潜蚀作用下覆盖型岩溶塌陷试验研究

Experimental study on overlying karst collapse under the action of underground corrosion

摘要

【目的】明确潜蚀在覆盖型岩溶塌陷中所起的作用对岩溶塌陷机理研究具有重要意义。为确定在潜蚀作用下覆盖型岩溶塌陷的塌陷模式，【方法】设计并搭建了一款物理模型装置，并以徐州废黄河区域新生街与民主北路塌陷为研究对象，在现场勘查基础上，结合研究区的工程地质条件和钻探资料，开展物理模型试验。【结果】结果显示：民主北路塌陷形态为近圆形，平均塌陷范围和塌陷深度分别为35 cm、26 cm;新生街塌陷形态为近圆形，平均塌陷范围和塌陷深度分别为23 cm、17.75 cm。【结论】结果表明：民主北路土层是由最开始的“土洞型”塌陷演化为“沙漏型”塌陷，新生街土层从始至终为“沙漏型”塌陷，“沙漏型”塌陷的塌陷坑范围大小与土层厚度有关，土层越厚，塌陷范围越大；民主北路土层表层位移曲线呈波动向上型，新生街土层表层位移曲线呈阶梯向上型；潜蚀速率越快，土颗粒流失速率变快，土体沉降量越大，越容易发生地面塌陷；原土层颗粒级配越大，潜蚀后通过管道流出土颗粒级配越大。通过试验研究潜蚀作用下岩溶塌陷的演化过程与特征，对岩溶塌陷的防治具有实际意义和参考价值。

Abstract

[Objective] It is of great significance for the study of karst collapse mechanism to clarify the role of water creep in overlying karst collapse. In order to determine the collapse mode of covered karst collapse under the action of underground corrosion, [Methods] A physical model device was designed and built, and the physical model test was carried out on the basis of field investigation, combined with the engineering geological conditions and drilling data in the study area, taking the collapse of Xinsheng Street and Minzhu North Road in the abandoned Yellow River area of Xuzhou as the research object. [Results] The result show that the collapse shape of Minzhu North Road is nearly circular, with an average collapse range of 35 cm and an average collapse depth of 26 cm. The collapse shape of Xinsheng Street is nearly circular, with an average collapse range of 23 cm and an average collapse depth of 17.75 cm. [Conclusion] The results show that the soil layer of Minzhu North Road has evolved from the initial “cave-type” collapse to the “hourglass-type” collapse, while the soil layer of Xinsheng Street has been an “hourglass” collapse from beginning to end. The size of the collapse pit of the “hourglass” collapse is related to the thickness of the soil layer; the thicker the soil layer, the larger the collapse range. The displacement curve of the surface layer of the soil at Minzhu North Road showed a fluctuating upward trend, while the displacement curve of the surface layer of the soil at Xinsheng Street showed a stepped upward trend. The faster the latent erosion rate, the faster the soil particle loss rate, the larger the soil settlement, and the more likely a ground collapse will occur. The larger the particle gradation of the original soil layer, the larger the particle gradation of the soil that passes through the pipeline after latent erosion, and vice versa. The experimental study of the evolution process and characteristics of karst collapse under latent erosion has practical significance and reference value for the prevention and control of karst collapse.

关键词

潜蚀作用 / 覆盖型岩溶 / 塌陷特征 / 物理试验 / 影响因素 / 变形 / 地下水

Key words

underground corrosion / covered karst / collapse characteristics / physical test / influencing factors / deformation / groundwater

基金资助

国家重点研发计划“深部岩溶塌陷风险精准防控技术装备研发”(2022YFC3003301)