Some geotechnical aspects of road design and construction in glacial materials. Symposium. Summaries of papers

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analysis of slopes made of soil. It is shown that the computation can i n c o ~ a t e a failure criterion which agrees well with ~ a t trad~tlonally used in soil mechanics. [[he behaviour of many idealized slol~es and of two ~sdbaz~ m~nt dams is predicted trader two different loading conditions: that which &~lles dan-ing sequential construction in the field contra~ted ~Ith that which applies during testing in %he centrifuge laboratory. Autho 468 WHALLEY, WB Q%~ I~NIV.BELFAST, GB ~ac~ors affecting the slope sta~illty of lateral moraine faces with angles greater than 90 degrees. Symposium. Summaries of papers. MIDLAND SOIL MECH, FOLE~D.ENU,NG SOC.SYMP.0N ENGNG BEHAVIOI]K OF GLACIAL MATERIALS,BIRMINGHAM, APRIL, 1975. The steepness of the proximal faces of Alpine moraines has indicated a problem in explaining their stability. A simple Culmann stability analysis for F=I showed that very large values of angle (greater than 65deg. ) are required to give stability with the apparent cohesion intercepts determ~led from depth ].5in and large scale triaxial tests. Cementation by salts from percolating water has been discounted. It is thought that slow compaction with a consolidation load due partly to alternating positive and negative pore water pressures may give rise to the very high bulk densities determined in the field ~ud that such processes may help explain the anomalous steepness of these slopes. 469 BOSS-BROWN, DM DAMES AND MDORE, L.AoCALIF.UBA The influence of excavation technique on rock slope design. Abstract of paper for Soc. Min.~ugrs 1975 AIME Ann.Meetlng,New York. MIN. ENGNG. ALME,V26, NI2, DEC. 197~, P60. Factors such as blastlng,face cleaning,water control and the use of rock improvement techniques are discussed and related to rock slope design.The extra costs incurred are related to the steeper slope angles usually obtained. 47O PRIOR, DB Q U E ~ S UNIV.BELFAST,GB GRAHAM, J ROY ,MILIT. COLL. KINGSTON, CDN Landslides in the Magho districk of Fermauagh, Northern Ireland. IBF,2T,23 R . EI~GNG GEOL.V8, N4, DEC. 1974, P341-359. "Notational slumps,shallow debris slides and active shallow rotational slides are identified on slopes developed on rocks of Carboniferous age.The rotational slides occur on shales which weather to produce a clay-rich soil. Direct shear tests ware conducted on the soil and conventional stability analyses suggest that the residual cohesion parameter is significant.Stability calculations involve the use of a dimensionless stability coefficient.Auth. 471 L0,KY LEE3CF An evaluation of the stability of natural slopes in plastic Champlain clays.llF,4T,27R. CAN. GEOTECH.J .Vll,N1, FEB, 1974, P165-181. A method of stability analysis was developed to accomodate the distinctly monlinear nature of the strength envelopes for these clays in the low stress range appropriate to stability problems.Using this method natural slope failures were evaluated using strength characteristics determined with block samples from sites of recent slides in Quabac.The results of stability analyses of eleven slides indicate that the field strength generally approaches the post-peak condition.To verify this,the state of stress of two slpoes before sliding was determined by a finite element method accounting for work-softening behaviour .Auth.

47Z H~MEL, JV Rock strength from failure cases .Leftbank slope stability study-Libby Dam and Lake Koocanusa,Montama.Final report.39F,11T~ DEPT.ARMY, MISSOURI RIV.DIV.CORPS ENGR,OMAHA, USA.JULY 1974,239P. Slope stability problems involving fault and Joint hounded rock masses occurred in the left abutment and left bank areas of Libby Dam during construction.Results of investigations are summarized in the report where emphasis has been placed on determination and interpretation of in-situ shear strengths for geologic discontinuities in hard rock slopes .It was impossible to obtain the degree of geologic information needed to reliably evaluate the stability of the left bank rock ribs due to the size and their structural complexity.Nevertheless several conclusions were drawn concerning 1.failure conditions for small rock wedges,2.in-situ shear strength parsmeters for geologic discontinuities,end3.1eft bank rib stabillty.Auth. 473 PITEAU, DR Plan geometry and other factors relating to natural rock slope stability applied to design of De Beers mine.Report.57F,24T,17R. TECH .BULL. 190. DEFT. ~ G Y , MINES, RESOURCES, OTTAWA, CDN. JUNE, 1974,120P. As part of a ms,or study relating to the stability of rock slopes of De Beers mine and four other mines in Kimberly, an attempt was made to determine the controlling factors which either lead to or detract from the stability of the slopes.The main objective was to assess whether the natural breskback of the slopes would Jeopardise the main railway line near the pit .A study was made of the slope breakback and other related factors in the four big holes of the diamond mines in the area.

Groundwater problems 474 S'l-r.T~, GC UNIV" .OXFORD, GB An assessment, using three field studies, of the theoretical concept of the efficiency of drainage layers in an embankment.lOF,7R. G~DTECHNIQUE,V24,N4, DEC. 1974, P467-474. Three embankments (one at Selset Dam-Teesdale, one at Miraflores Dam, Colombia, and the M6 motorway trial e ~ bankment at Ki11~g~on-Wastmorland) have been studied. In each case, the pore-water pressure that might be expected to develop in the absence of drainage was calculated. This was then compared with the measured porepressure to estimate the degree of dissipation due to the drainage system. By relating this to the calculated efficiency, the theoretical concept can be assessed in comparison with observed behaviour. 475 00CKSEI~E, JE HIGHT,Z~ Some geotechnical aspects of road design and construction in glacial materials. Symposium.~mm~ies of papers. MIDLAND SOIL MECH.FOUND.ENGNG.80C.SYMP.ON ~GNG.BEHAVIOUR OF GLACIAL MAT .,BIRMINGHAM, AFRIL,1975. A comparison of the engineering properties of glacial materials investigated at the sites of ms,or road schemes in Cumbria, Cleveland, the GlasgDw area and Northern Ireland is presented. ~ v a t i o n s in design and field control were necessary to incorporate some of these materials into embankments and to allow their safe excavation in cutting. Particular reference is made to the inclusion of 'wet' boulder cl~vs within selected embankments and the use of the Benke1-~n Beam and a 18rge compaction

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machine as field control tools. The performance of these materials during construct%gn is discussed and attention is drawn to some of the difficulties they pose; these include their resilient behaviour under traffic loading, their susceptilbility to m~isture content change, and the unpredictable ground water conditions with which they are associated.Auth.

a narrowed part just above the cone-shaped point, of 36me. diameter. This has advantages in that i) Results are con~arable to those of the discontintous mechanical sotundings, and 2) more detailed information is obtained regarding the composition and strength of various soil layer s.

476 COCKSEDGE, JE HIG}~2,IY~ Artesian slopes in glaciated landscapes and their influemce on the stability of road cuttings. Symposium. Summaries of papers. MIDLAND SOIL MECH.FOUND.~GNG.SOC.SYMP.ON ENGNG.BE. HAT/DUR OF GLACIAL MAT.,BIRMINGH~M, APRIL 1975. An artesian slope is defined and the conditions necessary for its development are reviewed. The stability problems posed both during and after construction of road cuttings in the till capping layer of an artesian slope are examined. Two case histories are presented in which the existence of gla~_ial artesian slopes was recognised and extensive drainage measures were necessary to ensure stability of road cuttings. Auth.

H~PER,JA OVE ARUP AND PARTNERS,IONDON,GB Analysis of a circular raft in adhesive contact with a thick elastic layer. 13F,4T,33R. GEOTECHNIQUE, V2h, N4, DEC .1974, P561-580. The problem ~onsidered is that of a circular raft of finite flexibility in adhesive contact with a thick isotcopic elastic layer underlain by a rigid base. Using the displacemant finite element method, solutions are obtained for a homogeneous layer and also for one particular form of linearly heterogeneous layer. Eight-noded isoparametric elements are used, and the accuracy of the numerical solution is shown to be adequate, provided that certain simple procedures are followed.

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Influence of dynamic loads due to explosions or earthquakes 477 AWOJOBI, ~D UNIV. L~30S NIGERIA. SOBAYO, OA Ground vibrations due TO seismic detonation in oil exploration. 8F, 5R. INT. J. E~qTHQ. ENGNG. STRUCT. DYNAM.VB, N2, OCT- D ~ . 1974, P171-181. This paper records an empirical relation based on field tests in Mid-Western and Rivers States of Nigeria. The depth of the buried explosive is introduced as an additional parameter TO the extent of vibration at the building site, the distance of the building from the expiosive, the energy content of the explosive, and the frequency of detonation; and the resulting empirical relation shows the effects of these parame.ters on the extent of surface vibration.

478 VF~LETSOS, AS

RICE UNIV. HOUSqDN, TEXAS, USA

~,JW Dynamic behaviour of buildlng-foundation systems.lhF,26R. INT .J.E&~THQ. ~GNG. STRUCT. DYNAM .V3 ,N2,0 CT- DEC. 1974, P121-138. A discussion of the effects of soil-structure interaction on the dynamic response of linear structures which respond as single-degree-of-freedom systems in their fixed base condition is pcesented. The structures a~e presumed to be supported at the surfaces of a homogeneous, elastic half space and to be excited at the base. The free-field ground motions investigated include a harmonic motion, a relatively s i d l e pulse-type excitation and an actual earthquake record. Comprehensive response strata are presented for a range of the parameters defining the problem and the results used To assess the accuracy of a simple method of analysis the latter is discussed only briefly. Emphasis is laid on results which show that the interaction effect warrants design considerations.

Experimental and numerical techniques 479 HEIJ~,WJ The dutch cone test: study of the shape of the elec. trical cone. Conference.Session one.7F,3R . PROC .EIGH~ INT.CONF.ON SOIL MECH.FOUND.ENGNG. FDSCOW, VI. i, 1973, PISI- 18~. Delft soil mechanics laboratory has carried out an extensive series of tests, the results of which are discussad in this paper, on the shape of the electrical cone used for sounding the soil. A cone is suggested which has

481 GRAHAM, J Plasticity solutions To stability problems in sand. 8F, IT,Z4R. CAN.GEOTECH. J.VlI, N2,MAY, 1974, P238- 247. Plasticity solutions for failut-e loadings in sand have reached the stage where confidence can be expressed in the available computational procedures. However, predicted loads often do not agree particularly well with laboratory model results, and significantly over-estlmate the ultimate loading on full-scale structures. If care is taken in specifying boundary conditions to conform wi%h observations of model behaviour, then ~Dod agreement is obtained between theoretical and model results. By using the curvature of the Mohr.Coulomb envelope in the an~ulysis, it has beeu possible tO s~gest limits TO the magnitude of the scale-effect in sands. These have been con~ared with corresponding experimental values for passive retaining walls and surface footings. Reasonable trends of behaviour have been established. Auth.

4~ WILSON, G Accurate measurement of dlsplacement.2F. CAN. GEOTECH. J .Vll,N2, MAY 1974,1>306-309. The effects of lateral displacements on building structures may be accurateSJ and economically measured by the method described here .The temsiorztug device of the Ports Mark II Horehole Extensometer is graduated To 0.0025 cm.Some relatively inexpensive hardware has been used To adapt this ins. trument for measuring horizontal dlsplacem~nts using steel tape.Reference points can be mounted on the columns of existing buildings or in boreholes.Measucemants can be taken by one person and over distances of 6m displacements can be measured To an accuracy of 0.O91 cm under ideal conditions. Auth.

Rock and soil improvement techniques Bolts and anchors 4~ IS~M Suggested methods for rockbolt testing. 8F. ISRM COMMISSION ON STANDARD.ZAB.FIELD TESTS. COMMXTfnF~ ON FIELD TESTS,DOCUMENTjN23MAR.1974,16P. This pap_r is presented in three sectio.n~:_ I) Suggested methods for determining the strength of a rockbolt anchor (pull test); 2) Suggested method for determining rockbolt tension using a Torque wrench; 3) Suggested ~ethod for moniToring rockbolt tension using load cells. For each suggested metl~d the scope, of the test,