砂卵石土改良新型泡沫剂的开发与应用

Development and Application of New Foam Agent for Sandy Gravel Soil lmprovement

砂卵石土具有内摩擦角大、流动性差、渗透系数大、黏聚力低等特点,为解决盾构在砂卵石地层施工时会引起出土困难、地下水喷涌等问题,通过表面活性剂复配试验,得到一种新型泡沫改良剂配方“m(AOS)∶m(APG0810)∶m(HPMC)∶m(氯化铵)=4∶6∶1∶5”,最优发泡浓度为3%~5%.基于石家庄城市轨道交通5号线一期工程的砂卵石地层,配置卵石含量50%、60%、70%的砂卵石土,加入自制泡沫剂和膨润土进行改良,发现随着2种改良剂注入率的增加,砂卵石土的坍落度逐渐增大,并得到了不同含石量砂卵石土满足盾构施工中“理想状态土体”要求的改良剂注入率,为砂卵石土的改良提供了依据.

Sandy gravel soil is characterized by large internal friction angle,poor fluidity,large per-meability coefficient and low cohesion.In order to solve the problems such as difficult excavation and groundwater gushing caused by shield construction in sandy pebble stratum,a new type of foam improv.er formula“m(AOS):㎡(APG0810):m(HPMC):m(ammonium chloride)=4:6:1:5”was obtained through surlactant compounding test,and the optimal foam concentration was 3%~5%Based on the sandy gravel stratum of Shijiazhuang Rail Transit Line 5 Phase Project,sandy gravel soil with pebble content of 50%,60%and 70%was configured,and self-made foam agent and bentonite were added for improvement.lt is found that with the increase of injection rate of the two modifiers,the slump of sandy gravel soil gradually increases,and the injection rate of the modifier for sandy gravel soil with different stone content meeting the requirements of“ideal soil mass”in shield construction is obtained,which provides a basis for the improvement of sandy gravel soil.