Laboratorio de Geotecnia
Besides continuing with its usual activities, the Laboratorio de Geotecnia has fully joined the works demanded by the Network of High Velocity Railways, through an agreement with the Public Entity Agency of Railway Infrastructures (GIF), with a duration of 3 years.
Slide in slats with alternation of quartzite in the section Toreno-Villablino of the C-631 road
In RESEARCH, TECHNOLOGICAL DEVELOPMENT AND INNOVATION, the works initiated in the year 2000 to validate in situ the technique of 'dynamic consolidation' of habour embankments through tests with pressuremeters, piezocones and surface waves continued. With respect to the implementation of an 'in hole' type suspended ground-probe for the characterisation of different type of soils inside borings through the propagation velocity of P and S waves, a methodology was developed to identify the elastic potential of the various strata intercepted, interpreting the signals received in the domain of the frequencies.
In the field of Environmental Geotechnology the project SCAPS, carried out by the Corps of Engineers of the USA, was analysed, identifying the modifications that would be necessary to introduce in the ground-probe sensors, used in the aforementioned country, for the detection in situ of heavy metals and volatile organic compounds so that, without drilling, they can be adapted to the field equipment nowadays available at the Laboratorio de Geotecnia.
In laboratory techniques, the experimental programme started in the year 2000 to compare the determination method of organic material contents in the soil was completed, following the UNE 103204:1993 norm and the Walkley-Black method, achieving a more precise, comfortable and quick procedure to carry out that determination, modifying the last procedure with potentiometric titration. The study to substitute the classic methods collected in the Spanish norms to determine sulphates and other cations of soil samples for new techniques quicker and safer based on ionic cromatography was also finished.
Detail of the slide in the section Toreno-Villablino of the C-631 road
The RDI project for the implementation of new laboratory techniques to measure small deformations in soil cylindrical specimens was finished. Finally, within the programme of Sustainable Development of the European Union, the project SUPERTRACK, whose objective is to investigate the medium and long term behaviour of ballast platforms in high velocity railway lines, combining numerical modelling, in situ measurements and laboratory tests, was put forward, in cooperation with GIF, RENFE and other foreign institutions. There was also participation in the European projects ROCKFALL and GEOTHENET for the study of road safety in the presence of rock slides and the development of cooperation activities with other European geotechnical centres, respectively.
Checking of the improvement of fills dynamically consolidated in Algeciras with the surface waves equipment of CEDEX
In TECHNICAL ASSISTANCE the cooperation with directive centres of the Ministries of Fomento, Environment, Education Culture and Sports, Autonomous Communities (Andalucía, Castilla y León), county councils, city councils, public organisations and private companies continued.
For the Directorate General of Roads of the Ministry of Fomento, normative recommendations were elaborated and technical assistance provided for problems that appeared in the National Road Network.
In the first case, geotechnical recommendations on foundation works for roads and the test norm NLT-261 that regulates the execution of the BORRO'S type dynamic penetration test were drawn up.
Also in technical assistance for the already mentioned Directorate General, the works on the considerations, from a geotechnical point of view, of the earth works in the sections San Juan del Puerto, connection of Aljaraque, and West Lepe of the A-49 highway from Seville to the Portuguese frontier in the province of Huelva, were finished. The preliminary study of the stability problems existing in several excavations of the section Pobla de Segur-Senterada, in the N-260 of the Road's Unit of Lérida in the demarcation of Catalonia also concluded.
The present state of the excation at the KP 241 of the A-52 highway in Galicia, section Barbantes-Orense, was the object of a study, whose results were collected in a Technical Report, as well as the works made to design the soil reinforcement in the variant of Écija of the N-IV highway and those relative to slope stabilisation in the N-611 road in Herrera de Pisuerga (Palencia).
The existing documentation on the possible influence of the Cantabrian highway in the archaeological deposits of the Tito Bustillo cave (Ribadesella) was also under study..
Erosion in the supporting earth fill of an overpass in the A-49 highway
The following works were also made for the aforementioned Directive Centre:
- Technical assistance and analysis of the geotechnical aspects in the Piles-Infanzón section of the Cantabrian highway in the variant of the N-632 road from Llovio (Ribadesella) to Canero (Luarca).
- Complementary survey of the slopes in the section Cigales-Arrojo (Valladolid) of the Castilla highway and visit to the KP 438 of the national road N-232, issuing in both cases a Technical Report
Finally, the following works ought to be underlineds:
- Technical Report on the instability of the pile's diafragm wall placed at the KP 105 of the CN-340 in its intermediate realignment of Algeciras.
- Study and proposal of the correcting measures to palliate the subsidence produced between the KP 5+800 and 8+800 of the A-2 highway in the section El Palmar-Alcantarilla.
- Study of stabilising measures for the excavation slope located at the KP 386 of the N-IV in the province of Córdoba.
- Technical Report on the subsidence phenomena observed in the South ring road of Valencia and measures to be adopted.
An important agreement of three year duration, that will be formalised next year, was prepared for the GIF to study the long term behaviour of ballast railway platforms. This project will demand full-scale tests, that will reproduce the climatic conditions and the short and long term mechanical behaviour of the infrastructures in the Spanish high velocity railway lines. Its conclusions will provide the adequate techniques for the conservation and rehabilitation of ballast platforms.
Compression load test with a 300 t jack on a micropile in the Casón del Buen Retiro (Madrid)
Works in the habours of Algeciras, Vigo and Málaga were made for the public entity Puertos del Estado. These works included technical advising in the study of the dredge and foundation slopes for the caissons and the boring campaign for the sheet-pile fishing port in Puerto de Santa María (Cádiz); the follow-up of the dock 9 and counterdike of the Málaga port settling; checking of the improvement achieved, by mechanical consolidation, in the mechanical properties of the earthfills used for the enlargement of the harbour of Algeciras, and harbour analysis through numerical techniques of the dynamic behaviour in front of waves of the shelter docks built with moored caissons.
There was cooperation with the Ministry of Environment in water matters and the disposal of residues.
Technical assistance to the Directorate General of Hydraulic Works and Water Quality (DGHWWQ) of the Ministry of Environment was given, both on singular works in dams and channelling and in waste water treatment and water quality policies. In the first case, the drawing up of the final report on the channelling works of the Sorravides stream, municipality of Torrelavega, the conclusion of the study on the geotechnical instrumentation of the Collado de Contretras dam (Valencia) and the study on the settling registered in the fill test of the biological reactors of the Galindo treatment plant ought to be mentioned.
Also for the same Directive Centre, the study on the load tests in the foundation piling of the waste water treatment plant of Macua and the survey and control of settlings in the new deposit for water supply in Oviedo were finished. A first report on the control and interpretation, by geophysical techniques, of the humidity contents in the core of the Canales dam (Granada) was also drawn up in 2001.
The Directorate General of Environmental Quality and Evaluation of the Ministry of Environment is carrying out, in collaboration with the Autonomous Communities, an ambitious plan for the control of solid waste, for which the construction of treatment plants is fundamental. The Laboratorio de Geotecnia has prepared a catalogue of waste materials usable in construction. The technical reports corresponding to the research on the behaviour of solid urban waste and dynamic compaction applied to landfills were also issued; these included the compaction techniques and the measurement of permeability of clay materials for the waterproofing and sealing of landfills and the considerations on the European Directive for disposal of inert residues and analysis of the existing models for the study of pollutant transport in the soil.
Execution of a pile screen in the N-IV highway
Singular works of great importance for our national patrimony were made for the Board of Constructions of the Ministry of Education, Culture and Sports, within the already regular annual agreement of technical assistance. The study and drawing up of the report, with geotechnical considerations, on the execution of the pile diafragm wall for the public library of Palma de Mallorca ought to be underlined. The geotechnical study of the works for the enlargement of the Casón del Buen Retiro (Madrid) also continued and the final report was issued with the results of the load tests made in situ.
The great technical complexity and the socio-economic impact of the actions demanded by the Andalucía Local Government deserve special attention. The agreement of technical assistance for the final closure works of the mining waste pond of Aznalcóllar continued, with the drawing up of the report corresponding to the second semester of the year 2000, the report on the closure project presented by BOLIDEN APIRSA S.L. and the final report. The final report of the agreement for the analysis of the information and present data of the five deposits of mining waste was also drawn up, with a view to a future evaluation of their safety conditions and possible environmental impacts, including the recommendations on the geotechnical conditions of the exploitations.
Repair works in the collector of the South ring road of Valencia
Within the agreement of technical assistance with the Castilla y León Local Government for the control of the second phase of exploitation of the dangerous waste deposit in Santovenia de Pisuerga (Valladolid), complementary works for the dating of the municipality underground waters and the evaluation of the causes and consequences of the conductivity increase detected in a boring and a well within the disposal were made. Also, for the Directorate General of Roads of the Advisory Board of Fomento of the said Local Government, the stability of the slopes in the C-631 road, section Toreno-Villablino, were under study.
Technical assistance was given to the County Council of Teruel through permanent advising to the Direction of the Works for the injection and consolidation of soil in Orihuela del Tremedal, the survey with georadar of the subsoil in the Carlos Castel square, in the centre of Teruel, and the study for the improvement, using the armoured injection technique, of the geotechnical properties of the said square subsoil, all within the ambit of restoration actions undertaken by the CEHOPU.
In the municipal area, the actions in the municipalities of Castropol and Medina-Sidonia along 2001 ought to be mentioned.
The studies on the causes of the slide produced in Mirandilla St were made for the Council of Castropol, Asturias, together with the correcting measures and the elaboration of a repair project. The causes of the instability of the cliff situated to the east of La Punto dock were also under study, including the measures proposed and the elaboration of a project for the stabilisation and general consolidation of the cliff.
Deposit of mining waste "El Cobre" in Minas de Riotinto, Huelva
Finally, the drawing up of an agreement with the Soil Public Company of Andalucía, whose aim is to identify the correcting measures on the soil in the Santa Catalina suburb of Medina-Sidonia (Cádiz), where a geotechnical survey campaign was defined and a first hydrological study of the underground waters of the aforementioned municipality made, should be also underlined.
Monographic article
Project "SUPERTRACK"
Within the frame of the Strategy of Sustainable Development of the European Union, approved in the European Council of Gotebourg celebrated in June 2000, a preponderant role was given to the calculation, modelling and simulation techniques that make possible to improve the service and safety conditions of transportation infrastructures. In this context, the research project SUPERTRACK has been elaborated, with a duration of 3 years from 2002 and a total cost estimated in some 2.564.138 euros, whose objective is, besides the accumulation of the experience acquired by different European countries in the short and medium term maintenance of high velocity railway lines, to ponder the following aspects:
Outline of the 8 x 5 x 4 m box with load and environmental control systems that will be used in CEDEX for the full scale simulation of the long term behaviour of ballast platforms
- Estimation of the long term behaviour of ballast platforms in high velocity railway lines
- Study of actions directed to reduce maintenance costs during the service period of this type of platforms.
- Development of a methodology to allow the early identification of problematic ballast sections by studying the behaviour of the different layers forming the railway platform.
- Implementation of rehabilitation techniques for the conditioning of ballast sections without interrupting railway traffic and at an acceptable cost.
- Development of a numerical model to predict the non linear behaviour at a short, medium and long term of railway ballast platforms.
Eight working teams of Spain, France, Norway and Sweden take part in this research project. Three of these teams belong to national railway institutions, such as the Agency of Railway Infrastructures (GIF) and the National Network of Spanish Railways (RENFE) in Spain and the Societé Nationale des Chemins de Fer (SNCF) in France; two form part of research institutes and centres, such as the Centro de Estudios y Experimentación de Obras Públicas (CEDEX) in Spain and the Norwegian Geotechnical Institute (NGI) in Norway; other two are integrated in academic bodies, such as the École Central de Paris (ECDP) and the Linköping University of Sweden (LU); finally, consulting companies, such as the Geodynamique et Structure Companie (GDS), with head office in France, are also represented.
PHASES OF THE PROJECT
The global scientific objective pursued by this project is a detailed research on the static and dynamic long term behaviour of ballast railway platforms for high velocity lines. This research, primarily based on the study of a ballast platform placed in a box specially built in laboratory that reproduces the environmental conditions and traffic loads induced in situ by the crossing of high velocity trains, will be accompanied by numeric simulations, other laboratory tests and in situ measurements and auscultation of this type of platforms. Specifically, the project includes the following phases:
- Data collection on ballast railway platforms from conventional and high velocity railway lines.
Triaxial equipment available in CEDEX to test sub-ballast specimens of 6 inches diameter
- Selection of four ballast railway platforms, one in Spain and the other in France, belonging to high velocity railway lines that are going to be in service in the near future; other two platforms, one in each of the above said countries, belonging to conventional railway lines that need rehabilitation.
- Geotechnical characterisation in situ by means of static and dynamic tests of the four ballast platforms previously selected and their instrumentation with movement, humidity and temperature sensors.
- Construction and instrumentation in laboratory, in a special box for geotechnical tests of 8x5x4 m (see Figure 1), of one of the selected platforms in a high velocity railway line that makes possible to simulate, through a dynamic system of load application and control of the environmental conditions (insolation, rain, frost) the behaviour of the platform at a short, medium and long term.
- Determination in laboratory, by triaxial tests in 1,5, 4, 6 and 9 inches diameter (see Figures 2 and 3) of the static and dynamic deformation modules of the materials forming all and each of the layers that conform the platforms of reference. The resistant characteristics of the ballast of the aforementioned platforms will be simultaneously established with the equipment available at present in the Laboratorio de Geotecnia, with a 1m x 1m x 1m cut box (see Figure 4).
- Characterisation in laboratory of the short term mechanical behaviour of the platform and comparison with the data obtained in situ.
- Characterisation in laboratory of the medium and long term behaviour of the platform and implementation of a numerical model to reproduce that behaviour, incorporating the non linear effects of the train-platform-soil interaction.
- Rehabilitation, without interrupting the railway traffic, of two experimental sections (one in Spain and the other in France) through controlled injections of sleeve tubes in the conventional lines chosen, where conservation problems exist.
- Drawing up of a set of recommendations for the project, construction and maintenance of ballast platforms for high velocity railway lines, incorporating the data and results obtained along the execution of the project
FORESEEABLE RESULTSS
Triaxial equipment available in CEDEX to test ballast specimens of 252 mm diameter
Through the research project SUPERTRACK, the long term non linear behaviour of ballast railway platforms for high velocity trains and the different materials that form them will be under study, simulating their behaviour with full scale models and laboratory tests. This study aims to obtain information that will make possible to develop a numerical model to predict the static and dynamic behaviour of the materials used in this type of platforms at a medium and long term. An improvement method will be also implemented, based on the concept of hydraulic fracture by controlled concrete injections to rehabilitate ballast sections with structural problems without interrupting railway traffic, comparing it with other new reinforcement techniques. Finally, all the information obtained will be compiled and a Guide prepared, anticipating its usefulness for the long term conservation of ballast platforms in high velocity railway lines.
CONTRIBUTION TO THE EUROPEAN ECONOMIC PROGRESS
At present, maintenance works in railway companies represent some 6% of their annual return. This corresponds, as an average, to some 15.000 euros per kilometre and year. A 10% of the said expenditure can be attributed to the maintenance of the platform geometric characteristics, that is made nowadays with ballasting operations in most railway lines. Obviously, any activity that makes possible to reduce the volume of this type of operations means a reduction in costs and an increase in the availability of railway lines for transport. Therefore, the implementation of techniques to reach this objective offers financial and functioning advantages, especially in zones where ballasting has proved ineffective at a long term.
The project SUPERTRACK will make possible to develop a working methodology and to put into operation a numerical model that, incorporating the global behaviour of the whole of the railway platform and the supporting soil, will serve to quantify advantages and disadvantages, in front of new techniques, of the methods used at present in the maintenance of ballast platforms. There will be also possible to quantify and predict the consequences that can have, on this type of structures, the increase in a near future of the circulation velocity and the load per axle in high velocity trains, facilitating the medium term adoption of the adequate strategies to take into account these effects in the European Union.
Direct cut equipment available in CEDEX to test ballast specimens of 1 x 1 x 1 m
Finally, from a scientific and development point of view, the results obtained in the project will contribute to elevate the level of the present knowledge on the non linear long term dynamic behaviour of granular materials with relation to transport infrastructure works.