某防洪闸水泥土搅拌桩复合地基计算分析

Calculation and Analysis of Cement-soil Mixing Pile Composite Foundation of a Flood Gate

水泥土搅拌桩具有经济环保、施工方便、技术成熟等优势,广泛应用于水工建筑物地基处理。文章以水沟防洪闸为例,提出水泥土搅拌桩复合地基处理既要满足强度要求,又要避免"悬浮"桩型,减小处理后的地基沉降。水泥土搅拌桩设计时,首先应结合场区的地质条件,选择承载力较高的地层作为桩端持力层,确定有效桩长。然后根据确定的有效桩长,分别按照桩长范围内的侧阻力特征值、端阻力特征值和桩身强度分布计算单桩竖向承载力特征值,取二者较小值作为单桩竖向承载力特征值。最后根据采用的单桩竖向承载力特征值假定不同桩间距、不同布桩型式试算复合地基承载力,本着既能满足上部荷载要求,又尽量减少处理工程量的角度出发,选择桩间距1.25 m、梅花形布桩处理方案来进行地基处理。

Cement-soil mixing pile is widely used in foundation treatment of hydraulic structures because of its economic and environmental protection,convenient construction and mature technology.Taking the flood gate of gully as an example,a treatment scheme of cement-soil mixing pile composite foundation is put forward in this paper,which should not only meet the strength requirements,but also avoid the suspended pile type,so as to reduce the settlement of the foundation after treatment.In the design of cement-soil mixing pile,the stratum with higher bearing capacity should be selected as the pile tip bearing layer and the effective pile length should be determined according to the geological conditions of the site.Then,according to the determined effective pile length,the characteristic values of side resistance,end resistance and pile strength distribution within the range of pile length,the characteristic value of vertical bearing capacity of single pile are calculated according to the characteristic values of lateral resistance,end resistance and pile strength distribution within the range of pile length respectively,and the smaller value is taken as the characteristic value of vertical bearing capacity of single pile.Finally,according to the characteristic value of vertical bearing capacity of single pile,the bearing capacity of composite foundation is calculated by assuming different pile spacing and pile arrangement types.From the perspective of meeting the upper load requirements and minimizing the amount of engineering work,the treatment scheme of plum pile with pile spacing of 1.25 m are selected for foundation treatment.