考虑渗流场影响深埋圆形隧洞的弹塑性解

ELASTO-PLASTIC ANALYTICAL SOLUTION OF DEEP-BURIED CIRCLE TUNNEL CONSIDERING FLUID FLOW FIELD

将深埋圆形隧洞各影响因素简化为轴对称。首先,求解得到渗流场;然后,以渗透体积力方式作用在应力场,求解得到弹性位移和应力解析表达式,再应用Mohr-Coulomb屈服准则,求解得到塑性应力和塑性半径的解析表达式。通过考虑和不考虑渗流场影响两种方法的实例分析表明,随着洞内外水头差的逐渐增大,渗流场对应力场的影响作用将显著增大,但对切向应力的影响程度要比径向应力的大,且径向应力和切向应力不再符合无渗流时的分布规律,出现大小值交换;同时,随着内水水头的增大,洞周压应力和塑性半径逐渐减小,直到出现无塑性区;另外,考虑渗流场影响计算得到的塑性半径要比不考虑时大。

It is assumed that all the influence factors surrounding deep-buried circle tunnel are axially symmetrical. Firstly,the solution of fluid flow field is resolved. Secondly,analytical formulae of elastic stress and displacement are obtained considering the body force of seepage. Thirdly,applying Mohr-Coulomb yield criterion,analytical formulae of plastic stress and plastic radius are obtained. An example is analyzed and contrasted with and without considering fluid flow field. The research shows that the influence of seepage field on stress field is intensive along with the gradient increment of inner and outer water head of tunnel,and the influence degree on tangent stress is more than that on radial stress. The distribution law of stress is not coincide with and without considering fluid flow. The compressive stresses and plastic radius are gradually decreased along with the increasing inner head,and the plastic radius may be zero if the inner head increases continually to some extent. The influence with considering influence of fluid flow is larger than that without considering the influence.