Charakterystyka lessów lubelskich jako podłoża budowlanego
Abstract
Characteristics of the Lublin loess as a building subsoil.
A b s t r a c t. The loess subsoil constitutes over 50% of the Lublin area and determines the geotechnical conditions of the western side of the River Bystrzyca. The paper discusses the geological structure of this part of Lublin and presents an analysis of the results of field research carried out by the author. The research methodology and the method of deriving parameters for the loess subsoil are also proposed. The Lublin loesses were divided into three main facies groups: aeolian (typical loess), aeolian-diluvial and aeolian alluvial. The basis for the division and parametric characteristics of individual facies were mainly in-situ tests: CPT/CPTU static soundings, DMT/SDMT flat dilatometer tests and PMT Menard pressuremeter tests. The collected data allowed characterizing each of the facies groups and developing a synthetic geological cross-section representing the geological structure of the western part of Lublin. The number of analysed tests allowed stating that the data from CPT/CPTU static soundings are representative for Lublin. Data from DMT/SDMT tests can be considered representative, but further research is needed to refine them and, for example, to separate them by facies. Data from pressuremeter tests should be treated as preliminary. The analyses show that the most common facies in Lublin is silty aeolian one called typical loess, which, according to the author, constitutes approximately 75–80%, and their parameters are of key importance for the design of buildings. The remaining facies groups are about 8–15% for aeolian-diluvial loess and 8–10% for aeolian alluvial loess. Typical loesses are macroscopically homogeneous, but their varying stiffness is reflected in in-situ tests. The basic research method for loess subsoil should be CPT/CPTU static soundings, while the most representative parameter for geotechnical layers is the cone resistance qc. Details of the geological structure and parameters should be performed with DMT, SDMT and PMT tests, as well as laboratory tests, the necessary scope of which can be determined after the development of the subsoil model from the results of CPT tests.
A b s t r a c t. The loess subsoil constitutes over 50% of the Lublin area and determines the geotechnical conditions of the western side of the River Bystrzyca. The paper discusses the geological structure of this part of Lublin and presents an analysis of the results of field research carried out by the author. The research methodology and the method of deriving parameters for the loess subsoil are also proposed. The Lublin loesses were divided into three main facies groups: aeolian (typical loess), aeolian-diluvial and aeolian alluvial. The basis for the division and parametric characteristics of individual facies were mainly in-situ tests: CPT/CPTU static soundings, DMT/SDMT flat dilatometer tests and PMT Menard pressuremeter tests. The collected data allowed characterizing each of the facies groups and developing a synthetic geological cross-section representing the geological structure of the western part of Lublin. The number of analysed tests allowed stating that the data from CPT/CPTU static soundings are representative for Lublin. Data from DMT/SDMT tests can be considered representative, but further research is needed to refine them and, for example, to separate them by facies. Data from pressuremeter tests should be treated as preliminary. The analyses show that the most common facies in Lublin is silty aeolian one called typical loess, which, according to the author, constitutes approximately 75–80%, and their parameters are of key importance for the design of buildings. The remaining facies groups are about 8–15% for aeolian-diluvial loess and 8–10% for aeolian alluvial loess. Typical loesses are macroscopically homogeneous, but their varying stiffness is reflected in in-situ tests. The basic research method for loess subsoil should be CPT/CPTU static soundings, while the most representative parameter for geotechnical layers is the cone resistance qc. Details of the geological structure and parameters should be performed with DMT, SDMT and PMT tests, as well as laboratory tests, the necessary scope of which can be determined after the development of the subsoil model from the results of CPT tests.