修建沿海高速公路软土地基的处理方法.rar

修建沿海高速公路软土地基的处理方法

在沿海地区广泛分布着海相沉积、湖相沉积和河相沉积的软弱淤泥粘土层。这种土的特点是含水量高，压缩性大，强度低，透水性差。由于其压缩性高，透水性差。地基承载力和稳定性不满足工程要求。因此在此种地基上修筑高速公路必须采取加固处理措施，现就当前普遍采用的几种处理方法做一简要比较说明。
1、振冲碎石桩
由于淤泥抗剪强度低，内聚力较小、灵敏度高、振冲扰动后其  强度必将会迅速降低，往往发生触变现象，所以成桩可能性小，在淤泥土质上不宜采用此种方法。
2、深层(水泥土)搅拌复合地基
如果场地的淤泥层较厚，复合地基的承载力较低，路基回填后淤泥固结引起地面沉降所产生的负摩擦力引起承载力的进一步降低。采用此种方法设计时虽桩径、桩长都加大，水泥用量加高，但承载力仍可能达不到设计图纸要求。现场和室内试验结果相差较大。虽然加固造价较昂贵，但效果并不是十分理想。
3、石灰桩
石灰桩对软土加固的主要作用是吸水胀发使桩间加固土脱水挤密，因而提高承载力，但由于淤泥渗透系数小，不利于软土脱水固结，试验表明石灰桩脱水加固效果很小，一般强度提高仅达15%－20%左右，同时当地也无生石灰资源，且需
Construction of coastal highway soft approach

Widely distributed in coastal marine sediments, lake sediments and river silt deposition in the soft clay layer. This soil is characterized by high water content, compression of large, low strength and poor permeability. Because of its high compressibility, permeability difference. Bearing capacity and stability does not meet the engineering requirements. Therefore, construction of highways in such foundation reinforcement measures must be taken now on the current treatment methods commonly used to make a few relatively brief description.
1, gravel pile
As the silt of low shear strength, cohesion small, high sensitivity and the strength of vibration after the perturbation will be quickly reduced, often occurs thixotropy phenomenon, so the possibility of a small pile in silt soil is not suitable to this method.
2, deep (cement) mixing composite foundation
If the venue thick silt layer, the lower the bearing capacity of composite foundation, Backfill land subsidence caused by consolidation after the sludge generated by friction caused by the negative to further reduce the carrying capacity. Although using this method to design pile diameter, pile length is increased, heightening the amount of cement, but still may not reach the design capacity requirements of the drawings. Field and laboratory test results were quite different. Although the reinforcement cost more expensive, but the effect is not very satisfactory.
3, lime pile
Lime pile of soft soil reinforced absorbent main role is to send inflation to pile reinforcement compaction of soil dehydration, thus increasing capacity, but the sludge permeability coefficient, is not conducive to the consolidation of soft soil dehydration, results showed that lime pile reinforcement effect is dehydration small, the general strength increased only about 15% -20%, while local resources and no lime, and the need to