Influence of sample preparation and mode of testing on the shear strength characteristics of laterite soils from Southwestern Nigeria

The Shear Strengths of four laterite soils from Southwestern Nigeria are investigated through:

1. consolidated undrained triaxial compression tests with pore water measurements on Standard Proctor compacted soils and
2. direct shear tests on remoulded soils.

The Shear Strength parameter obtained in both cases are high with those of the first method being generally higher than those of the second method. However, in view of the relative ease of execution, the second method is preferred especially with regards to local/minor and farm constructions.     

Influence of capillary water on compressive strength of marls

Tests of compressive strength carried out on calcareous marl samples showed very different results in the four following cases:

1. the test was made in air on a dry sample,
2. in air on a sample saturated with water by capillary rise,
3. in air on a fully water-saturated sample,
4. in water on a fully water-saturated sample.

These results are interesting on a theretical point of view, and also on a practical point of view for works to be carried out under the ground-water table.     

A study of karst seepage for the pengshui hydroelectric project on the Wujiang River

The Pengshui Hydroelectric Project is located in a region of carbonate rock. Karst seepage is one of the major problems. Three problems have been studied during the investigation:

1. The determination of probable paths and the amount of seepage.
2. The formation of deep karst and its influence on reservoir seepage.
3. The influence of hot springs on reservoir seepage.

A great deal of geological mapping, drilling, karst investigation, radiowave prospecting between boreholes, comprehensive well logging, pumping tests and cave plugging tests, have been performed to solve the problems. A great deal of data has been obtained to provide a basis for the design of treatment measures for seepage prevention.     

Évaluation et cartographie des risques géotechniques de dégradation des ouvrages d'assainissement une aide à la gestion des eéseaux

A sewage collector can be considered as a composite structure, comprising the collector itself and its geological envelope both sticking together. Its durability is directly linked with the geotechnical behaviour of the soil, as testified by the analysis of numerous pathological cases observed in structures which it is possible to inspect in the Paris urban area. The author proposes a methodology enabling these parameters of influence to be taken into account without recourses to costly procedures of investigation. Based on the principles of mapping risks of soil movements, the method involves two stages:

-The geotechnical classification of soils in terms of their vulnerability to stresses to which they may be subjected.

-The establishments of maps or profiles predictive of risks. in accordance with qualitative criteria derived from the interpretation of existing geological information.

Tested and applied to the inspectable sewage system of the Val-de-Marne and Seine-Saint-Denis Departments, this procedure can be extended to urban systems where sufficient geotechnical documentation is available to obviate the need for any in situ investigation.     

Relation entre les caracteristiques des granulats et les proprietes des materiaux qu'ils permettent d'elaborer. Recherches en laboratoire et sur chantier

The introduction of the report presents data concerning the evolution of the traffic in the Cracow District between 1965 and 1983, and the aggregates used for road construction during the same period. The most important characteristics aggregates made of crushed rocks in the district are dealt with. Mineral aggregates usually belong to II–III class, and require improvements to achieve better physico-mechanical properties and after improvement they are commonly used for roadbases, basecourses and wearing courses. This report also deals with the relations between the characteristics of aggregates and the properties of same stabilized materials:

1. Mechanical stabilization for sub-base,
2. Stabilization of aggregates with granulated slag and hydrated lime for roadbases,
3. Stabilization of aggregates with granulated slag and with cement for roadbases,
4. E. Fly-ash concrete and stabilization of sand with cement for roadbases,
5. Hot bituminous mixtures/with asphalt as a binder/for basecourses,
6. Hot bituminous mixtures/with coal tar pitch as a binder/for wearing courses.

For all stabilized materials, the main results of the laboratory tests achieved during the preparation of mixes are presented, as well as the tests realized on compacted mixtures inside the road, under the traffic. It proved that satisfactory road-bases, base-courses and wearing courses could be made of aggregate of a rather poor quality. The choice of the technique must derive from the quality of the aggregates. The permanent technical control of the laboratory is necessary at all stages: designing, realization and maintenance.     

Classification, à base technique et géologique,des sables néerlandais

The working group "Sand" of the Dutch national Center for Road Research has elaborated a general classification of the Dutch sands, based on two principles:

1. a standardization of the language and the coherent choice of several indices and characteristics determined from the cumulative granulometric curve.
2. the determination of their geologic origin and peculiarly of the characteristics which (as lithology) most directly influence their utilization.

On this base, the Dutch sands may be distributed into seven "families". The practical applications of this classification for using these sands as materials for selected fill in road construction are being considered and, in his conclusion, the author draws the attention to the manner of using and interpreting the Sand Equivalent test.     

Sous-produits industriels comme granulats routiers

Relation between the characteristics of the aggregates and the properties of some materials—Experimental research works (laboratory or site). Industrial by-products used are as follows:

- as an aggregate:

? stone and gravel pit refuse

? crushed blast furnace slag

? incenerator waste slag

- as a binder:

? hydraulic and non-hydraulic fly ash

? granulated blast furnace slag

? hydrated and carbide lime refuse.

Pavement layers applied are as follows:

- unbound base courses: mechanical stabilisation using stone pit refuse, crushed blast furnace slag, waste incinerator slag

- with hydraulic binder: (cement, fly-ash, granulated slag):

? lean concrete with crushed blast furnace slag and stone pit refuse

? hydraulically bound crushed blast furnace slag, waste incinerator slag, and sand obtained as refuse at sieving

- with hydrocarbon binder:

? bituminous stone pit refuse, bituminous crushed blast furnace slag, and bituminous mixture of gravel and sand and waste incinerator slag

? rolled asphalt with crushed blast furnace slag.

     

Effects of evaporite removal on the mass properties of limestone

A considerable thickness of anhydrite has been removed by solution from Magnesian Limestone of County Durham in North-east England. To the west the extent of the anhydrite was formerly limited by the front of the well known Permian reef complex. The anhydrite beds thickened to the east and have been proved in borings a few miles offshore. Solution of the anhydrite has been ascribed to circulating groundwaters. The general circulation, and hence solution of anhydrite, would have been limited to the east by the fresh to saltwater interface approximately coincident with the present coastline. By using the methods available for predicting ground strains and subsidence associated with the underground mining of coal seams, it is possible to predict:

1. the direction and position of maximum surface strain in the limestones above the anhydrite
2. the localiation of brecciation in the associated limestones as the anhydrite was removed.

The resultant changes in the mass properties of the formerly well-bedded limestones are described and discussed.     

A collapse doline in Wood Buffalo National Park Alberta,Canada

Flat-lying dolostones of the Devonian Keg River Formation form an escarpment about 30 m high, 30 km west of Fort Smith on the boundary of Alberta and the North West Territories of Canada. The dolostone is underlain by gypsum beds of the Devonian Chinchaga Formation. Gypsum solution causes numerous collapse dolines in the Keg River Formation. One doline, 45 m in diameter, has 15 m high, vertical walls of dolostone. We have applied 3 systems, developed to determine the support necessary for underground openings of a given span in a give rock mass, to the assessment of the natural opening beneath the doline. From the characteristics of the rock mass, a 15 m unsupported span in the formation can be expected to stand-up for about one month. We suggest that unsupported natural openings exist which are about three times larger than any we would design in the rock mass because:

1. Underground opening design is conservative;
2. Natural sethods of excavation cause less damage to the surrounding rock than artificial excavation methods; and
3. Natural solution channels tend to form with their axes parallel to gaping joints. These gapes tend to close if substantial compressive stresses exist normal to the joints. Thus, the major axes of natural underground openings tend to parallel the largest compressive stresses in the rock mass, an arrangement which enhances the stability of the openings.

     

Une analyse de la deformation des couches de base non traitees

The checking of standardised properties does not allow a complete judgment to be made about the behaviour of the material on the road. This is mostly the case with unbound layers of the road. Before constructing the road, the following tests are carried out in the laboratory:

- Particle size distribution

- Shape of the aggregate

- Impact value

- Susceptibility to freezing.

On the basis of the test results, the suitability of the materials for road construction is judged, although no test results on strains in practice are available. For this reason a research has been carried out using full-scale test sections to establish the relation between the following parameters and deformation on the road as measured by the plate-bearing test:

- Particle size distribution

- Shape index

- Flake index by sieving with parallel slots

- Void content

- Water content

- Subgrade stiffness.

The stiffness of the frost-layer and the road-base-layer were calculated using a Boussinesq settlement analysis. The results showed that the stiffness of the different layers could be expressed as a transcendental function in three parameters of the settlement of the layer. Linear multi-regression analysis enabled the relation to be established between the three stiffness parameters for the first loading and the particle size distribution, shape of the aggregate voids and water-content. As a result of the work, it is now possible to establish the relationship between laboratory testing of aggregates and the contractual requirements for the finished layer.     

Stabilisation des terrains karstiques par injection le cas du lutetien gypseux de la region de Paris

1. The general stability of buildings in gipsiferous areas needs to adapt their foundations to karstic risks. According to the geological context and the characteristics of the building to be constructed it is possible to have recourse to either deep foundations which are released from the karstic level or to superficial or semi-superficial foundations Security must be guaranteed by adapting additional measures which consist of periodical control of the foundation site or its stabilization by injection. This last mentioned solution seems to be most suitable for the gipsiferous karst of the Lutetium in the region of Paris, by means of simple blocking she solution cavities or by means of consolidating the area by motar.
2. Optimation of the treatments requires good knowledge of the karstic environment which only allows correct evaluation of the nature of products and way of application. Although there are a lot of parameters concerning injection there is one distinct connection between the registered absorption rates at several sites and the degree of karstification in the gipsiferious zones. This degree of karstification may be characterized by a void index which represents the average of all anomalies shown by the drillings. The determination of that average void ratio is indispensbble for the definition of the quantities and for the elaboration of the steps of injection. The best approximation is given by drill-recording (progress of drilling and pressure)

     

Caractéristiques des masses et marnes du gypse et de leurs faciès d'altération dans la région parisienne méthodologie des études géotechniques

The author presents the principal results of a research project concerning a geological formation widely represented in the natural region of Parisis, North of Paris, which is dreaded by geotechnicians: masses and interstratified marls of ludian gypsum. The impossibility of making ground observations essential to a thorough study of the phenomena of weathering of the gypsum, and notably its substitution, led to the work being undertaken along the following lines:

-Modelling of the geological infractructure of the gypseous slopes.

-The quest for indicators of the lithology and distribution of the residual masses and interstratified marls of gypsum, and the valuable role of diagraphs of natural radioactivity.

-The incidence of the weathering of the gypsum on the mechanical (pressiometric) characteristics of the gypseous areas.

-A methodology of geotechnical surveys on gypseous sites.

A progressive approach is proposed, beginning with a feasibility study, followed by a detailed study of the evolutive nature of the site, essential to the establishment of a suitably adapted project, and concluding with a mechanical characterisation necessary for the structural design of foundations.     

Hungarian experiences gained with the aggregate abrasion test

Since 1979 the Institute for Transport Sciences /KTI/ in Hungary has dealt with abrasion tests. This testing method is an adaptation of British Standard BS 812:P.3.9:1975. The results obtained are as follows:

-The Hungarian testing method is based on oven-dried chippings

-The Hungarian method considers the actual chipping volume.

-The actual abrasion value can be determined with ±5% accuracy, on 90% probability level from test results on eight samples.

-The KTI standard gives limits for the abrasion value.

     

Recherches sur les argiles Egyptiennes pour la production de granulats legers

In some countries, serious problems will have to be faced, due to the absence of natural gravels and the development of building construction from lightweight concrete may be an interesting solution. From this point of view we approach, in this work, the procedure of lighweight aggregate production of four Egyptian clay deposits, which could provide valuable stocks. In this way, this paper presents:

-chemical, mineralogical and thermal characterization of clays;

-correlation between characterization and bloating;

-physical and mechanical properties of produced lightweight aggregates;

-evolution of physical characteristics of aggregates as a function of firing conditons.

     

Les matieres en suspension dans les estuaires

This paper, devoted to the behaviour of suspended matters in estuaries, deals successively with:

- the nature and origin of sediments suspended in some estuaries

- the behaviour of suspended materials: flocculation, falling rate of flakes, shrinkage, rheology, picking up by currents, slides inside the deposits

- the sedimentary movements of floating materials in the estuaries: transport under the influence of the tides, sedimentary materials available in the estuary, influence of the river discharge and of the salinity, ejection of suspended matters out of the estuary,

- volume of the deposits in some estuaries.

     

Etudes Françaises de materiaux de substitution

The authors examine the substitution materials studies realized in France during the last 10 years with the “Tax on Aggregates” financial support. The different types of substitution are first looked into:

-substitution of crushed hard rocks to fluviatile sands and gravels, whose reserves are becoming exhausted or sterilized by environmental constraints;

-materials not respecting standard specifications of aggregates: 1) soft rocks; 2) soils (fine sands, clayey sands, moraines, superficial deposits); 3) quarries, mines and industrial wastes.

Technical possibilities of uses for these “out of standards” materials are examined for natural or treated materials.     

Gestion des risques et des crises liés à l'instabilité des carrières souterraines abandonnées

Instability of underground excavations and karsts generally leads to violent events that affect zones which are difficult to locate precisely. For this reason, monitoring and alarm systems are not very efficient and risk management must therefore be essentially focused on prevention. In France, the aim of such prevention is to find a balance. Although the French legal and regulatory framework is rational, it is deficient in certain respects, and particularly faces difficulties concerning implementation as revealed by the development of the Plans of Exposure to Risks (PER) having taken too long. The comments made during the symposium held at Nainville-les-Roches have lead to the proposal of a number of improvements for the present system:

-promote a global approach which integrates risk management into land-use planning, ensuring coherence between national, regional, departmental and local plans,

-develop an operational approach for each “basin” at risk,

-speed up hazard mapping by its separation from regulatory procedures,

-develop plans for crisis management at a municipal level; bring experts, technical services and emergency services closer together and involve populations at risk in the preparation process,

-launch an operational information policy on the risks and develop a true culture of risk prevention,

-set up a local public service responsible for risk management of underground excavations within areas of greatest risk.

     

Protection et amenagement des sites d'interet geologique

Quarry workfaces sometimes constitute precious sources of scientific—mainly geological—data. Some quarries have contributed to the definition of the international stratigraphic scale (stratotypes), others can be of pedagogical interest or natural curiosity (palaeontology, pedology, archaeology, zoology, botany, ...). Recent studies have shown that some French sites of international geological interest have been irremediably destroyed and others considerably endangered. It has been possible to carry out some studies and work on certain quarry sites in order to preserve and make use of endangered scientific zones, in particular with financial aid from the “Taxe Parafiscale sur les Granulats”. Amongst these operations—presently in progress or already finished—, particular mention may be made of the following:

- the Saucats-La Brède sites (Gironde): Aquitanian and Burdigalian stratotypes;

- the Pontlevoy (Loir-et-Cher) and Channay S/Lathan (Indre-et-Loire) falun quarries, which present characteristic facies of the Helvetian of the Bassin Parisien;

- the Hettange-Grande site (Moselle), Hettangien stratotype;

- the Cuise-La-Motte sand-pits (Oise), Cuisan stratotype, and those of Mailly-Champagne (Marne), characteristic of the Ludian.

Work of this nature is usually undertaken to restore and secure old quarry faces, to protect them against the effects of weather and the public, and to make them accessible to visits. In certain cases, some sites have even been classified as natural reserves.