In situ recycling is one of the most effective methods to dispose of earth pressure balance(EPB)shield waste muck with residual foaming agents with high moisture content.In this context,response surface methodology(RS...In situ recycling is one of the most effective methods to dispose of earth pressure balance(EPB)shield waste muck with residual foaming agents with high moisture content.In this context,response surface methodology(RSM)was employed to quantify the effects of independent variables,including flocculant dosage,defoamer dosage,and muck drying mass(MDM)and their interactions on defoaming-flocculation-dewatering indices.The polymeric aluminum chloride(PACL)and hydroxy silicone oil-glycerol polypropylene ether(H-G)were selected as the flocculant and defoamer.The contents of surfactants and foam stabilizers in residual foaming agents were determined using the proposed empirical equation.The defoaming ratio,antifoaming ratio,turbidity,moisture content,filtration loss ratio,and fall cone penetration depth were considered as dependent variables.The accuracy of developed RSM models was verified by the analysis results of variance,residuals,and paired t-test.Combined with the desirability approach,an optimal mixing ratio of 0.078 wt%PACL,0.016 wt%H-G,and 27.882 wt%MDM was recommended,leading to a defoaming ratio of 98.34 vol%for residual foams and a moisture content of 56.72 wt%for pressure-filtration cakes.Our findings were demonstrated to be able to provide useful guidance for prediction and optimization of the in situ recycling indicators of EPB shield waste muck in metro tunnel construction sites.展开更多
Estimating the properties of foam-conditioned clay soils is important for both conditioning and recycling goals in earth pressure balance(EPB)shield tunneling.In this study,the vacuum dewatering behaviors of foam-cond...Estimating the properties of foam-conditioned clay soils is important for both conditioning and recycling goals in earth pressure balance(EPB)shield tunneling.In this study,the vacuum dewatering behaviors of foam-conditioned clay soils were investigated,with their potential use as an alternative means to assess foam optimization being examined.A series of laboratory and fieldtests was conducted,including vacuum dewatering tests that considered the effects of filtrationtime and pressure,vane shear tests,and improved cone pullout tests under different gravimetric water content(w)and foam injection ratio(FIR)conditions.It was found that the filtrate loss(FL),which characterizes dewaterability,was increased by extended vacuum filtrationtime and elevated pressure.While increases in w and FIR enhanced FL,reductions were observed in the undrained shear strength(cu),tangential adhesion stress(Fs),and normal adhesion stress(Fn).Furthermore,a linear decrease in FL with increasing mechanical indices(cu,Fs,and Fn)was demonstrated by both laboratory and fielddata fittingresults,regardless of w,FIR,and dewatering conditions.This study provides novel insights into the understanding of vacuum dewatering mechanisms in foam-conditioned clay soils,while a simple approach is proposed for evaluating foam conditioning effectiveness in EPB shield tunneling applications.展开更多
盾构施工过程中产生的大量渣土不仅污染环境,而且会增加运输和处置成本。为解决这一问题,以南京地铁6号线某区间工程为依托,提出将盾构开挖排放的粉质黏土层渣土回收再利用于壁后注浆的技术方法。通过室内试验、SPSS(statistical packag...盾构施工过程中产生的大量渣土不仅污染环境,而且会增加运输和处置成本。为解决这一问题,以南京地铁6号线某区间工程为依托,提出将盾构开挖排放的粉质黏土层渣土回收再利用于壁后注浆的技术方法。通过室内试验、SPSS(statistical package for the social sciences)多元非线性回归分析及多目标规划优化方法,研究渣土浆液性能随水灰比、硬化剂A和硬化剂B掺比(与水泥质量之比)的变化规律,并确定渣土浆液性能与成本的最优配比。研究主要结论为:1)TW-G系列产品适用于高含泥量浆液,其中硬化剂A具有缓凝和减水作用,硬化剂B具有促凝作用。2)多目标规划优化结果显示,性能最优配比为水灰比0.75,硬化剂A掺比为0.86%,硬化剂B掺比为12.95%;成本最优配比为水灰比0.84,硬化剂A掺比为3.66%,硬化剂B掺比为2.91%。3)现场实践表明,相比于普通单液硬性浆,渣土浆液性能更佳,用于盾构壁后注浆后地表沉降控制在12 mm以内,管片上浮控制在25 mm以内,且能够减少渣土外运10%以上,成本降低35%左右。展开更多
基金supported by the National Youth Top-notch Talent Support Program of China(Grant No.00389335)the National Natural Science Foundation of China(Grant No.52378392)the“Foal Eagle Program”Youth Top-notch Talent Project of Fujian Province(Grant No.00387088).
文摘In situ recycling is one of the most effective methods to dispose of earth pressure balance(EPB)shield waste muck with residual foaming agents with high moisture content.In this context,response surface methodology(RSM)was employed to quantify the effects of independent variables,including flocculant dosage,defoamer dosage,and muck drying mass(MDM)and their interactions on defoaming-flocculation-dewatering indices.The polymeric aluminum chloride(PACL)and hydroxy silicone oil-glycerol polypropylene ether(H-G)were selected as the flocculant and defoamer.The contents of surfactants and foam stabilizers in residual foaming agents were determined using the proposed empirical equation.The defoaming ratio,antifoaming ratio,turbidity,moisture content,filtration loss ratio,and fall cone penetration depth were considered as dependent variables.The accuracy of developed RSM models was verified by the analysis results of variance,residuals,and paired t-test.Combined with the desirability approach,an optimal mixing ratio of 0.078 wt%PACL,0.016 wt%H-G,and 27.882 wt%MDM was recommended,leading to a defoaming ratio of 98.34 vol%for residual foams and a moisture content of 56.72 wt%for pressure-filtration cakes.Our findings were demonstrated to be able to provide useful guidance for prediction and optimization of the in situ recycling indicators of EPB shield waste muck in metro tunnel construction sites.
基金supported by the National Youth Top-notch Talent Support Program of China(Grant No.00389335)the National Natural Science Foundation of China(Grant No.52378392)the“Foal Eagle Program”Youth Top-notch Talent Project of Fujian Province(Grant No.00387088).
文摘Estimating the properties of foam-conditioned clay soils is important for both conditioning and recycling goals in earth pressure balance(EPB)shield tunneling.In this study,the vacuum dewatering behaviors of foam-conditioned clay soils were investigated,with their potential use as an alternative means to assess foam optimization being examined.A series of laboratory and fieldtests was conducted,including vacuum dewatering tests that considered the effects of filtrationtime and pressure,vane shear tests,and improved cone pullout tests under different gravimetric water content(w)and foam injection ratio(FIR)conditions.It was found that the filtrate loss(FL),which characterizes dewaterability,was increased by extended vacuum filtrationtime and elevated pressure.While increases in w and FIR enhanced FL,reductions were observed in the undrained shear strength(cu),tangential adhesion stress(Fs),and normal adhesion stress(Fn).Furthermore,a linear decrease in FL with increasing mechanical indices(cu,Fs,and Fn)was demonstrated by both laboratory and fielddata fittingresults,regardless of w,FIR,and dewatering conditions.This study provides novel insights into the understanding of vacuum dewatering mechanisms in foam-conditioned clay soils,while a simple approach is proposed for evaluating foam conditioning effectiveness in EPB shield tunneling applications.
文摘盾构施工过程中产生的大量渣土不仅污染环境,而且会增加运输和处置成本。为解决这一问题,以南京地铁6号线某区间工程为依托,提出将盾构开挖排放的粉质黏土层渣土回收再利用于壁后注浆的技术方法。通过室内试验、SPSS(statistical package for the social sciences)多元非线性回归分析及多目标规划优化方法,研究渣土浆液性能随水灰比、硬化剂A和硬化剂B掺比(与水泥质量之比)的变化规律,并确定渣土浆液性能与成本的最优配比。研究主要结论为:1)TW-G系列产品适用于高含泥量浆液,其中硬化剂A具有缓凝和减水作用,硬化剂B具有促凝作用。2)多目标规划优化结果显示,性能最优配比为水灰比0.75,硬化剂A掺比为0.86%,硬化剂B掺比为12.95%;成本最优配比为水灰比0.84,硬化剂A掺比为3.66%,硬化剂B掺比为2.91%。3)现场实践表明,相比于普通单液硬性浆,渣土浆液性能更佳,用于盾构壁后注浆后地表沉降控制在12 mm以内,管片上浮控制在25 mm以内,且能够减少渣土外运10%以上,成本降低35%左右。
