洪儒宝, 简文彬, 陈雪珍. 2023. 覆盖型岩溶土洞对地下水升降作用的响应及其塌陷演化过程研究[J]. 工程地质学报, 31 (1): 240-247. doi: 10.13544/j.cnki.jeg.2020-396.
    引用本文: 洪儒宝, 简文彬, 陈雪珍. 2023. 覆盖型岩溶土洞对地下水升降作用的响应及其塌陷演化过程研究[J]. 工程地质学报, 31 (1): 240-247. doi: 10.13544/j.cnki.jeg.2020-396.
    Hong Rubao, Jian Wenbin, Chen Xuezhen. 2023. Study on response of covered karst soil cave to groundwater changes and its collapse evolution process[J]. Journal of Engineering Geology, 31(1): 240-247. doi: 10.13544/j.cnki.jeg.2020-396.
    Citation: Hong Rubao, Jian Wenbin, Chen Xuezhen. 2023. Study on response of covered karst soil cave to groundwater changes and its collapse evolution process[J]. Journal of Engineering Geology, 31(1): 240-247. doi: 10.13544/j.cnki.jeg.2020-396.

    覆盖型岩溶土洞对地下水升降作用的响应及其塌陷演化过程研究

    STUDY ON RESPONSE OF COVERED KARST SOIL CAVE TO GROUNDWATER CHANGES AND ITS COLLAPSE EVOLUTION PROCESS

    • 摘要: 福建省岩溶塌陷地质灾害发育,其发育程度仅次于滑坡、崩塌地质灾害。为研究岩溶塌陷的演化过程,本文以福建省典型覆盖型岩溶塌陷为研究对象,现场采取了覆盖层土样,在自制的物理模型箱中布设光纤光栅应变传感器、孔隙水压力计、沉降计等监测仪器获取不同条件下覆盖层土体的应力-应变信息,分析了覆盖层土体的响应情况,研究了典型覆盖层岩溶塌陷的发展演化过程。研究结果表明:(1)第四系覆盖层孔隙水位升降作用下,土层的孔隙水压力值基本呈等幅变化,底层土体变形最弱,顶层土体变形最大,两者的应变差值最大可达5倍。水位升降对土洞周围土体的破坏较小,土洞尚未形成。(2)岩溶水水位反复升降的过程中,孔隙水压力的增减与渗流水位变化同步;同一水平面上越靠近溶洞的土体产生的应变越大,且土层越高,应变差值越大,顶层土体应变差值达2000με。土洞顶板变形在水动力作用与真空吸蚀作用下不断向上发展,当变形发展超过临界土洞高度40 cm时,形成地面塌陷。(3)典型覆盖型岩溶塌陷演化过程可划分为土洞发育-覆盖层内部塌陷-地表塌陷3个不同阶段。(4)闽西南岩溶土洞塌陷大多发生于山间盆地河谷两侧地下水强径流排泄区,覆盖层厚度较大,多为第四系冲洪积的砂砾、含砾石黏性土、粉质黏土层等,其成灾机理具其地域特征。

       

      Abstract: Karst collapses are developed in Fujian Province and are second only to landslides and collapses. In order to study the evolution process of karst collapse, the typical covered karst collapse in Fujian Province is taken as the research object in this paper. On-site soil samples were taken. Fiber-optic grating strain sensors, pore water pressure gauges, settlement gauges, and other monitoring instruments were installed in a self-made physical model box to obtain stress and strain information of the overburden soil under different conditions. The response of the overburden soil is analysed. The development and evolution process of typical overburden karst collapse is proposed. The results show that: (1)Under the effect of the pore water fluctuations in the Quaternary overburden, the pore water pressure of the soil layer changes basically at the same amplitude. The largest deformation occurs in the top soil while the smallest deformation occurs in the subsoil. The fluctuation of the water level has little damage to the soil, and the soil cave has not formed yet. (2)In the process of the karst water level rising and falling repeatedly, the pore water pressure increases and decreases synchronously with the change of the seepage water level. The soil closer to the cave on the same horizontal plane produces greater strain. The higher the soil layer, the greater the strain difference. The deformation of the roof of the soil cave continues to develop upwards under the action of hydrodynamic force and vacuum erosion. When the deformation develops beyond the critical soil cave height of 40cm, the ground collapse occurs. (3)The evolution process of typical covered karst collapse can be divided into three stages: the first stage is the development and formation of soil caves, the second stage is the internal collapse, and the third stage is ground collapse. (4)The karst soil cave collapse in southwestern Fujian mostly occurs in the strong groundwater runoff drainage area on both sides of the intermountain basin and the valley. The overburden layer is thick, mostly composed of the Quaternary alluvial gravel, gravel-bearing clayey soil, and silty clay layer. The disaster mechanism has its regional characteristics.

       

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