大理至丽江铁路软土特性及软基处理措施

滇西北盆地软土十分发育,山间低洼地、河谷也有软土发育.大理至丽江铁路经过软土区,软土地基工程地质问题突出.通过对大丽铁路软土工程地质特性及软基处理措施的深入研究,得出以下主要结论:新构造运动是影响大丽铁路软土发育和分布特点的根本原因;4个地貌单元分布软土23.518 km,成因以湖积为主,次为冲洪积,少量为坡洪积,偶有坡积残积土因积水浸泡为软土;软土工程地质分层多,呈现出集中连片与多点零星、层状与透镜状交替,空间变化快、变化大的分布特点;软土物理化学活性强,具有天然含水量高、天然孔隙比高、压缩性高、塑性指数高、强度低、固结系数低、渗透系数低的特点.提出的软土地基处理措施建议经施工和多年运营验证,经济合理、安全可靠.

Soft Soil Characteristics and Soft Foundation Treatment Measures of Dali to Lijiang Railway

The soft soil is very developed in Yunnan northwestern basins, and the low-lying land and river valley between mountains also have soft soil development. Dali to Lijiang Railway goes through the soft soil area, the engineering geological problems of soft soil foundation are prominent. Through the further study on the engineering geological characteristics of soft soil and soft foundation treatment measures of Dali to Lijiang railway, the following conclusions are drawn： the neotectonic movement is the fundamental reason for the soft soil development and distribution characteristics of Dali to Lijiang railway ; the distribution length of soft soil in 4 geomorphological units is 23. 518 kin. In the formation causes of soft soil, lake sediment is the main, alluvial-diluvial deposits is secondary, slope- diluvial deposits is the least, occasionally slope-residual soil becomes soft soil because of water immersion. There are many soft soil engineering geological layers. The distribution of soft soil presents the characteristic of concentrated and sporadic, layered and lenticular alternately, quick and large spatial variation. The soft soil has strong physical-chemical activity and the following engineering geological characteristics ： high natural moisture content, natural void ratio, compressibility and plasticity index, while low shear strength, coefficient of consolidation and coefficient of permeability. After the project construction and years of operation verification, it is proved that the treatment measures of soft soil foundation are economic and reasonable, safe and reliable.