Quang Minh TN

Trng H M a cht

n tt nghip nghnh a cht cng trnh

M UVi s tng trng kinh t mnh m hin nay, vic pht trin c s h tng l mt vn cp thit, c bit l cc thnh ph ln th vic xy dng c s h tng cng tr nn cp bch. H Ni l mt trong nhng thnh ph ng u trong c nc v tc pht trin kinh t v thu ht nhiu lao ng khp mi ni v lm vic. Cng vi s pht trin v kinh t l vic xy dng cc c s h tng, cc khu th, cc khu nh ti nh c cho nhn dn n nh i sng. H Ni cn l ni du lch rt th v thu ht rt nhiu khch du lch trong nc v khch quc t. Nhm mc ch cho sinh vin trc khi ra trng c trang b v hiu bit v ngh nghip, chng ti c trng i hc M a Cht khoa a Cht, B mn a Cht Cng Trnh cho php i thc tp tt nghip v lm n. Trong thi gian thc tp ti c khoa a cht, B mn a cht cng trnh phn cng thc tp ti cng ty c phn t vn thit k khao sat va xy dng THT. Ti c trc tip tham gia vo cng vic kho st CCT ngoi hin trng v cng tc th nghim trong phng. Vi nhng ti liu thu thp c trong qu trnh thc tp, ti c c gio Th.S Nguyn Th Hin v B mn a cht cng trnh giao cho n tt nghip vi ti: nh gi iu kin a cht cng trnh Tr s cc tn s v tuyn in 115 Trn Duy Hng, Cu Giy,H Ni giai on thit k c s. Thit k kho st a cht cng trnh cho cc hng mc ca tr s trn giai on thit k k thut. Thi gian thi cng phng n 2 thng. Qua thi gian 03 thng , vi s n lc ca bn thn kt hp vi s hng dn tn tnh ca c gio Th.S Nguyn Th Hin cng cc thy c trong b mn a cht cng trnh (CCT), v cc anh ch trong Cng ty C phn t

Sinh vin: Phm Quang Minh _KT_K51

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Trng H M a cht


vn thit k khao sat xy dng THT, gip ti hon thnh n ng thi hn vi ni dung nh sau: M u Phn I: Phn chung v chuyn mn; Chng I: c im a l t nhin khu vc nghin cu. Chng II: c im trm tch t H Ni. Chng III: nh gi iu kin a cht cng trnh khu vc xy dng. Chng IV: Cc vn a cht cng trnh. Phn II: Phn thit k v t chc thi cng; Chng I: Thit k cc phng n kho st a cht cng trnh; Chng II: T chc sn xut v d ton chi ph kho st. Ngoi ra cn c cc ph lc km theo: - Bn trm tch t vng H Ni t l 1/50.000; - Mt ct a cht cng trnh; - Bng tng hp ch tiu c l cc lp t ; - S b tr h khoan cng trnh kho st CCT. Tuy nhin do kin thc ca bn thn cn hn ch v thiu kinh nghim thc t nn khng th trnh khi nhng sai st trong khi lm n. Ti rt mong c s nhn xt, gp v nh gi ca cc thy c gio trong b mn cng nh cc bn ng nghip. Ti xin chn thnh cm n! Sinh vin

Phm Quang Minh


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Lp: CCT

Trng H M a cht


PHN MT

PHN CHUNG V CHUYN MN


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CHNG 1

C IM A L T NHIN KHU VC NGHIN CU1.1. V tr a l H Ni l th ca nc Cng ho x hi ch ngha Vit Nam, l trung tm vn ho, kinh t ca c nc. H Ni nm trung tm ng bng Bc B, c to a l nh sau: T 20053 n 21023 v Bc; T 105044 n 106002 kinh ng; H Ni c din tch 3.324,92km 2 v tip gip vi cc tnh nh: Pha Bc gip tnh Thi Nguyn, Vnh Phc; Pha Nam gip tnh H Nam, Ha Bnh; Pha ng gip vi Bc Giang, Bc Ninh v Hng Yn; Pha Ty gip vi Ha Bnh, Ph Th. V mt hnh chnh, H Ni gm 10 qun ni thnh: Ba nh, Cu Giy, ng a, H ng, Thanh Xun, Hon Kim, Ty H, Hai B Trng, Hong Mai, Long Bin v 18 huyn ngoi thnh: Ba V, Chng M, an Phng, ng Anh, Gia Lm, Hoi c, M Linh, M c, Ph Xuyn, Ph Th, Quc Oai, Sc Sn, Thch Tht, Thanh Oai, Thanh Tr, Thng Tn, T Lim, ng Ha v th x Sn Ty. 1.2. Dn c Sau t m rng a gii gn y nht vo thng 10 nm 2010, thnh ph H Ni c 6,913 triu dn v nm trong 17 th c din tch ln nht th gii. Theo thng k th dn s H Ni phn b khng u, ch yu tp trung cc qun ni thnh, cc huyn ngoi thnh th mt dn s thp hn. Dn c thnh ph H Ni ch yu l ngi Kinh, mt s l ngi Sn Du, Dao, Mng, Ty. 1.3. Kinh t Sinh vin: Phm Quang Minh _KT_K514

Lp: CCT

Trng H M a cht


H Ni l trung tm vn ho, chnh tr ca c nc. Nh chnh sch m ca, giao lu thng mi ca ng v Nh nc nn nn kinh t ca thnh ph my nm gn y pht trin mnh v tng i ng u. S pht trin v kinh t em li nhiu thay i cho b mt thnh ph. Cng vi s pht trin ca nn kinh t, nhu cu ca ngi dn tng, y mnh qu trnh th ho, ko theo mt s ngnh nh xy dng v dch v pht trin theo. Ngoi ra H Ni cng ang thu ht c rt nhiu nh u t nc ngoi xy dng c s sn xut ti H Ni. 1.4. Giao thng L thnh ph th v c v tr khu vc trung tm ca min Bc, bn cnh con sng Hng, giao thng t H Ni n cc tnh khc ca Vit Nam tng i thun tin, bao gm c ng khng, ng b, ng thy v ng st. Giao thng ng khng, ngoi sn bay quc t Ni Bi cch trung tm khong 35 km, thnh ph cn c sn bay Gia Lm pha ng, thuc qun Long Bin. Tng l sn bay chnh ca H Ni nhng nm 1970, hin sn bay Gia Lm ch phc v cho cc chuyn bay dch v ca trc thng, gm c dch v du lch. H Ni l u mi giao thng ca nm tuyn ng st trong nc v mt tuyn lin vn sang Bc Kinh, Trung Quc, i nhiu nc chu u. Cc bn xe Pha Nam, Gia Lm, Lng Yn, Nc Ngm, M nh l ni cc xe ch khch lin tnh ta i khp quc gia theo cc quc l 1A xuyn Bc Nam, quc l 2 i Vnh Phc, Ph Th, Tuyn Quang, H Giang, quc l 3 i Thi Nguyn, Cao Bng, quc l 5A i Hi Phng, Qung Ninh, quc l 6 i Ha Bnh, Sn La, Lai Chu, quc l 32 i Ph Th... Giao thng ng thy, H Ni cng l u mi giao thng quan trng vi bn Ph en i Hng Yn, Nam nh, Thi Bnh, Vit Tr v bn Hm T Quan i Ph Li. 1.5. c im a hnh


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a hnh H Ni thp dn theo hng t Bc xung Nam v t Ty sang ng vi cao trung bnh t 5-20m so vi mc nc bin. Nh ph sa bi p, ba phn t din tch t nhin ca H Ni l ng bng, nm hu ngn sng , hai bn sng Hng v chi lu cc con sng khc. Phn din tch i ni phn ln thuc cc huyn Sc Sn, Ba V, Quc Oai, M c vi cc nh nh Ba V cao 1.281m, Gia D 707m, Chn Chim 462m, Thanh Lanh 427m, Thin Tr 378mKhu vc ni thnh c mt s g i thp, nh g ng a, ni Nng. 1.6. Sng ngi H Ni c mt mng li sng ngi phc tp, cc con sng an xen, to nn nt c trng cho mng li thy vn ni y so vi cc khu vc khc. Do tnh phc tp ca mng li thy vn ko theo nhng c trng kh ni bt i vi iu kin a cht thy vn. C th k n mt s con sng cng cc h ni bt l: 1.6.1. Sng Hng Sng Hng l sng ln th hai Vit Nam chy t Vn Nam Trung Quc vo Vit Nam Lo Cai v chy qua H Ni. on qua H Ni c s trc din dc nh t 0,02 n 0,05m/km. Hng nm sng Hng mang mt lng ph sa rt ln ra bin, trung bnh l 96,46.106T/nm. 1.6.2. Sng ung Sng ung nm pha thnh ph H Ni, l sng phn l chnh ca sng Hng (22,8%), n ni vi h thng sng Thi Bnh v chy ra bin. 1.6.3. Sng Nhu Sng Nhu nm pha Ty thnh ph, l mt nhnh ca sng Hng. Sng chy qua huyn T Lim, c ni sng l ranh gii t nhin gia H Ni v H Ty. Lu lng dng chy ma kh ca sng t 4,088m 3 n 17,442m3. Thu ch ca sng c iu tit bng cng Thy Phng phc v ti tiu cho nng nghip. Sinh vin: Phm Quang Minh _KT_K516

Lp: CCT

Trng H M a cht


1.6.4. Sng T Lch Bt ngun t ni thnh (ph c) v n Thanh Tr nhp vo sng Nhu, l sng c o vt li lm h thng tiu thot nc ca Thnh ph. Lu lng ma kh t 2,339m 3 n 4,143m3. y l h thng tiu nc thi t nhin ca thnh ph. 1.6.5. Sng y Sng y c chiu di khong 240km v lu vc (cng vi ph lu sng Nhu) hn 7500Km 2 trn a bn cc tnh thnh H Ni, Ha Bnh, H Nam, Ninh Bnh v Nam nh. L mt phn lu ca sng Hng, sng y nhn nc ca sng Hng a phn H Ni gia huyn Phc Th v huyn an Phng. Qung sng ny c tn l sng Ht hay Ht Giang. Ch sng Hng tip nc l Ht Mn. Lu lng ca sng bt thng nn ma ma th l qut li thm dng sng quanh co un khc nn d to ra nhng ghnh nc ln. n ma kh th lng sng c ch cn kh. 1.6.6. Sng C L Sng C L (cn gi l sng Ph L) l mt chi lu ca sng Cu v tng l phn lu ca sng Hng. N vn tch ra khi sng Hng x Trung H, huyn Yn Lc, Vnh Phc v hp lu vi sng Cu ti ng ba Xa, x Tam Giang, huyn Yn Phong, tnh Bc Ninh, cch khng xa ch sng Cng hp lu vi sng Cu. u ngun sng C L hin nay l huyn M Linh (H Ni) v ngun nc ca sng ch yu t cc dng sui t dy ni Tam o. Sng C L to thnh ranh gii t nhin gia huyn Sc Sn vi huyn M Linh v gia huyn Sc Sn vi huyn Yn Phong. Ton chiu di ca sng l 89km, trong on trn a bn Vnh Phc di 27km. 1.6.7. Sng Kim Ngu Sng Kim Ngu l mt phn khc ca sng T Lch, gi ch c tc dng l sng thot nc cho ni thnh H Ni. 1.6.8. Sng Tch Sinh vin: Phm Quang Minh _KT_K517

Lp: CCT

Trng H M a cht


Sng Tch hay cn gi l sng Tch Giang l ph lu cp I ca sng y, thuc h thng sng Hng, bt ngun t dy ni Ba V, u ngun l cc h Sui Hai, ng M. Sng Tch chy theo hng Ty Bc - ng Nam, bn b phi l sng Hng, qua cc huyn Ba V, Sn Ty, Thch Tht, Quc Oai, Chng M v M c. 1.6.9. H Ty Nm pha Bc thnh ph H Ni rng 539ha, chu vi h trn 12km, n l h mng nga ca sng Hng. ng thi ca H Ty ph thuc vo ng thi ca sng Hng, tuy c ngn bi h thng nhng vn c quan h thu lc vi sng Hng, h y nc quanh nm. 1.6.10. H By Mu Nm pha ng Bc thnh ph H Ni, rng 4 ha v l h ln th hai sau H Ty. H quanh nm y nc. 1.7. Kh hu Kh hu H Ni tiu biu cho vng Bc B vi c im ca kh hu nhit i gi ma, ma h nng, ma nhiu v ma ng lnh, t ma. Thuc vng nhit i, khu vc quanh nm tip nhn lng bc x Mt Tri rt di do v c nhit cao. V do tc ng ca bin, H Ni c m v lng ma kh ln. Mt c im r nt ca kh hu H Ni l s thay i v khc bit ca hai ma nng, lnh. Ma nng ko di t thng 5 n thng 9, km theo ma nhiu, nhit trung bnh 29,20C. T thng 11 ti thng 3 nm sau l kh hu ca ma ng vi nhit trung bnh 15.2 0C. Cng vi hai thi k chuyn tip vo thng 4 v thng 10, khu vc c bn ma xun, h, thu, ng. 1.7.1. Nhit Nhit trung bnh hng nm kh cao t 13oC n 23,5oC. Nhit cao nht vo t thng 5 n thng 7 v thp nht vo thng 1. - Nhit thp nht trong nm: 2,7oC; Sinh vin: Phm Quang Minh _KT_K518

Lp: CCT

Trng H M a cht


- Nhit cao nht trong nm: 38oC; - Nhit trung bnh c nm: 23,4oC. Lng ma cao nht trong nm tp trung trong cc thng 7, 8, 9, s ngy ma trung bnh hng nm l 140 ngy, vo ma lnh (ma kh) thng c ma nh v ma phn, ma nng (ma ma) c khi c ma lin tc trong na thng. - Lng ma cao nht: 2000 mm; - Lng ma ti thiu: 1500 mm; - Lng ma trung bnh trong nm: 1670 mm. 1.7.2. m tng i - m cao nht: 88%; - m thp nht: 80%; - m trung bnh: 84,5%. 1.7.3. Lng bc hi Lng bc hi trung bnh trong nm l 722 mm/nm. 1.7.4. Gi H Ni chu nh hng ca khu vc gi ma r rt, c hai hng gi chnh l: - Gi ma h: Ch yu l gi ng Nam t thng 4 n thng 10. - Gi ma ng: Ch yu l gi ng Bc t thng 11 n thng 3 nm sau. Tc gi c trm kh tng Long Bin thng k nh sau:

Thng Tc mnh nht Trung bnh

1 12 3.3

2 11 3

3 12 3.3

4 14 3.1

5 10 3.2

6 16 3.2

7 14 3.0

8 12 2

9 14 2.5

10 16 2

11 10 2

12 16 2.8


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CHNG 2 C IM TRM TCH T, A CHT THY VN V CC HIN TNG A CHT T NHIN VNG H NI 2.1. c im trm tch T Theo bn trm tch T vng H Ni t l 1/50.000 ca on a cht H Ni cng b nm 1989 th trm tch T chim din tch khong 800 km2, c ngun gc khc nhau, c hnh thnh t Pleistoxen. T cc kt qu x l, tng hp cc kt qu phn tch v thnh phn vt cht, c sinh, ho l mi trng, a vt l (karota l khoan) cho php phn chia cc phn v a tng trm tch T vng H Ni theo th t m t t di ln trn nh sau: 2.1.1. H tng L Chi (aQ1 lc) Trm tch tng L Chi khng l ra trn b mt m b trm tch tr hn ph ln trn, ch quan st thy trong cc l khoan c su t 45m n 69m thuc cc tuyn mt ct qua ni thnh. Chiu dy tng bin i t 2,5m n 24,5m. Da vo cc ti liu karota, thch hc, a tng ngi ta cho rng c s phn nhp tng i u n t ht th n ht mn, n th hin r nt chu k tch t aluvi. Theo thnh phn thch hc, c sinh trm tch tng L Chi c chia thnh 3 tp v mt tp khng phn chia adQ gm tch t sn tch v bi tch theo th t t di ln trn nh sau: Tp khng phn chia adQ: - Tch t bi tch: gm ct, bt, st ln t dm laterit, sn thch anh mu vng, nu, xm nu. - Tch t sn tch l tch: gm tng, cui, dm, si, sn, ct, bt, st ln ln, mu gch nu. Tp 1 (di): gm cui, si, ct, bt, st mu xm, xm nu. Cui ch yu l thch anh, silic, t cui l vi, kch thc cui t 2 3cm, t cui Sinh vin: Phm Quang Minh 10 _KT_K51 Lp: CCT

Trng H M a cht


kch thc t 3 5cm. mi mn tt v rt tt. B dy tp khong 10m, nm ngay trn tng trm tch Vnh Bo (N2vb). Tp 2 (gia): thnh phn gm ct ht nh, ct bt mu xm, xm vng. Thnh phn khong kh n gin: Thch anh chim 90 97%, cn li l cc khong vt khc. mi mn v chn lc ca trm tch tt. Chiu dy tp ny khong 3,5 n 10m. Tp 3 (trn): gm bt, st, ct mu xm vng, xm en, mi mn v chn lc km. Trong tp ny i ch c ln t bn thc vt, thm ch c c thc vt cha phn hu ht. Tp ny c chiu dy khong 0,2 n 4,5m. Nhn chung tng L Chi ch quan st thy trong cc l khoan vng ng bng H Ni. S thnh to ca n c lin quan n qu trnh bc mn, xm thc v ra tri. 2.1.2. H tng H Ni (aQ1-21hn) Tng ny ch gp pha ng Nam thnh ph, c nguc gc tch t sng, sng l hn hp v gp trong hai dng mt ct khc nhau l mt ct cc vng ph v mt ct cc vng l. Trong vng nghin cu ch gp mt ct vng ph, mt ct ny gp hu ht trong cc l khoan ven ra thnh ph, su t 33,5 n 69,5m. Theo th t t di ln, mt ct vng ph c chia ra lm 3 tp nh sau: Tp 1 (di): gm cui ln tng (kch thc t 7 10cm, c ni t 15cm), si sn v rt t bt xen k, mi mn t km n trung bnh, chn lc tt. B dy tp t 10 34m, y l i tng cha nc phong ph v c cht lng tt cho sinh hot v cng nghip. Tp 2 (gia): gm si, sn, ct ht th, ct bt mu xm vng, xm nu, ch yu l thch anh v mt t silic, fensfat, c mt vi khong cht nng. mi mn v chn lc tt, b dy tp khong 10m. Tp 3 (trn): gm bt st c mu nu, xm vng, xm en cha mn thc vt, chiu dy tp ny khong 4m, c tui Pleistoxen mun. Sinh vin: Phm Quang Minh 11 _KT_K51 Lp: CCT

Trng H M a cht


Tng chiu dy tng H Ni vng ph khong 35 50m. 2.1.3. H tng Vnh Phc (aQ22 vp) Trm tch tng Vnh Phc l ra trn din rng, trong vng nghin cu l ra mt s ni nh C Nhu, Xun nh. B mt ca tng ny nm cao tuyt i ln hn 10m. Nt c trng ca tng ny l trn b mt c hin tng laterit ho yu, c mu sc loang l d nhn bit. Tng Vnh Phc c s chuyn i nhanh v thnh phn ht theo khng gian t st, st ln bi chuyn thnh bi ct. Tt c cc thnh phn t th n mn khi l ra trn mt u b phong ho loang l, c quan h bt chnh hp vi tng Hi Hng. Tng ny c chiu dy khong 61m. Qua phn tch mu t ngi ta thy tng ny c ngun gc lc a. Theo thnh phn thch hc tng Vnh Phc chia ra 4 tp t di ln trn gm c: Tp 1 (di): gm cui si nh, ct ln t st bt c mu xm vng. Thnh phn khong vt ch yu l thch anh (trn 90%), cn li l cc khong vt khc, cu to phn lp ng hng v phn cho, mi mn v chn lc trung bnh. Chiu dy ca tp ny khong 10m. Tp 2: thnh phn ct ln bt, ct vng, thnh thong c thu knh si nh, c mu xm vng, nu. Thnh phn khong vt ch yu l thch anh. mi mn v chn lc t trung bnh n tt. Chiu dy tp khong 33m. Tp 3: thnh phn gm st caolin mu xm trng, st bt mu xm vng (tch t dng h st). Chiu dy tp bin i t 2 10m. Tp 4 (trn): thnh phn st, bt st mu en, xm vng, c ngun gc tch t m ly. Hm lng st chim t 12,9 n 45%. Mt s ni gp nhiu thu knh si nh. Khong vt st l hydromica v kaolinit. Chiu dy tp bin i t 3 5m. 2.1.4. H tng Hi Hng (Q21-2 hh)

Sinh vin: Phm Quang Minh 12 _KT_K51

Lp: CCT

Trng H M a cht


Trm tch tng Hi Hng gm: trm tch h - m ly (lbQ 21-2 hh1), trm tch bin (mQ21-2 hh2). Trm tch h (lQ21-2 hh2), trm tch m ly (bQ21-2 hh3). Cc trm tch ca vng ny phn b ch yu pha Nam v ri rc mt s vng pha Bc thnh ph H Ni. Trm tch tng Hi Hng chia lm 3 ph tng: 2.1.4.1. Ph tng di (bQ21-2hh1): trm tch ny c thnh to vo thi k bin tin v phn b ch yu pha ng Nam thnh ph H Ni, c ngun gc h - m ly. Thnh phn ch yu l st, bt st cha hu c mu en, xm en. Nhiu ni phn trn ca trm tch l lp than bn dy t 1 2m. Cc trm tch ca ph tng phn b trc tip trn b mt bo mn, b phong ha loang l ca tng Vnh Phc. B dy ca ph tng bin i t 2 6m v n trn 20m. 2.1.4.2. Ph tng gia (mQ21-2hh2, lQ21-2hh2): trm tch ca ph tng ny gm hai ngun gc khc nhau: + Trm tch ngun gc bin: C thnh phn ch yu l st mn, st bt c mu xm xanh, xanh l, y c ln t mn thc vt. Khong vt ch yu l hydromica, montmorolit v clorit. Chiu dy trm tch khong 0,4 4m. + Trm tch ngun gc h: C thnh phn l st, bt st mu xm vng, xm xanh, y c t si nh v kt vn st. Cc trm tch ny thng phn b trn cc trm tch ph tng Hi Hng di. B dy ca trm tch bin i t 0,2 4m. Ph tng Hi Hng gia nhn chung b ph bi cc trm tch tng Thi Bnh v ph trn cc trm tch ph tng di Hi Hng, nhiu ni c ph trn cc trm tch tng Vnh Phc. 2.1.4.3. Ph tng trn (bQIV1-2hh3): Trm tch ph tng ny c ngun gc m ly sau bin tin v hu nh khng gp trong khu vc H Ni. Thnh phn gm trm tch than bn, st bt ln t ct mu en cha mn thc vt b bn ho. Mn thc vt cha phn hu ht c mu xm en, khi kh nh Sinh vin: Phm Quang Minh 13 _KT_K51 Lp: CCT

Trng H M a cht


xp. Chng t l ra, ch yu b ph bi cc bi tch ca h tng Thi Bnh, chiu dy khong 0,5 4m. 2.1.5. H tng Thi Bnh (aQIV3 tb) y l nhng trm tch tr nht c ngun gc bi tch sng, chng phn b hu ht trn ton b b mt ca vng nghin cu vi b dy n 30m v c chia lm 2 ph tng: 2.1.5.1. Ph tng di (aQIV3tb1): Trm tch ph tng ny c chia lm 4 tp gm c: Tp 1 (di): c thnh phn l cui si, ct ln t bt st mu nu nht, nm ph trn b mt bc mn ca trm tch tng Vnh Phc. Chiu dy tp thay i t 3 18m. Tp 2: c thnh phn l ct bt st ln mn thc vt, mu xm. B dy tp thay i t 1 3m. Tp 3: c thnh phn l bt st ln mn thc vt, mu xm. B dy tp thay i t 1 3m. Tp 4 (trn): c thnh phn gm bt st ln mn thc vt c mu xm nu (tch t t h - m ly). Chiu dy tp khong 1m v rt him gp trong khu vc. 2.1.5.2. Ph tng trn (aQIV3tb2): cc trm tch ny c ngun gc aluvi tr phn b trong khu vc ngoi . Chng l cc trm tch hin i tng bi bi, lng sng. Ph tng ny chia lm 2 tp gm c: Tp 1: c thnh phn l cui, si, ct ln t bt st mu xm vng. B dy tp thay i t 3 10m. Tp 2: thnh phn l bt st mu nu nht, cha c, hn, trai nc ngt v mn thc vt. Khong vt ch yu l kaolinit, hydromica v clorit. B dy tp thay i t 2 5m. 2.2. c im a cht thy vn


Lp: CCT

Trng H M a cht


Vi mc ch nghin cu phc v cho cng tc kho st a cht cng trnh (CCT), trong chng ny ch cp n phc h cha nc trm tch t. Da vo thnh phn thch hc, ngun gc thnh to, mc phc tp ca t , c im thy lc v mc cha nc c th chia ra thnh hai tng cha nc theo th t t di ln trn nh sau: 2.2.1. Tng cha nc Thi Bnh Trm tch tng Thi Bnh phn b hu nh ton b khu vc H Ni, nc di t phn ln cha trong ct pha, ct c ngun gc aluvi, y cch nc ca tng l st, st pha ca tng Vnh Phc. Nc c p lc khong 0,02 0,03 kG/cm2, h s thm K = 0,8 2,5 m/ng., lu lng nc o c trong cc h khoan khong 1,3 1,8 l/s. ng thi ca nc khng n nh, khng dao ng theo ma v theo ng thi ca nc sng Hng, chiu su mc nc n nh t 1,2 1,5m. c tnh ho hc ca nc kh tt, nc trong, khng mi v v khng p. Ngun cung cp ch yu l nc ma, nc mt. Thnh phn ho hc ca nc c biu din bng cng thc Cuc Lp nh sau: HCO 3 71Cl 28,5 M 0,4 CO 4,4 pH 7,2 (Na + K) 54 Ca 23 Mg 212

Tn nc: Bicacbonat Clorua Natri. cng tm thi: 6,5 mgl/l. cng vnh cu: 1,57 mgl/l. Hm lng CO2 n mn: 13,9 mg/l. Hm lng CO2 t do: 1,6 mg/l. 2.2.2. Tng cha nc h tng H Ni Tng cha nc ny c thnh phn ch yu l sn si, cui nh ln t ct mu xm vng, y l tng cha nc c p. Tng ny c h s thm kh


Lp: CCT

Trng H M a cht


cao, mt s ni K = 4 5m/ng., lu lng nc kh ln do c quan h trc tip vi nc sng Hng v sng T Lch. Loi hnh ho hc ca nc l sunfat natri canxi kali. Tng khong ho: M = 0,1 1 g/l. Nhit : T = 20 24oC. pH = 6 7. Thnh phn ho hc ca nc c biu din di dng cng thc Cuc Lp nh sau: HCO 3 53 Cl 42 o M 0,64 T23 C (Na + K) 65 Ca 30 Tn nc l: Bicacbonat Clorua Natri Canxi. Ngoi ra y cn l tng cha nc phong ph nht ang c khai thc phc v cho n ung, sinh hot ti H Ni. Nc trong, khng mi v, khng c tnh n mn btng. 2.3. Cc hin tng a cht t nhin 2.3.1. Vn ln do khai thc nc ngm Theo ti liu thu thp c th hng ngy cc nh my nc trn a bn H Ni khai thc khong 700.000 n 1.200.000 m3 nc ngm phc v cho sinh hot ca ton khu vc. Chnh v vy xy ra hin tng ln mt t vi tc kh nhanh. Trong tng lai lng nc ngm b khai thc c th s tng ln do hin tng ln mt t cng din ra nhanh chng. V vy khi thit k cc cng trnh phi ch n vn ny. 2.3.2. Hin tng ngp v bn ngp Sau nhng trn ma ln, nhiu ng ph H Ni b ngp ng. Vi nhng trn ma trn 100 mm/ngy, trn a bn H Ni c khong 70 80 a im b ngp, trong trn 20 a im b ngp nghim trng ko di t 2 gi n vi ngy, su ngp thay i t 20 30cm n 60 80cm.


Lp: CCT

Trng H M a cht


Cc vng thng b ngp ng trn a bn H Ni ri rc nhiu ni trong ni thnh, tp trung pha Nam thnh ph. Nguyn nhn gy ngp ng trn a bn H Ni bt ngun t iu kin t nhin, gn vi xu th ln gia tng khu vc ny. Song nguyn nhn ch yu l do tc ng t yu t con ngi, l vic xy dng nh ca thiu quy hoch hp l, cc cng trnh xy dng ln lp cc h thng ao h, trong khi h thng cng thot nc th cha ph hp v hp l. iu ny gp phn trc tip gy ra hin tng ngp ng trong thnh ph, c bit l trong nhng nm gn y khi nhp xy dng thnh ph gia tng. 2.3.3. Hin tng ng t Theo cc ti liu c cng b th trn khu vc H Ni c th xy ra ng t khong 6 Richter. y l mc kh nguy him cho cc cng trnh xy dng cao tng nn khi thit k cc to nh cao tng phi xem xt n cc nh hng ca ng t.


Lp: CCT

Trng H M a cht


CHNG 3 NH GI IU KIN A CHT CNG TRNH KHU VC XY DNG 3.1. iu kin a hnh, a mo Din tch kho st nm ta i 115 Tr n Duy Hng, C u Gi y, thnh ph H Ni, cng trnh nm gia khu dn c mt cao. Lin k vi n l cc cng trnh c xy dng vi quy m, kt cu ti trng khc nhau. Trn b mt din tch ny ti thi im kho st hi n ang v ng nha xe, sn tenis, nha cao t ng,nn vi c v n chuy n ma y khoan va o vi tri kha o sa t la r t kho khn, vi th c n pha i co bi n pha p gia i pho ng m t b ng tr c khi thi cng. a hnh khu v c xy d ng thu c loai ia hinh ng bng tich tu, nm trong ng bng sng Hng. M t b ng co c t cao trong khoa ng +5.98m n +6.85m. 3.2. c im a tng v tnh cht c l ca t Cn c theo cc ti liu thu thp c trong qu trnh khoan kho st ngoi hin trng, th nghim xuyn tiu chun (SPT) v kt qu phn tch th nghim cc ch tiu c l ca cc mu t trong phng th nghim, trong phm vi chiu su cc h khoan kho st th nn t trong khu vc d n c chia thnh 7 lp v c th tnh c sc chu ti quy c (R o) v mdun tng bin dng (Eo) nh sau: * Mun tng bin dng Eo. 1 + e0 m (kG/cm2) Eo c xc nh theo cng thc: E o = k a 1 2 Trong : eo l h s rng ban u. a1-2 l h s nn ln ng vi cp p lc trong khong P = 1 kG/cm2 v P = 2 kG/cm2. - l h s bin dng ngang, c ly nh sau: Sinh vin: Phm Quang Minh 18 _KT_K51 Lp: CCT

Trng H M a cht


= 0,8 i vi ct = 0,62 i vi st pha

= 0,74 i vi ct pha = 0,4 i vi st

mk l h s chuyn i mun tng bin dng trong phng sang mun tng bin dng bng phng php ti trng tnh ngoi hin trng. Vi t c trng thi t do chy n chy th m k = 1. t c trng thi t do mm n cng th mk c xc nh theo bng sau: mk ng vi e 0,65 0,75 3,5 3,0 4,5 4,0 6,5 6,0

Loi t Ct pha St pha St

0,45 4,0 -

0,55 4,0 5,0 -

0,85 2,0 3,0 5,5

0,95 2,5 5,0

1,05 2,0 4,5

* Sc chu ti quy c Ro. Ro c tnh theo cng thc sau: Ro = m.[( A.b + B.h). + c.D] Trong : m l h s in kin lm vic. Vi t yu bo ho nc ly m < 1, cn trong cc trng hp khc ly m = 1; A, B, D l cc h s c tra bng ph thuc vo , c; b l chiu rng mng quy c, ly bng 100 cm; h l chiu su mng quy c, ly bng 100 cm; c l lc dnh ca t di y mng ( kG/cm2 ); - l khi lng th tch t nhin ca t ( kG/cm3). i vi t ht th ta c th xc nh Eo, Ro bng cch tra theo tiu chun xy dng 45 78. T ta c th s b phn chia a tng v c cc ch tiu c l ca cc lp t nh sau: 3.2.1. Lp 1: Nn b tng, cat san, t lp Sinh vin: Phm Quang Minh 19 _KT_K51 Lp: CCT (kG/cm2)

Trng H M a cht


Lp nay phn b trn toan b khu vc khao sat, gp trong tt ca cac h khoan t trn mt n su t 2.2m(HK1 , HK4) n (HK2) . Chiu day thay i t 2.2m n 2.6m trung binh 2.3m Do thanh phn va trang thai khng ng nht nn khng ly mu t thi nghim lp nay. 3.2.2. Lp 2: Set mau xam nu, xam vang, trang thai deo cng y l lp st mau xam nu, xm vang, trng thi do cng. Lp ny gp trong hu ht trong cc h khoan. Chiu su gp mt lp, y lp v chiu dy lp bin i nh sau: Tn h HK1 HK2 HK4 su gp mt lp (m) 2.2 2.6 2.2 su gp y lp (m) 5.3 5.3 4.7 B dy ca lp (m) 3.1 2.7 2.5

T bng s liu trn cho thy, chiu su gp lp bin i t 2.5 n 3.1m. Chiu dy lp bin i khng ln, chiu dy nh nht l 2.5m (HK4), chiu dy ln nht l 3.1m (HK1). Chiu dy trung bnh khong 2.8m. Cc ch tiu c l ca lp t nh sau: STT 1 Cc ch tiu c l Thnh phn ht 10.0 5.0 5.0 2.0 2.0 1.0 1.0 0.5 0.5 0.25 0.25 0.1 0.1 0.05 0.05 0.01 0.01 K hiu P n v % Gi tr Xtb 0.2 0.1 0.6 1.1 1.7 6.7 19.2 17.0 7.3 XttII


Lp: CCT

Trng H M a cht


0.005 < 0.005

46.1

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

m t nhin Khi lng th tch t nhin Khi lng th tch kh Khi lng ring H s rng l rng bo ho m gii hn chy m gii hn do Ch s do st Gc ma st trong Lc dnh kt H s nn ln Sc chu ti quy c Mdul tng bin dng

W w c eo n G Wl Wp Ip Is C a1-2 Ro Eo

% g/cm3 g/cm3 g/cm3 % % % % % kG/cm2 cm2/kG kG/cm2 kG/cm2

29.5 1.91 1.48 2,73 0.847 45.9 95.0 40.3 21.8 18.5 0.42 11052 0.17 0,023 1.43 111

3.2.3. Lp 3: Cat hat nho xen kep cat pha mau xam nu, xam en, trang thai xp. y l lp cat hat nho xen kep cat pha mau xam nu, xam en, trang thai xp. Lp ny gp trong tt c cc h khoan kho st. Chiu su gp mt lp, y lp v chiu dy lp bin i nh sau: Tn h HK1 HK3 su gp mt lp (m) 5.3 5.1 su gp y lp (m) 16.3 8.3 B dy ca lp (m) 11.0 3.2 Lp: CCT


Trng H M a cht


HK4

4.7

11.2

6.5

T bng s liu trn ta thy chiu su gp lp bin i t 3.2 n 11.0m, chiu dy lp bin i kh mnh, chiu dy nh nht l 3.2m (HK3), chiu dy ln nht l 11.0m (HK1). Chiu dy trung bnh ca lp l 6.5m.

Ch s th nghim SPT v cc ch tiu c l ca lp t nh sau: TT 1 Ch tiu Thnh phn ht 5.0 2.0 2.0 1.0 1.0 0.5 0.5 0.25 0.25 0.1 0.1 0.05 0.05 0.01 0.01 0.005 K hiu P n v % Gi tr 0.3 1.4 5.3 33.5 48.1 8.2 1.7 0.5 Lp: CCT


Trng H M a cht


TT 2 3 4 5 6 7

Ch tiu < 0.005 T trng Gc ngh khi kh Gc ngh khi t Th nghim xuyn tiu chun Cng chu ti quy c Mun tng bin dng

K hiu c w SPT R0 E0

n v g/cm3 ba kG/cm2 kG/cm2

Gi tr 1.0 2.66 35022 23014 8 1.20 135

3.2.4. Lp 4: Ct hat nho mau xam nu, xam ghi, trang thai cht va y l lp ct pha mu xm vng, xm nu trng thi do v c ln ct ht mn, vng, xm vng. Lp ny gp trong tt c cc h khoan kho st. Chiu su gp mt lp, y lp v chiu dy lp bin i nh sau: Tn h HK1 HK3 HK4 su gp mt lp (m) 16.3 8.3 11.2 su gp y lp (m) 28.5 26.0 29.2 B dy ca lp (m) 12.2 17.7 18.0

T bng s liu trn cho thy, chiu su gp lp bin i t 12.2m n 18.0m. Chiu dy lp bin i trong phm vi nh, chiu dy nh nht l 12.2m (HK1), chiu dy ln nht l 18.0m (HK4). Chiu dy trung bnh ca lp l 15.8m.


Lp: CCT

Trng H M a cht


Ch s th nghim SPT v cc ch tiu c l ca lp t nh sau: TT 1 Ch tiu Thnh phn ht 5.0 2.0 2.0 1.0 1.0 0.5 0.5 0.25 0.25 0.1 0.1 0.05 0.05 0.01 0.01 0.005 < 0.005 T trng Gc ngh khi kh Gc ngh khi t Th nghim xuyn tiu chun Cng chu ti quy c Mun tng bin dng K hiu P n v % Gi tr 0.1 0.5 3.8 31.1 55.5 8.0 0.6 0.2 0.3 2.65 35013 23028 17 1.50 180

2 3 4 5 6 7

c w SPT R0 E0

g/cm3 ba kG/cm2 kG/cm2

3.2.5. Lp 5: Ct ht trung mau xam xanh, xam vang, trang thai cht vacht Sinh vin: Phm Quang Minh 24 _KT_K51 Lp: CCT

Trng H M a cht


y l lp ct hat trung mau xam xanh, xam vang, trang thai cht vacht. Lp ny gp hu ht trong cc h khoan. Chiu su gp mt lp, y lp v chiu dy ca lp bin i nh sau:

Tn h HK1 HK2 HK3

su gp mt lp (m) 28.5 28.3 26.0

su gp y lp (m) 42.9 43.3 41.7

B dy ca lp (m) 14.4 15.0 15.7

T bng s liu trn ta thy chiu dy ca lp bin i nh, chiu dy ln nht l 15.7m (HK3). Chiu dy trung bnh ca lp l 15.3m. Ch s th nghim SPT v cc ch tiu c l ca lp t nh sau: TT 1 Ch tiu Thnh phn ht 10.0 5.0 5.0 2.0 2.0 1.0 1.0 0.5 0.5 0.25 0.25 0.1 0.1 0.05 T trng Gc ngh khi kh Gc ngh khi t Th nghim xuyn tiu chun Cng chu ti quy c Mun tng bin dng K hiu P n v % Gi tr 0.1 0.2 0.6 4.4 68.5 22.4 3.9 2.65 37000 23027 30 2.50 350

2 3 4 5 6 7

c w SPT R0 E0


3.2.6. Lp 6: Cui ln soi cat xam trng, xam en trang thai rt cht. Sinh vin: Phm Quang Minh 25 _KT_K51 Lp: CCT

Trng H M a cht


y l lp cui ln soi cat xam trng, xam en trang thai rt cht. Lp ny cng gp trong tt c sc h khoan. Chiu su gp mt lp, y lp v chiu dy lp bin i nh sau: su gp mt lp (m) 42.9 43.3 41.7 su gp y lp (m) 70.3 70.6 B dy ca lp (m) 27.4 27.3

Tn h HK1 HK2 HK3

T bng s liu trn ta thy, chiu su gp lp bin i t 27.3m n 27.4m. Chiu dy ca lp bin i nh, chiu dy nh nht lm 27.3 (HK2), chiu dy ln nht l 27.4m (HK1,3). Chiu dy trung bnh ca lp l 27.3m. Trong lp ny cng tin hnh th nghim SPT trong cc h khoan, kt qu th nghim; Cc ch tiu c l ca lp t nh sau: TT 1 Ch tiu Thnh phn ht > 10.0 10.0 5.0 5.0 2.0 2.0 1.0 1.0 0.5 0.5 0.25 0.25 0.1 0.1 0.05 T trng Th nghim xuyn tiu chun Cng chu ti quy c Mun tng bin dng K hiu P n v % Gi tr 63.0 12.6 8.9 6.1 4.2 2.6 1.3 1.2 2.65 >100 5.00 >1000

2 3 4 5

SPT R0 E0


3.2.7. Lp 7: a cat bt kt mau xam xanh, xam ghi. Sinh vin: Phm Quang Minh 26 _KT_K51 Lp: CCT

Trng H M a cht


y l lp a cat bt kt mau xam xanh, xam ghi. Lp ny cng gp trong tt c sc h khoan. Chiu su gp mt lp, y lp v chiu dy lp bin i nh sau: su gp mt lp (m) 70.3 70.6 su gp y lp (m) 81.3 B dy ca lp (m) 11.0

Tn h HK1 HK2

Trong lp ny cng tin hnh th nghim SPT trong cc h khoan, kt qu th nghim nh sau: TT 1 2 3 4 Tn ch tiu Khi lng th tch T.N Khi lng ring Cng khng nn mt trc khi bo ha Cng khng nn mt trc khi kh 3.3. iu kin a cht thy vn Cn c vo a tng v qu trnh kho st cho thy .Khu vc tru s cuc v tuyn in co 2 tng cha nc. Mc nc th nht nm su 1.01.2m ,ch yu l nc ma v nc thi sinh hot. Mc nc th hai t su 16.4m n 17.6m din tch xy dng. Tng cha nc ny c mc nc tnh n nh su 17m ty theo ma ma hay ma kh v ch khai thc ca nh my nc ln cn. Ngoi tng cha nc ct cui si th cn c lp ct lp c kh nng tng tr v lu thng vi nc mt. Nc trong tng ny khng p. Mc nc trong tng ny cao hay thp bin i theo iu kin kh hu (ma ngm nc v nng bc hi). Tuy rng, nc trong ct lp c th chy vo cng trnh nhng mc khng ng k. Kt qu o Sinh vin: Phm Quang Minh 27 _KT_K51 Lp: CCT K hiu n s nbh nk Gi tr 2.71 2.73 2.73 2.75 92.0 231.0 102.0 255.0 n v g/cm3 g/cm3 kG/cm2 kG/cm2

Trng H M a cht


mc nc trong h khoan quan trc t trong tng ny cho thy mc nc n nh ti thi im kho st l 1m so vi ming h. Kt qu phn tch thnh phn ha hc ca nc cho thy nc khng c kh nng n mn b tng, hm lng cc nguyn t trong nc khng nh hng ti qu trnh dnh kt xi mng ca cc khoan nhi hay tng trong t. 3.4. Nhn xt Nn t c cu trc gm7 lp. T lp s 2 xung cc lp 7 b dy ln v tng i n nh. Theo chiu su phn b cc lp t c c trng khng ct v mdun bin dng cao nm di nhng lp c cc c trng khng ct v mdun bin dng thp. n su 42m (HK3) l lp cui si chiu dy ln c kh nng chu ti rt cao. Nn t c 2 tng cha nc. Tng ch a nc th nht nm su 1.2m,ch yu l nc ma v nc thi sinh hot khng giu tr lng nc nn khng nh hng ti qu trnh thi cng tng hm. Tng cha nc phong ph tr lng ln nm su di nn khng nh hng ti qu trnh thi cng tng hm. Tm li khu vc tru s cu c t n su t v tuy n i n c nn a cht tng i n nh, khng nh hng ti qu trnh thi cng xy dng.


Lp: CCT

Trng H M a cht


CHNG 4 CC VN A CHT CNG TRNH TRU S CUC TN S V TUYN IN- 115 TRN DUY HNG 4.1. Cc c trng ca cng trnh v nn 4.1.1. Cc c trng cng trnh Tr s cc tn s v tuyn in 115 Trn Duy Hng, C u Giy Ha Ni c d kin xy dng 40 tng vi chiu cao khong 135m. Ta nh c 1 tng hm t chiu su 4m so vi ct hin ti. Theo thit k s b din tch mt bng ca ta l ..m2, tng din tch sn xy dng ..m2. - Kin trc v kt cu To nh c kin trc tha mn cc chc nng ca cc phng chc nng, khu vui chi gii tr, cc phng ngh, ni xe v v. Do , kt cu cng trnh theo thit k s b l kt cu khung, sn kt hp li chu lc, vi yu cu tin cy ca cng trnh cp 2. - Ti trng cng trnh: T hp ti trng theo thit k s b thn cng trnh th cc h thng ct v li s chu cc lc tc dng khc nhau, trong kt cu li chu lc c ti trng theo cc phng ngang v thng ng l ln nht. Sau khi xem xt y cc thnh phn trong t hp ti trng vi tin cy ca cng trnh cp 2, ti trng cng trnh tc dng theo phng thng ng lm c s nh gi cc vn cng trnh c xc nh 2500 tn. 4.1.2. Cc c trng cu trc nn Trn c s kt qu nh gi iu kin a cht cng trnh khu vc xy dng tr s cc tn s v tuyn in 115 Trn Duy Hng cho thy nn t xy dng cng trnh ny c cu trc vi cc lp t m chiu day cc ch tiu c trng khng ct, bin dng, nh sau:


Lp: CCT

Trng H M a cht


Lp

Thnh phn lp

Trng thi

dy lp (m)

S SPT trung bnh Ntb

Lc dnh kt c (kg/c/ m2)

Mdun tng bin dng E0 kg/cm2

Sc chu ti quy c R0 kg/cm2

Gc ma st trong ( )

1

t lp St pha xm nu ,xm vng Ct pha Do cng

2.3

2

2.7

9

0.17

111

1.42

11052

3

xm nu,xm en Ct ht

Xp

6.5

8

135

1.20

4

nh xm nu,xm ghi Ct ht

Cht va

15.8

17

180

1.50

5

trung xm xanh,xm vn Ct ln

Cht va

15.3

30

350

2.5

6

si xm trng,xm en ct bt

Rt cht

27.3

>100

>1000

5.00

7

kt xm xanh,xm ghi

Rt cht

Vi c im kt cu, kin trc v cu trc nn s pht sinh cc vn a cht cng trnh khng ch lin quan n s n nh lu di ca cng trnh nh cc vn kh nng chu ti ca t nn, s n nh ln ca cng trnh, n nh y ni, thm ca tng hm m cn c c nhng vn pht sinh Sinh vin: Phm Quang Minh 30 _KT_K51 Lp: CCT

Trng H M a cht


ngay trong qu thi cng trnh nh vn nc chy vo h mng, vn n nh h o. Mc pht sinh cng nh tnh cht nguy hi ca cc vn a cht cng trnh y cn phi c xem xt theo cc gii php mng v cc bin php thi cng. 4.2. nh gi cc vn a cht cng trnh Vi ti trng tng i ln do gii php mng m tai trng cng trnh truyn xung lp cui si l gii php hp l nht. Vn t ra l bin php thi cng. Thi cng mng cc b tng c sn bng phng php p v cc khoan nhi b tng l 2 gii php c th p dng. Tuy nhin trong iu kin a hnh xy chen, di chuyn tp kt ca cc phng tin thi cng c gii nng siu trng siu trng vo khu vc ph xa l rt kh khn. Trong iu kin c 2 bin php thi cng mng cc thng thng u bc l nhng bt cp. Mt bin php kh thi c th khc phc nhng mt tn ti l bin php thi cng cc khoan nhi ng knh nh D600. y l loi mng gn y c s dng tng i ph bin trong cc khu th ng dn H Ni v Thnh ph H Ch Minh. Tuy nhin cc vn sc chiu ti v bin dng ln cng trnh ni chung cha c sng t bng nhng cc c ng knh ln. Do vy sng t cc vn ny cho din tch xy dng s nh gi theo cc kch thc khc nhau. 4.2.1.Cc thng s tnh ton ch tiu c l ca t Trong bng kt qu th nghim cc ch tiu c l ca cc lp t c trong ti liu mi ch l kt qu tnh c trc tip, ngoi ra cn mt s ch tiu c l cn c tnh ton ti phng th nghim, bao gm:

Khi lng th tch kh c:

c =

w (g/cm3) 1+ 0,01W

Trong : c: Khi lng th tch kh; (g/cm3) Sinh vin: Phm Quang Minh 31 _KT_K51

Lp: CCT

Trng H M a cht


w: Khi lng th tch ca t trng thi t nhin; (g/cm3) W: m t nhin ca t. H s l rng t nhin ca t e0: e0 = s 1 ; c Trong : s: Khi lng ring ca t; (g/cm3).

l rng ca t n:

n = 1

c ; sn: l rng.

Trong :

bo ha G:G= 0,01.W . s (%) ; e0

Ch s do IP :

IP = WL WP (%); Trong : WL: m gii hn chy; WP: m gii hn do. st B:B= W WP ; IP

M um tng bin dng ca t E0 (TCXD 45:78):

* i vi t dnh: - Mun tng bin dng Eo. 1 + e0 m Eo c xc nh theo cng thc: E o = k a 12 Trong : eo - l h s rng ban u. (I-1)


Lp: CCT

Trng H M a cht


a1-2 - l h s nn ln ng vi cp p lc trong khong P = 1 kG/cm 2 v P = 2 kG/cm2. - l h s bin dng ngang, c ly nh sau: Bng 4.1: Bng tra h s Tn t Ct 0,8 Ct pha 0,74 St pha 0,62 St 0,4

mk - l h s chuyn i mun tng bin dng trong phng sang mun tng bin dng bng phng php ti trng tnh ngoi hin trng. Vi t c trng thi t do chy n chy th m k =1. t c trng thi t do mm n cng th mk c xc nh theo bng sau: Bng 4.2: Bng tra gi tr mk Tn t Gi tr ca mk ng vi ga tr h s rng e eo 0,45 0,55 0,65 0,75 0,85 0,95 1,05 Ct pha 4,0 4,0 3,5 2,0 2,0 St pha 5,0 5,0 4,5 4,0 3,0 2,5 2,0 St 6,0 6,0 5,5 5,5 4,5 * i vi t ri: - M un tng bin dng (E0) c tnh theo cng thc ca T.P. Tassios, A.G. Anagnostoponlos: E0 = a + C*(N30 + 6) (I-2) Trong : N30 - Gi tr xuyn tiu chun; H s a = 40 khi N > 15 v a = 0 khi N < 15. C - H s ph thuc vo loi t tra bng. Bng 4-3: Bng tra gi tr C t loi Ct ln si Sn si Loi t Ct mn Ct va Ct to st sn ln ct H s C 3 3,5 4,5 7 10 12 *Gc ma st trong c tnh theo cng thc: = 12 * N +15 () Ro c tnh theo cng thc sau: Sinh vin: Phm Quang Minh 33 _KT_K51 Lp: CCT (I-3)

p lc tnh ton quy c ca lp t R0 (TCXD 45:78):

Trng H M a cht


Ro = m*[( A*b + B*h)* + C*D] ( kG/cm2 )

(I-4)

Trong : + m: h s iu kin lm vic ca t nn ph thuc vo tng loi t. * t ct ht nh m = 0,8; * t ct ht bi m = 0,6; * Cc loi t khc m = 1. A, B, D - l cc h s c tra bng ph thuc vo , C. b - l chiu rng mng quy c, ly bng 100 cm. h - l chiu su mng quy c, ly bng 100 cm. C - l lc dnh ca t di y mng ( kG/cm2). - l khi lng th tch t nhin ca t ( kG/cm3). tin s dng ngi ta lp sn bng sau: Bng 4-4- Bng tra gi tr R0 (TCXD 45:78): Loi t t hn to: Cui v dm ln ct Si v sn gm cc mnh t ct: Ht th v to, khng ph thuc m Ht va khng ph thuc m Ht nh: + t m + m v bo ho Ht mn v bi + t m + m 6 5 5 4 4 3 3 2 3 2,5 2 1,5 Sinh vin: Phm Quang Minh 34 _KT_K51 Lp: CCT + Kt tinh + Trm tch 6 5 3 R0 kG/cm2

Trng H M a cht


+ Bo ho nc T s cho ct cht v mu s cho ct cht va. Bng 4.5: Bng tra gi tr A, B, D () 0 2 4 6 () 8 10 12 14 16 18 20 A 0.00 0.03 0.06 0.10 A 0.14 0.18 0.23 0.29 0.36 0.43 0.51 B 1.00 1.12 1.25 1.39 B 1.55 1.73 1.94 2.17 2.43 2.73 3.06 D 3.14 3.32 3.51 3.77 D 3.93 4.17 4.42 4.69 4.99 5.31 5.66 () 22 24 26 28 () 30 32 34 36 38 40 42 A 0.61 0.72 0.84 0.98 A 1.15 1.34 1.55 1.81 2.11 2.46 2.88 B 3.44 3.87 4.37 4.93 B 5.59 6.34 7.22 8.24 9.44 10.55 12.51

1,5 1

D 6.04 6.45 6.90 7.40 D 7.95 8.55 9.22 9.79 10.80 11.73 12.79

4.3. Cc vn v sc chu ti 4.3.1 Hng mc nh 7 tng c trng ti 250 tn/tr 4.3.1.1. Chn loi cc, kch thc cc, vt liu v kt cu cc Cn c vo cu trc nn ca v tr xy dng v ti trng cng trnh tc dng l 250T/tr, ta chn gii php mng cc b tng c sn tit din 25x25cm, chiu di mi cc 9m, b tng mc 250# c R bt =1250 (T / m 2 ) , ct thp dc chu lc l 4 thanh thp gai 20-CT-5, ct thp ai l ct trn trn 8, mi cc c bo v bng bn thp. Cc c th hin hnh 1


Lp: CCT

Trng H M a cht


10,4m 0.2 m

Thp 8 ai

3

0,05m

2

hp ch4 2 0

4.3.1.2. Chn chiu su t i cc v chiu di cc. B tng lm i c mc 300#, chiu su t i l h = 2.0m. B dy ca i l 1.5m, mt i t cch mt nn 0.5m, u cc ngm vo i l 0.5m. Vy chiu di cc cn li l 8.5m v tng su t mt t n mi cc l 10.5m. Vi cch chn nh trn th cm vo lp 4 ct ht nh mu xm nu, xm ghi, trng thi cht. 4.3.1.3. Xc nh sc chu ti ca cc a, Xc nh sc chu ti ca cc theo vt liu lm cc. p dng cng thc : Pvl = m. .(Rbt.Fbt + Rct.Fct) m : H s lm vic, ly m = 0.85 (II-2)

: H s un dc ca cc, ly =1Rbt : Cng chu nn dc trc ca b tng lm cc, gi tr ca nc tra bng. Vi b tng mc 300 th R bt =40%.300 (KG/ cm 2 ) = 1200 (T/

m2 )Sinh vin: Phm Quang Minh 36 _KT_K51 Lp: CCT

Trng H M a cht


R bt =1200 (T/ m 2 ) Rct : Cng chu ko gii hn ca ct thp, tra bng. Vi ct thp nhm CT5 th Rct = 2400 (KG/cm2) = 24000(T/m2) Fct : Din tch tit din phn ngang ca ct thp ch :FCT = n.2

.d 2 4

20 103 3 2 2 Fa = 4 = 1, 256.10 (m ) = 0.001256 (m ) 2

Fbt : Din tch tit din phn btng:.d 2 FBT = 4

(0.34) 2 Fbt = 3.14* = 0.09 (m2) 4

Thay cc gi tr vo ta c: Pvl = 0.85*1*(1200*0.09+ 24000*0.001256) Pvl = 117.42 (T) b) Xc nh sc chu ti ca cc theo t nn Theo quy phm sc chu ti i vi cc ma st chu nn c xc nh theo cng thc:n

Pdn = 0.7.m.(1. 2 .U . i .l i + 3.Fc.R )i =1

(II-2)

Trong : m: H s iu kin lm vic, m =0.85. 1: H s k n nh hng ca phng php h cc, 1 =1. 2: H s k n ma st gia t v cc, 2 =1.


Lp: CCT

Trng H M a cht


3: H s nh hng ca vic m rng chn cc n sc chu ti ca nn t mi cc, 3 = 0.7. U: Chu vi tit din ngang ca cc; U= 0.30*4 =1,2 (m) li : Chiu dy ca lp t th i m cc xuyn qua. n: S lp t trong phm vi chiu di cc. i : Lc ma st gii hn trung bnh ca mi lp t m

cc xuyn qua. Fc: Tit din ngang ca cc. Fc=0.30*0.30=0.09 (m2)R : Cng ca t nn mt phng mi cc, -

c tra theo bng 3.6 gio trnh Nn - mng ph thuc vo chiu su trung bnh lp t di mi cc, loi t v st ca t di mi cc. Vi chiu su t mi cc l 10,5m k t mt t v t trong lp ct nn ta c R = 244+30%*244 = 317,2 (T/m2). Bng 4:3.1. Bng kt qu tnh ton i . .l i Tn lp 2 3 4 su 1.2 6.7 21.9 Chiu dy mi lp m cc i qua li 1.2 5.5 15.2 st Is 0.42 Tn t St Ct Ct

i1.5 4.3 5.7

i. .l i1.8 23.65 86.65

ti.li Tra bng v thay vo cng thc ta c:

111.1

Pn= 0.7*0.85(1*1*1.2*111.1 + 0.7*0.09*317.2) = 91.2 (T) Sinh vin: Phm Quang Minh 38 _KT_K51 Lp: CCT

Trng H M a cht


Sau khi tnh sc chu ti theo hai cch ta thy Pvl > Pdn v vy ta s dng ti trng tnh ton Ptt = Pn = 91.2 (T). 4.3.1.4. Xc nh s lng cc trong i v kim tra sc chu ti ca t nn a) Xc nh s b kch thc i: m bo cho vic thi cng c d dng v cc cc nh hng ln nhau, theo TCXD 45 78 th khong cch gia cc tr ca cc phi tha mn: Kc 3.d (vi d l ng knh cc) Din tch y i c xc nh s b nh sau: F =

N tb tb .h

(II-3)

N: ti trng tnh ton tc dng ln ct, Ntt = 250 T tb: khi lng th tch i v t nm trn i, tb = 2.2 T/m3 tb: ng sut trung bnh di y i. Vi khong cch gia cc tr cc l 3d th ng sut trung bnh di y i s l: tb = (3.d )2 = ( 3 * 0.30 ) 2 = 112.6 (T/m2) h: chiu su y i, h = 2,0 m Thay cc gi tr vo cng thc (II-3) ta c : F =Ptt 91.2

N 250 = = 2.31 m2 112.6 2.0 * 2.2 tb tb .h

Chn din tch i = 3 m2 Trng lng i v t ph ln i c xc nh nh sau: Qm = F* tb*h = 2.31*2.2*2.0 = 10.16(T) b) Xc nh s lng cc trong i. p dng cng thc: Sinh vin: Phm Quang Minh 39 _KT_K51 Lp: CCT

Trng H M a cht


nc = *

NPtt

(II-4)

: h s vt ti, ly = 1,0.

N : tng ti trng tc dng ln ct, N = Ptc + G = 250 + 10.16=260.16 (T)Thay cc gi tr vo ta c : nc = 1*260.16 = 2.85(cc) 91.2

tin b tr cc ly nc = 3. Nh vy mi i s gm 3 cc . Do ti trng tc dng ng tm nn cc c b tr thng mng li hnh vung, khong cch gia tim cc cc l 1.2m, khong cch t tim cc bin n mp ngoi ca cc l 0.25m

Fd = ( 1.2 + 0.2.2 + 0.1 )( 1.2+ 0.2.2 + 0.1) = 1.7 . 1.7 =2.89 ( m 2 ) Cc c b tr nh hnh II-1 di y:


Lp: CCT

Trng H M a cht


0 ,5m

1 ,5m 0,5m10,5m 8,5m

1,7 m 0 ,05m 0 ,05m 1,2m 0 ,4m

c) Cu to v tnh ton i cc. --> Din tch i thc t l: 1,7*1.7 = 2,89 m2 --> Trng lng i v t ph ln i thc t l: Qm = 2,89*2,0*2,2 = 12,716(T) d) Kim tra lc tc dng trn cc Theo iu kin: pH =

Nnc

P tt= 91.2 (T). Do iu kin c tho mn --> thit k nh trn l hp l. e) Kim tra cng ca t nn di mi cc:


Lp: CCT

Trng H M a cht


kim tra n nh ca nn t ta quan nim cc v t nh mt mng khi qui c v coi n nh mt mng trn nn thin nhin. Phm vi mng khi qui c c xc nh bng gc ,tc tb = 4tc Trong tb l gc ma st trung bnh ca cc lp t ttc mi cc tr ln. tb c xc nh theo cng thc:

tc tb =

.l ltc i i

i

(II-6)

trong :tc tb - gc ma st tiu chun trung bnh ca cc lp t m

cc xuyn qua li- tng chiu dy cc lp t m cc xuyn qua li - chiu dy cc lp t cc xuyn qua.

4.3.2.Hng mc nh 40 tng c trng ti 2500 tn/tr 4.3.2.1. Chn loi cc, kch thc cc, vt liu v kt cu cc


Lp: CCT

Trng H M a cht


Cn c vo cu trc nn ca v tr xy dng v ti trng cng trnh tc dng l 2500T/tr, ta chn gii php mng cc khoan nhi, ta chn cc loi vt liu lm cc nh sau: - Cc btng ct thp, tit din trn, ng knh 1m; - i cc c lm bng btng ct thp, btng mc 300#; - Ct thp dc l thp A-III, chn 12 thanh ng knh 20; - Ct thp ai l thp A-II, ng knh 12. 4.3.2.2. Chn chiu su t i v chiu di cc Theo kt qu kho st CCT, da vo c im a tng y chia ra thnh 7 lp, ti chn lp th l lp 6 t mi cc. (Cui ln si,ct xm trng, xm en, trng thi rt cht), c sc chu ti tt, c E0 = >1000 kG/cm2, R0 = 5.0 kG/cm2. N30= > 100 ba. - Chiu su h cc thit k l 38 m, cc cm vo lp l 1m. - su chn i l 3m k t mt t. Cc ngm vo i 0,5m. - Vy chiu di cc k t y i cn li l 35m. 4.3.2.3 Xc nh sc chu ti ca cc theo phng thng ng 4.3.2.3.1. Sc chu ti ca cc theo vt liu lm cc Sc chu ti ca cc theo vt liu lm cc c tnh theo cng thc sau: Pvl = m*(m1*m2*Rbt*Fbt + Rct*Fct) Trong : m - H s lm vic ca cc, ly m = 1; m1 - H s lm vic i vi cc khoan nhi b tng bng ng theo phng thng ng, ly m1 = 0,85; m2 - H s iu kin lm vic ca cc k n nh hng ca phng php thi cng cc. Khi thi cng trong huyn ph st chn m2 = 0,7; Rbt - Cng chu nn gii hn ca btng. Vi btng mc 300 # ta c Rbt = 1300 (T/m2); Fbt - Din tch tit din phn btng ca cc. c tnh nh sau: d Fb = . = (0,5)2*3,14 = 0,785 m2 2 Rct - Cng chu ko gii hn ca ct thp. Vi thp chn l thp A-III, ta c Ra = 36000 (T/m2). Fct - Din tch tit din ca ct thp. Sinh vin: Phm Quang Minh 43 _KT_K51 Lp: CCT2

Trng H M a cht


Fct = 12**r2 = 12*0,000314 = 0,00377 (m2) Nh vy ta c: Pvl = 1*(0,85*0,7*1300*0,785 + 36000*0,00377) = 742,9 (T) 4.3.2.3.2. Sc chu ti ca cc theo t nn. Sc chu ti ca cc theo t nn c xc nh nh sau: Pdn = k*m*(F* R + U* * i *li) Trong : k v m - l h s ng nht ca t v h s iu kin lm vic. i vi cc khoan nhi th k.m = 0,5.R - Cng ca t nn mt phng mi cc, c tra theo TCXD

(5.10)

205- 1998 ph thuc vo chiu su t mi cc, loi t v st ca t di mi cc. Vi chiu su t mi cc l 40m k t mt t v t trong lp st pha, trng thi cng, nn ta c R = 1500 T/m2. F - Din tch tit din ngang ca cc; F = *r2 = 3,14*(0,5)2 = 0,785 m2 U - L chu vi tit din ngang ca cc; U = 2**r = 2*3,14*0,5 = 3,14 m li - L chiu dy ca lp th i tip xc vi mt bn ca cc; i - Cng tiu chun ca lp t th (i) ca t nn theo mt bn

ca cc, c tra theo TCXD 205- 1998 ph thuc vo chiu su k t gia lp t n mt t (zi), st ca t v loi t. Do cc khoan nhi c a qua cc lp t 2 n lp 6 nn ta c: Bng 4:3.2. Bng kt qu tnh ton i . .l iTn lp 2 3 4 5 su 1.2 6.7 21.9 37.2 Chiu dy mi lp m cc i qua li 1.2 5.5 15.2 15.3 st Is 0.42 Tn t St Ct Ct Ct

i1.5 4.3 5.7 10

i. .l i1.8 23.65 86.65 153


Lp: CCT

Trng H M a cht


ti.li

264.1

Vy sc chu ti ca cc theo t nn l: Pdn = 0,5*(0,785*1500 + 3,14*264.1) = 1003.4 T Ta thy Pvl < Pdn nn chn Ptt = Pvl = 742,9 T. 4.3.2.4. S b kch thc i i cc c cu to bng btng ct thp mc 300 #, thi cng bng phng php trc tip. Chn chiu su chn i l 3m, cc ngm vo i khong 0,5m. Kch thc i cc c tnh theo cng thc sau: P tk Fd = tb (5.11) tb .h Trong : Ptk - Ti trng thit k tc dng ln y i, Ptk = 2500(T); H - Chiu su y i k t mt t, h = 3m; tb - Khi lng th tch trung bnh ca btng v t trn i, tb = 2,2 3 (T/m ). tb - ng sut trung bnh ca t di y i, c tnh nh sau: P tt tb = ( 3d ) 2 Trong : Ptt - Sc chu ti tnh ton ca cc, Ptt = 742,9(T); d - ng knh cc, d = 1m; Vy tb = (3)2 = 82,54 (T/m2) Vy din tch y i c xc nh s b nh sau:742,9

Fd =

2500 = 31 .9 m2 82 .54 2.2 * 2Lp: CCT

4.3.2.5. Xc nh s lng cc trong i Sinh vin: Phm Quang Minh 45 _KT_K51

Trng H M a cht


S lng cc trong i c xc nh theo cng thc sau: N n . tt (5.12) P Trong : n - S cc trong i; - H s kinh nghim c k n nh hng ca ti trng ngang v mmen, ly = 1,5; Ptt - Sc chu ti tnh ton ca cc, Ptt = 742,9 T; N - Tng ti trng thng ng tnh ton tc dng ln i cc, c xc nh nh sau: N = Ptk + Gd Trong : Gd - L trng lng ca i v t trn i. Gd = 1,1*Fd*h* tb = 1,1*8,31*3*2,2 = 60,39 T Trong : 1,1 - L h s k n s lch tm; tb - Khi lng th tch trung bnh ca i v t trn i, tb = 2,2 t/m3. Vy: N = Ptk + Gd = 2500 + 60,39 = 2560,39 T S lng cc trong i l:

n c 1.5 *

2560 .39 = 3.44 cc 742 .9

Vy ta chn s cc l n = 4 cc. 4.3.2.6. Cu to v tnh ton i cc Khong cch gia cc cc l: C = 3d = 3*1 = 3m Chiu su cc ngm vo trong i l h1 = 0,5m. Chn chiu cao i l hd = 2,5m. Chiu cao lm vic ca btng trn nh cc l: h2 = hd - h1 = 2,5 - 0,5 = 2m


Lp: CCT

Trng H M a cht


m bo, ta kim tra kh nng chng chc thng ca i. i khng b chc thng khi: P tt h2 U.{ } Trong : U - Chu vi cc, c xc nh nh sau: U = 2**r = 2*3,14*0,5 = 3,14 m {} - Lc khng ct cho php ca b tng lm i, ly = 125 T/m2. Vy chiu cao chng chc thng ca i l: h2 3,14 *125 = 1,8m Vy chiu cao ca i chn l hp l. Ta c s b tr cc trong i nh sau:h d = 2,5m h 2 = 2m h 1 = 0.5m

742,9

0.5m 1m 2,2m

3m 0,6m

5m

4.3.2.7. Kim tra lc tc dng ln cc Lc tc dng ln cc phi tho mn iu kin sau: Sinh vin: Phm Quang Minh 47 _KT_K51 Lp: CCT

Trng H M a cht


Pm =

N Ptt n

(5.13)

Trong : Pm - Ti trng tnh ton tc dng ln mi cc theo phng thng ng. N - Tng ti trng tnh ton tc dng ln cc, N = 2560,39 T. n - S cc trong i, n = 4 cc. Vy ta c: 2560 .39 Pm = = 640.09 < 742,9 T 4 Nh vy ti trng tc dng ln cc nh hn sc chu ti tnh ton ca cc, cho nn thit k cc nh vy l hp l. 4.3.2.8. Kim tra cng t nn kim ta cng t nn di mi cc ta coi cc v t xung quanh cc l mt mng khi qui c, phm vi ca mng khi qui c c gii hn bi gc m nh hnh:

0 m ,5 2 m ,5

0 m ,5 2 m ,5

3 m 7

Hnh 5.4: S mng khi quy c =TB 4

(5.14) Lp: CCT


Trng H M a cht


TB =

i * li li

Trong : TB - Gc ma st trong trung bnh ca cc t m cc i qua; li - Chiu dy ca tng lp t cc xuyn qua; i - Gc ma st trong ca lp th i; Thay vo cng thc ta c:110 46'*1.2 + 5.5 + 15.2 + 15.3 = = 1.432 = 10 43' 35tc tb

Thay vo cng thc ta c:=10 43' = 0 0 25' 4

- Chiu rng mng khi qui c xc nh theo cng thc: Bq = B + 2*h*tg (5.15) Trong : h - Chiu di cc tnh t y i, h = 35,0 m; B- Khong cch gia hai mp ngoi ca cc theo chiu rng, B = 1m. Thay vo cng thc (5.15) ta c: Bq = 1 + 2 *35* tg 0 0 25' = 1.5m - Chiu di mng khi qui c xc nh theo cng thc: Lq = L + 2h.tg (5.16) Trong : L - khong cch gia hai mp ngoi ca cc theo chiu di, L= 4 m; Thay vo cng thc (2- 16) ta c: Lq = 4 + 2 *35 * tg 0 0 25' = 4.5 m - Din tch ca mng khi quy c l: Fq = Bq * Lq = 1.5*4.5 = 6.75 m2 -Tng ti trng tc dng ln mng khi quy c: N0 = Ntc + Pqu Trong : Ntc - Ti trng tiu chun tc dng ln mng khi quy c, Ntc = 2500T Pqu - Trng lng mng khi quy c c xc nh theo cng thc: Sinh vin: Phm Quang Minh 49 _KT_K51 Lp: CCT

Trng H M a cht


Pqu = tb*h*Fqu

(5.17)

Trong : tb - Khi lng th tch trung bnh ca cc lp t v cc, ly tb = 1,96 T/ 3 m h - chiu di cc tnh t mt t cho n mi cc, h = 38m; Fqu - din tch y mng khi quy c, Fq u= 127,3m2; Pqu =1,96 * 38 * 127,3 = 9481 T. Thay vo cng thc ta c: N0 = 2500 + 9481= 12341 T p lc ti y mng khi quy c c xc nh theo cng thc:

tb =

N 0 12341 = = 96.94 T/m2 q qu 127.3

m bo iu kin chu lc, p lc cng trnh truyn xung y mng khi quy c phi tho mn iu kin sau (i vi ti trng ng tm): tb RH Gc ma st trong ca lp

= 12 * N + 15 0 = 12 *100 + 15 0 = 50 0 04 'p lc tiu chun ti y mng khi quy c, RH tnh theo cng thc: RH = m*[ A*Bq * + B*hq * + C*D ] (5.18) Trong : A, B, D - cc h s tra bng ph thuc vo . V cc t vo lp 6 c N30 = 100. > 50 0 04 ' , tra theo bng TCXD 45: 78 ta c: A = 3.66 B = 15.64 D = 14.61 Bq - Chiu rng mng khi quy c, Bq = 1.5 m; hq - Chiu su mng khi quy c, hq = 38,0 m; - Khi lng th tch trung bnh ca cc lp t m cc i qua, = 1,96 t/m3; - Khi lng th tch ca lp t di mi cc, = 1,92 t/m3; Sinh vin: Phm Quang Minh 50 Lp: CCT _KT_K51

Trng H M a cht


C - Lc dnh n v ca lp t di mi cc, C = 0,266 kG/cm2; m - H s k n iu kin lm vic, m = 1; Thay s vo cng thc ta c: RH = 1 * (3.66 * 1.5 *1,96 + 15.64 * 38,0 * 1,92 + 14.61 ) = 1166.46 T/m2 Ta thy RH = 1166.46 T/m2 > tb = 82,54 T/m2. Vy t nn n nh v cng . 4.3.2.9. Kim tra i cc trnh kh nng chc thng ca cc i vi i cc, th vic thit k i cc phi tho mn iu kin sau: p = dn < [ ] (5.19) U .h Trong : U: chu vi ca cc, U = 3,14(m) h: b dy ca i cc, h = 3(m) [ ] : cng khng ct gii hn ca b tng, [ ] = 1 Rn , vi 10 mac b tng 300 th Rn =130 (KG/cm2) =1300 (T/m2), nn

[ ] = 1 .1300 = 130 (KG/m2)10

Pdn: lc tc dng ln cc hay phn lc ca nn t ln cc, Pdn =1003.4 (T).

=

1003 .4 = 106.5 (T/m2)

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