基于Biot固结理论的闸基灌注桩基础变形计算

杨宁 刘灿

摘 要：甘肃省张掖市黑河小孤山水电站枢纽采用闸坝型式，基础河床覆盖着深厚的淤泥质土，采用混凝土灌注桩群桩措施进行基础处理。为研究闸基处理后变形情况，采用Biot固结理论，基于有限元法对多工况下桩基变形进行计算，并将计算结果与后期运行中枢纽上游、中游和下游3排共计15个监测点连续106期的监测数据进行对比。结果表明：①工程从开挖至正常运行和发生地震情况的桩基变形有限元计算结果与按照规范计算的结果较为接近;②枢纽工程建设完成后对其进行连续监测，将监测数据与计算数据对比，二者基本吻合，基础处理方案合理、有效，计算方法合理;③混凝土灌注桩群桩基础的处理措施改善了淤泥质软土的剪切变形和不均匀沉降，为工程的安全运行提供了保障。

关键词：Biot固结理论;闸基;混凝土灌注桩群桩;变形计算

中图分类号：TU473.1+4   文献标志码：A

doi：10.3969/j.issn.1000-1379.2020.07.028

Abstract：The sluice and dam are used in the Xiaogushan Hydropower Station of Heihe River in Zhangye City， Gansu Province. The river bed of the foundation is covered with deep silty soil and the foundation treatment is carried out by concrete grouting pile group piles. In order to study the deformation of sluice foundation after treatment， Biot consolidation theory was used to calculate the deformation of pile foundation under multiple conditions based on finite element method. Then the calculation results were compared with the monitoring data for 106 consecutive periods of 15 monitoring points in 3 rows of upstream， middle stream and downstream of the later operation hub. The results show that a） the results of pile foundation deformation base on finite element calculation method from excavation to normal operation and earthquake occurrence are close to those calculated according to the specifications; b） continuous monitoring is carried out after completion of complex project construction， and the monitoring data are basically in agreement with the calculation data， which shows that the foundation treatment scheme is reasonable， effective and the calculation method is reasonable and; c） treatment measures for pile group foundation of concrete cast-in-place piles improve shear deformation and uneven settlement of silty soft soil， which provides guarantee for safe operation of the project.

Key words： Biot consolidation theory; sluice foundation; concrete pile group; deformation calculation

在軟土地基上进行水利水电工程建设，对于软土地基性质的研究、加固处理技术的探索是土木工程界所关注的重点、难点和热点[1]。根据水工建筑物类别对地基承载力的要求以及基础处理引起的工程投资等问题，应针对不同情况对软土地基采取不同的处理措施。常用的处理方法有换填法、排水固结预压法、强夯法、灰土挤密桩法、振冲碎石桩法、高压喷射注浆法、水泥搅拌桩法、灌注桩群桩法等，其中：换填法广泛应用于土层厚度在4 m以内的浅层地基处理;排水……