深表土冻结施工的井筒,外层采用预制砌块的双层井壁,是一种目前认为比较好的结构型式,因为砌块砌完后可以立即承受冻土帷幕蠕变变形传来的施工荷载,与冻土帷幕共同支承外部的水土压力,而且又避免冻土帷幕由井壁内吸收热量融化后回冻产生的冻胀力。但是目前采用的预制块外形和计算方法都存在一定的问题,例如淮南地区的几个井筒,预制块外缘是直线形的,不仅块本身厚薄不均,组成的外壁外缘也是折线形的,此种形式的外壁,在径向均匀压力作用下,砌块内的应力很不均匀。此外,外壁砌块的计算方法也存在一定问题,如陆峰同志在“冻 Deep borehole construction of frozen wellbore, the outer layer of prefabricated double-wall lining, is currently considered a better structure, because the brick block immediately after construction can withstand the creep deformation of frozen soil from the construction load , Together with the frozen soil curtain to support the external water and soil pressure, but also to avoid frozen soil curtain wall by the absorption heat absorbed thaw thawing frost heaving force. However, the present precast block shape and calculation methods have some problems. For example, several wellbores in Huainan area have a linear shape of the outer edge of the precast block. The thickness of the block itself is not uniform, This form of the outer wall, under the uniform pressure in the radial direction, the stress within the block is very uneven. In addition, there are some problems with the calculation method of the outer wall blocks, such as Comrade Lu Feng