**4. Analysis and discussions**

be largely improved with the repetitive injection procedure, a total of 49 sleeve pipes were installed 5 m beyond the mat foundation. Their locations are depicted by solid grey circle in **Figures 7a** and **8a**. The spacing between the sleeve pipes was 2 m. The grout hose system of 1.5 shot with a quick setting grout (**Table 3**) was introduced to ensuring the compensation efficiency. Similarly, two stages of grouting were implemented; the first stage of sleeve

**O-3SiO2 Water**

**PR silica SG hardener Water**

**Cement Permarock PR actor Water**

**Cement Pulverised coal CaO Water**

**Figure 4.** Illustration of the proposed multiple and simultaneous grouting system.

110 Current Topics in the Utilization of Clay in Industrial and Medical Applications

Volume (L) 56.7 11 132.3

**Table 2.** Grout mixture with 2-s setting time for the jacking-up grouting (Case A).

**Na2**

Volume (L) 150 350

**Table 3.** Grout mixture with 25-s setting time for the stabilisation grouting (Case B).

Weight (kg) 100 ± 25 12.5 ± 2.5 5 ± 2 160

Weight (kg) 400 300 90 250

**A liquid (200 L)**

**B liquid (200 L)**

**A liquid (500 L)**

**B liquid (500 L)**

#### **4.1. Multiple and simultaneous grouting results**

The effectiveness of the proposed multiple and simultaneous grouting programme for the Case A was demonstrated using the measured column elevations from SB 1 to SB 7. The column elevation before each day grouting and the change in the column elevation after grouting were measured. **Figure 5** shows the relationship between the grout take and the change in the column elevation for this simultaneous and multiple jacking-up grouting. Most of grouts were injected into the southwest corner (SB 7), and the associated change in the column elevation measured 15.6 cm at the end of the grouting, as shown in **Figure 5**. Only a few grouts were injected into the northeast corner (SB3) and resulted in a nearly unchanged column elevation. The elevation change contour lines of the mat foundation were also prepared based upon the monitoring results of the column elevation change. The volume between the mat foundation contour lines before grouting and those after grouting represented the elevated volume of tilted building at the end of each day. Additionally, the volume between the mat foundation contour lines after grouting and those before next day grouting corresponded to the overnight settled volume of tilted building caused by the dissipation of excess porewater pressure resulting from previous grouting. Thus, both the elevated efficiencies defined by the ratio of the elevated volume to the injected grout volume and the settled efficiency defined by the ratio of the settled volume to the injected grout volume can be derived.

**Figure 6** shows the cumulative elevated, settled and injected grout volumes, respectively, against each grouting day of this jacking-up grouting. From day one, the elevated volumes were greater than the settled volumes for each grouting day, which indicated a benefit from the reaction block, resulting from the stabilisation grouting. In the event that the soils subjected to the stabilisation grouting are not satisfactorily strengthened and showed an inability of

while the elevated volume measured 3.2 m<sup>3</sup>

. The overnight settled volume measured 3.9 m<sup>3</sup>

**Figure 7.** (a) Contour lines of mat foundation before grouting of day one, (b) contour lines after grouting of day one, (c)

contour lines before grouting of day two and (d) compensation efficiency from day one (Case B).

equal to 5.5 m<sup>3</sup>

the elevated volume of 3.2 m<sup>3</sup>

, corresponding to the migrated volume being

, which indicated the compensation efficiency being negative.

however was greater than

113

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**Figure 5.** Relationship between the column elevation change and the grout take for the jacking-up grouting (Case A).

providing sufficient reaction force for levelling the tilted building, the final compensation efficiency may be negative as the resettlement overrides the ground heave. The results from the end of the jacking-up grouting showed that the elevated, settled and injected grout volumes measured 35.7, 3.9 and 134 m<sup>3</sup> , respectively, corresponding to the final compensation efficiency of 23.7% which is derived by subtracting the settled efficiency of 2.9% from the elevated efficiency of 26.6%. Upon the completion of the jacking-up grouting, this building initially tilted to the southwest at an angle of 1/68 was restored to the near level at an angle of 1/328 in 11 days.

**Figure 7** shows the elevated, settled and injected grout volumes, respectively, from day one of the jacking-up grouting for the Case B. The injected grout volume measured 8.7 m<sup>3</sup> ,

**Figure 6.** Variations of the elevated, settled and compensation efficiencies for the jacking-up grouting (Case A).

while the elevated volume measured 3.2 m<sup>3</sup> , corresponding to the migrated volume being equal to 5.5 m<sup>3</sup> . The overnight settled volume measured 3.9 m<sup>3</sup> however was greater than the elevated volume of 3.2 m<sup>3</sup> , which indicated the compensation efficiency being negative.

providing sufficient reaction force for levelling the tilted building, the final compensation efficiency may be negative as the resettlement overrides the ground heave. The results from the end of the jacking-up grouting showed that the elevated, settled and injected grout volumes

**Figure 5.** Relationship between the column elevation change and the grout take for the jacking-up grouting (Case A).

of 23.7% which is derived by subtracting the settled efficiency of 2.9% from the elevated efficiency of 26.6%. Upon the completion of the jacking-up grouting, this building initially tilted to the southwest at an angle of 1/68 was restored to the near level at an angle of 1/328 in 11 days. **Figure 7** shows the elevated, settled and injected grout volumes, respectively, from day one of the jacking-up grouting for the Case B. The injected grout volume measured 8.7 m<sup>3</sup>

**Figure 6.** Variations of the elevated, settled and compensation efficiencies for the jacking-up grouting (Case A).

, respectively, corresponding to the final compensation efficiency

,

measured 35.7, 3.9 and 134 m<sup>3</sup>

112 Current Topics in the Utilization of Clay in Industrial and Medical Applications

**Figure 7.** (a) Contour lines of mat foundation before grouting of day one, (b) contour lines after grouting of day one, (c) contour lines before grouting of day two and (d) compensation efficiency from day one (Case B).

Notwithstanding that, the normally consolidated clay owing to the repetitive injection procedure was likely to be changed to the slightly overconsolidated clay. This was verified through the positive compensation efficiency of 4.3% from day four where the elevated, overnight settled and injected grout volumes measured 7.5, 5.2 and 54.7 m<sup>3</sup> , respectively, as shown in **Figure 8**. The injection was subsequently suspended for 7 days to investigate how long it takes for the excess porewater pressure to dissipate. The results showed that it took 5 days to reach the cumulative settlement of 3.82 m<sup>3</sup> being almost identical to the elevated volume of 3.9 m<sup>3</sup> at day four, as shown in **Figure 9**. **Figure 10** shows the cumulative elevated, overnight settled, migrated and injected grout volumes, respectively, against each grouting day of this jacking-up grouting. The cumulative elevated volume surpassed the cumulative settled volume at day four, and from day four on, the cumulative elevated volume was greater than the cumulative settled volume for each grouting day. It is due to the fact that the higher the overconsolidated ratio, the lesser the soil compressibility, and the higher the final compensation efficiency. It is inferred that a sand deposit due to its lesser compressibility would provide better compensation efficiency than a clay deposit in general. The final compensation efficiency of 11.1% was derived by subtracting the final settled efficiency of 6.0% from the final elevated efficiency of 17.1%, as shown in **Figure 10**. This eight-storey building originally tilted to the southwest at an angle of 1/190 was restored to near level at an angle of 1/707 in 18 days.

#### **4.2. Lessons learnt**

Both the presented grout injection cases adopted two-stage grouting, that is, stabilisation grouting and jacking-up grouting. The results from the Case A showed that from day one on, the elevated volume was greater than the overnight settled volume for each grouting day, leading to the final compensation efficiency being equal to 23.7%. This eight-storey building originally tilted to the southwest at an angle of 1/68 was restored to near level at an angle of 1/328 in 11 days.

Compared to the Case A, the overnight settled volume from day one of this jacking-up grouting for the Case B measured 3.9 m<sup>3</sup> was greater than the elevated volume of 3.2 m<sup>3</sup> , leading to the compensation grouting being equal to −8.2%. The positive compensation grouting of 4.3% was first observed as the cumulative elevated volume of 7.5 m<sup>3</sup> from day four surpassed the cumulative overnight settled volume of 5.2 m<sup>3</sup> . From day four on, the cumulative elevated volume was greater than the cumulative overnight settled volume for each grouting day. The final compensation efficiency measured 11.1% was lower than 23.7% from the Case A, which was most likely due to the inappropriate grout hose system and adopted grout mixture. The use of two-shot grout hose system is not only to minimise the generation of the excess porewater pressure during soil hydrofracturing process but to prevent the negative compensation efficiency from occurring at early stage. Additionally, the shorter the setting time of grout, the lesser the excess porewater pressure generated, and the higher the compensation efficiency. Two-shot grout hose system along with extra quick setting grout may provide an access of achieving a higher final compensation efficiency for lifting of tilted building.

**Figure 8.** (a) Contour lines of mat foundation before grouting of day four, (b) contour lines after grouting of day four, (c)

Clay Grouting Mechanisms and Applications http://dx.doi.org/10.5772/intechopen.74091 115

contour lines before grouting of day five and (d) compensation efficiency from day four (Case B).

Notwithstanding that, the normally consolidated clay owing to the repetitive injection procedure was likely to be changed to the slightly overconsolidated clay. This was verified through the positive compensation efficiency of 4.3% from day four where the elevated,

shown in **Figure 8**. The injection was subsequently suspended for 7 days to investigate how long it takes for the excess porewater pressure to dissipate. The results showed that it took

overnight settled, migrated and injected grout volumes, respectively, against each grouting day of this jacking-up grouting. The cumulative elevated volume surpassed the cumulative settled volume at day four, and from day four on, the cumulative elevated volume was greater than the cumulative settled volume for each grouting day. It is due to the fact that the higher the overconsolidated ratio, the lesser the soil compressibility, and the higher the final compensation efficiency. It is inferred that a sand deposit due to its lesser compressibility would provide better compensation efficiency than a clay deposit in general. The final compensation efficiency of 11.1% was derived by subtracting the final settled efficiency of 6.0% from the final elevated efficiency of 17.1%, as shown in **Figure 10**. This eight-storey building originally tilted to the southwest at an angle of 1/190 was restored to near level at an angle

Both the presented grout injection cases adopted two-stage grouting, that is, stabilisation grouting and jacking-up grouting. The results from the Case A showed that from day one on, the elevated volume was greater than the overnight settled volume for each grouting day, leading to the final compensation efficiency being equal to 23.7%. This eight-storey building originally tilted to the southwest at an angle of 1/68 was restored to near level at an angle of

Compared to the Case A, the overnight settled volume from day one of this jacking-up grout-

to the compensation grouting being equal to −8.2%. The positive compensation grouting of

volume was greater than the cumulative overnight settled volume for each grouting day. The final compensation efficiency measured 11.1% was lower than 23.7% from the Case A, which was most likely due to the inappropriate grout hose system and adopted grout mixture. The use of two-shot grout hose system is not only to minimise the generation of the excess porewater pressure during soil hydrofracturing process but to prevent the negative compensation efficiency from occurring at early stage. Additionally, the shorter the setting time of grout, the lesser the excess porewater pressure generated, and the higher the compensation efficiency. Two-shot grout hose system along with extra quick setting grout may provide an access of

4.3% was first observed as the cumulative elevated volume of 7.5 m<sup>3</sup>

achieving a higher final compensation efficiency for lifting of tilted building.

was greater than the elevated volume of 3.2 m<sup>3</sup>

at day four, as shown in **Figure 9**. **Figure 10** shows the cumulative elevated,

, respectively, as

, leading

from day four surpassed

. From day four on, the cumulative elevated

being almost identical to the elevated

overnight settled and injected grout volumes measured 7.5, 5.2 and 54.7 m<sup>3</sup>

5 days to reach the cumulative settlement of 3.82 m<sup>3</sup>

114 Current Topics in the Utilization of Clay in Industrial and Medical Applications

volume of 3.9 m<sup>3</sup>

of 1/707 in 18 days.

**4.2. Lessons learnt**

1/328 in 11 days.

ing for the Case B measured 3.9 m<sup>3</sup>

the cumulative overnight settled volume of 5.2 m<sup>3</sup>

**Figure 8.** (a) Contour lines of mat foundation before grouting of day four, (b) contour lines after grouting of day four, (c) contour lines before grouting of day five and (d) compensation efficiency from day four (Case B).

**5. Conclusions**

building.

basin, the following conclusions can be drawn:

rity of their mat foundations.

**Acknowledgements**

**Conflict of interest**

**Author details**

Wen-Chieh Cheng

University of Technology are much appreciated.

Address all correspondence to: w-c.cheng@xauat.edu.cn

Xi'an University of Architecture and Technology, Xi'an, China

From the results of an application of the proposed multiple and simultaneous grouting programme for levelling up the two tilted buildings seated on the soft soil deposits in Taipei

Clay Grouting Mechanisms and Applications http://dx.doi.org/10.5772/intechopen.74091 117

**1.** Two-stage grouting was deemed to be necessary; the reaction block created from the first stage of grouting (the stabilisation grouting) was to provide the reaction forces required in the second stage of grouting (the jacking-up grouting) to level up the tilted

**2.** Two-shot grout hose system along with extra quick setting grout might be used not only to mitigate the generation of the excess porewater pressure during soil hydrofracturing process but to prevent the negative compensation efficiency from occurring at early stage.

**3.** The proposed multiple and simultaneous grouting programme gave an effective access of jacking the two tilted buildings back to near level without damaging the structural integ-

**4.** The final compensation efficiency of 11.1% from Case B lower than that from Case A was most likely due to the inappropriate grout hose system and grout mixture. The use of twoshot grout hose system led to a reduced amount of the excess porewater pressure generated during injection, leading to a higher compensation efficiency. The shorter the setting time of grout, the lesser the shrinkage of grout, and the higher the compensation efficiency.

Discussions and opinions exchange with retired Professor James C. Ni at National Taipei

The author declares there is no conflict of interests regarding the publication of this article.

Institute of Tunnel and Underground Structure Engineering, School of Civil Engineering,

**Figure 9.** Excess porewater pressure dissipation with time after grouting of day four (Case B).

**Figure 10.** Variations of the elevated, settled and compensation efficiencies for the jacking-up grouting (Case B).
