The URL can be used to link to this page

Home My WebLink About3151; PALOMAR AIRPORT ROAD; SLOPE STABILTY ANALYSIS; 1988-08-28- , l•./, •. 2 4, American Engineering Laboratories, Inc. SA".D.tego, CA 92126 -4t4r Tekphone (619) 695-3730 I San Diego • Modesto • Corona le Yucca Valley, CITY OFCARLSBAD .. , .- . August 26,1988 2075 Las Palmas Drive - . - - Job No. G-6137A Carlsbad, California 92009 -- : Attention Mr. Al Virgilio SUBJECT: SLOPE STABILITY ANALYSIS PALOMAR AIRPORT ROAD STATION 100 + 00 Gentlemen: In accordance with your request,' we have performed slope stability analysis on the cut slope' along the north side of Palomar Airport Road near station 100 + 00. The following summarizes -the analsis arid provides- recommendations for project development. -ç INTRODUCTION Original alignment and out slope onfiguration hear Station 100 + 00 required the removal of power poles near 'the top of ihe , existing cut slope along the north- side of Palomar Airport Road. Since relocation of power poles would delay construction in this area of. the proposed road widening, 'the Cityof Carlsbad is investigating alternative slope configurations to allow, the power poles to remain in place S - CITY OF CARLSBAD PAGE 2 .. PALOMAR AIRPORT ROAD AUGUST 26, 1988 SLOPE STABILITY ANALYSIS ' '. .' JOB NO. G-8137A EXISTING SITE CONDITIONS 0 •' The existing slope measured to be approximately 22 feet , high and cut to an. approximateslope of "l:l(horizontal:vertical). The slope was examined and found to, 'contain numerous •surficial 0 slumps extending to a: depth of approximately 3-feet. Slope materials, consist of colluvium/weatherèdchannel materials from the top of slope down approximately 8; feet 'tapering to 0 approximately 4 , feet to the west. This material overlies. 0 0 •' interbeds of cemented. silty. sand material with thin claystoné 0 • beds of the DelMar or Friars formation. Bedding planes appear • to be dipping 7-12 degrees out0 of'slope. ':''" '0' 0 • MATERIAL PROPERTY DETERMINATION , ' 0 0,0 • 0 0 0 0 Samples of typical formational materials were 'obtained for 0 testing. A horizontal bench was cut 'into the sandstone materials 0 along the slope • face and a block sample was obtained from this bench. • Internal material strength parameters were determined by performing direct shear tests on specimens cut fromthe block • sample. The, testing results. indicated the following parameters: . 0 • • Apparent Cohesion • 0 •• •• 420. psf • • •• 0' 0 ••. 00 • 00' • Internal Friction Angle,' : 30 degrees 0 • ' • CITY OF CARLSBAD PAGE 3 PALOMAR AIRPORT ROAD , : AUGUST 26, 198.8 SLOPE STABILITY. ANALYSIS .' .. JOB NO. G-613.74 SLOPE STABILITY. ANALYSIS Slope stability, analysis was performed on the existing slope as well as proposed slope configurations using Bishops simplified method of: slices.' Slope height, material profile, and slope configuration was based on grading plans and observations made' S during', our field reconnaissance: The profile was,assumed to , contain interbedded sandstdn'e/siltstone and claystone as, shown on the attached figures. ' • ' ' ' Results . of the analysis indicate that' the slope, in its. present'' • condi'tion, has a factor of safety against deep seated failure of 1.2 and 'a factor' of safety at 'br slightly , below 1.0 'for surficial stability. Analysis of a slope cut back to 1 5 to 1 indicated a factor , of safety for deep seated and surficial failure of 1.4 and 1.3 respectively. • CONCLUSIONS AND RECOMMENDATIONS. ' . ' S '• '• " ' S , Our analysis 'ind'icated .'-that, slopes steeper than approximately. S ',, 1.5 to 1 'do' not-meet: generally accepted. slope stability safety ' ' ' factors. We 'therefore' recommend that if' the slopes are not constructed • t,o' ,current • plans and specifications that surficial and deep, seated stability be improved through 'the. installation • .of a retaining wall or. 'facing and reinforOement of the slope, ' with' shotcrete and anchor bolts.' . • American Engineering Laboratories -. , - 1 / 11 American Engineering Laboratories I SLOPE STABILITY ANALYSIS STABRG FOR1 IONS C) COPYRIGHT 1984 GEOSOFT ALL RIGHTS RESERVED PALOMAR AIRPORT ROAD I 0 1 CONTROL DATA H NUMBER .OF SPECIFIED CENTERS 'NUMBER OF DEPTH LINIITINOTANGENTS 0 NUMBER OFIVERTICAL SECTIONS . , . . . 6.. NUMBER OF SOIL LAYER BOUNDARIES ': • .3.' . :. NUMBER OF FORE PRESSURE LINES '. NUMBER OF POINTS DEFINING COHESION PROFILE 0 SEISMIC COEFFICIENT Si S2 = t)t) flU SEARCH STARTS AT CENTER '. Th fl WITH FINAL GRID OF 2 ALL CIRCLES FA5 THROUGH THE POINT ( 7: U 42 U GEOMETRY', SECTIONS 20 25 ti 49 ' .64.,C) 77. fi Q) ) T CRACKS' 20.0 18.0 i8.:). 33.0 42.0 42.0 : • • W IN CRACK 20.0 18.0 18.0 :.:.o 42.0 ' 42.0 .. BOUNDARY 1 2o ) 1.8 .0 18 ') U 42.0 42 BOUNDARY-2 31.0 .25.0 25.0 33.0.42.0 42.0 BOUNDARY. 3 50.0 50.0 50.c) ' so;o :so. .o 50.0. SOIL PROPERTIES . • LAYER ' : . • . , COHESION. FRICTIONANSLE. . ., DENSITY . • . . . , ' 1 . • . '1 . 420.0 .'.. . 30.0 , .135.0 . • • . . • 2 I 0 20U U 25 U 125.0 FS (OMS) NUMBER TANGENT RAD I US (X) CENTER .('Y) CENTER ;.FS(BISHOP) 1 42 1 6 A . 7&0 6.0 i.324 1.2S4- 2 42.0' '36.0 74.0 . 6.0 1.247 1.223 :3. ,:.: 73.0 ,' .6.0 1.237.' 1.2.1 4 42A. 36A 80 0 Li .1 .271 1 27'i .5 42.4. '34.4 .' 78.0 8.0 1.249 1.249 4211 46 .1 , 76.0' '-' 0 L.231, A.217- - 7 42.1 : 34.1 . 76.0 . 1,229' 1.217 3' 42.4' ' 34,4 :78.0. . s.o. 1.249 1.249 9 42.1 321, . 76.0 10.0 ' 1235 1-.229 - 10 -' 42.0 : 74.0, '-. '8,0 . . 1.235 1.21. 11 42.4 . . 32.4 -: '-.78.0' . 10.0- 1.281 1290 • 12 . ' 42.0 . 32.0 . -: •74.(>' 10.0. . 1.229 1.210 1:3 . 42.0. .36.0 ,. - -74.0 .. .6.0 1.247 1.22 7S.0 1 2:7 1 2:1 F S MIN1MUM= 1 229 FOR THE CIRCLE OF CENTER :76. 1) S. I)) STA8RG S S • , •5•: • .5 . .5 5 S • American •Engineering Laboratories SLOPE STABILITY ANALYSIS STAF3RG • • • PORTIONS (C). COPYRIGHT. 1984 GEOSOFT . ALL RIGHTS RESERVED* **c1( X* *4 P.ALOMAF: AIRPORT ROAD 15:1 . . . . . S • CONTROL DA TA NUMBER' OF SPECIFIED CENTERS •. 0 . . . : NUMBER OF DEPTH LIMITING TANGENTS: .' • .. NUMBER OF: VERTICAL SECTIONS .• ' .• NUMBER OF SOIL LAYER BOUNDARIES NUMBEROFF'OREPRESSURELINE.S . 0 • • . • NUMBER OF POINTS DEFINING COHESION PROFILE 0 • • SEI Sill IC COEFFICIENT I, S2 SEARCH STARTS .AT CENTER 6.0),WITH FINAL GRID OF 2.0 ALL CIRCLES PASS THROUGH THE POINT C 73.0 420) •. . .. S GEOMETRY S .. • . S • • •' •. . SECTIONS 2.0 2.0. .4,() 4.0 7.0 90.(1 • . S • • a T CkACS 2 C) 15 13.(-). t) 42 L) 42 ) W IN CRACK 200 iso • 18t:) • 33.0 . 42.0 42;0 • • . BOUNDARY ) ) 18 13.0 t) 42 42 BOUNDARY 2 31.).: 25.0 290 33.0 42.0 42.0 • . S BOLINDARY 3:50.0 50.0. 50.01 500 .so.o 50,0 • • : SOIL PROPERTIES • •. LAYER • • S COHESION FRICTION ANGLE • DENSITY . . • I .. • 420,0 • •3(,3 • 135,( • S • 2 2n C) : 125 NUMBER TANGENT RADIUS (X) CENTER ' ('/) .CENTER 'FS(8ISHOP) .FS(OMS) 42 1 36.1 7} t 6. 0'1 442 1.394 2 42.0 :300 ' 74,0 ,. 6.0 .' ' 1.460 1.447 3. 42.; '30.1 Z70. i 10 () 1.442' 1 4 427,' 36.7 66.0. .5'. . 6.0 . 1.517 1.444 S '42.1' z4011 ' .. 700 ' 2.0,. 1.459 1.416. • '6 .42.0'' "36.0 '' 72.0 . 6.0 • 7 ' 42 ' .6.0 , , 74.0 , 6.0: ' 1.460 ' ' 1.447 8 42.0 72 t 8.0 1 444 1.419 .9'• 42.0 . 38.0 . '' 72..0 . . . S 4.0 ' 1.438 1.407 It) 42 & 38 O 74 t 4 OP. 1,449 1.430 11 .'' 42.1 .. WE 70.0 .,'. 4.0 .. 1.449 1.406' ' 12 42,0 ''40:0' . 7o '. 2.0 ' . 1.442 ,. 1.410 42.0 - Z4.0:1,, 74.0 0 .1.460- 1.447 . 14. . 42,1' 36.1 . '7c.0. • 6.0 ' ' 1.442 '1.399 15 '. 42.1-.' 40.1 . • 7>( ' . 2 0 1.459 1,416' 42o V74.o 20 1445 142' ' S MINIMU1= 1 48 FOR THE CIRCLE OF CENTER ( -421 0''; 4 )) * * ** * ** * 40K S