岩溶建筑地基溶蚀程度及深度分布规律

Dissolution degree distribution law with depth in building ground in karst terrain

基于碳酸盐岩溶蚀机理,从岩性因素和水的溶蚀能力方面分析以碳酸盐岩为主的建筑地基溶蚀能力和溶蚀程度的深度变化规律,并通过工程案例对其普遍合理性进行验证。研究结果表明:按深度的指数函数拟合的溶蚀率曲线拟合系数一般可达0.90以上,表明以碳酸盐岩为主的建筑地基溶蚀程度一般具有随深度增大呈指数衰减的特征;岩体裂隙是影响溶蚀程度深度分布特征的决定因素,岩石类型和水的溶蚀能力是影响岩溶发育的区域性因素,对建筑地基溶蚀程度的深度分布特征影响不大;岩面溶蚀程度高于洞隙溶蚀程度,合理的表征指标不应忽略岩面溶蚀特征,否则将难以合理刻画出地基溶蚀程度的深度衰减规律。

Based on dissolution mechanics of carbonate rock, the variation of dissolution capacity and degree with depth in building foundations were analyzed from the viewpoints of rocks’ solubility and the water’s dissolution capability, and they were both verified with specific engineering cases. The results show that the curve fitting coefficients of dissolution rate curve fitted by a depth-exponential function are generally more than 0.90, which indicates that dissolution degree in karst ground dominated by carbonate rocks generally decreases exponentially with the increase of depth. The rock fissures are the key factor for distribution feature of dissolution degree, and rock type and dissolution capacity of groundwater are important for regional karst feature distinct but not obvious for dissolution degree variation with depth in karst building ground. Dissolution degree of rock surface is higher than cavern dissolution degree, and so a reasonable dissolution degree indicator should not overlook the dissolution characteristics of rock surface, otherwise the depth attenuation law of dissolution degree will not be reflected rationally.