Grzegorz Wrzesiński

Influence of the rotation of principal stress directions on undrained shear strength

Abstract Influence of the rotation of principal stress directions on undrained shear strength. The paper presents the results of research on natural cohesive soil carried out in the Hollow Cylinder Apparatus (HCA). The main goal of this study was to determine the values of undrained shear strength at different angle of the rotation of principal stress directions. The research were carried out with anisotropic consolidation and shearing in undrained conditions (CAU) on cohesive soil with overconsolidation ratio (OCR) equals 4 and plasticity index (Ip) about 77%. The results of laboratory tests allow to assess the influence of the rotation of principal stress directions on undrained shear strength

Testing of Undrained Shear Strength in a Hollow Cylinder Apparatus

Abstract The paper presents the results of tests performed in a Torsional Shear Hollow Cylinder Apparatus on undisturbed cohesive soils. The tests were performed on lightly overconsolidated clay (Cl) and sandy silty clay (sasiCl). The main objective of the tests was to determine the undrained shear strength at different angles of rotation of the principal stress directions. The results of laboratory tests allow assessing the influence of rotation of the principal stress directions on the value of undrained shear strength that should be used during designing structure foundations

Strength and Numerical Analysis in the Design of Permeable Reactive Barriers

Permeable reactive barriers are one of the most important in situ technologies in groundwater remediation. Most of the installed PRBs have tended to use singular reactive media, but there is an increasing number of applications using combined or sequenced media to treat mixtures of contaminants within a groundwater plume. The concept of a multi-layered permeable reactive barrier (MPRB) to prevent and protect groundwater along traffic routes, especially in ecologically and naturally valuable areas, was developed following several field and laboratory investigations conducted in the Department of Geotechnical Engineering of the Warsaw University of Life Sciences. In accordance with the guidelines of the Interstate Technology & Regulatory Council for the selection of reactive materials, numerous laboratory and field investigations should be performed to determine the environmental conditions, type and concentrations of the contaminants, and the physical-chemical and permeability properties of the reactive materials. However, the deformation and strength properties of the reactive materials should be also considered in the design and evaluation of the safety conditions. In this paper, strength and deformation properties of silica spongolite, zeolite, and activated carbon were investigated using direct shear and oedometer tests. The laboratory test results were used in numerical calculations with the application of the finite element method. The aim of this study was to define the impact of the installation stages of a multi-layered permeable reactive barrier on the stability of a road embankment. Numerical analysis may prevent, reduce or eliminate the risk in the case of a breakdown during the construction or/and exploitation of a PRB.

Technologie wykonania przepuszczalnych barier reaktywnych

Przepuszczalne bariery reaktywne (PBR) to jedna z innowacyjnych technologii zabezpieczania i oczyszczania środowiska gruntowo-wodnego i jednocześnie alternatywna w stosunku do energochłonnej metody „pompuj i oczyszczaj”. PBR to konstrukcja inżynierska w podłożu gruntowym wypełniona materiałem reaktywnym, w której podczas przepływu wód gruntowych dochodzi do przechwycenia zanieczyszczeń lub redukcji ich stężeń do wartości akceptowalnych. Od początku stosowania wykorzystano szereg technologii ich wykonania, obejmujących m.in. tradycyjne i alternatywne technologie wykopowe, iniekcję, mieszanie wgłębne oraz różne konstrukcje, w zależności od parametrów zanieczyszczeń i warunków terenowych. Pomimo szerokiego stosowania nadal istnieją nierozwiązane problemy dotyczące ich wykonania i długoterminowego działania. W artykule przedstawiono przegląd technologii PRB, który obejmuje stan techniki, zalety i ograniczenia oraz perspektywy zastosowania jej w Polsce.