【摘要】 通过塌陷的地质模式概化,设计物理模型实验探索岩溶空腔在开放、密闭条件下,地下水位下降时水气压力变化的规律。实验结果表明:(1)在密闭条件下水位下降时,空腔内的水气压力处于负压状态,并呈有规律的波动,波动周期和幅度主要受初始水位的影响;(2)在密封-开放-密封实验中,当系统突然转为开放条件时,岩溶空腔内的水气压力发生突变,压力突变值可达密闭系统条件下最大波动值的3倍;(3)岩溶空腔水位下降过程中,水气压力对岩溶空腔顶部有周期性的高频振动作用,具有压力脉动的特征;(4)密闭条件下的岩溶空腔水位下降引起的水气压力变化可通过时间变量的一次函数来描述,函数斜率受出水口及岩溶空腔截面积影响,截距与初始水位紧密相关。对水气压力所产生的高频振动特征进行深入研究,将有助于岩溶塌陷机理及防治研究的突破。更多还原

【Abstract】 Through the generalization of geological model of collapse, aphysical experimental model was designed to explore the changeof water-gas pressure within the karst cavity under the conditions of both openand closed systemswhen groundwater level declined. The experimental results show that,(1) When the karst cavity is of a closed system, negative pressure with regular fluctuations appears during the declining process of groundwater. Their periodicity and amplitude of fluctuations relate well to the initial water level.(2) Once the airtight systemsuddenly turns into openone, a sudden change of water-gas pressure within karst cavity occurs. This change value could reach 3 times of original value.(3) The periodical high-frequency vibration of water-air pressure is acting on the cavity roof during the declining process of groundwater and has the characteristics of pressure pulsation.(4) The change of water-gas pressure caused by the decrease of water level under closed condition can be described by a linear function of time variable. The slope of the function is affected by the section area of karst cavity and the outlet. The intercept of the function is closely related to initial water level. The effect of high-frequency vibration of water-air pressure on overburden needs further studies,which will contribute to the formation mechanism of karst collapseand breakthroughs in prevention research.更多还原