管棚成孔失水引起地表沉降因素分析

利用Biot固结理论,对管棚成孔和推进过程中因渗水而引起的沉降进行计算分析,研究管棚施工时间、管棚数量、不同的管棚直径和地层不同的渗透系数对地表沉降的影响。分析结果表明,若管棚施工从钻孔到注浆的时间控制在2 h以内,则地表最大沉降量小于5 mm;若该时间为8 h,则对应的地表沉降量可达10mm。随着管棚直径的增加,管棚施工中因失水引起的地表沉降量也随之增加。地层渗透系数的大小对沉降量的影响很大。提出控制管棚成孔和推进时间、尽可能地缩短管棚施工时间、采用小直径管棚、管棚施工中采用间隔施工等控制失水沉降的技术措施。

Analysis of Ground Surface Settlement Induced by Water Loss in the Drilling Phase of Pipe Roof Construction

By means of Biot consolidation theory,the ground surface settlement induced by seepage during the drilling phase of pipe roof was analyzed.The effect of construction period,the number of pipe roof,and various diameters of pipe roof and different coefficient of permeability on ground surface settlement was studied.Analysis results show that when the construction time of drilling and grouting can be controlled within 2 h,the maximum ground surface settlement is less than 5 mm.And when the time is 8 h,the ground surface settlement can reach 10 mm.The ground surface settlement induced by water loss will increase with the increase of the diameter of pipe roof.The coefficient of permeability influences the ground settlement violently.Based on the analysis,some measures to control the ground settlement are presented,which includes: to control the construction time of pipe roof drilling and grouting,to adopt the pipe roof with smaller diameter and to drill the pipe roof with alternation method.