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Recent content by sango

  1. sango

    Mine tunneling in soft ground

    Dear all, Please kindly advise what are the common sizes of forpole umbrella for mine tunnelling in soft ground? Thanks.
  2. sango

    Permanent and Initial Ground Support for Tunnel Excavation

    Dear all, By using estimated Q-values and empirical design chart proposed by Barton (1993), spacing of rock bolts, length of the bolts and thickness of shotcrete (unreinforced or reinforced) for ground supporting of a tunnel can be determined. My questions are: (1) How to determine size of...
  3. sango

    Permeability of lined tunnel

    Dear lha, You are right. The permeability of joint without gasket is much higher than the concretre section. Having such arrangement is to allow the liner behaving in "semi-drained" condition, in which water can be drained throught the joints. In my case, dewatering is not a concern and the...
  4. sango

    Permeability of lined tunnel

    Dear all, Any information on the permeability of segmental concrete lining that without gasket in the connections. Thanks.
  5. sango

    Design groundwater of rock tunnel

    It is a deep rock tunnel underground of about 200m. Desk studies find out there is no major water source above the tunnel. Packer tests have been carried out to determine the permeablity of the rock mass. (1) What is the next step to predict the inflow in rock during tunneling? I know there is...
  6. sango

    Design groundwater of rock tunnel

    Dear all, I am preparing a rock tunnel lining design. The tunnel is proposed to be drilled through hilly region which is far above the sea level. I think the groundwater in rock is mainly come from rainfall. As it is a preliminary design, no groundwater monitoring is carried out. I assume a...
  7. sango

    Drained and undrained shear strength of clay for shoring design

    Thx. xixia, Would u pls tell me the details and the reference of the emperical relationship as u suggested. I know there is a correlation between the ratio of undrained shear strength of N.C. clay (cu) and effective vertical stress (v') to plasticity index (Ip)as proposed by Skempton. Cu/v'...
  8. sango

    Drained and undrained shear strength of clay for shoring design

    Thx. DRC1. Yes, I agree with u. For N.C. clay, positive pore water pressure will built up during shearing and short term effect for the design is more critical. But, suction in O.C. clay will dissipate with time and long term effect controls the design. My next question is: If loading...
  9. sango

    Drained and undrained shear strength of clay for shoring design

    Dear all, Why undrained strengths (or total stress approaches) instead of drained strengths (or effective stress approaches)are adopted in shoring design in CLAY? How does drained and undrained shear strength of clay affect the design of temporary or permanent sheetpile? which type of...
  10. sango

    Long Term Behaviour of Bangkok Clay

    Dear all, I am doing a finte difference numercial analysis on a lateral loaded piles in Bangkok Clay. I have carried out undrained analysis (short term stability checking?) that allows built up of excess pore water pressure. I need to study the long term stability, My questions are as...
  11. sango

    Why MD always overlying Alluvium

    Dear Members, I am an asistant geotechnical engineer in hong kong. I currently carry out ground investigation study in a reclamation area. It is reavelaed that Marine Deposit (MD), which in general composes of soft, greenish gray, CLAY, overlies Alluvium. Any reasons behind for this phenomenon?
  12. sango

    toppling failure

    Before considering whether need to perform further analysis, I think further information regarding the studying rock feature is required. Moreover, caution should be given to use of conventional stereographic analysis and generalised assumptions about joint sets, as the stereplots may obscure...
  13. sango

    Settlement analysis on reclamation area

    Dear all, I have a project regarding settlement analysis on reclamation region. The background of the study are: (1) Continous ground settlement was found over past 15 years. This was reviewed by records of settlement markers (nearest 5 years) and visual inspections on site. Settlement on...
  14. sango

    Design of tieback soldier pile wall

    Sorry for the unclear information. Let me clarify the situation. A large platform was proposed to form in a slope by excavtion. Therefore, a retaining wall in form of solider piles with tiebacks was constructed to facilitate the excavation. The soldier pile wall was retaining about 6.0m soil...
  15. sango

    Design of tieback soldier pile wall

    I had a site formation design on a sloping ground. The marjor construction activities including: (1) installation of soldier pile 1.5m c/c (2) carrying out excavation into stages with tieback and wailing installation. The soldier piles, wailing beams and tiebacks form a rigid frame system to...
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