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1 UNCLASSIFIEDAD NUMBERLIMITATION CHANGESTO:FROM:AUTHORITYTHIS PAGE IS UNCLASSIFIEDADB080279 Approved for public release; distribution authorized to Gov't. agenciesonly; Administrative/Operational Use; 05 MAR1984. Other requests shall be referred to NavalCivil Engineering Lab., Port Hueneme, CA ltr dtd 30 Jan 1986 REPfiOOUCrU A* ,,UVt !U"i!-f i frX.'tNbr ML 1 D MZ2. AUTHORITY:.. T^#^l^v hU,f* i:^-^;?V^^ \H SM -NS TNNO: N-1688 P TITLE: DESIGN GUIDE FOR DRAG EMBEDMENT ANCHORS 8 Oi 1 I> <M [S O R 00 fe o 03 * ITUAD- R- Taylor, NCEL and MU nun. p valent, Brian Watt & Associates DATE: January- 1984 SPONSOR: Naval Sea Systems Command ^.]

2 MAR 5 1984 H- u PROGRAM NO: 42-040 NAVAL CIVIL ENGINEERING laboratory PORT HUENEME, CALIFORNIA 93043 5 MAR 384 This publication is required < * fur administrative or operational fmm only. Distribution is limited to Government agencies. Ouier requests must be referred to the Naval Civil Knguieciing laboratory . Port Hucnemc, CA 9J04J. OTIC FILE COPY 84 0 3 O08 I 3 I .a E I .l. *?1 _ r e. tfl* "O "- 5= 5 & S> > o o ri ~ 6 JE srsrsrs - CM ID d -d oi 5 C II o o = A A S3 8 <l c 8 fc ONi- UJ ON- 9- * 3 -1 2 O > 5 O *- CN O CN *-* to ^ II i E Is Is > 0) w ill! 'tti (Q I! IS ill z o a i !

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4 ! If * 5 S f &. c S - 2 n - t a, .. -w -. v -. -. >! Is1 UNCLASSIFIED SECURITY CLASSIFICATION OF TMIS PAGE 'When Pmtm Fntned) REPORT DOCUMENTATION PAGE 1 REPORT NUMBFR TN-1688 2 GOVT ACCESSION NO 4. TITLE f-nd Submit) DESIGN GUIDE FOR DRAG EMBEDMENT ANCHORS 7 AUTHORC , R. Taylor, NCEL and P. Valent, Brian Watt & Associates 9 PERFORMING ORGANIZATION NAME AND ADDRESS NAVAL CIVIL ENGINEERING laboratory Port Hueneme, California 93043 t CONTROLLING OFFICE NAME ANO ADORESS Naval Sea Systems Command Washington, DC 20362 14 MONITORING AGENCY NAME AOORESSdf Ji rr nl (mm Conlr.>//m Othrr) READ INSTRUCTIONS BEFORE COMPLETING FORM 3 RECIPIENT'S C*T*LOG NUMBER <7C) U 4 TYPE Of REPORT & PERIOD COVERED Final; Sep 1982 - Sep 1983 6 PERFORMING ORG REPORT NUMBER 8 CONTRACT OR GRANT NUMBE flri) to PROGRAM ELEMENT PROJECT TASK AREA A WORK UNIT NUM9 ERS 62543N; 42-040 12 REPORT DATE January 1984 13 NUMRER OF PAGES 71 '5 SECURITY CL ASS (ol th,t rmport) UNCLASSIFIED 'S DECL ASSiFiCATION DOWNGRADING SCHEDULE I DISTRIBUTION STATEMENT fo( rhi, 5 MAR 1984 This publication is required fevMMMHt for administrative or operational ^ only.

5 Distribution is limited to Government agencies. Other requests must be referred to the Naval Civil Engineering laboratory , Port Hueneme, CA 93043. T DISTRIBUTION STATEMENT (ol Iht mbalrsrt inlrnd tm Bl^ck 10. >t ditlrtmni horn Hiporl) SUPPLEMENTARY NOTES H EY 0 OSi nd pJfnM. 6v blor mtmbr Anchors, moorings, holding capacity, seafloor soils -.* .IT! - . us a. J* It I mry wiJ iitrnnty ft b!>,- * < This design guide provides an overview to the selection and sizing of drag embedment anchors and mooring chains and to the diagnosis and solution of typical drag anchor per- formance problems. The site information required for anchor type selection is outlined.

6 Two options for sizing the drag anchor arc offered. The more exacting of these options includes a method for determining the moo'Hg load resistance developed by that length of mooring chain embedded in and sliding on cc csivc seafloor soils. Example problems for anchor continued 00 , j N I) H?3 EOlTiONOf ' NOV S IS OBSOLET UNCLASSIFIED SECURITY CL ASSlFlC AT,ON OF THI: PAOf W>**l> /'*! - %- % > * -w ."- UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGEOU ! > < Enimrmd) 20. Continued system design on cohesionless and cohesive seafloors are provided. The last section outlines drag anchor performance problems and provides possible solutions.

7 More detailed information can be found in the references. D i *-\ .>.iv..1 r\- .1 lou/ .:'v;.Hy Cede 'Av.'t ' i -no / - < 0, Library Card Naval Civil Engineering laboratory DESIGN GUIDE FOR DRAG EMBEDMENT ANCHORS (Final), by R. Taylor. NCEL and P. Valent. Brian Watt & Associates TN-1688 71 pp illut January 1984 UNCLASSIFIED 1. Anchors 2. Holding capacity 42040 This design guide provides an overview to the selection and sizing of drag emlicdment anchors and mooring chains and to the diagnosis and solution of typical drag anchor performance problems. The site information required for anchor type selection is outlined.

8 Two options for sizing the drag anchor are offered. The more exacting of tiiesc options includes a method for determining the mooring load resistance developed by that length of mooring chain embedded in and sliding on cohesive seafloor soils. Example problems for anchor system design on cohesionless and cohesive seafloors are provided. The last section outlines drag anchor performance problems and provides possible solutions. More detailed information can be found in the references. UNCLASSIFIED SCCUS'TY *lOWOF T liP4i|' ,n[', v" PREFACE m The Naval Civil Engineering laboratory (NCEL) was tasked to improve the Navy's capability to select and design drag embedment anchors.]

9 Beginning in 1979, NCEL has conducted a 3-year anchor test program, sponsored by the Naval Facilities Engineering Command (NAVFAC) and Naval Sea Systems Command (NAVSEA), to accurately describe drag embedment anchor behavior. Data from this test program were used to develop and validate procedures to predict anchor holding capacity as a function of seafloor type and engineering properties. Preparation of this design guide was sponsored by NAVSEA. The guide is structured to be used by the novice as well as those experienced in ocean operations or mooring design. This design guide provides an overview to the selection and sizing of drag embedment anchors and mooring chains and to the diagnosis and solution of typical drag anchor performance problems.

10 The site information required for anchor type selection is outlined. Two options for sizing the drag anchor are offered. The more exacting of these options includes a method for determining ^he mooring load resistance developed by that length of mooring chain embedded in and sliding on cohesive seafloor soils. Tables or charts within this guide can be used independently for routine anchor selection and cost estimating purposes, and they can be used within the structured (flow-charted) format provided to determine detailed anchor system performance. Depending on the design option selected, this includes anchor drag distance, embedment depth, holding capacity, anchor chain capacity, and characteristics of the mooring chain system.