Wyniki wyszukiwania - BazTech

1

Effect of ureolytic bacteria on compressibility of the soils with variable gradation

Wasil Mariola, Wydro Urszula, Wołejko Elżbieta

Architecture Civil Engineering Environment

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2023

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Vol. 16, no. 3

131--139

EN

The aim of this study is to present the effect of treatment with ureolytic bacteria (Sporosarcina pasteurii) on the compressibility parameters of mineral and anthropogenic soils. In the presence of the urease enzyme, secreted by a strain of Sporosarcina pasteurii bacteria, urea hydrolysis occurs, allowing CaCO3 to be precipitated. The literature suggests applying the Microbially Induced Calcite Precipitation (MICP) method to non-cohesive soils. In order to determine whether the biomineralization process occurs in other soil types, cohesive and anthropogenic soils were tested in the laboratory. Compressibility tests were carried out in the laboratory on MICP-treated and untreated soils as reference samples. The process of biocementation in the soil is made possible by the introduction of bacteria into the soil and subsequent activation by a cementation solution (consisting of urea and calcium ions Ca2+). This paper presents the methodology for introducing bacteria into the soil, as well as the effect of the biomineralization process on the deformation parameters of the tested materials.

2

Determination of mechanical properties of soils based on CPTU data

Chmielewska Iwona

Architecture Civil Engineering Environment

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2023

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Vol. 16, no. 3

55--64

EN

The study aimed to interpret the results of cone penetration tests with pore pressure measurement (CPTU). Tests were performed on a section of the designed road about 200 m long. The subsoil under consideration was characterized by organic soils deposited to a depth of approximately 8 m. Due to the problematic soil and water conditions, improvement with geosynthetic encased columns (GEC) was performed. According to the Recommendations for Design and Analysis of Earth Structures using Geosynthetic Reinforcements – EBGEO, the constrained modulus Eoed and effective friction angle φ’ of soil below the GEC column base should be higher than 5 MPa (Eoed > 5 MPa) and 30° (φ’ > 30°), respectively. In this study, the Eoed and φ’ parameters were determined based on CPTU tests conducted in 12 locations. Analysis of the CPTU data showed that the constrained modulus and effective friction angle of the soil deposited below the GEC column base did not meet EBGEO requirements in most locations. It was also concluded that the minimum value of the constrained modulus required by EBGEO is too low compared with the requested value of the effective friction angle.

3

The use of cohesive soils improved with lime as an example of circular economy in earthworks

Gosk Wojciech

Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

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2022

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Nr 3

10--20

EN

A common practice in civil engineering during earthworks is the usual replacement of cohesive soils (fine soils), excavated during earthworks, with non-cohesive soils (coarse soils). Until recently, such a procedure was dictated primarily by economic and technical reasons. From an economic point of view, the ease of access and therefore low cost of using such soils instead of cohesive soils was crucial. The technical reason is, above all, the ease of compacting fine soils (as opposed to cohesive soils) and well-developed and well-known engineering methods for controlling their compaction. The situation changed radically when the new environmental regulations came into force and enforcement by the inspection authorities began. Currently, soil removed from a construction site according to regulations should be classified as waste. This fact has completely changed the approach of participants in the construction process to the use of local soils, especially cohesive soils (e.g. clays). Their use "on site" has stopped being an expensive option and has become a necessity. This paper presents aspects of the use of lime-improved cohesive soils that can be successfully used on site as excavation backfill. Problems related to the proper preparation of soil-lime composites are described, as well as the results of compaction tests. The paper presents the author's own methodology for selecting the content of quicklime in the soil-lime composite.

4

Research on launching technology of shield tunnel in Ho Chi Minh Metro line 1

Nguyen Xuan Loi, Wu Li, Nguyen Khanh Tung, Bui Quang Anh, Nguyen Huy Hoang, Luu Hoang Phuong

Archives of Civil Engineering

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2021

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Vol. 67, nr 1

387--401

EN

The use of subway tunnel engineering technology has become more professional and refined with the growth of society and the advancement of science and technology. The initial construction process of a subway tunnel shield is the most critical part of the entire engineering system. Shield launching period construction is the most prone to accidents in the shield construction process, directly related to the smooth through the shield tunnel. The line 1 of Ho Chi Minh (HCM) Metro is the first subway line, the full length of 19.7 km, the underground road length of 2.6 km from km 0 + 615 to km 2 + 360, from Ben Thanh market, and then through the Sai Gon river and 14 station (including 3 underground stations and 11 elevated stations), reach Suoi Tien park and is located in Long Binh area station, underground building blocks including Ben Thanh market station to Opera House station interval, Opera House station, Opera House station to Ba Son station interval. This paper selects Shield launching period of Opera House station to Ba Son shaft interval as an example, analyze the key construction technology, construction control parameters and launching considerations of shield machine.

5

Laboratory Study of Soil Shear Strength Improvement with Polyester Fibres

Nguyen Giang

Fibres & Textiles in Eastern Europe

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2019

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Vol. 27, no. 2 (134)

91--99

EN

The paper deals with a laboratory study of soil shear strength improvement with polyester fibres. Soils CS and CH were mixed with polyester fibres of 70mm length as random reinforcement in an amount of 0.5% and 1.0%. Improvement of the soil shear strength was measured by direct shear tests with a shear box of 0.3 × 0.3 × 0.08 m size. Results show that the improvement rate is different for CS and CH. For soil CS, polyester fibres increased the angle of the internal friction (even by 45.2% with 1% of polyester fibres), as well as the cohesion (by 48.2% with 0.5% of polyester fibres), but also decreased it (by 27.5% with 1% of polyester fibres). For soil CH, fibres decreased the angle of internal friction (by 7.8%) but increased the cohesion by 322.7%. Analysis of the specimen number and result uncertainty shows that various combinations of the 3 specimens provide different results; hence tests with at least 4 specimens are recommended.

PL

Artykuł dotyczy laboratoryjnego badania poprawy wytrzymałości na ścinanie gleby z zastosowaniem włókien poliestrowych. Gleby CS i CH zmieszano z włóknami poliestrowymi o długości 70 mm jako zbrojenie losowe w ilości 0,5% i 1,0%. Poprawę wytrzymałości na ścinanie gleby mierzono za pomocą testów bezpośredniego ścinania przy użyciu zestawu ścinania o wymiarach 0,3 × 0,3 × 0,08 m. Wyniki pokazują, że wskaźnik poprawy jest inny dla CS i CH. W przypadku CS włókna poliestrowe zwiększyły kąt tarcia wewnętrznego nawet o 45,2% przy udziale 1% włókien poliestrowych, a także zwiększyły spójność o 48,2% przy udziale 0,5% włókien poliestrowych, ale także zmniejszyły ją o 27,5 % z udziałem 1% włókien poliestrowych. W przypadku gleby CH włókna poliestrowe zmniejszyły kąt tarcia wewnętrznego o 7,8%, ale zwiększyły spójność o 322,7%. Analiza liczby próbek i niepewności wyniku pokazuje, że różne kombinacje 3 próbek dają różne wyniki, dlatego zaleca się testy z co najmniej 4 próbkami.