滨海软土基坑开挖过程中的时间效应  

Time-Dependent Effect in a Deep Excavation in the Coastal Soft Soils

作　　者：秦善良 熊皓 孙梦尧 陈保国[2] QIN Shanliang;XIONG Hao;SUN Mengyao;CHEN Baoguo(Sinohydro Bureau 7 Co.Ltd.,Chengdu 610081;China University of Geosciences,Wuhan 430074)

机构地区：[1]中国水利水电第七工程局有限公司,成都610081 [2]中国地质大学(武汉)工程学院,武汉430074

出　　处：《土工基础》2023年第6期945-949,共5页Soil Engineering and Foundation

基　　金：中国电建集团铁路建设有限公司科技项目经费资助(STT-SJQ-SG0022020-KY-001)。

摘　　要：软土地区基坑开挖过程中,坑内自由面暴露的土体在土压力的作用下会出现蠕变现象,围护结构位移随着土体暴露时间增加而增大;此外,钢筋混凝土内支撑的早期刚度也会随着养护时间的延长而增长,其控制围护结构变形的能力也会相应增长。在二者共同影响下,如何平衡好蠕变时间及混凝土内支撑养护时间,对控制结构变形具有重要意义。以深圳滨海软土地区前海站基坑工程为背景,分析了土体蠕变对围护结构位移、支撑结构内力的影响,并分析了蠕变时间和混凝土内支撑养护时间对围护结构位移的影响规律。结果表明:在养护时间为28 d条件下,仅考虑软土蠕变时,围护结构位移分别增加了13.9%、9.3%、5.3%;同时考虑蠕变和内支撑刚度影响时,每一道软土开挖工况均存在一个最佳施工周期,大约为12~16 d;故当软土地层开挖深度较浅时,应同时考虑软土蠕变和内支撑刚度影响,随着开挖深度增大应优先考虑混凝土早期刚度的影响,确保养护时间。During the deep excavation in soft soils,the exposed soil in the excavated area will experience creep effect under the earth pressures.The deflection of the supporting structure will also increase with the increase of exposed time.At the same time,the strength of the reinforced concrete strut will also increase with the increase of curation time,therefore,the capacity of deformation control of the strut will also increase.Therefore,balancing the creep time and the curation age of the reinforced inner strut has a special meaning for the deformation control of the excavation supporting structure.This paper presents a case history of a deep excavation supporting project Qianhai Station of Shenzhen near shore marine soft soils.The influence of creep in the soft soils and the curation time of the reinforced concrete on the deformation of the supporting structure and the internal force in the strut are discussed.The results indicate that,under the curation time of 28 days,if the creep effect is considered in the supporting structure,the deformation increased 13.9%,9.3%and 5.3%.If both the curation and the creep effect are considered,each excavation has an optimized period of 12-16 days.When the excavation depth is shallow,the effects of both creep in the soft soils and the curation time in the reinforced concrete curation time should be considered.When the excavation depth is large,enough curation time in the reinforced concrete strut should be considered since the stiffness of the strut is important in this stage.

关 键 词：基坑 软土蠕变 内支撑刚度 时间效应 

分 类 号：TU473[建筑科学—结构工程]