24 • Tip san KHOA HOC ft CONG NGHE
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ren cd sd nghien cdu, tdng hdp va phan tfch cac tai lieu dja chat cdng trinh thu thap dddc td ket qua nghien cdu cua de tai va cac tai lieu thu thap td cac cd quan nghien cdu dja chat cdng trinh trong tinh cung cap, dac diem dja chat cdng trinh cua viing thj xa Tay Ninh dddc md ta chi tiet nhd sau:1. Dac diem cau true dia chat.
Vdi muc dfch phuc vu quy hoach xay ddng nen chiing tdi chi trinh bay dac diem cau triic dia chat trong pham vi nen da't chju anh hddng ciia tai trpng cua cac cdng trinh thdng thudng, nghTa la tinh td mat dat den dp sau 25 -^ 30m, bao gdm cac thanh tao magma xam nhap va cac tram tfch DeTd .
Cac thanh tao magma xam nhap (Mz): Cac thanh tao magma xam nhap phan bd d phfa Ddng viing thj xa Tay Ninh. Thanh tao magma duy nha't trong vCing la cac da xam nhap thuoc phdc he Djnh Quan (Di, GDUK,dq). Chiing Id ra d khu vdc niii Ba Den gdm 2 pha xam nhap chfnh va 1 phada mach.
Cac thanh tao magma xam nhap cd dac tfnh cdng chac, ft ndt ne, hien dang dddc khai thac lam vat lieu xay ddng. Tuy cd kha nang chju tai trpng cao nhUng dien phat trien cac thanh tao nay ft thich hdp de lam nen thien nhien cho cac cdng trinh xay ddng vi be mat cd dp ddc Idn.
Cac tram tfch De td: Cac tram tfch De Td bao gdm cac thanh tao ngudn gdc sdng va ngudn gdc sdng - dam lay phan bd tren phan cdn lai cua viing thj xa Tay Ninh. Cac phan vj dia tang vdi nhieu ngudn gdc khac nhau. Can cd vao cac dac diem thach hpc, cd sinh ... cac tram tfch nay dddc chia thanh cac kieu phdc he thach hpc nhd sau: Phdc he thach hpc a'^Q,';
Phdc he thach hpc a'^Q,"'; Phdc he thach hpc a™Q,''; Phdc he thach hpc a'Q,'; Phdc he thach hpc a'^'^Q,'; Phdc he thach hpc a^^Q^;
Phdc he thach hpc ab°Q2; Phdc he thach hpc deluvi(dQ),
• Ths. Doan Ngoc Toan Lien doan Quy tioacti va Dieu tra Tai nguyen nUdc mien Nam 2. Dac diem dia hinh dia mao.
Viing thj xa Tay Ninh bao gdm cac dang dja hinh sau: Dja hinh ddi nui va dia hinh thanh tao dosdng.
Dang dja hinh doi nui: bao gdm cac sUdn niii thanh tao tren cac khdi xam nhap nhd nui Ba Den. Sddn cd dp ddc trung binh 15 - 40°, den 50 - 60°. TrSc dien dpc cua sddn cd dang 16m, mang Iddi ddng chay tam thdi rat phat then.
Cac qua trinh phong hda, bdc mdn - xam thUc va dd Id xay ra manh me. Tren mat sddn lo ra nhieu tang deluvi cd ki'ch tbddc Idn td 1 -2m den 7 - 8m. Dddi chan sddn, tao nen dai vat gau sddn tfch daitdi4-5km bao quanh sddn.
Dia hinh thanh tao do song:
Bai boi ven ldng tudi IHolocen muon, thdi muon (Q/J.
Bai bdi ven Idng phan bd d viing thi xa Tay Ninh dpc theo cac sdng Tru Phat, rach Tay Ninh va cac sudi khac trong viing. Cac bai boi tUdng ddi bang phang, be mat cd hddng nghieng thoai ve phfa Idng sdng. Cac bai boi nay dang trong giai doan dang binh thanh va thay ddi theo miia va cd xu hddng thu hep ddng chay.
Them tich tu - xam thdc bac II tudi Pleistocen muon, thdi muon (QfJ
Dda vao dac diem tram tich cau tao them, mdc dp chia cat xam thdc, dp cao va dien phan bd cua them dddc chia ra:
Them tfch tu xam thdc: phan bd d phfa Tay Nam viing thj xa Tay Ninh, be mat them cd dp cao td 5 den 20m dddc cau tao bdi cac tram tfch aQ,^ bao gdm cat bdt san sdi mau xam nhat. Be mat them bang phang, Idpn sdng thoai bi chia cat yeu bdi cac gd cao 2 - 5m, dinh bang, sddn thoai. Ria them, d cac bp phan chuyen xudng be mat them tfch tu bac I la sddn ddc 3-10°. Dp chenh cao ciia sddn khdng Idn, bi rda trdi-xam thdc khe ranh yeu, O ndi them tie'p giap vdi them tich tu - xam thdc bac Mi, be mat them
• TIP san KHOA HOC ft CONG NGHE 25
•trung xudng dang Idng chao. Dai trung rpng bao quanh them bac III thddng bi ngap nudc.
Them xam thUc - tich tu bac III tuoi Pleistocen muon, thdi sdm (Qf,):
C h i i n g phan bd d dp cao 20 - 30m, phan bd xung quanh khdi mil Ba Den. Be m a t t h e m nhin chung b&ng phang, bj chia cSt ye'u bdi cac mang sudi nhd thanh cac gd ddi thap (cao 5 - 7m), dinh bang, rpng, sddn rda trdi ddc 3 - 4°.
Ria them bi rda trdi va xam thdc yeu bdi khe ranh xdi mdn. Them dddc cau tao bdi cac tram tfch cd tudi Pleistocen gida - muon (Q,^'^) vdi thanh phan gom cat bdt lan san mau xam vang, thddng bj laterit hda khdng deu.
3. Dac diem dia chat thiiy van.
Theo ket qua nghien cdu cua cac lo khoan trong vung thi xa Tay Ninh, mUc nUdc dddi dat phu thudc vao dp cao dja hinh va thay doi theo mua. Muc nUdc dddi da't thay ddi td 0,2 den 7,3m. Nhin chung mUc nUdc ngam cd anh hudng ft nhieu den viec thi cdng mdng cho cac cdng trinh xay ddng, nhd lam keo dai thdi gian c d ket va liin dn dinh cua cdng trinh, dac biet la nhdng cdng trinh Idn hoac cdng trinh ngam va cong trinh cd tai trpng dpng n h u c a u , dudng...
Ket qua phan tfch thanh phan hda hoc nudc dddi da't lay td cac cdng trinh khai dao, cac lo khoan dia chat cdng trinh trong vung cho thay nudc dudi da't cija viing nghien cdu cd 3 loai an mdn ddi vdi be tdng cbii yeu la an mdn rda lua, an mdn carbonic, an mdn axit, Trong vung thi x a T a y Ninh khdng hien dien an mdn sulfat,
4. Cac qua trinh va hien tddng dia chat dgng Ida cong trinh.
Viing thi xa Tay Ninh hinh thanh cac qua trinh va hien tUdng dia chat dpng ldc cdng trinh d a n g c h i j y sau:
Vung thddng bi ngap ung: Qua trinh nay thddng xay ra vao miia mda tai nhdng viing cd dia hinh thap va thoat nudc kem ven thung lung rach Tay Ninh, lam cho nhieu ndi bi ngap ung 0,5 den 0,7m vdi thdi gian khoang 2 den 3 thang trong nam (xem ban do dja chat cdng trinh). Trong nhdng nam gan day qua trinh nay xay ra thddng xuyen va keo dai hdn do pha rdng dau nguon va hoat dpng cua con ngudi lam giam kha nang thoat nudc.
Mdt nguyen nhan khac gay ra ngap iing la he thdng kenh Tay lam cho muc nddc ngam chung quanh dang cao lam giam kha nang thoat nudc vao mua mda va nhdng ngay xa n u d c t d h d Dau Tieng.
Lay hda: Qua trinh nay thudng xay ra tren cac bai bdi va cac dai trung tfch tu sdng - dam lay ven thung lung rach Tay Ninh. Lu lut hang nam tran ngap cac bai bdi va trung lay ven sdng, do thoat nudc cham va thdi gian ngap ling keo dai lam cho qua trinh lay hda xay ra thuan Ipi hdn. Ket qua da hinh thanh tren be mat Idp bun set, b i i n s e t p h a c h d a m i i n thdc vat mau xam den, trang thai chay nhu d phia Nam rach Tay Ninh.
Boi lang: Qua trinh nay thddng xay ra d sudi Lam V6 lien quan vdi qua trinh xam thdc bd va van chuyen vat lieu td ndi xa den. Ket qua da lam day sdng nhieu noi nang cao td 0,5 den 0,7m hoac hinh thanh cac bai bdi ven sdng, sudi,
Dong dat:Theo cac tai lieu cua Nguydn Dinh Xuyen (1985) va Pham Khoan (1985) thi d VLing thi xa Tay Ninh chUa cd bieu hien dpng da't, vung thj xa Tay Ninh thupc ddi kien true cd bieu hien dpng da't ye'u, Cach 40km ve phfa Tay viing nghien cdu cd ddi phat sinh cap dpng da't trung binh: M= 5,25 vdi chu ky 3,5nam/lan.
5. Tinh chat cd ly cua dat da.
Ket qua tdng hpp cac tai lieu trong phdng va ngoai trdi da phan chia da't da trong viing thj xa Tay Ninh thanh 4 loatthach hpc, Cac loatthach hpc dupc chia ra thanh 9 phdc he thach hpc, cac phdc he thach hpc lai dupc phan ra thanh 21 kieu thach hpc vdi tfnh chat cd ly ciia chung nhUsau:
- Loat thach hoc deluvi:
Trong pham vi viing thj xa Tay Ninh loat thach hpc nay phan bd thanh dai hep d phfa Ddng, day la san pham rda trdi td tren sudn niii dupc tfch dpng lai thanh sddn tfch tu xung quanh cac khdi nui Ba Den vdi chieu rdng thay ddi td 100 - 200m den khoang 1km. Thanh phan tram tfch bao gom dam, cudi, sdi, cat pha, set, day 0,5 - 2m. Be day ciia loat thach hoc nay bien ddi td 0,40m den 2,00m, trung binh 1,04m. Nhin chung vung phan bd loat thach hpc nay khdng thuan Ipi cho viec dat mdng
Its-
26 • Tip san KHOA HOC ft CONG NGHE
us- cdng trinh vi cd chieu day mdng va dp ddc dja hinh Idn.
- Loat thach hoc sdng - dam lay:
Trong pham vi viing thj xa Tay Ninh loat thach hpc nay chi cd mdt phdc he thach hpc ngudn gdc sdng - dam lay tudi Holocen (ab°Q2).
Ket qua khoan khao sat cho tha'y phdc be thach hpc nay phan bd dpc theo hai ben bd rach Tay Ninhtdio khoan DT3ve phia Nam tdi bet viing.
Phan Id tren be mat dia binh vdi dien tfch nhd khoang 1km^ phdc be thach hpc nay phii bat chinb hpp len phdc he thach hpc ngudn gdc sdng tudi Holocen (a'^'QJ. Phdc he thach hpc nay gdm cd bai kieu thach hpc la biin set va bunsetpha.
Kieu thach hpc biin set: Thanh phan thach hpc la biin set mau xam den, Kieu thach hpc nay gap tai cac Id khoan DT9, TX109 va TX110. Be day ciia kieu thach hpc nay thay ddi td 1,50m (lo khoan DT9) den 3,50m (Id khoan TX109), be day trung binh la 2,20m, Sdc chju tai quy ddc tai cac Id khoan R, = 0,40kG/cm^
Kieu thach hpc biin set pha: Thanh phan thach hpc la bun set pha mau xam den. Trong pham vi viing thi xa Tay Ninh kieu thach hpc nay chi gap tai Id khoan DTI 6 vdi be day la 3,00m.
- Loat thach hgc sdng:
Trong pham vi viing thj xa Tay Ninh, loat thach hpc nay bao gdm cac phdc he thach hpc ngudn gdc sdng tudi Holocen (a^^^Q^), phdc he thach hpc ngudn gdc sdng tudi Pleistocen thUpng (a^"Q,^), phdc he thach hpc ngudn gdc sdng tudi Pleistocen thUdng (a^Q,^), phdc he thach hpc ngudn gdc sdng tudi Pleistocen trung - thddng (a'^'^Q,"'), phdc he thach hpc ngudn gdc sdng tudi Pleistocen trung - thdpng (a^Q,^'^) va phdc he thach hpc ngudn gdc sdng tudi Pleistocen ha (a'^Q,'). Cac phdc he thach hpc nay phan bd rdng trong pham vi viing, khdng bat gap cac phdc be nay tai phfa Ddng nPi hien hdu niii BaDen.
Phdc he thach hgc nguon gdc sdng tudi Holocen (a'"OJ.
Phdc he thach nay phan bd dpc theo hai bd rach Tay Ninh, sudi Lam Vd, sudi Sau, sudi Tra On va sudi Vang. Phdc he thach hpc nay phu
trdc tiep len phdc he thach hpc ngudn gdc sdng tudi Pleistocen thdpng va phdc be thach hpc ngudn gd'c sdng tudi Pleistocen trung - thddng.
Phdc he thach hpc nay bao gdm hai kieu thach hpc la set va cat pha.
Kieu thach hpc set: Thanh phan thach hpc la set mau xam trang, xam vang, trang thai dec mem den deo cdng, be day thay ddi td 1,8m den 3,00m, be day trung binh la 2,40m. Sdc chiu tai quy ddc la 0,72kG/cm^
Kieu thach hpc cat pha: Thanh phan thach hpc la cat pha mau xam den, xam trSng, trang thai deo. Be day thay ddi td 0,50m den 4,50m, be day trung binh la 2,50m, Sdc chju tai quy ddc la 1,31 kg/cm'.
Phdc he thach hgc nguon gd'c sdng tuoi Pleistocen thddng (a'^'Q').
Phdc he thach nay phan bd tren dien rpng ci phfa Nam va Tay ctja vung Thi xa Tay Ninh, phu trdc tiep len phdc he thach hpc a^Q,' va phdc he thach hpc a'^'Q,''. Phdc he thach hpc nay bao gdm cac kieu thach hpc set pha, set, cat pha, set pha l i n san laterit, set lan san laterit va cat pha lim san, Theo ket qua khoan khao sat thi trong phdc he thach hpc nay co 4 cap be day la < 2m, 2 den 5m, 5 den 10m va >
10m. Cac kieu thach hpc trong phdc he se ddpc md ta nhddddiday:
Kieu thach hpc set pha: Thanh phan thach hpc la set pha mau xam trang, nau vang, xam nau vang, ddm dd, trang thai deo mem den cdng. Kieu thach hpc nay phan bd rdng, be day thay ddi td 1,00m den 11,40m, be day trung binh la 4,82m.
Kieu thach hpc set: Thanh phan thach hpc la set mau xam xanh, nau dd, xam trang, trang thai deo mem den cdng. Kieu thach hpc nay phan bd rdng va khdng Id ra tren be mat dja hinh. Be day thay ddi td 1,20m den 15,20m, be day trung binh la 6,99m.
Kieu thach hpc cat pha: Thanh phan thach hpc la cat pha mau vang nhat, xam tr&ng, xam nau vang, trang thai chay den cdng. Kieu thach hpc nay phan bd rdng, be day thay ddi td 1,00m den 11,30m, be day trung binh la 4,04m.
Kieu thach hpc set lan san, iSn san laterit:
Thanh phan thach hpc la set lan san, I l n san laterit mau xam vang, xam trSng, nau dd, trang
• Tip san KHOA HOC ft CONG NGHE 27
ra- thai nda cdng den cdng. Kieu thach hpc nay phan bd d trung tam keo xudng phfa Nam, be day thay ddi td 0,90m den 3,60m, be day trung binh la 1,65m.
Kieu thach hpc set pha iSn san, lan san laterit: Thanh phan thach hpc la set pha l i n san, l i n san laterit mau xam t r i n g , vang, nau dd, trang thai deo m e m den cdng. Kieu thach hpc nay phan bd rdng, be day thay ddi td 0,90 den 3,50m, be day trung binh la 2,10m.
Kieu thach hpc cat pha lan san: Thanh phan thach hpc la cat pha l i n san mau xam t r i n g , xam vang, trang thai deo den cdng. Be day thay ddi td 2,20m den 7,80m, be day trung binh la 4,43m.
Phdc he thach hgc nguon gd'c sdng tudi Pleistocen thddng (a^Of).
Phdc be thach nay khdng Id ra tren be mat dia binh. Theo mat c i t Dja chat cdng trinh thi phdc he phan bd khdng lien tuc, chi tdn tai d phfa Tay Nam va mpt phan phfa Ddng Nam va bj phdc he thach hpc a'^^Q,^ phii true tie'p len.
Phdc he thach hpc nay bao gdm hai kieu thach hpc la cat mjn, trung, thd l i n san va kieu thach hpc san sdi.
Kieu thach hpc cat min, trung, thd l i n san:
Thanh phan thach hpc la cat mjn, trung, thd l i n san mau xam t r i n g , vang, nau d d , trang thai rdi den chat, Kieu thach hpc nay phan bd rpng nhdng khdng lien tuc, be day thay ddi td 1,20m den 10,80m, bd day trung binh la 5,52m.
Kieu thach hpc san sdi: Thanh phan thach hpc la san sdi, kieu thach hpc nay khdng Id ra tren be mat dja hinh, ton tai dddi dang thau kinh. Be day thay ddi td 0,80m den 1,90m, be day trung binh la 1,35m.
Phdc he thach hgc nguon gd'c sdng tudi Pleistocen trung thddng (d'^Q'').
Phdc he thach nay phan bd tren dien rdng.
Id ra d trung tam va phfa B i c cua v i i n g , phu true tiep len phdc he thach hpc a ^ Q , " , phfa Tay va phfa Nam bi phdc he thach hpc a'^"Q,^ va phdc be thach hpc a^Q,^ phii true tiep len. Phdc he thach hpc nay bao gdm cac kieu thach hpc set pha, set, cat pha, set pha l i n san, l i n san laterit, set l i n san, l i n san laterit va cat pha l i n san. Theo ket qua khoan khao sat thi trong phdc he thach hpc nay bao gdm 4 cap be day la
< 2m, 2 - 5 m , 5 - 10m v a > 10m.
Kieu thach hpc set pha: Thanh phan thach hpc la set pha mau xam t r i n g , nau v a n g , nau dd, trang thai deo cdng den cdng. Kieu thach hpc nay phan bd rpng, be day thay ddi td 0,80m den 12,50m, be day trung binh la 3,81m.
Kieu thach hpc set: Thanh phan thach hpc la set mau xam t r i n g , nau vang, nau dd, trang thai deo mem den cdng. Kieu thach hpc nay phan bd rdng va khdng Id ra tren be mat dia hinh. Be day thay ddi td 0,80m den 10,50m, be day trung binh la 4,90m,
Kieu thach hpc cat pha: Thanh phan thach hoc la cat pha mau xam den, xam t r i n g , trang thai deo den cdng. Kieu thach hpc nay phan b d rpng nhung khdng lien tuc trong vung. Be day thay ddi td 0,80m den 10,50m, be day trung binh la 2,62m.
Kieu thach hpc set lan san, l i n san laterit:
Thanh phan thach hpc la set l i n san, l i n san laterit mau vang, xam nau, nau d d , trang thai nda cdng den cdng. Kieu thach hpc nay phan bd khdng lien tuc, be day thay ddi td 0,20m den 3,50m, be day trung binh la 2,03m.
Kieu thach hpc set pha l i n san, l i n san laterit: Thanh phan thach hpc la set pha l i n san, l i n san laterit mau xam t r i n g , nau vang, nau dd, trang thai deo mem den cdng. Kie'u thach hpc nay khdng Id ra tren be mat dja hinh, phan bd khdng lien tuc va tdn tai dddi dang thau kfnh. Be day thay ddi td 0,80m den 5,50m, be day trung binh la 2,52m,
Kieu thach hpc cat pha l i n san: Thanh phan thach hpc la cat pha l i n san mau xam t r i n g , ddm vang, trang thai deo. Kieu thach hpc nay khdng Id ra tren be mat dia binh va chi b i t gap tai vj trf Id khoan TX4 vdi be day 1,50m,
Phdc he thach hgc nguon gdc sdng tudi Pleistocen trung thddng (a^Qf').
Phdc he thach nay phan bd tren dien rpng, bi phdc he thach hpc a''"Q,'"'phLi trpc tiep len.
Phdc he thach hpc cd mpt kieu thach hpc cat min, trung, thd l i n san.
Kieu thach hpc cat mjn, trung, thd l i n san:
Thanh phan thach hpc la cat mjn, trung, thd l i n san mau vang, xam t r i n g , trang thai rdi den chat. Kieu thach hpc nay phan bd rpng, be day thay ddi td 1,80m den 16,00m, be day trung o
28 • Tap san KHOA HOC ft CONG NGHE
us- binh la 7,75m.
Phdc he thach hoc nguon gd'c sdng tudi Pleistocen ha (a'^Q,').
Phdc he thach nay phan bd d phfa Ddng nam ciia viing vdi dien tfch khoang 3km^
khdng Id ra tren be mat dja hinh va bj phdc he thach hpc a'^'Q,'' phiJ trdc tiep len, Phdc be thach hpc nay gdm hai kieu thach hpc la set va catpha.
Kieu thach hpc set: Thanh phan thach hpc la set mau xam vang, tring loang id, trang thai cdng. Trong pham vi viing thi xa Tay Ninh hau het cac lo khoan chda khoan vao Idp nay. Tfnh den dp sau khao sat kieu thach hpc nay cd be day thay ddi td 0,20m den 3,50m, be day trung binh la 1,40m.
Kieu thach hpc cat pha: Thanh phan thach hpc la cat pha mau xam vang, ddm t r i n g , trang thai cdng. Trong pham vi viing thj xa Tay Ninh kieu thach hpc nay chi bat gap tai vj trf lo khoan DT14vdibeday6,20m,
- Loat thach hgc magma xam nhap:
Thanh tao magma duy nhat trong viing la cac da xam nhap thudc phdc he Dinh Quan (Di, GDi/K,dq), Chung Id ra d khu vUc niii Ba Den gdm 2 pha xam nhap chfnh va 1 pha da mach.
Cac thanh tao magma xam nhapcd dac tinh cdng c h i c , it ndt ne, hien dang ddpc khai thac lam vat lieu xay ddng, Tuy cd kha nang chju tai trpng cao nhdng dien phat trien cac thanh tao nay ft thfch hdp de lam nen thien nhien cho cac cdng trinh xay ddng vi be mat cd dp ddc Idn,
Ket luan: Trong pham vi anh hddng cua mdng cac cdng trinh xay ddng va nen dat (0- 30m) cac thanh tao dat da ddpc phan chia thanh 4 loat thach hpc la loat thach hpc deluvi, loat thach hpc sdng - dam lay, loat thach hpc sdng va loat thach hpc magma xam nhap va dddc chia thanh 9 phdc he thach hpc. Cac phdc he thach hpc dddc chia ra 21 kieu thach hpc.
Kieu thach hpc biin set dai dien cho phdc he thach hpc ngudn gdc sdng - dam lay tudi Holocen (ab°Q2) cd cac tfnh chat cd ly chu yeu:
khdi Iddng the tfch = 1,571g/cm^ gdc ma sat trong = 6°08', ldc dfnh ket C= 0,095kG/cm'.
Kieu thach hpc cat pha dai dien cho phdc he thach hpc ngudn gdc sdng tudi Holocen (a^'^Qj)
cd cac tfnh chat cd ly chu yeu: khdi Iddng the tich = 1,87g/cm^ gdc ma sat trong - 15°33', ldc dfnh ket C= 0,071 kG/cm'.
Kieu thach hpc set pha dai dien cho phdc he thach hpc ngudn gd'c sdng tudi Pleistocen thddng (a^"Q,^) cd cac tfnh chat cd ly chii yeu:
khdi Idpng the tfch = 1,96g/cm^ gdc ma sat trong = 16°49', ldc dfnh ket C= 0,201 kG/cm'.
Kieu thach hpc cat l i n san sdi dai dien cho phdc he thach hpc ngudn gdc sdng tudi Pleistocen thddng (a^Q,^) cd cac tfnh chat cd ly chii yeu: khdi Idpng the tfch = 1,89g/cm^ gdc ma sat trong = 25°57', ldc dfnh ket 0=
0,049kG/cm'.
Kieu thach hpc set pha dai dien cho phdc he thach hpc ngudn gdc sdng tudi Pleistocen trung - thddng (a™Q,'') cd cac tfnh chat cO ly chu yeu: khdi Iddng the tfch = 1,93g/cm^ gdc ma sat trong = 19°07', ldc dfnh ket C=
0,257kG/cm',
Kieu thach hpc set dai dien cho phdc he thach hpc ngudn gdc sdng tudi Pleistocen trung - thUdng (a™Q,^"^) cd cac tfnh chat cd ly chii yeu: khdi IdPng the tfch - 1,99g/cm^ gdc ma sat trong = 16°07', ldc dfnh ket C=
0,374kG/cm'.
Kieu thach hpc cat l i n san sdi dai dien cho phdc he thach hpc ngudn gdc sdng tudi Pleistocen trung - thupng (a^Q,''^) cd cac tinh chat cd ly chu yeu: khdi Iddng the tfch = 1,89g/cm', gdc ma sat trong = 26°32', ldc dfnh ke'tC=0,111kG/cm'.
Kieu thach hpc cat pha dai dien cho phdc he thach hpc ngudn gdc sdng tudi Pleistocen ha (a'^Q,') cd cac tfnh chat cO ly chu yeu: khdi Idpng the tich = 1,99g/cm^ gdc ma sat trong = 27°04', ldc dfnh ket C= 0,300kG/cm'.
Nhin chung phan Idn dien tfch nghien cdu cd cau tnic da't nen va tfnh chat cP ly ciia da't da thuan Ipi cho viec dat mdng xay ddng cdng trinh. Trd vai khu vdc hep ven rach Tay Ninh cd phan bd Idp da't yeu va sdc chju tai nhd. Tuy nhien be day nhd nen kbi xay ddng cd the gia cd mdng hoac sd dung Idp da't tiep theo lam tang chiu ldc chfnh cbo cdng trinh. •
