摘要
为深入研究冻结井外层井壁的外载,在巨野矿区特厚冲积层冻结法凿井过程中,开展了竖井井壁冻结压力的现场实测研究。实测表明:最大冻结压力Pmax普遍接近甚至超过按重液公式计算的永久水平地压P0;Pmax/P0的平均值为1.08。外壁浇筑后15d内,冻结压力增长迅速,超过57%～68%的地层中,7,10,14d冻结压力P(t)分别达到最大值Pmax的72%,77%,81%。分析认为,冻结壁内外部冻胀力的积聚,是冻结压力超过重液水平地压的根本原因。外壁设计荷载(冻结压力)的标准值应按重液水平地压取值;并应采取适当措施,减缓冻胀力积聚,减小冻结压力。此外,应确保外壁混凝土的7,10,14d立方块抗压强度分别达到其设计值的80%,85%,90%,以保证外壁的早期安全。
In order to thoroughly investigate the load of outer shaft lining, in-situ measurements on freezing pressure of vertical shaft lining are carried out during boring with freezing method sinking in deep alluvium in Juye coalfield. The in-situ measurements reveal that the maximum freezing pressure Pmax generally approches, even exceeds the pennant horizontal ground presure Po （estimitated according to the heavy liquid formulation）; the average value of Pmax/P0 is 1.08. The freezing pressure increases sharply within 15 d after the outer shaft is cast, in more than 57%-68% of the total strata, the freezing pressure P（t） at 7, 10, 14 d, reaches 72%, 77%, 81% of Pmax respectively. It is indicated that the accumulation of frost heave pressure inside and outside the ice wall is the ultimate reason that the freezing pressure usually exceeds the permant horizontal ground pressure. Consequently, characteristic value of the load （i.e., freezing pressure） of outer shaft lining should be assumed to be equal to the pennant horizontal ground pressure, meanwhile, proper measures shoud be taken to reduce the frost heave pressure so as to reduce freezing pressure. Further more, the compressive strength of outer shaft lining at 7, 10, 14 d, should respectively reach 80%, 85%, 90% of its design value so as to guarantee the safety of outer shaft lining during the early period.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2009年第2期207-212,共6页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(50704033)
中国矿业大学青年科研基金项目(2005A006)
关键词
深厚冲积层
冻结法凿井
冻结压力
现场实测
deep alluvium
freeze sinking
freezing pressure
in-situ measurement
