**3. Geological and geotechnical parameters of the study**

The design of the tunnel was performed on the basis of a geological and geomechanical survey conducted from recent geotechnical survey includes the following investigations:


It noted that any study must lead to the acquisition of the following information with the maximum possible degree of reliability, considering the wide range of technical resources currently available in the geological survey field:

**3**

**Table 2.**

*Total-rating results.*

**Figure 2.**

**Table 1.**

*Design and Construction for Tunnel Face Stability: Theoretical and Modeling Approach*

• Structural geological and hydrogeological conditions and the natural stress

• The physical characteristics, the strength and deformability of the geological

Geology of the area crossed by the tunnel is essentially of Cretaceous age (Telliennes Tablecloths) and consists of marl and limestone in the form of strongly folded and sheared blocks (**Figure 2**). These are covered by Quaternary deposits

**N Parameters Coefficients Rating**

3 Spacing of discontinuities < 600*mm* 5

5 Groundwater Damp 10

Total rating 12.5

R0 (R0 0.1 < *MPa*) 0

6.5

(115–3.3Jv) 0–25 very poor 3

Digging against the dip −12

Slickensided surfaces; 3–10; 10–20; 0.1–5 > < 5 ; *mm* 5 mm; highly altered

*DOI: http://dx.doi.org/10.5772/intechopen.96277*

state of the ground to be tunneled;

bodies affected by the excavation:

consisting of clays, silts and conglomerates.

*Plan and geological section of the T4 tunnel and the collapse point.*

compression

(RQD)

discontinuities

discontinuity orientations

*Results according to the RMR classification system in the PK 230 + 586.5.*

Total rating <21 Class V

Average stand up time 30 min for 1 m span C « KPa » <100 ϕ °( ) <15 Description Very poor rock

1 Resistance to uniaxial

2 Rock Quality Designation

4 Conditions of

6 Rating adjustment for

• The hydrogeological conditions in the rock mass.

*Design and Construction for Tunnel Face Stability: Theoretical and Modeling Approach DOI: http://dx.doi.org/10.5772/intechopen.96277*


Geology of the area crossed by the tunnel is essentially of Cretaceous age (Telliennes Tablecloths) and consists of marl and limestone in the form of strongly folded and sheared blocks (**Figure 2**). These are covered by Quaternary deposits consisting of clays, silts and conglomerates.

#### **Figure 2.**

*Slope Engineering*

field on the Tunnel face.

**2. Case study. Djebel El Kantour tunnel**

construction technique for better estimation the vertical and longitudinal deforma-

T4 tunnel is located in the north-east of the department of Constantine. It crosses Djebel El Kantour from south to north with a total length of 2500 m. Its cover is higher than 15 m, and reaches 224 m in maximum points (**Figure 1**).

the structure and the service conditions during the constructions process.

**3. Geological and geotechnical parameters of the study**

• Geological surveys conducted by geologists' experts;

The design of the tunnel was performed on the basis of a geological and geomechanical survey conducted from recent geotechnical survey includes the following

It noted that any study must lead to the acquisition of the following information

• A recognition campaign by core drilling, in situ and laboratory tests.

technical resources currently available in the geological survey field:

with the maximum possible degree of reliability, considering the wide range of

The section of the tunnel was chosen according to the geometric characteristics, the geological and geotechnical data tests performed on the ground in question as well as the height of the cover. To take into account the natural conditions of the surrounding terrain, an arched profile has been adopted to ensure the stability of

To solve this problem, many techniques have been used to stabilize the face, but the technique did not yield the expected results. Therefore, the prime contractor applied a new technique called the Fiberglass Technique (FIT). However, it proved inadequate in this case, due to its high cost and the limited effectiveness. This is mainly due to the poor mastery of the excavation method, which in turn, was not suitable to this type of rocks. In this study, we try to demonstrate, via a numerical modeling tool, the relationship between the attack section and the deformation

tions, as well as the failure mechanisms to the front of the tunnel face.

**2**

investigations:

*Position of the tunnel T4.*

**Figure 1.**

*Plan and geological section of the T4 tunnel and the collapse point.*


#### **Table 1.**

*Results according to the RMR classification system in the PK 230 + 586.5.*


**Table 2.** *Total-rating results.* *Slope Engineering*


**Table 3.**

*Geotechnical parameters.*

The design of the tunnel was carried out on the basis of geological and geotechnical studies. The results of RMR classification are presented in **Table 1**.

The table below (**Table 2**) shows the value of the rock classification (Rock Mass ratings) determined after application of the Total rating.

In our case, the rocks are of marl-clay-sandstone type (**Table 3**).
