岩溶场地地表水体对抗浮水位影响及取值研究

文章针对贵州山区岩溶场地中，近湖泊或水库分布场地、靠河流岸边场地、河湾场地、河流三角地场地等4种不同地表水体场地的抗浮水位取值进行了研究，得到如下结论:①抗浮水位取值可通过:勘察期间场区地下水最高水位（H_kmax）、可能的意外补给造成该层地下水位的变幅值（ΔH₀）、该层地下水相对勘察时的最大变幅值（ΔH_e）三者之和求得；②近湖泊或水库分布场地抗浮水位取值可以利用反推法或经验法获得。通过场地与湖（库）水水力比降反推在洪水期场地的最高地下水位；靠河流岸边场抗浮水位取值应以历史最高洪水位为基础，根据场区岩溶发育程度、建筑物与河流距离及水力比降综合分析确定，抗浮水位应在历史最高洪水位基础上增加0.5~1.0 m为宜；河湾地段场地抗浮水位取值应查明历史最高洪水位、水力坡降和场地岩体完整性、岩溶发育程度及规模，在岩体透水性、岩溶贯通好的场地增加0.5~1.0 m应较为宜；河流三角地段抗浮水位取值应确定地下径流方向、与河流间的水力比降及工程位置的最高水位，在岩体透水性、岩溶贯通好的场地增加0.5~1.0 m应较为适宜。 

Study on the influence of surface water on anti-floating water level and the value taking of the level in karst sites

Aiming at the karst site in Guizhou， this paper studies the anti-floating water level values of four different surface water sites， i.e. the distribution site near lake or reservoir， the site near river bank， the site of river bend and river delta. The following conclusions are obtained， （1） When the thickness of phreatic aquifer is greater than the depth of foundation， the maximum groundwater level of the site is consistent with the anti-floating water level. If the site is located in the low-lying area or in the distribution area of confined aquifer， the anti-floating water level is higher than the groundwater level. （2） The value of anti-floating water level can be obtained by the sum of the following three， the maximum groundwater level （H_kmax） in the site during the survey， the amplitude of the groundwater level of this layer caused by possible accidental recharge （ΔH₀） and the maximum amplitude of groundwater in this layer during relative survey （ΔH_e）. （3） For the site near the lake or reservoir， the value can be obtained by the inverse method or empirical method， and the maximum groundwater level of the site in the flood period can be deduced by the hydraulic gradient between the site and the lake （reservoir）. For the site near the river bank， the value shall be obtained based on the highest historical flood level. For the river reach without water level observation data in historical period， the value shall be obtained based on the highest historical flood level investigated on site， the karst development degree of the site， the distance between buildings and rivers， and the comprehensive analysis of hydraulic gradient. The value shall be added by 0.5-1.0 m based on the historical highest flood level. For the river reach that has been designed and controlled， the value shall be obtained based on the designed flood level. For fragile underground buildings， the value is suggested to be obtained based on the checked flood level， and then based on the karst development degree of the site， the distance between the buildings and the river， and the comprehensive analysis of hydraulic gradient. For the site in the river bend the value shall be obtained based on the historical highest flood level， hydraulic gradient， the integrity of the site rock mass， and the degree and scale of karst development. It is appropriate to increase 0.5-1.0 m in the site with sufficient rock permeability and karst penetration. For river delta， the value shall be obtained based on the direction of underground runoff， the hydraulic gradient with the river and the maximum water level at the project location. It is appropriate to increase 0.5-1.0 m in the site with sufficient rock permeability and karst penetration. This study is of reference significance for the engineering construction in karst development area.