Grouting

ground improvement technique- grouting and its methods and applications

1. 1 GROUTING

2. 2 GROUTING Injection of a slurry or a liquid solution into a soil or rock formation The grout subsequently hardens - increases the strength and decreases compressibility and permeability .

3. MODES OF GROUTING 3 Permeation or Penetration- Grout flows into soil voids freely with minimal effect Compaction or Controlled displacement- Grout remains more or less intact as a mass and exerts pressure on soil Hydraulic Fracturing or Uncontrolled displacement- Grout rapidly penetrates into a fractured zone created when the grout pressure is greater than tensile strength of soil or rock

4. 4

5. 5 Grout Characteristics

6. Groutability 6 To obtain satisfactory performance, grain size distribution should be known because it shall show the relationship between the grout particle size and the void dimensions. Pumping pressure should not be large enough for particles of soil to be disturbed. Grouting pressure is limited to 20 kN/m 2 Quality of a grout must be sufficiently fluid to enter the soil quickly The movement should not be too fast Rate of injection of a grout depends on Viscoity of the grout Permeability of soil Shear strength of soil

7. 7 Desirable properties of grout Suitable viscosity High Viscosity for Coarse and Moderately Permeable soils Low Viscosity for Fine grained soils of low permeability Correct setting time Max. Volume with minimum weight Strength Stability Durability

8. Groutability Ratio D 15 = Particle size at which 15% of the soil is finer D 85 = Particle size at which 85% of the grout is finer 8

9. 9 Stability Capacity of grout to remain in a fluid state and not segregate into separate components Setting Time Time required for the grout to set into cemented mass or gel Early setting causes difficulty in the grout reaching its destination Late setting causes the grout being washed away if seepage is occuring through soil Permanence Resistance the grout possesses against being displaced from the soil voids with time Toxicity Capacity of grouts to contaminate the grout water coming in contact with it.

10. GROUT MATERIALS 10 Suspensions – Grout particles in suspension in a liquid medium- Cement+ Water, Clay etc Emulsions – Minute droplets of liquid in suspension- Asphalt or bitumen with water Solutions – Liquid homogenous mixture of two or more materials- Chemical Grouts

11. SUSPENSION GROUTS- GROUTING WITH SOIL GR > 20 Soil can be used to fill up voids in coarse grained soils Soil used as grout- very fine grained Clay grouts – to reduce permeability Kaolinite and Illite based clays – low viscosities – filler grouts Bentonite – to control viscosity strength and flow properties Mud jacking – to raise pavement slabs and to underpin shallow building foundations

12. SUSPENSION GROUTS- GROUTING WITH CEMENT Uitable for cracks or voids wider than 0.2 mm Usually formed from OPC and Water Water cent ratio – 0.5:1 to 5:1 Rapid hardening cement – prefered in ground with flowing water Super sulphated cement – for fissured rocks Admixtures such as bentonite used to keep the cement particles in suspension Seepage cut off beneath dams, ground water control

13. EMULSION GROUTS – ASFALT EMULSION Anionic or cationic asphaltic globules are manufactured by choosing proper emulsifying agent The globules (1 to 2 µm dia ) along with water used as grout to fill soil voids and rock fissures Rock fissues of 10 µm size and medium silts can be grouted Slow setting emulsions generally chosen – they can travel longest distnce into the material

14. 14 SOLUTION GROUTS – CHEMICAL GROUTING Chemical grouts like silicates and acrylic resins Solidify by chemical reaction Seepage barriers, stabilisation of soils around tunnels Principle of injection-permeation grouting

15. 15

16. GROUTING SYSTEMS- ONE SHOT & TWO SHOT 16

17. 17

18. Grouting Procedure 18 Depending on the material to be grouted (Rock, natural soil or fill), its quality and the purpose of grouting, a well planned procedure has to be adopted to attain the desired result Ground Investigation Grout Holes pattern Grouting Plant and Equipment Grouting sequence Grouting methods

19. 19 Ground Investigation Provides information regarding the ground- whether it can be grouted or not Choice of grouts-type and amount Include a geological survey, Drilling boreholes, Collection of samples for laboratory tests

20. Grout Holes Pattern 20 Based on the nature of work, the number of drill holes, depth and pattern to be decided Follows a grid pattern such that radius of penetration is sufficient to cause slight overlapping between adjacent holes

21. Grouting Plant and Equipment 21 Measuring Tank – To control the volume of grout injected Mixer – To mix grout ingredients Agitator – To keep solid particles in suspension until pumped Pump – To draw the grout from the agitator to deliver to the pumping line Control fittings – To control the injection rate and pressure so that the hole can be regularly blend with water and thin grout Piping connected to grout holes

22. 22

23. 23

24. 24

25. GROUTING SEQUENCE

26. 26 GROUTING METHODS

27. Permeation Grouting 27 Grout fills the pores without any volume changes. Include Cement grouts, bentonite grouts and chemical grouts. Grouting into an open hole in self-supporting ground through pipes at the surface through an injection pipe held in place in the hole or casing by a packer. From a pipe driven into the ground and withdrawn as injection proceeds Through a pipe left in place in the ground as with a tube

28. 28 Permeation Grouting

29. 29 Grouting Plant for permeation grouting

30. Applications of Permeation G routing 30 Seepage Control For making vertical seepage barriers beneath hydraulic structures Stoppage of seepage through joints of underground structures such as tunnel lining/ basement wall, etc. Soil Solidification and Stabilization For stabilization of soil around tunnels and shafts

31. 31 Compaction grouting A good option if the foundation of an existing building requires improvement, since it is possible to inject the grout from the side or at an inclined angle to reach beneath the building A bulb shaped grouted mass is formed. Soil-cement grout Can be performed as pretreatment before the structure is built

32. Applications of Compaction Grouting 32 Densification of loose stratum i ) underlying dense soil ii) beneath foundations or floor slab-slab jacking Filling of large underground cavities Densification of collapsible soils Densification of soils showing organic degradation

33. 33 Jet Grouting Involves the injection of low viscosity liquid grout into the pore spaces of granular soils. This creates hardened soils to replace loose liquefiable soils Jet grouting is used as replacement technique, in which soils ranging from silt to clay and weak rocks can be treated This method consists of lowering a drill pipe into a 150 mm dia bore hole The drill pipe is specially designed which simultaneously conveys pumped water, compressed air and grout fluid. Three systems of jet grouting Single, Double & Triple

34. 34 Systems of jet grouting

35. Sequence in Single Jet Grouting 35

36. Triple Jet Grouting 36 At the bottom end of the pipe two nozzles are provided at 500 mm apart. The upper nozzle (1.8 mm diameter) delivers water surrounded by a collar of compressed air to produce a cutting jet. The grout is delivered through the lower nozzle (7 mm dia )

37. Triple Jet Grouting Method 37

38. Schematic diagram for Triple Jet Grouting 38

39. Applications of Jet Grouting 39 Groundwater control Movement control Support Environmental

40. Ground Water Control 40 Preventing flow either through the sides or into the base of an excavation Controlling groundwater during tunneling Preventing or reducing water seepage through a water retention structure such as a dam or flood defence structure Preventing or reducing contamination flow through the ground

41. Movement Control 41 Prevention of ground or structure movement during excavation or tunnelling Supporting the face or sides of a tunnel during construction or in the long term Increasing the factor of safety of embankments or cuttings Providing support to piles or walls to prevent or reduce lateral movement

42. Support 42 Underpinning buildings during excavation or tunnelling Improving the ground to prevent failure through inadequate bearing Transferring foundation load through weak material to a competent strata

43. Environmental 43 Encapsulating contaminants in the ground to reduce or prevent contamination off site or into sensitive water systems Providing lateral or vertical barriers to contaminant flow Introducing reactive materials into the ground to treat specific contaminants by creating permeable reactive barriers

44. Circuit Grouting 44 Based on the principle of grouting from the top downwards. A drill hole is bored to the depth of the bottom zone and grout is pumped down the grout pile and returned up the drill hole.

45. Point Grouting 45 In shallow work of 10 to 12 m deep the grout is injected from the points of a driven or jetted lance. Injections are delivered at pre-determined positions along the line of drive and also on the return in systems where a second reacting grout ingredient is to be placed independently of the initial injection.

46. Electrokinetic Injection 46 Stabilization of silty soils may not be possible by chemical or admixture perhaps because of lack of confinement or the necessity to avoid disturbance of the ground. Chemical stabilizers are introduced at the anode and carried toward the cathode by electro-osmosis. Direct current electrical gradients of the order of 50 to 100 Volts/m are required.

47. 47 Soil Fracture Grouting Root-like zones of grout material is formed in the soil mass Sleeved pipe grouting technique is used Used for restoration of verticality of a tilted building

48. 48

49. 49 Grouting arrangements Curtain grouting

50. 50 Blanket grouting

51. General Applications of Grouting 51 Seepage Control For making vertical seepage barriers beneath hydraulic structures Stoppage of seepage through joints of underground structures such as tunnel lining/ basement wall, etc. Soil Solidification and Stabilization For stabilization of soil around tunnels and shafts Vibration Control Chemical grouting through machine foundation soil will alter the elastic properties of the soil and results in increased rigidity of the base resulting in decrease of amplitudes.

52. 52 Seepage Control

53. 53

54. 54

55. 55 Soil Solidification and Stabilization

56. 56

57. 57

58. 58

59. 59

60. 60

61. 61

62. 62

63. 63

64. 64

65. 65

66. Using soil fracture grouting 66