水泥土夯扩挤密桩对湿陷性黄土层水平应力的影响  

Influence of Rammed⁃Expanded Soil⁃Cement Compaction Pile on Horizontal Stress of Collapsible Loess Layer

作　　者：胡金山[1] HU Jinshan(China Railway First Survey and Design Institute Group Co.Ltd.,Xi’an 710043,China)

机构地区：[1]中铁第一勘察设计院集团有限公司,西安710043

出　　处：《铁道建筑》2023年第6期127-131,共5页Railway Engineering

摘　　要：以铁路站房区湿陷性黄土地基为研究对象,采用水泥土夯扩挤密桩进行预加固,结合处理前后室内试验和原位测试结果,研究桩长、桩间距对水泥土挤密桩处理效果的影响,揭示了处理前后加固深度内桩间土层水平应力和超固结比变化规律。结果表明:桩间距显著影响桩间土挤密效果,桩长的影响较小,当桩间距从1.2 m减小为1.0 m时桩周塑性区挤密效果显著增强,采用水泥土夯扩挤密桩处理湿陷性黄土地基时建议桩间距不大于1.0 m;锥尖阻力、侧壁阻力、水平应力比和超固结比随深度的增大呈现出先增大后减小的变化规律,埋深0~12 m范围内水平应力比在2~4变化,超固结比OCR在4~12变化,说明水泥土夯扩挤密桩显著增大了土层水平应力和强度,但深度大于12 m时水泥土夯扩挤密桩的处理效果减弱。研究结果从土层水平应力角度揭示了水泥土夯扩挤密桩的加固机理,可为湿陷性黄土地区水泥土夯扩挤密桩的工程应用提供技术支持。Taking the collapsible loess foundation in the railway station building area as the research object,the rammed-expanded soil-cement compaction piles were used for pre reinforcement.Based on the results of indoor and in�situ tests before and after treatment,the effects of pile length and pile spacing on the treatment effect of soil-cement compaction piles were studied.The changes in horizontal stress and overconsolidation ratio of the soil layer between piles within the reinforcement depth before and after treatment were revealed.The results show that the spacing between piles significantly affects the soil compaction effect between piles,while the influence of pile length is relatively small.When the pile spacing is reduced from 1.2 m to 1.0 m,the compaction effect of the plastic zone around the pile is significantly enhanced.When using rammed-expanded soil-cement compaction piles to treat collapsible loess foundation,it is recommended that the pile spacing should not exceed 1.0 m.The cone tip resistance,sidewall resistance,horizontal stress ratio,and overconsolidation ratio show a pattern of first increasing and then decreasing with increasing depth.The horizontal stress ratio varies between 2~4 within 0~12 m of burial depth,while the overconsolidation ratio varies between 4~12.This indicates that the rammed-expanded soil-cement compaction pile significantly increases the horizontal stress and strength of the soil layer,but the treatment effect of the rammed�expanded soil-cement compaction pile is weakened when the depth is greater than 12 m.The research results reveal the reinforcement mechanism of rammed-expanded soil-cement compaction piles from the perspective of horizontal stress in the soil layer,which can provide technical support for the engineering application of rammed-expanded soil-cement compaction piles in collapsible loess areas.

关 键 词：黄土地基 水泥土挤密桩 试验研究 桩间土 挤密效果 水平应力 

分 类 号：TU475.3[建筑科学—结构工程]