滨海盐渍土改良试验及钉形搅拌桩承载力评估

Experiment on improvement of coastal saline soil and evaluation of bearing capacity of nail shaped cement-soil mixed pile foundation

针对滨海盐渍土地区水泥土搅拌桩地基处理问题,通过室内试验研究了含海盐量对土体塑液性指标等物理参数的影响,以及对三轴剪切强度力学参数的弱化作用;此外,通过不同材料配合比的改良试验,研究了水泥盐渍土强度随含盐量等变化的规律,表明水泥土含盐或者浸泡海盐水,对于强度都有弱化影响,水泥、粉煤灰固化剂都可以一定程度抵消海盐的不利影响,而且后者效果更明显。在上述试验基础上,从水泥土材料强度、桩-土侧摩擦与端部阻力、P—S计算曲线等方面,综合计算评估钉形水泥土搅拌桩单桩以及复合地基承载力特征值,表明固化剂改良的搅拌桩处理后,含盐软基能满足承载能力设计要求。在钉形的异形桩的承载力理论计算以及工程验证等方面,仍有待进一步深入。

To handle the problem on foundation treatment with cement soil mixing piles in coastal saline soil area,laboratory tests were taken to study the influence of sea salt content on physical parameters,such as plastic index of soil,as well as on the mechanical parameters of three axis shear strength;In addition,the strength of saline soil mixed cement,which is changed with salt content,was studied by improving tests with different mix ratio of materials,It is indicated that the soil mixed cement has decreased strength due to containing salt or soaking into saline water,and as the curing agents both the cement and the fly ash can increase the strength to a certain extent,moreover,the latter effect is more obvious.On the basis of the above tests,the bearing capacity of the single pile and the composite foundation is evaluated comprehensively by utilizing the strength of cement-soil material,pile soil side friction and end resistance,pile P-S curves and so on.The results show that the soft foundation containing salt can have required bearing capacity by treated with the improved cement-soil-mixing piles.Since nail shaped pile is different from equal diameter pile,this research need more validation by theoretical study and engineering practice for further.