CHAPTER 3 GROUTING FILLING VOIDS TO PREVENT EXCESSIVE SETTLEMENT GROUTING MAY BE USED IN THE FOLLOWING APPLICATIONS: FILLING VOIDS TO PREVENT EXCESSIVE SETTLEMENT TO INCREASE ALLOWABLE PRESSURE OF THE SOIL BOTH FOR NEW STRUCTURES AND / OR ADDITIONS TO EXISTING STRUCTURES. CONTROL OF GROUNDWATER FLOW PREVENTION OF LOOSE - LOOSE TO MEDIUM SAND DENSIFICATION UNDER ADJACENT STRUCTURES (I.E. BOTH FOR VERTICAL AND LATERAL MOVEMENTS) DUE TO ADJACENT EXCAVATIONS, PILE DRIVING ETC. GROUND MOVEMENT CONTROL DURING TUNNELING OPERATIONS

SOIL STRENGTHENING TO REDUCE LATERAL SUPPORT REQUIREMENT SOIL STRENGTHENING TO INCREASE LATERAL AND VERTICAL RESISTANCE OF PILES. STABILIZATION OF LOOSE SANDS AGAINST LIQUEFACTION FOUNDATION UNDERPINNING SLOPE STABILISATION VOLUME CHANGE CONTROL OF EXPANSIVE SOILS THROUGH PRESSURE INJECTION OF LIME SLURRY (ONLY FOR SOME EXPANSIVE SOILS NOT ALL) THREE WAYS OF INTRODUCING GROUT MATERIAL INTO THE SOIL ARE POSSIBLE: A. PERMEATION GROUTING :GROUT FILLS THE SOIL PORES. ESSENTIALLY NO CHANGE IN THE VOLUME OR STRUCTURE OF THE ORIGINAL GROUND. B. DISPLACEMENT OR COMPACTION GROUNTING C. HYDRAULIC FRACTURE OR ENCAPSULATION OR SQUEEZE GROUTING

GROUTS DISPLACEMENT OR COMPACTION GROUTS : STIFF, LOW SLUMP (0-5 CM) MIXTURES OF CEMENT, SOIL, AND / OR CLAY AND WATER LIME SLURRIES ARE MOST COMMONLY USED IN ENCAPSULATION GROUTING

IN WATER / CEMENT GROUTS w/c= 0.5/1 – 6/1 HAVE BEEN USED. IF 0.5/1 RATIO IS USED STRENGTH WILL BE HIGHER BUT IT WILL BE HARDER TO INJECT. SEGREGATION AND FILTERING WILL BE LESS. CHEMICALS (LIKE CALCIUM LIGNOSULFONATE) ARE ADDED TO CONTROL FLUIDITY AND PENETRATION AND SETTING TIME (30 sec -- VERY LONG) AND PLASTISIZERS TO PREVENT FLOCCULATION.

IN SOIL / CEMENT GROUTS, VOLUMES OF SOIL 4-6 TIMES THE VOLUME OF CEMENT ARE MOST COMMON ALTHOUGH RATIOS FROM 1 TO 12 HAVE BEEN USED. VOLUME OF THE MIXING WATER VARIES FROM ABOUT 3/4 - 2 TIMES THE VOLUME OF CLAY PER BAG CEMENT IN CEMENT-CLAY GROUTS. VOLUME OF THE MIXING WATER VARIES FROM 1/3-1 TIMES THE LOOSE VOLUME OF SAND PER BAG OF CEMENT IN CEMENT - SAND GROUTS GENERALLY MINIMUM WATER CONTENT WHICH WILL STILL YIELD AN INJECTABLE UNXIUIE IS USED. SULFATES AND SULFATE BEARING GROUND WATER ARE THE ENEMY OF CEMENT. PARTICULATE GROUTS CANNOT BE INJECTED AS PERMEATION GROUTS INTO SOILS FINER THAN MEDIUM TO COARSE SANDS. THIS APPROXIMATELY CORRESPONDS TO A PERMEABILITY OF ABOUT 5x10-4 cm/sec.

AREAS OF USE : CEMENT GROUTS : FOR BOTH IMPERMEABILISATION AND STRENGTH INCREASE SOIL, CLAY AND CHEMICAL GROUTS : IMPERMEABILISATION AND COMPACTION GROUTING CLAY GROUTS : LIMITED USE (USUALLY FILLING VOIDS ETC) CLAY-CEMENT GROUTS : FILLING VOIDS, MUDJACKING

TYPES I AND II PORTLAND CEMENT ARE SUITABLE FOR SOILS COARSER THAN 0 TYPES I AND II PORTLAND CEMENT ARE SUITABLE FOR SOILS COARSER THAN 0.60 mm. TYPE III PORTLAND CEMENT IS SUITABLE FOR SOILS COARSER THAN 0.42 mm. (BENTONITE: 0.25 mm) ACCORDING TO CARON, PARTICLES 50 micron SIZE CAN BE INJECTED TO COARSE SAND (> 0.8 mm). COLLOIDAL SUSPENSIONS CAN BE INJECTED INTO MEDIUM SAND ( 0.1 TO 0.8 mm). FINE SANDS & SILTS REQUIRE NEWTONIAN SOLUTIONS OF LOW VISCOSITY. THE ABILITY OF PARTICULATE GROUTS TO PENETRATE A FORMATION IS OFTEN INDICATED IN TERMS OF A GROUTABILITY RATIO. SOME GROUTABILITY RATIOS THAT HAVE BEEN PROVEN USEFUL ARE GIVEN BELOW:

GROUTING CONSISTENTLY POSSIBLE GROUTING NOT POSSIBLE FOR ROCKS GROUTING POSSIBLE NOT POSSIBLE

SOILS CONTAINING < 10 % FINES ARE USUALLY PERMEATION GROUTED WITH CHEMICALS. IF FINES CONTENT > 15 % EFFECTIVE CHEMICAL GROUTING MAY BE DIFFICULT, FOR FINES CONTENT > 20 % PERMEATION GROUTING WILL NOT BE POSSIBLE BUT CHEMICAL GROUTS NOT BE DISTRIBUTED ALONG AND THROUGH HYDRAULIC FRACTURES. Fig 3.3 Modulus of Deformation versus qu

STRUCTURAL CHEMICAL GROUTING IS QUITE POPULAR. USE OF HIGH POLYMERS IN JAPAN IS FORBIDDEN OFTEN THE ACCIDENT IN 1974 AS A RESULT OF INJECTION OF ACRYLAMIDES (GROUNDWATER POLLUTION EVEN IN THE USE OF SILICATES PH VALUE OF GROUND WATER AROUND INJECTION POINTS IS REQUIRED TO BE <8.6. THUS, NEW NON-ALKALINE SILICATE GROUTS HAVE BEEN DEVELOPED. THESE CONSIST OF SILICA - SOL SOLUTIONS WITH PH VALUE OF 1 TO 2. STRUCTURAL CHEMICAL GROUTING IS QUITE POPULAR. Fig 3.4 Various Structural Grouting Applications

COMPACTION GROUTING THE FOLLOWING ARE IMPORTANT IN COMPACTION GROUTING LAYOUT OF HOLES IN NUMBER LOCATION OF HOLES & INCLINATION DEPTH SEQUENCE OF HOLES GROUTED PROCEDURE OF GROUTING INDIVIDUAL HOLE

TYPICAL APPLICATION DETAILS ARE : MIN DISTANCE TO THE SURFACE TRIANGULAR PATTERN USUALLY, 1.5 - 5 M SPACING PRIMARY (~5 M) / SECONDARY HOLES, GROUT TAKES HOLES UNDER FOUNDATIONS, RATHER THAN OPEN AREAS; PERIPHERAL HOLES FIRST < # 200 % 10 - % 30, SAND IN COMPACTION GROUTING 100% PASSING NO.8 SIEVE, A COARSER SAND WILL CAUSE WATER TO BE DRIVEN OUT. PORTLAND SAND, FINE SAND AND WATER % 12. CEMENT $ 2800 KN/M2 GROUT PRESSURES 0-4200 kN/m2

TWO BASIC METHODS FOR CONSTRUCTION: 1 . FROM TOP TO DOWN 2. FROM UP TO BOTTOM GROUTING IS DONE IN STAGES, ONLY 0.75 - 1.0 m OF HOLE IS GROUTED AT A TIME.

PROCEDURE FOR GROUTING FROM TOP TO BOTTOM DRILL A HOLE TO THE TOP OF THE ZONE (MIN. 1.5 M) INSERT A CASING IN THE HOLE AND FILL THE ANNULAR SPACE BETWEEN THE CASING AND THE HOLE WITH QUICK SETTING CEMENT. DRILL THROUGH TIE CASING AND ADVANCE THE HOLE 1-2.5 m. NEVER EXCEED 3-3.5 METERS. PUMP IN GROUT UNTIL THERE IS "REFUSAL" OR SLIGHT MOVEMENT OF THE GROUND SURFACE. REPEAT THE PROCEDURE (ITEMS 3 AND, 4) AFTER HARDENING OF THE PREVIOUSLY PLACED GROUT UNTIL THE BOTTOM OF THE ZONE TO BE STABILIZED IS REACHED.

PROCEDURE OF GROUTING FROM BOTTOM TO UP: DRILL A HOLE TO THE BOTTOM OF THE ZONE TO BE STABILIZED PLACE CASING TO WITHIN A METER OF THE BOTTOM OF THE HOLE.THE CASING SHOULD BE A SNUG FIT AND MAY REQUIRE PUSHING OR DRIVING INTO PLACE. SOMETIMES IT IS DRIVEN ENTIRELY (i.e. PREDRILIING ELIMINATED) PUMP IN THE GROUT UNTIL 'REFUSAL' IS ACHIEVED (OR SLIGHT) RAISE THE CASING PUMP AGAIN AND REPEAT 4 AND 5 UNTIL THE GROUND SURFACE IS REACHED.

TOP-DOWN METHOD IS MORE EXPENSIVE BUT THERE ARE SUBSTANTIAL ADVANTAGES : GREATER TAKE OF GROUT PER HOLE AND MORE EFFECTIVE, HIGHER PRESSURES MAY BE USED WHEN GOING DEEPER. IN PROBLEM SOILS EXTEND TO THE SURFACE FROM TOP TO DOWN IS ESSENTIAL. PLOT 'TAKES' TO CONTROL THE RELATIVE SOIL CONDITIONS CONTROL OF PUMPING RATE IS THE MOST IMPORTANT CONSIDERATION OF GROUTING TECHNIQUE. MAX. PRESSURE DEVELOPED AND QUANTITY OF GROUT INJECTED DEPEND ON PUMPING RATE

RAPID PUMPING IS ECONOMICAL BUT IT CAUSES PRESSURE BUILD UP AND EARLY RAISING OR RUPTURE OF THE OVERLYING SOIL. THEREFORE LIMIT THE GROUT QUANTITY INJECTED AND AMOUNT OF DENSIFICATION. THEREFORE APPROPRIATE PUMPING RATE IS BASICALLY DEPENDENT ON THE AMOUNT OF PRESSURE AND RATE OF PRESSURE BUILD UP WHICH ARE INFLUENCED BY ;SOIL TYPE, DEGREE OF COMPACTION, MOISTURE CONTENT,DEPTH OF INJECTION, CONFINING SOIL AND STRUCTURAL PRESSURE. IN MOST MIXED SOILS BEGINNING RATE WILL BE ON THE ORDER OF 0.3 m3/min. 3 -5 m3/min IS APPLIED IN VERY LOOSE SOUS AND SOILS WITH LARGE VOIDS. 0.003 -0.014 m3/min IS USED IN UNDRAINED CLAYS AND HIGHLY PLASTIC CLAYS. PRESSURES : 350 KPA - 1700 KPA WITHIN 1.5 - 2 M OF THE SURFACE AND UP TO 3500 kPa OR MORE WHEN D > 6 M, SELDOM > 4200 kPa EXCEPT OPEN THE TIGHT HOLE (7000 kPa).

COMPARISON BETWEEN JET GROUTING METHODS CCP JSG CJG SSS-MAN GROUTING PRESSURE(MPa) 20 40 20-70 TYPE OF SUSPENSION CEMENT WATER AIR PROTECT CEMENT-WAT. WATER AIR. WATER MIXTURE TYPE JET SEMI-DISP. FULL DISPLACEMENT DIAMETER OF (mm) 1.2 3-3.2 1.8-2.3 2.O-2.8 VELOCITY(r/s) 0.33 0.10 0.08 0.05-0.12 COLUMN (m) 0.8 2.0 3.0 3.5 SOIL EXC.GRAVEL ALL EXC. GRAVEL