Covered Karst Landforms: Complexification of Methods to Estimation of Morphometric Parameters in Engineering Purposes

Abstract

The research is aimed to search of optimal solution in integration of various methods for predicting the sizes of karst-suffosion deformations on the ground surface or at the base of shallow foundations. Necessity of integration is dictated by engineering-geological conditionsof the karst areas and the complexity of their reliable study with using modern approaches (drilling, geophysics etc.). From this point of view increasing of authenticity of the final forecast is in direct dependency from completeness of investigation of sizes of observed surface karstforms and features of behavior soils massif above the karst cavity. The mechanism of the karst process in the soils thickness is defined, first of all, by geological structure (thickness and interleaving of different soil layers), hydrogeological conditions and the physical-mechanicalproperties of soils. At the present day are known three basic mechanisms of soil deformation over karst cavity: karst-collapse, karst-suffosion and karst-suffosion-collapse mechanism. Even in the conditions of one site these mechanisms can be interleave during the year, which makesthe karst formation process hard-to-predict in part of diameters of sinkholes and subsidence zones. Today are known and applicable next four methods to estimations of possible sizes of karst-suffosion deformations: 1) method of analogy, 2) probabilistic method, 3) deterministic(calculated) method, 4) laboratory physical modeling method. Each of four methods for predicting the sizes of karst-suffosion deformations has its own advantages and disadvantages, which limit the possibility of using any one of them in different natural environments of karstdevelopment. To improve objectivity and reach necessity accuracy of estimation of diameters and depths of surface karst deformations in engineering-geological purposes a block-scheme of integrations of different forecasting methods is recommended. This scheme is based on the data about surface karst area, the depth of occurrence of karst rocks and level of responsibility of the projecting object.

Geology-engineering integration to improve drilling speed and safety in ultra-deep clastic reservoirs of the Qiulitage structural belt

“…1). Under the action of strong compressive stress, a series of folds, fold-related faults and sudden structures are formed along the deep detachment layer (Shcherbakov et al, 2018). Besides, many drilling and completion engineering problems arise.…”