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临江地下结构进行浮力计算时,其抗浮设计水位直接采用地面高程或江河水位是不合理的,需要对场地进行渗流分析才能确定。在沿用本奈特假定的前提下,推导出一种简化算法用于临江二元地层的渗流分析,可得到强透水层中的水头分布。在此基础上,提出地下结构物底板水压力的实用计算方法为抗浮设计提供依据。其方法适用于堤前、堤后覆盖层有不同的厚度和渗透系数,以及宽度为有限或无限的边界情况。该法计算简便,结果足够精确。经过算例验证和比较,堤后小型结构物对强透水层中的水头分布影响不大,但大型结构物和堤后宽度收窄将会显著抬高水头。位于覆盖层中的地下室底板浮力呈中跨大、四周边跨小的分布形态,但位于强透水层中时则呈线性分布。
In the calculation of buoyancy of Linjiang underground structure, it is unreasonable to directly adopt ground elevation or river water level in the anti-floating design water level, and the seepage analysis of the site needs to be confirmed. Based on Bennett’s assumption, a simplified algorithm is derived for the seepage analysis of the Linjiang Binary Formation, and the head distribution in the permeable layer can be obtained. On this basis, the practical calculation method of water pressure on the floor of underground structure is proposed to provide basis for anti-floating design. The method is suitable for embankment, embankment after the cover has different thickness and permeability coefficient, and the width of limited or unlimited boundary conditions. The method is simple and the result is accurate enough. After verification and comparison of the examples, the small structure after embankment has little effect on the water head distribution in the aquitard, but narrowing the width of the large structure and the embankment will significantly raise the water head. The buoyancy of the basement floor located in the overburden is large in midspan and the distribution around the four sides is small. However, the buoyancy in the basement floor located in the overburden presents a linear distribution.