内河水下边坡稳定性及加固方案研究

Study on Stability and Reinforcement Scheme of Underwater Slope in Inland Water

内河水域水下基槽开挖扰动及泥沙回淤对基槽边坡影响极大,为保证水下基槽开挖稳定性,本文以天津海河隧道工程为例,采用有限差分法对基槽开挖过程中水下边坡的稳定性进行分析,并对水下基槽加固方案进行了研究.结果表明:开挖扰动及泥沙回淤将明显降低边坡稳定性,尤其在应力集中区域极易发生边坡失稳;在坡脚位置采用钻孔灌注桩进行抗滑加固,可有效限制水下边坡的侧向位移,提高边坡稳定性.针对本文工程,考虑水下成桩施工因素,加固桩参数宜取大值,其中加固桩长应不小于10 m,并应超过潜在滑动面深度,建议桩长14 m、桩径1200 mm和桩距2 m作为坡脚护坡桩参考尺寸.

During the excavation of underwater slope in inland waters,the excavation disturbance and sediment siltation will significantly affect the stability of the underwater slope.Based on an underwater foundation trench construction in the midstream of Haihe River in Tianjin,the stability of underwater slope during the excavation is studied by the finite difference method.Meanwhile,some different reinforcement schemes of underwater bored revetment piles are discussed.The research result shows that the excavation disturbance and siltation will significantly reduce the stability of underwater slope,especially in some stress concentration region of the slope,and the reinforcement at the slope foot by bored pile could effectively limit the lateral displacement of the underwater slope.Considering this engineering project and the pile construction elements under water,the paper proposes that the reinforcement pile parameters should be maximal,and the recommended size of the pile at the slope foot is that the length should be 14 m(longer than 10 m,exceeding the depth of potential sliding surface),the diameter should be 1200 mm and the spacing should be 2 m.