Tap chi KHKT Mo Bia chdt, so 31,712010, tr 79 83 KHAI THAC M 6 & XAY DL/NG CONG TRINH NGAM (trang 79 95) PHirONG PHAP NO MIN GIA ClTOfNG NEN DAT YEU NHU" VAN BACH, Truong Dgi hgc Md Dia chdt Tom tat N[.]
Tap chi KHKT Mo -Bia chdt, so 31,712010, tr.79-83 KHAI THAC M & XAY DL/NG CONG TRINH NGAM (trang 79-95) PHirONG PHAP NO MIN GIA ClTOfNG NEN DAT YEU NHU" VAN BACH, Truong Dgi hgc Md - Dia chdt Tom tat: Nd duoc sir dung nhiiu linh vuc vdi nhimg muc dich khdc Di gia cudng nin ddt yiu cd thi sir dung phuang phdp nd nen ep: nd vdi luong thudc ddi sdu nen ddt, nd vdi luong thudc dgt d bi mat nin ddt vd nd vdi lugng thudc ddt lap nude trin bi mat nin ddt Nhimg thdng so chii yiu ciia cdc phirong phdp niu tren Id: khdi luong thudc nd, chiiu sdu ddt thudc vd trinh tu nd dugc thay ddi: mat dat da tang len, Id \ Dat van de hdng giam di, the tich nen dat giam va mdi lien Nd dugc su dung nhieu ITnh vuc ket giua cac phan tu nen dat tang, cudi cung nen cua cac nganh: cdng nghiep md, xay dung, giao dat dugc gia cd ben ban thdng van tai, thuy Igi, thuy dien, qude phdng Nhu'ng thdng sd chii yeu ciia sdng dap la: v.v Vdi nhung muc dich khac nhu: pha ap luc cue dai, tdc lan truyen, thai gian tac vd va djch chuyen dat da, thao dd cac cdng dung va xung lugng ciia sdng nd trinh, nen ep kim loai v.v Xung lugng ciia sdng nd dugc xac djnh [3]: Dat da la ddi tugng tac ddng chinh cua nd Nang lugng chat nd thudng dugc su dung 1= Jp(t).dt, MPa.s (1) de tac ddng len dat da vdi muc dich: pha vd dat da ciing, nen ep nen dat yeu va tao mat dd: p(t) la ap lire sdng nd thay ddi theo tach khai thac da khdi thdi gian Khi pha vd dat da, nang lugng chat nd dugc Bang thuc nghiem nd lugng thudc nd sir dung de dap vd dat da nguyen khdi tap trung, ap luc cue dai ciia sdng nd dugc xac dang cue nhat dinh Khi dd thdng sd quyet dinh dinh: chi la chi tieu thudc nd q - ehi phi thudc nd de pha vd don vj the tich dat da vdi miic dap : 53,3.(2/Q ) ' ' - \ MPa (2) R vd xac dinh (kg/m^) [2] - Khi sii' dung phuong phap nd de tach , MPa.s (3) va da khdi can dam bao sau nd da cdn lai R ^ nguyen khdi va da dugc tach khdng bi dd: p,„„^ la ap luc cue dai, Mpa; pha buy, ket cau ciia nd dugc bao toan O day Q la khdi lugng thudc nd, kg; nang lugng chat nd cat da theo cac mat dugc R la khoang each tinh tu tam lugng thudc, m dinh vi trudc bang cac Id khoan, tach khdi da Dudi tac dung cua sdng dap nd Id khdi nguyen khdi va bao toan tinh nguyen ven hdng ciia nen dat yeu giam di ciia nd Nhu vay, nang lugng chat nd dugc su Dac trung co' ban ciia nen dat yeu nd dung thdng qua chi tieu thudc nd mat qm - chi nen ep la he sd mat tuong ddi ciia Idp (chi sd phi thudc nd de tao do'n vj dien tich mat mat ldp): tach (g/m^) [4] e - e max I, (4) - Khi nd nen ep nen dat yeu nang e —e lugng chat nd dugc su dung thdng qua ap lire inax mill (n,r.x-n)n-n,„,J cua san pham nd Vdi sir lan truyen cua hoac: L (5) Pmax(P-Pmin) (nmax-nm,n)(l-n) P(Pma.-Pm,n) sdng dap phat sinh nd, ket cau ciia nen dat 79 do: e„„,.p„„„,n„,^^ la he sd Id hdng mat khung khoang vat va Id hdng d trang thai toi vun: e,™„-Pmax•",.,„ 'a nhu'ng tri sd tuo'ng ii'ng d trang thai nen; e.p n la nhirng tri sd tuong iing d trang thai tu nhien Tri sd Ip thay ddi tu (trong chinh trang thai toi vun) den (trong chinh trang thai nen ep) Tri sdlpcang nhd thi kha nang nen ep nen dat yeu bang nd cang Idn Cac phuong phap no de nen ep gia cudng nen dat yeu De nen ep nen dat yeu cd the su dung phuong phap nd min: - Nd vdi lug'ng thudc dat sau nen dat (nd sau); - Nd vdi lugng thudc dat d be mat nen dat (nd tren be mat); - Nd vdi lugng thudc dat ldp nude tren be mat nen dat nd (nd dudi nude) 2.1 Nd sdu a Chiiu sdu ddt thudc Tren co' sd nd thuc nghiem vdi lugng thudc dat sau cat hat nhd, hat trung va bao hoa nude, de dam bao nen ep cue dai, mdi quan he giua lugng thudc nd va chieu sau dat thudc phai tuan thii nhu sau: = k|.h' =0.055h'\kg , (6) dd: Q la khdi lugng thudc nd, kg; k| la he sd thuc nghiem; h la chieu sau dat thudc, m Cdng thiic tren tinh cho thudc nd amdnit N " )KB Khi su dung loai thudc nd khac thi: Ok=k,.Q,kg dd: kk= 0.8 H- 1,16 la he sd chuyen ddi (theo nhiet lugng thudc nd su' dung); /) Chiiu sdu nen ep Chieu sau nen ep dugc xac dinh: h,,^, =k,.h = l,5.h m , (7) hoac: h„, = ^ m Hinh Sut kin be mat (1) va viing pha buy ket cau (2) nd lugng thudc don dgc dat sau nen dat d Bdn kinh tdc dung nd hiiu qud Ban kinh tac dung nd hieu qua cd the xac dinh theo cdng thiic: (10) k^.yO , m He sd thuc nghiem k4 cd the dugc lua chgn theo bang Khoang each giua cac lugng thudc nhiing trudng hgp cu the cd the tinh chinh xac bang each nd thii' nhung lugng thudc don ddc Nhung thdng sd chu yeu xac djnh theo cac cdng thuc (6), (8), (10) vdi nhung he sd thuc nghiem dugc the hien tren hinh Bang Cac gia trj ID, ks va k4 TT Cat Hat nhd Hat trung binh (8) Khi tang mat ban dau, chieu sau nen ep giam Ddi vdi cat cd mat trung binh, chieu sau nen ep giam den L3h e Bdn kinh nen ep cue dgi 80 Ban kinh nen ep cue dai phu thudc vao mat ban dIu cua nin dlt, lugng chiia kep va mot loat nhijng yeu td khac Khii sut liin "bl mat theo phuong thang diing 0,4 0.3-0,4 >0,4 25-15 9-8 8-7 5-4 2,5 3-2,5 2,5 R^.h h„,.(m) 14 ^^t1 - !•„ 12 n h„ 10 RhH(k4=5.0) Iiy RK4(k4 = 4.0) Rh,(k4=3,0) /ilil^ / / > ^ ^ / ^ V 10 12 14 16 Q, (kg) Hinh Bilu xac djnh chilu sau dat thudc h, ban kinh tac dung hieu qua R^q k4 khac va chieu sau nen ep hne vdi khdi lugng thudc cue dai la Q e Sd dot nd , -, Xac dinh dieu kien dam bao sut liin be mat nhat dinh sd lugng loat nd nhd nhat Cd the xac dinh sa luge sd loat nd can thiet bang phuo'ng phap thuc nghiem g Phuong phdp phd va cdu tnic theo Idp Trong trudng hgp nen ep nhieu tang, cd the tang chieu sau va ban kinh nen ep bang phuong phap pha vd cau tnic ciia nen dat theo ldp Trong phuong phap nay, dau tien nd nhung lugng thudc hang tren Khi dd phan tren ciia nen dat chuyen vao trang thai nen, dan den chuyen tam thai trgng lugng nen dat hay mot phan cua nd hoi nude va giam iing suat nen khung khoang vat ciia ldp nam dudi Neu thuc hien nd nhung lugng thudc tang dudi sau nd nhung lugng thudc tren se phii vd de dang ban cau tnic nhung ldp dat phia dudi lam tang chieu sau va ban kiiih nen ep nen dlt Tang dudi nd khdng cham ban so vdi thdi gian A, (A, =0,2t„, vdi t„e thdi gian nen ep ldp dau tien h „>,•) tiep theo cd the nd thuc nghiem \a dd sul kin theo thdi gian Khi tana tham nude va giam chieu day ciia nen nen ep tri sd gidi han ciia cham At se giam Ddi vdi tang tren, khdi lugng Q va ban kinh tac dung hieu qua dugc xac dinh theo cdng thiic (1) va (10); ddi vdi tang thii' cung nhan dugc nhu tang dau tien Chieu sau dat thudc a tang thii' 2: h = h , cdn chieu sau nen ep tdng cgng: h„e = (2,6^3,0)h Phuong phap pha vd cau tnic cua nen dat theo ldp cho phep tang chieu sau nen ep giam va cd the thii tieu hoan toan su anh hudng bat Igi nen ep nen dat khdng bao hoa nude Phuong phap cd the dat ket qua tdt nen ep nen dat bao hoa nude cd mdi lien ket yeu bang lugng thudc tuong ddi nhd 2.2 Nd be mat Khi sii' dung lugng thudc dap ngoai nd be mat, cdng viec dugc tien hanh don gian hon Tuy nhien, nen ep nen dat, tac dung nd kem hieu qua hon so vdi nd sau cung khdi lugng thudc nd Khi nd lugng thudc dap ngoai su thoat tu san pham nd vao qu\en nen nen dat khdng kip bien dang boi sdng nd Nhiing thdng sd ciia sdng dap nhu: ap luc cue dai tren mat sdng va xung lugng cua nd nho hon 81 dang ke so vdi nd sau Do dd nd chi mot phan rat nho nang lugng dugc su dung de pha vd ket cau ciia nen dat Vdi nhiing dac diem nhu vay, nen ep nen dat yeu vdi nd be mat, ban kinh tac dung va chieu sau nen ep giain nhieu Bang nd thuc nghiem cho thay ban kinh tac dung hieu qua bang mot nua so vdi nd lugng thudc sau Khi nd be mat: Rhq = (0.5^0,6)k4^ m , (11) d day: k4 - he sd dugc xac djnh theo bang 1; Q - khdi lug'ng thudc nd, kg Cdn chieu sau nen ep hne=l2\/^ hayQ=0,58.h^,e ,m (12) Cung nhu nd sau, lugng thudc dap ngoai bd tri theo mang d vudng, nd ddng thai tirng nhdm lugng thudc, tao tren mat bang mot dudng bien kin Nhugc diem ciia nd be mat la pha vd tinh lien tuc ciia nhung ldp phia tren cua nen dat tao pheu nd Mac du nen ep nen cat bao hoa nude, pheu nd chiia day cat bi nen ep, song mat cua su sap xep cat chiing cd the nhd hon so vdi cat bi nen ep d xung quanh Dgt nd tiep theo dan den nen ep cat pheu nd trudc, nhung cd su khac biet nhat djnh Thuc te cho thay nd be mat cd the dugc su dung de nen ep nen dat yeu den chieu sau 3ITI Khi chieu day Idp nen ep Idn, khdi lugng thudc nd phai tang va tang the tich pheu nd Trong trudng hgp naN nen su' dung nd sau 2.3 No dirdi l&p nude nen ep nen ddt Nd dudi nude de nen ep nen dat tuong ddi yeu cd hat bat ky, la nd vang Mot nhung dieu kien nen ep cd hieu qua la khdng cd pheu nd vang tren nen dat hoac pha vd dat nd Mat khac, lugng thudc cang gan mat dat tac dung cang manh chieu day ciia ldp va tang chieu sau gia cd nen dat Gia cdng sd lieu thuc nghiem [I] da xac dinh dugc khoang each nhd nhat tii' lugng thudc den mat dat, dam bao khdng tao pheu vang, khoang each dd la: Ah = k5.(VQ)'' ,m , (13) dd: Q - khdi lug'ng thudc nd, kg; kj.^i nhirng he sd phu thudc vao loai dat da va loai thudc nd 82 Hieu qua nhIt la nd nen ep nude, trird-ng hgp phln Idn nang lugng no tao sdng dap Chilu sau tac dung ciia lugng thudc nd nen ep nude (m) dugc xac djnh: h = k,.5/Q m , (14) d day: 1^, - he sd thuc nghiem Khdi lirg-ng thudc nd hgp ly de nen ep nin dlt nude cd thi nhan dugc tuan thu dilu kien (13) va (14) cd tinh den chieu sau Idp nude tren nen dat: H= Ah + h hay: H=k5.( VO)"' + U-'^ ^ m (15) Khi sii' dung nguyen tac tuong duong, cdng thiic (15) cd the bieu dien dudi dang: H=k7(V0)^'^ ,m (16) Khdi lugng thudc nd hgp ly: Q=ks.HP ,kg , dd:P=— m va k8= (— f ^ k, Theo sd lieu nd thuc nghiem [1], nhung lugng thudc nd don ddc (trdtin), nhung he so thuc nghiem nhung cdng thiic (13), (14) va (15) dugc the hien d bang Bang Nhung he sd thuc nghiem Nen k5 dlt Cat sdi kg p k9 kio 0.35 1.95 2.66 1,22 0,1 2.46 1,8 2.0 1^.1 ky 1^4 Cat bao 0.35 1,95 2,66 1,22 0,1 2,46 3,0 2,5^3.0 hoa nude Khi khdi lugng thudc hgp ly (xac djnh theo cdng thiic 16), hay nhd hon khdi lugng thudc hgp ly, chilu sau nen ep hieu qua (m) dugc xac djnh: ;, , (17) h„e = k