(1. School of Civil Engineering，Lanzhou University of Technology，Lanzhou，Gansu 730050，China；2. Western Engineering Research Center of Disaster Mitigation in Civil Engineering of Ministry of Education，Lanzhou University of Technology，Lanzhou，Gansu 730050，China；3. School of Civil Engineering，Qinghai University，Xining，Qinghai 810016，China)
Abstract：For the purpose of rapid drainage of surrounding rock before excavation of water-rich loess tunnels，a method of electro-osmosis combined with vacuum is proposed，and the theoretical analysis and experimental research on the drainage consolidation process are carried out. Firstly，based on the theory of porous media and the principle of unsaturated soil mechanics，a mathematical model of mutual coupling of electric field，pore pressure field and displacement field under the combined action of electro-osmosis and vacuum is established. Then，the drainage consolidation law of soil under the combined action of electro-osmosis and vacuum is deeply analyzed by using the finite element method. Combined with the indoor model test，the application effect of this method in the rapid drainage of water rich loess is further analyzed. The results show that the combined action of electro-osmosis and vacuum can effectively improve the drainage efficiency of soil，but when the initial permeability is large，the phenomenon of “pore pressure reversal” will appear in the later stage of combined drainage，which will lead to the low drainage efficiency in the later stage of combined drainage，which explains that increasing the voltage in the later stage of combined drainage can not improve the drainage efficiency. The electrode spacing mainly has a great influence on the change of pore water pressure in the later stage of electro-osmosis combined with vacuum preloading drainage，and when the anode potential is constant，the pore water pressure does not change monotonically with the electrode spacing.
[1] 侯晋芳，刘文彬. 电渗法与电渗法联合真空预压法加固超软土地基的室内试验分析对比[J]. 中国港湾建设，2018，38(2)：30–34.(HOU Jinfang，LIU Wenbin. Experimental analysis and comparison of consolidation of ultra-soft soil under electro-osmotic and vacuum preloading-electro-osmosis[J]. China Harbour Engineering，2018，38(2)：30–34.(in Chinese))
[2] 王 军，张 乐，刘飞禹，等. 真空预压–电渗法联合加固软黏土地基试验研究[J]. 岩石力学与工程学报，2014，33(增2)：4 181–4 192.(WANG Jun，ZHANG Le，LIU Feiyu，et al. Experimental study of vacuum preloading combined reinforcement with electro-osmosis in soft clay ground[J]. Chinese Journal of Rock Mechanics and Engineering，2014，33(Supp.2)：4 181–4 192.(in Chinese))
[3] 曹永华，高志义. 电渗法中排水固结理论与实践的若干问题[J]. 中国港湾建设，2010，(3)：22–24.(CAO Yonghua，GAO Zhiyi. Some problems on theory and application of drainage consolidationin electroosmotic for ground improvement[J]. China Harbour Engineering，2010，(3)：22–24.(in Chinese))
[4] 王柳江，刘斯宏，汪俊波，等. 真空预压联合电渗法处理高含水率软土模型试验[J]. 河海大学学报：自然科学版，2011，39(6)：671–675.(WANG Liujiang，LIU Sihong，WANG Junbo，et al. Model test for high-water-content soft soil treatment under vacuum preloading in combination with electroosmosis[J]. Journal of Hohai University：Natural Science，2011，39(6)：671–675.(in Chinese))
[5] WANG J，MA J，LIU F，et al. Experimental study on the improvement of marine clay slurry by electroosmosis-vacuum preloading[J]. Geotextiles and Geomembranes，2016，44(4)：615–622.
[6] 孙召花，余湘娟，高明军，等. 真空–电渗联合加固技术的固结试验研究[J]. 岩土工程学报，2017，39(2)：250–258.(SUN Zhaohua，YU Xiangjuan，GAO Mingjun，et al. Experimental studies on vacuum preloading incorporated with electro-osmosis consolidation for dredger fill[J]. Chinese Journal of Geotechnical Engineering，2017，39(2)：250–258.(in Chinese))
[7] ZHANG L，HU L. Laboratory tests of electro-osmotic consolidation combined with vacuum preloading on kaolinite using electrokinetic geosynthetics[J]. Geotextiles and Geomembranes，2019，47(2)：166–176.
[8] 徐 伟，刘斯宏，王柳江，等. 真空预压联合电渗法加固软基的固结方程[J]. 河海大学学报：自然科学版，2011，39(2)：169–175.(XU Wei，LIU Sihong，WANG Liujiang，et al. Analytical theory of soft ground consolidation under vacuum preloading combined with electro-osmosis[J]. Journal of Hohai University：Natural Science，2011，39(2)：169–175.(in Chinese))
[9] 吴 辉，胡黎明. 真空预压与电渗固结联合加固技术的理论模型[J]. 清华大学学报：自然科学版，2012，52(2)：182–185.(WU Hui，HU Liming. Analytical models of the coupling of vacuum preloading and electro-osmosis consolidation for ground stabilization[J]. Journal of Tsinghua University：Science and Technology，2012，52(2)：182–185.(in Chinese))
[10] 王柳江，刘斯宏，汪俊波，等. 电场–渗流场–应力场耦合的电渗固结数值分析[J]. 岩土力学，2012，33(6)：1 904–1 911.(WANG Liujiang，LIU Sihong，WANG Junbo，et al. Numerical analysis of electroosmostic consolidation based on coupled electrical field-seepage field-stress field[J]. Rock and Soil Mechanics，2012，33(6)：1 904–1 911.(in Chinese))
[11] YUAN J，HICKS M A. Influence of gas generation in electro-osmosis consolidation[J]. International Journal for Numerical and Analytical Methods in Geomechanics，2016，40(11)：1 570–1 593.
[12] BISHOP A W. The principle of effective stress[J]. Teknisk Ukeblad，1959，39：859–863.
[13] FREDLUND D G，MORGENSTERN N R. Stress state variables for unsaturated soils[J]. Journal of the Geotechnical Engineering Division，1977，103(5)：447–466.
[14] LU N. Is matric suction a stress variable[J]. Journal of Geotechnical and Geoenvironmental Engineering，2008，134(7)：899–905.
[15] LU N，LIKOS W J. Rate of capillary rise in soil[J]. Journal of Geotechnical and Geoenvironmental Engineering，2004，130(6)：646–650.
[16] 刘国华，王振宇，黄建平. 土的电阻率特性及其工程应用研究[J]. 岩土工程学报，2004，26(1)：83–87.(LIU Guohua，WANG Zhenyu，HUANG Jianping. Research on electrical resistivity feature of soil and it?s application[J]. Chinese Journal of Geotechnical Engineering，2004，26(1)：83–87.(in Chinese))
[17] CHAPUIS R P，AUBERTIN M. On the use of the Kozeny Carman equation to predict the hydraulic conductivity of soils[J]. Canadian Geotechnical Journal，2003，40(3)：616–628.
[18] VAN GENUCHTEN M T. A closed‐form equation for predicting the hydraulic conductivity of unsaturated soils[J]. Soil science society of America Journal，1980，44(5)：892–898.
[19] 李 瑛，龚晓南，张雪婵. 电压对一维电渗排水影响的试验研究[J]. 岩土力学，2011，32(3)：709–714.(LI Ying，GONG Xiaonan，ZHANG Xuechan. Experimental research on effect of applied voltage on one-dimensional electroosmotic drainage[J]. Rock and Soil Mechanics，2011，32(3)：709–714.(in Chinese))
[20] 蔡袁强. 吹填淤泥真空预压固结机制与排水体防淤堵处理技术[J]. 岩土工程学报，2021，43(2)：201–225.(CAI Yuanqiang. Consolidation mechanism of vacuum preloading for dredged slurry and anti-clogging method for drains[J]. Chinese Journal of Geotechnical Engineering，2021，43(2)：201–225.(in Chinese))
[21] SUN Z，GAO M，YU X. Vacuum preloading combined with electro-osmotic dewatering of dredger fill using electric vertical drains[J]. Drying Technology，2015，33(7)：847–853.
[22] HU R，CHEN Y F，ZHOU C B. Modeling of coupled deformation，water flow and gas transport in soil slopes subjected to rain infiltration[J]. Science China Technological Sciences，2011，54(10)：2 561–2 575.
[23] 吴 辉. 软土地基电渗加固方法研究[博士学位论文][D]. 北京：清华大学，2015.(WU HUI. Soft soil improvement by electro-osmosis techniques[Ph. D. Thesis][D]. Beijing：Tsinghua University，2015.(in Chinese))
2023, Vol. 42 
