Prediction of plastic zone size around circular tunnels in non-hydrostatic stress field

This paper discusses the calculation of plastic zone properties around circular tunnels to rock-masses that satisfy the Hoek–Brown failure criterion in non-hydrostatic condition,and reviews the calculation of plastic zone and displacement,and the basis of the convergence–confinement method in hydrostatic condition.A two-dimensional numerical simulation model was developed to gain understanding of the plastic zone shape.Plastic zone radius in any angles around the tunnel is analyzed and measured,using different values of overburden(four states)and stress ratio(nine states).Plastic zone radius equations were obtained from fitting curve to data which are dependent on the values of stress ratio,angle and plastic zone radius in hydrostatic condition.Finally validation of this equation indicate that results predict the real plastic zone radius appropriately.

浅谈钓罗非

罗非鱼是一种吃饵凶狠、生长快的小型鱼类。但不了解其习性也不易钓获丰收。钓罗非应注意以下几点。 一、在静水区,垂钓罗非鱼看风向,钓获量比较大。在池塘或水库,刮南风在北岸施钓,刮北风在南岸施钓,其余风向以此类推,只要气温适宜,必有收获。 二、依据罗非鱼“喜温”这一特性进行施钓,收获量较佳。

特殊环境用特殊钓法

我有几十年的钓龄了,过度的痴迷,使我常常在被钓友们认为是不宜垂钓或不能垂钓的环境下也不放弃钓鱼的机会。时间久了,多少也有了些经验,在此写出来,供钓友们参考。

虾饵

用虾做饵,钓鱼效果很好。常言说:“大鱼吃小鱼,小鱼吃虾米”。实际上,除鲢鱼外,无论是肉食性鱼类还是杂食性鱼类,均喜食活虾。何况使用虾做饵还有如下优点:取之方便,可随钓随取,减少制作鱼饵程序;虾饵挂钩牢固,耐水浸泡,特别适宜于在流水中垂钓。