强的亲水性和膨胀性。当粘土矿物吸水时,其中的蒙脱石发生体积膨胀对周围软土产生推挤作用。在受到荷载作用或遭受暴雨等影响时,其流变性灵敏度增加。土层中铁元素含量较高,软土区域含有的有机质能还原铁的氧化物,减弱铁氧化物的胶结作用。加之较强的水动力作用使得游离氧化铁流失,土层胶结作用减弱,孔隙比增大,压缩性强,土颗粒间粘结减弱,土体在荷载作用下触变性增强。(2)通过对试验样本进行线性回归分析,得到孔隙比、含水量、液塑限与取样深度的相关性,结果显示孔隙比、含水量与取样深度呈正相关；液限、塑限与含水量呈正相关,且相关性较高；渗透系数随深度增加而降低；固结系数、压缩模量随深度增加呈先减小后增加的趋势,固结系数与含水量呈负相关,且相关性较高,说明含水量越大,软土固结所需时间越长。(3)通过对经水泥土搅拌桩路基边坡的位移与应变模拟研究发现,路基边坡均不稳定,且具有较大位移。路基滑动面最可能发生的位置均在有淤泥质土存在的位置。对于淤泥质土埋深较浅的区域,水平位移最大的位置均出现在淤泥质土层上,竖向位移则是下部淤泥质土厚的一侧路基下沉较另一侧大；对于淤泥质土埋深较深的区域,淤泥质土层受路基影响小,水平位移最大的位置发生在填土和粘土层上,竖直位移则是路基两侧是上浮位移最大区域,路基下方是下沉位移最大区域,且均发生在填土和粘土层中。
[Abstract]:Most areas in Guizhou are mountainous, carbonate rocks are widely distributed, annual rainfall is large, groundwater dynamic condition is good, and soft soil is distributed in karst low-lying areas. The properties of soft soil are special and complex, especially the soft soil in mountainous area is distributed randomly and sporadically, and its composition has the characteristics of its own wide range and thickness, complex topography and geological conditions, and so on. In view of the above problems, a series of experimental studies on the engineering geological characteristics of soft soil in mountainous areas are carried out in this paper, and numerical simulation analysis of the stability of soft soil subgrade is carried out on the basis of experimental results and existing diseases. The results of laboratory tests show that the clay minerals in the overlying soil layer are high in content and have strong hydrophilicity and expansibility. When clay mineral absorbs water, the volume expansion of montmorillonite will push and squeeze the surrounding soft soil. The sensitivity of rheology is increased when subjected to loads or rainstorms. The content of iron in soil is high, and the organic matter in soft soil can reduce iron oxides and weaken the cementation of iron oxides. Combined with the strong hydrodynamic effect, the free iron oxide is lost, the cementation of soil layer is weakened, the porosity ratio is increased, the compressibility is strong, and the bond between soil particles is weakened. Through linear regression analysis of test samples, the correlation between porosity, water content, liquid-plastic limit and sampling depth is obtained. The results show that the porosity ratio, water content and sampling depth are positively correlated. The coefficient of consolidation and modulus of compression decreased first and then increased with the increase of depth, and the coefficient of consolidation was negatively correlated with the water content, and the correlation was higher, the coefficient of consolidation was positively correlated with water content, and the coefficient of permeability decreased with the increase of depth, and the coefficient of consolidation decreased first and then increased with the increase of depth, and the coefficient of consolidation was negatively correlated with water content. It shows that the larger the water content, the longer the consolidation time of soft soil.) by simulating the displacement and strain of the roadbed slope with cement-soil mixing pile, it is found that the roadbed slope is unstable and has a large displacement. The most likely position of subgrade sliding surface is where silt soil exists. For the area with shallow buried depth of silt soil, the maximum horizontal displacement occurs in the muddy soil layer, the vertical displacement is that the subgrade of one side of the lower silt soil is thicker than that of the other side, and for the area where the silt soil is buried deeper, the vertical displacement is greater than that in the other side. The maximum horizontal displacement occurs on the fill and clay layer, the vertical displacement is the largest area on both sides of the roadbed, and the maximum subsidence area is below the subgrade. Both occur in fill and clay layers.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U412

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