寒区硬岩隧道冻胀力的量值及分布规律

根据寒区硬岩隧道冻胀力产生的机理,推导冻胀力的计算公式,并以此得出冻胀力的分布规律服从正态分布。采用半公式半经验的方法,即“等效弹性当量系数法”计算出冻胀力的量值。衬砌结构所受的冻胀力是由衬砌结构与围岩之间积存的水体冻胀引起的,其方向始终垂直于衬砌结构。积存的水体深度主要取决于施工因素,可近似为毛洞超挖的高度。冻胀力的大小与衬砌结构和冰的弹性当量系数的平均值、围岩的弹性抗力系数的平均值、水的冻胀率和积存水体的深度等有关,其量值随围岩级别的不同而有所差异,通常情况下冻胀力取0.9~1.43 MPa;而对冬季地下水仍很丰富的地区,其冻胀力取为0.92~2.31 MPa。当其它因素一定时,冻胀力随衬砌结构弹性当量系数的增大而增大,说明衬砌结构刚度的增加对抑制冻害不利,因此衬砌结构宜柔不宜刚。

Magnitude and Distribution of Frost Heave Force for Cold Region Strong Rock Tunnels

Based on the mechanism of frost heave force acting on a cold region strong rock tunnel,the formula for calculating frost heave force is deduced and the conclusion that the distribution on frost heave force is normal school is drawn up.The magnitude of frost heave force is figured out by means of the half formula and half experience,namely the Equivalent Elasticity Coefficient Method.Frost heave force which acts on the lining structure is induced by the fact that the water between lining structure and wall rock is freezing and it is always vertical to lining structure.The depth of water mostly lies on construction factors and is approximately the height of exceeding excavation.The magnitude of frost heave force is related with the average value of the equivalent elasticity coefficient for lining structure,ice and surrounding rock,frozen-heave ratio,the depth of water and so on.The magnitude differs from the level of the surrounding rock,as a rule,it is between 0.9 and 1.43 MPa;and that in winter ground water is still quite abundant someplace,the magnitude is between 0.92 and 2.31 MPa.If other factors are the same,frost heave force increases along with the accretion of the equivalent elasticity coefficient,it shows that it is adverse for controlling the freezing damage when the rigidity of lining structure is increasing,so lining structure should be flexible,not be rigid.