This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of...This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of numerical analyses is performed to examine the effects of cover depth ratio(C/D),tunnel volume loss rate(h t)and volumetric block proportion(VBP)on the characteristics of subsurface settle-ment trough and soil volume loss.Considering the ground loss variation with depth,three modes are deduced from the volumetric deformation responses of the soil above the tunnel crown.Then,analytical solutions to predict subsurface settlement for each mode are presented using stochastic medium theory.The influences of C/D,h t and VBP on the key parameters(i.e.B and N)in the analytical expressions are discussed to determine the fitting formulae of B and N.Finally,the proposed analytical solutions are validated by the comparisons with the results of model test and numerical simulation.Results show that the fitting formulae provide a convenient and reliable way to evaluate the key parameters.Besides,the analytical solutions are reasonable and available in predicting the subsurface settlement induced by shield tunnelling in sandy cobble stratum.展开更多
The rheological behavior of phosphoric acid-water glass grout in different mixing ratios was studied. Grout made of water glass with Baume degree of 20° and 13.4% phosphoric acid by 1:1 volume ratio is found to b...The rheological behavior of phosphoric acid-water glass grout in different mixing ratios was studied. Grout made of water glass with Baume degree of 20° and 13.4% phosphoric acid by 1:1 volume ratio is found to be more effective in stopping water. Laboratory model test of water shutoff by grouting was conducted. Test results show that the diffusion length and water cutoff effect of the grout are significantly improved as the grout head is raised, due to the dilution of underground water, and it takes the grout longer than its gel time to cut off water.展开更多
As China＇s energy strategy moving westward, the surface movement and deformation characteristics due to high-intensive coal mining in the windy and sandy region become a research hotspot. Surface movement observation...As China＇s energy strategy moving westward, the surface movement and deformation characteristics due to high-intensive coal mining in the windy and sandy region become a research hotspot. Surface movement observation stations were established to monitor movement and deformation in one super-large working face. Based on field measurements, the surface movement and deformation characteristics were obtained, including angle parameters, subsidence prediction parameters, etc. Besides, the angle and subsidence prediction parameters in similar mining areas are summarized; the mechanism of surface movement and deformation was analyzed with the combination of key stratum theory, mining and geological conditions. The research also indicates that compared with conventional working faces, uniform subsidence area of the subsidence trough in the windy and sandy region is larger, the trough margins are relative steep and deformation values present convergence at the margins, the extent of the trough shrink towards the goaf and the influence time of mining activities lasts shorter; the overlying rock movement and breaking characteristics presents regional particularity in the study area, while the single key stratum, thin bedrock and thick sand that can rapidly propagate movement and deformation are the deep factors, contributing to it.展开更多
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.51538001 and 51978019).
文摘This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of numerical analyses is performed to examine the effects of cover depth ratio(C/D),tunnel volume loss rate(h t)and volumetric block proportion(VBP)on the characteristics of subsurface settle-ment trough and soil volume loss.Considering the ground loss variation with depth,three modes are deduced from the volumetric deformation responses of the soil above the tunnel crown.Then,analytical solutions to predict subsurface settlement for each mode are presented using stochastic medium theory.The influences of C/D,h t and VBP on the key parameters(i.e.B and N)in the analytical expressions are discussed to determine the fitting formulae of B and N.Finally,the proposed analytical solutions are validated by the comparisons with the results of model test and numerical simulation.Results show that the fitting formulae provide a convenient and reliable way to evaluate the key parameters.Besides,the analytical solutions are reasonable and available in predicting the subsurface settlement induced by shield tunnelling in sandy cobble stratum.
基金Projects(41472278,41202220)supported by the National Natural Science Foundation of ChinaProject(20120022120003)supported by the Research Fund for the Doctoral Program of Higher Education,China+1 种基金Project(2652012065)supported by the Fundamental Research Funds for the Central Universities,ChinaProject supported by Beijing Higher Education Young Elite Teacher Program,China
文摘The rheological behavior of phosphoric acid-water glass grout in different mixing ratios was studied. Grout made of water glass with Baume degree of 20° and 13.4% phosphoric acid by 1:1 volume ratio is found to be more effective in stopping water. Laboratory model test of water shutoff by grouting was conducted. Test results show that the diffusion length and water cutoff effect of the grout are significantly improved as the grout head is raised, due to the dilution of underground water, and it takes the grout longer than its gel time to cut off water.
基金Financial supports for this work, are provided by the National Natural Science Foundation of China （NSFC） ＆ Shenhua Group Corporation Limited key support project of the coal joint fund （U1361203） and NSFC under Grant No. 41501562. Thanks are also due to some participants for rendering assistant cooperation during studies.
文摘As China＇s energy strategy moving westward, the surface movement and deformation characteristics due to high-intensive coal mining in the windy and sandy region become a research hotspot. Surface movement observation stations were established to monitor movement and deformation in one super-large working face. Based on field measurements, the surface movement and deformation characteristics were obtained, including angle parameters, subsidence prediction parameters, etc. Besides, the angle and subsidence prediction parameters in similar mining areas are summarized; the mechanism of surface movement and deformation was analyzed with the combination of key stratum theory, mining and geological conditions. The research also indicates that compared with conventional working faces, uniform subsidence area of the subsidence trough in the windy and sandy region is larger, the trough margins are relative steep and deformation values present convergence at the margins, the extent of the trough shrink towards the goaf and the influence time of mining activities lasts shorter; the overlying rock movement and breaking characteristics presents regional particularity in the study area, while the single key stratum, thin bedrock and thick sand that can rapidly propagate movement and deformation are the deep factors, contributing to it.
