**7.10 Test methods**

Two samples of rock (length = 91–103 mm, diameter = 41–44 mm) were tested from each site under different constant axial pressures and different static pressure pressures for approximately 300 h. The experimental procedure follows the ASTM standard (ASTM D4406-93). The compression machine (fusion machine, 5000 kN) is used to apply the fixed axial load to the samples. Rock samples were placed in a three-axis cell (GDS) to provide constant confining pressure (**Figure 18**). The collected sample (Test # 1) of Catacomb of Kom El-Shoqafa is immediately loaded to the axial stress required at 1.45 MPa to limit the pressure by 225 kPa, and the applied axial stress was adjusted twice: the initial applied pressure was increased to 1 = 2, 17 MPa (+50%) after 98 h (2) then increased to σ1 = 2.53 MPa (+74%) after 125 h (3). The number in brackets refers to **Figure 18**, which displays the strain versus the time curve. Where the axial stress of up to 1.45 MPa and inventory pressures 510 kPa. Axial stress was not adjusted until the test ends after 200 h with steady-state creep with a small stress rate and without sample failure.

**Figure 20.**

**Figure 21.**

**Figure 22.**

**37**

*Strain versus time during the catacomb of Kom El-Shoqafa, triaxial creep test no. 2.*

*Uniaxial and Triaxial Creep Performance of Calcarenitic and Sandy Oolitic Limestone…*

*DOI: http://dx.doi.org/10.5772/intechopen.91720*

*Strain versus time curve during El-Shatby Necropolis, triaxial creep test no. 1.*

*Strain versus time during El-Shatby Necropolis, triaxial creep test no. 2.*

#### **Figure 18.**

*Triaxial creep test device, with constant axial load under confining pressure. Triaxial creep test device. The cylindrical specimen placed inside (GDS) cell is loaded vertically using the compression machine.*

**Figure 19.** *Strain versus time during the catacomb of Kom El-Shoqafa, triaxial creep test no. 1.*

*Uniaxial and Triaxial Creep Performance of Calcarenitic and Sandy Oolitic Limestone… DOI: http://dx.doi.org/10.5772/intechopen.91720*

**Figure 20.** *Strain versus time during the catacomb of Kom El-Shoqafa, triaxial creep test no. 2.*

**Figure 21.** *Strain versus time curve during El-Shatby Necropolis, triaxial creep test no. 1.*

**Figure 22.** *Strain versus time during El-Shatby Necropolis, triaxial creep test no. 2.*

**7.10 Test methods**

sample failure.

**Figure 18.**

**Figure 19.**

**36**

Two samples of rock (length = 91–103 mm, diameter = 41–44 mm) were tested from each site under different constant axial pressures and different static pressure pressures for approximately 300 h. The experimental procedure follows the ASTM standard (ASTM D4406-93). The compression machine (fusion machine, 5000 kN) is used to apply the fixed axial load to the samples. Rock samples were

placed in a three-axis cell (GDS) to provide constant confining pressure

*Geotechnical Engineering - Advances in Soil Mechanics and Foundation Engineering*

(**Figure 18**). The collected sample (Test # 1) of Catacomb of Kom El-Shoqafa is immediately loaded to the axial stress required at 1.45 MPa to limit the pressure by 225 kPa, and the applied axial stress was adjusted twice: the initial applied pressure was increased to 1 = 2, 17 MPa (+50%) after 98 h (2) then increased to σ1 = 2.53 MPa (+74%) after 125 h (3). The number in brackets refers to **Figure 18**, which displays the strain versus the time curve. Where the axial stress of up to 1.45 MPa and inventory pressures 510 kPa. Axial stress was not adjusted until the test ends after 200 h with steady-state creep with a small stress rate and without

*Triaxial creep test device, with constant axial load under confining pressure. Triaxial creep test device. The cylindrical specimen placed inside (GDS) cell is loaded vertically using the compression machine.*

*Strain versus time during the catacomb of Kom El-Shoqafa, triaxial creep test no. 1.*

axial load and compression pressure. Instantaneous strains were observed immediately after loading the range from 3 <sup>10</sup><sup>3</sup> to 3.2 <sup>10</sup><sup>3</sup> for the test number\_1, and 1.3 <sup>10</sup><sup>3</sup> to 2.2 <sup>10</sup><sup>3</sup> for the test number\_2. All samples show a long "slow low" primary transient creep and steady-state creep stages until the end of the test without acceleration or triple creep resulting in sudden failure. Observations on subsequent tests show that deformation increases rapidly at first to the first few hours of testing and tends to remain constant after that. Stress rates in a steady state

*Uniaxial and Triaxial Creep Performance of Calcarenitic and Sandy Oolitic Limestone…*

In this test, it was observed that crawling during the catacomb of Kom El-Shoqafa site Test no\_1 (where = 3 = 225 kPa) was faster than crawling during the catacomb of Kom El-Shoqafa site test no\_2 (where = 3 = 510 kPa) with the same axial pressure σ1 = 1.45 MPa: From 1 to 96 h after the start of each test, the axial strain accumulated (10–3) 3.5 for the catacomb of Kom El-Shoqafa site Test No. 1

Axial strain time curves are shown in shapes (**Figures 21** and **22**). The curves represent temporary and transient creeps of rock samples under constant axial load and confined pressure. Instantaneous strains were observed immediately after the

0.91 <sup>10</sup><sup>3</sup> to 1.8 <sup>10</sup><sup>3</sup> for number\_2 test. All samples show a long "slow low" primary transient creep and steady creep stages (constant slope) up to the end of the test at 300 h except test number\_1, which showed acceleration or triple creep stage leading to a sudden sample failure at 180 h where the confined pressure σ3 was small, that is, 210 KPa, while at test number\_2, it was 560 kPa and the axial pressure was the same for the eyes σ1 = 3.3 Mpa. Observations on subsequent tests showed deformation increases rapidly at first to the first few hours of testing and tends to remain constant after that. The first sample failed after the end of the test.

It was observed that creep through Shatby site Necropolis, test number 1 (where

**Table 3** summarizes the results of the triple axial crawl test. Axial strain time curves are shown in shapes (**Figures 23** and **24**). The curves represent transient and transient creep conditions of rock samples under constant axial load and compression pressure. Strains observed immediately after the loading range from 2.5 <sup>10</sup><sup>3</sup> to 2.7 <sup>10</sup><sup>3</sup> for test number\_1, and from 0.98 <sup>10</sup><sup>3</sup> to 2.3 <sup>10</sup><sup>3</sup> for test number 2. All samples show a long initial transient creep "characterized by slow rate of decline" and steady creep phases (constant slope) up to the end of the test at 300 h except the first sample, which shows a transient, steady, and triple-accelerated creep phase leading to sudden sample failure at 49 h immediately after adjusting the axial pressure from σ1 = 2 MPa to σ1 = 2.65 MPa. Observations on subsequent tests showed deformation increases rapidly at first to the first few hours of testing and tends to remain constant after that. Pressure rates in the steady state are 0.01 to 0.015 <sup>10</sup><sup>3</sup> <sup>h</sup><sup>1</sup>

In this test, it was observed that crawling through the site of Mustafa Kamel's cemetery in test 1 (where = 3 = 200 kPa) was faster than crawling through the site of Mustafa Kamel's cemetery. No\_2 test (where = 3 = 600 kPa) under the same axial

k3 = 210 kPa) was faster than creep through Shatby cemetery site, test no\_2 (where = 3 = 560 kPa) under the same axial pressure σ1 = 3.3 MPa: From 1 to 150 h

Necropolis site Test site 1 and 2.4 for Shatby site Necropolis Test No. 2.

.

) was 3.2 for Shatby

.

loading range from 2.5 <sup>10</sup><sup>3</sup> to 2.9 <sup>10</sup><sup>3</sup> for number\_1 test, and from

are 0.01 to 0.02 <sup>10</sup><sup>3</sup> <sup>h</sup><sup>1</sup>

*DOI: http://dx.doi.org/10.5772/intechopen.91720*

**8.2 El-Shatby Necropolis**

**8.3 Mustafa Kamel Necropolis**

**39**

.

and 2.7 for the catacomb of Kom Shoqafa website Test No. 2.

Pressure rates in the steady state are 0.01 to 0.015 <sup>10</sup><sup>3</sup> <sup>h</sup><sup>1</sup>

after the start of each test, the accumulated axial strain (10<sup>3</sup>

**Figure 23.** *Strain versus time during Mustafa Kamel Necropolis, triaxial creep test no. 1.*

**Figure 24.**

*Strain versus time curve during Mustafa Kamel Necropolis, triaxial creep test no. 2.*

Samples collected (test # 1) from the Shatby Necropolis site were immediately loaded on the required axial stress at 2.63 MPa to limit pressure at 210 kPa, the applied axial stress was adjusted once: the initial applied pressure was increased to = 1 = 3.30 MPa (+25%) after 26 h (2).

In Mustafa Kamel Test No. 2, the sample was loaded on the axial stress required at 2 MPa to limit pressures of 600 kPa without modifying the axial stress until the end of the test at 300 h without high creep.

During testing, axial distortion and time are recorded. The frequency of reading is once every second at the beginning of the test, and gradually decreases to once every half an hour after the first day of the test. This also depends on the deformation rate of each sample. The results are presented by stress time curves in **Figures 19–24**. Axial stress and axial pressure values are calculated.

#### **8. Test Results**

#### **8.1 Catacomb of Kom El-Shoqafa site**

Axial strain time curves are shown in shapes (**Figures 19** and **20**). The curves represent transient and transient creep conditions of rock samples under constant *Uniaxial and Triaxial Creep Performance of Calcarenitic and Sandy Oolitic Limestone… DOI: http://dx.doi.org/10.5772/intechopen.91720*

axial load and compression pressure. Instantaneous strains were observed immediately after loading the range from 3 <sup>10</sup><sup>3</sup> to 3.2 <sup>10</sup><sup>3</sup> for the test number\_1, and 1.3 <sup>10</sup><sup>3</sup> to 2.2 <sup>10</sup><sup>3</sup> for the test number\_2. All samples show a long "slow low" primary transient creep and steady-state creep stages until the end of the test without acceleration or triple creep resulting in sudden failure. Observations on subsequent tests show that deformation increases rapidly at first to the first few hours of testing and tends to remain constant after that. Stress rates in a steady state are 0.01 to 0.02 <sup>10</sup><sup>3</sup> <sup>h</sup><sup>1</sup> .

In this test, it was observed that crawling during the catacomb of Kom El-Shoqafa site Test no\_1 (where = 3 = 225 kPa) was faster than crawling during the catacomb of Kom El-Shoqafa site test no\_2 (where = 3 = 510 kPa) with the same axial pressure σ1 = 1.45 MPa: From 1 to 96 h after the start of each test, the axial strain accumulated (10–3) 3.5 for the catacomb of Kom El-Shoqafa site Test No. 1 and 2.7 for the catacomb of Kom Shoqafa website Test No. 2.

#### **8.2 El-Shatby Necropolis**

Axial strain time curves are shown in shapes (**Figures 21** and **22**). The curves represent temporary and transient creeps of rock samples under constant axial load and confined pressure. Instantaneous strains were observed immediately after the loading range from 2.5 <sup>10</sup><sup>3</sup> to 2.9 <sup>10</sup><sup>3</sup> for number\_1 test, and from 0.91 <sup>10</sup><sup>3</sup> to 1.8 <sup>10</sup><sup>3</sup> for number\_2 test. All samples show a long "slow low" primary transient creep and steady creep stages (constant slope) up to the end of the test at 300 h except test number\_1, which showed acceleration or triple creep stage leading to a sudden sample failure at 180 h where the confined pressure σ3 was small, that is, 210 KPa, while at test number\_2, it was 560 kPa and the axial pressure was the same for the eyes σ1 = 3.3 Mpa. Observations on subsequent tests showed deformation increases rapidly at first to the first few hours of testing and tends to remain constant after that. The first sample failed after the end of the test. Pressure rates in the steady state are 0.01 to 0.015 <sup>10</sup><sup>3</sup> <sup>h</sup><sup>1</sup> .

It was observed that creep through Shatby site Necropolis, test number 1 (where k3 = 210 kPa) was faster than creep through Shatby cemetery site, test no\_2 (where = 3 = 560 kPa) under the same axial pressure σ1 = 3.3 MPa: From 1 to 150 h after the start of each test, the accumulated axial strain (10<sup>3</sup> ) was 3.2 for Shatby Necropolis site Test site 1 and 2.4 for Shatby site Necropolis Test No. 2.

#### **8.3 Mustafa Kamel Necropolis**

**Table 3** summarizes the results of the triple axial crawl test. Axial strain time curves are shown in shapes (**Figures 23** and **24**). The curves represent transient and transient creep conditions of rock samples under constant axial load and compression pressure. Strains observed immediately after the loading range from 2.5 <sup>10</sup><sup>3</sup> to 2.7 <sup>10</sup><sup>3</sup> for test number\_1, and from 0.98 <sup>10</sup><sup>3</sup> to 2.3 <sup>10</sup><sup>3</sup> for test number 2. All samples show a long initial transient creep "characterized by slow rate of decline" and steady creep phases (constant slope) up to the end of the test at 300 h except the first sample, which shows a transient, steady, and triple-accelerated creep phase leading to sudden sample failure at 49 h immediately after adjusting the axial pressure from σ1 = 2 MPa to σ1 = 2.65 MPa. Observations on subsequent tests showed deformation increases rapidly at first to the first few hours of testing and tends to remain constant after that. Pressure rates in the steady state are 0.01 to 0.015 <sup>10</sup><sup>3</sup> <sup>h</sup><sup>1</sup> .

In this test, it was observed that crawling through the site of Mustafa Kamel's cemetery in test 1 (where = 3 = 200 kPa) was faster than crawling through the site of Mustafa Kamel's cemetery. No\_2 test (where = 3 = 600 kPa) under the same axial

Samples collected (test # 1) from the Shatby Necropolis site were immediately loaded on the required axial stress at 2.63 MPa to limit pressure at 210 kPa, the applied axial stress was adjusted once: the initial applied pressure was increased

In Mustafa Kamel Test No. 2, the sample was loaded on the axial stress required at 2 MPa to limit pressures of 600 kPa without modifying the axial stress until the

During testing, axial distortion and time are recorded. The frequency of reading is once every second at the beginning of the test, and gradually decreases to once every half an hour after the first day of the test. This also depends on the deforma-

Axial strain time curves are shown in shapes (**Figures 19** and **20**). The curves represent transient and transient creep conditions of rock samples under constant

tion rate of each sample. The results are presented by stress time curves in **Figures 19–24**. Axial stress and axial pressure values are calculated.

to = 1 = 3.30 MPa (+25%) after 26 h (2).

**8.1 Catacomb of Kom El-Shoqafa site**

**8. Test Results**

**38**

**Figure 23.**

**Figure 24.**

end of the test at 300 h without high creep.

*Strain versus time during Mustafa Kamel Necropolis, triaxial creep test no. 1.*

*Geotechnical Engineering - Advances in Soil Mechanics and Foundation Engineering*

*Strain versus time curve during Mustafa Kamel Necropolis, triaxial creep test no. 2.*


deformation of single crystals, (2) homogeneous deformation or uniform flow, and (3) deformation over a certain amount of stress. Here we will use the term ductile in the macroscopic sense of homogeneous deformation where inferior microscopic processes

*Uniaxial and Triaxial Creep Performance of Calcarenitic and Sandy Oolitic Limestone…*

Macroscopically, these microscopic processes form the flow of the calcite. Experimental evidence of Caracola flow includes (1) a broad shear area indicating distributed damage and intact granules in an extraction; (2) a large pore breakdown, often accompanied by small intracranial cracks caused by "fragmentation"; and (3) fractures. Unlike this distributed pervasive flow, the standard fragile deformation at low-effective pressures is characterized by an expansive fine fracture, leading to shear localization along narrower fracture zones, which often consist of sections linked to a zigzag pattern (e.g., [44–48]). In thin sections, the fragile fracture is evidenced by the presence of almost abundant small cracks, away from the shear fracture. Many of these miniature cracks are parallel to the main baseline pressure and may arise from axial splitting of healthy grains [42, 43] or cracking of

From previous experimental studies, the researchers agreed that distributed sedimentary rocks, for calcarenitic sedimentary rocks, are the dominant failure mechanisms in highly porous rocks, especially at high effective medium pressures [49–52]. On the contrary, the fragile local fracture dominates the rocks with low porosity, as

The catacombs of the Kom El-Shoqafa and Amod El-Sawari (Pompeii's pillar) site, located in the city center, 2.5 km from the sea coastline, are carved into the initial sandy limestone (cement limestone); Cross joints filled with fragmented sand and saturated with water in the lower parts. This unit is illustrated with loose sandstone. It is medium brown in color to decorate granulated limestone saturated with groundwater. It goes beyond the formation of the hayf (Pliocene) or the older

archeological sites, which are located close to the waterfront of Alexandria (Shatby Cemeteries, Mustafa Kamel Cemeteries), were excavated in internal limestone or calcite (coastal hills). Yellowish white upward become yellow brown bottom.

UCS values indicate that according to the classification adopted by the London Geological Society, which relies on the unrestricted compressive strength and the classification proposed by [33, 50]. These calcarenitic rocks from which excavations are carried out underground are classified as soft to very weak. It is also in good compliance with the Rock Quality Assignment System (RQD) for these types of soft rocks, where RR = 18 and RQD = 15–20% and a very poor quality range from 0 to 25. In addition, the results of static deformation tests indicate that the types of rock in

Based on tests carried out on air-dried samples prepared in the vertical direction,

It should be noted that the silica content at the Catacomb site in Kom El-Shoqafa is higher than in any area in Alexandria, possibly due to sedimentation processes, such as the high silica content that does not contain cement but is found as sand grains. In low rock durability and stiffness, high sand-like grain content reduces rock strength against salt crystallization and moisture pressures within rock pores. This is not only because of its high content of silica granules but also because it is a sparse rock. It is

Three stages of crawling behavior can be identified by uniaxial and triple-axis crawling tests. In some cases, the primary creep curve approaches a constant rate of

known that this type of limestone is characterized by low durability.

myosin. Surface quadruple deposits obscure actual contact. The other two

include improved shear pressure, granulation, and granular flow.

*DOI: http://dx.doi.org/10.5772/intechopen.91720*

well as in high-porosity rocks with low effective pressure.

grain boundaries.

**10. Conclusions**

question have high deformation.

**41**

#### **Table 3.**

*Triaxial creep test, testing program.*

pressure = 1 = 2 MPa: from 1 to 45 h after the start of each test, the accumulated axial strain (10<sup>3</sup> ) was 3.3 for Necropolis of Mustafa Kamel site Test no. 1 and 2.5 for the site of Mustafa Kamel cemetery test site 2.

Thus, the prevalence of cracking (in the fragile field) and pore breakdown (under high pressure conditions) are the prevailing deformation mechanisms of the selected rocks.

The cumulative results of various three-axis crawl tests, conducted at tight pressures ranging from 200 to 600 kPa, showed that crawling reduces the level of brittle stress on failure by 15–20% in relation to standard tests, and similarly, the resulting stress threshold (e.g., Pore breakdown (reduction)) is reduced by the same amount, while the volumetric component of the strain is diluted only in the absence of confined pressure, and shrinks completely even when σ3 decreases.

The instantaneous creep strain depends on axial pressure and confining pressure. In general, increased continuous axial pressure leads to greater axial stress. The pressure rate under high axial pressure is greater than the pressure under the lower axial pressure for the same fixed pressure. The higher the confined pressure, the smaller the resulting pressure. Comparison of results obtained from other soft rocks/salts indicates that the stress rate depends on the stress and previous strain. This is also consistent with the conclusion of Courthouse and Ong et al. who describe soft rocks as close.

The time-based foundational model of soft rocks developed by Zhang et al. can reproduce the general crawl characteristics of soft rocks with high precision. The crawl failure time to load the strain of the aircraft is longer than that of the three-axis load because the strain load frame controls the sample to expand.

#### **9. Micromechanics of creep in the calcarenitic rocks**

There is now a large body of evidence that rock deformation at low temperatures and pressures occurs through two mechanisms widely referred to as faulty flow and ductile flow. The term ductile is often used in three different contexts, including (1) plastic

*Uniaxial and Triaxial Creep Performance of Calcarenitic and Sandy Oolitic Limestone… DOI: http://dx.doi.org/10.5772/intechopen.91720*

deformation of single crystals, (2) homogeneous deformation or uniform flow, and (3) deformation over a certain amount of stress. Here we will use the term ductile in the macroscopic sense of homogeneous deformation where inferior microscopic processes include improved shear pressure, granulation, and granular flow.

Macroscopically, these microscopic processes form the flow of the calcite. Experimental evidence of Caracola flow includes (1) a broad shear area indicating distributed damage and intact granules in an extraction; (2) a large pore breakdown, often accompanied by small intracranial cracks caused by "fragmentation"; and (3) fractures. Unlike this distributed pervasive flow, the standard fragile deformation at low-effective pressures is characterized by an expansive fine fracture, leading to shear localization along narrower fracture zones, which often consist of sections linked to a zigzag pattern (e.g., [44–48]). In thin sections, the fragile fracture is evidenced by the presence of almost abundant small cracks, away from the shear fracture. Many of these miniature cracks are parallel to the main baseline pressure and may arise from axial splitting of healthy grains [42, 43] or cracking of grain boundaries.

From previous experimental studies, the researchers agreed that distributed sedimentary rocks, for calcarenitic sedimentary rocks, are the dominant failure mechanisms in highly porous rocks, especially at high effective medium pressures [49–52]. On the contrary, the fragile local fracture dominates the rocks with low porosity, as well as in high-porosity rocks with low effective pressure.

#### **10. Conclusions**

pressure = 1 = 2 MPa: from 1 to 45 h after the start of each test, the accumulated

The cumulative results of various three-axis crawl tests, conducted at tight pressures ranging from 200 to 600 kPa, showed that crawling reduces the level of brittle stress on failure by 15–20% in relation to standard tests, and similarly, the resulting stress threshold (e.g., Pore breakdown (reduction)) is reduced by the same amount, while the volumetric component of the strain is diluted only in the absence of confined pressure, and shrinks completely even when σ3 decreases. The instantaneous creep strain depends on axial pressure and confining pressure. In general, increased continuous axial pressure leads to greater axial stress. The pressure rate under high axial pressure is greater than the pressure under the lower axial pressure for the same fixed pressure. The higher the confined pressure, the smaller the resulting pressure. Comparison of results obtained from other soft rocks/salts indicates that the stress rate depends on the stress and previous strain. This is also consistent with the conclusion of Courthouse and Ong et al. who

The time-based foundational model of soft rocks developed by Zhang et al. can reproduce the general crawl characteristics of soft rocks with high precision. The crawl failure time to load the strain of the aircraft is longer than that of the three-axis load because the strain load frame controls the sample to expand.

There is now a large body of evidence that rock deformation at low temperatures and pressures occurs through two mechanisms widely referred to as faulty flow and ductile flow. The term ductile is often used in three different contexts, including (1) plastic

**9. Micromechanics of creep in the calcarenitic rocks**

Thus, the prevalence of cracking (in the fragile field) and pore breakdown (under high pressure conditions) are the prevailing deformation mechanisms of the selected

for the site of Mustafa Kamel cemetery test site 2.

**Specimen No. Testing period Confining**

From **19/10/2016** to **27/10/2016**

*Geotechnical Engineering - Advances in Soil Mechanics and Foundation Engineering*

From **21/11/2016** to **28/11/2016**

From **9/11/2016** to **16/11/2016**

From **29/11/2016** to **11/12/2016**

From **16/10/2016** to **18/10/2016**

From **12/12/2016** to **22/12/2016**

**Catacomb of Kom El-Shoqafa** test Ν\_1 (Sandy oolitic limestone)

**Catacomb of Kom El-Shoqafa** test

**El-Shatby Necropolis** test Ν\_1 (oolitic intraclastic limestone)

**El-Shatby Necropolis** test Ν\_2 (oolitic intraclastic limestone)

**Mustafa Kamel Necropolis** test Ν\_1 (Calcarenite rock)

**Mustafa Kamel Necropolis** test Ν\_2 (Calcarenite rock)

*Triaxial creep test, testing program.*

Ν\_2

) was 3.3 for Necropolis of Mustafa Kamel site Test no. 1 and 2.5

**pressure (σ3)**

**225 KPa σ<sup>1</sup> =**

**510 KPa σ<sup>1</sup> = 1.4**

**210 KPa σ<sup>1</sup> =**

**200 KPa σ<sup>1</sup> =**

**600 KPa σ<sup>1</sup> = 2 MPa**

**1.45 MPa**

**MPa**

**2.63 MPa**

**1.32 MPa**

**560 KPa σ<sup>1</sup> = 3.31 MPa**

**Time (h) 1 3 26 51 52 98 125 200 300**

> **σ<sup>1</sup> = 2.17 MPa**

> **σ<sup>1</sup> = 3.30 MPa**

> **σ<sup>1</sup> = 1.98 MPa**

**σ<sup>1</sup> = 2.53 MPa**

**σ<sup>1</sup> = 2.6 MPa**

axial strain (10<sup>3</sup>

describe soft rocks as close.

rocks.

**40**

**Table 3.**

The catacombs of the Kom El-Shoqafa and Amod El-Sawari (Pompeii's pillar) site, located in the city center, 2.5 km from the sea coastline, are carved into the initial sandy limestone (cement limestone); Cross joints filled with fragmented sand and saturated with water in the lower parts. This unit is illustrated with loose sandstone. It is medium brown in color to decorate granulated limestone saturated with groundwater. It goes beyond the formation of the hayf (Pliocene) or the older myosin. Surface quadruple deposits obscure actual contact. The other two archeological sites, which are located close to the waterfront of Alexandria (Shatby Cemeteries, Mustafa Kamel Cemeteries), were excavated in internal limestone or calcite (coastal hills). Yellowish white upward become yellow brown bottom.

Based on tests carried out on air-dried samples prepared in the vertical direction, UCS values indicate that according to the classification adopted by the London Geological Society, which relies on the unrestricted compressive strength and the classification proposed by [33, 50]. These calcarenitic rocks from which excavations are carried out underground are classified as soft to very weak. It is also in good compliance with the Rock Quality Assignment System (RQD) for these types of soft rocks, where RR = 18 and RQD = 15–20% and a very poor quality range from 0 to 25. In addition, the results of static deformation tests indicate that the types of rock in question have high deformation.

It should be noted that the silica content at the Catacomb site in Kom El-Shoqafa is higher than in any area in Alexandria, possibly due to sedimentation processes, such as the high silica content that does not contain cement but is found as sand grains. In low rock durability and stiffness, high sand-like grain content reduces rock strength against salt crystallization and moisture pressures within rock pores. This is not only because of its high content of silica granules but also because it is a sparse rock. It is known that this type of limestone is characterized by low durability.

Three stages of crawling behavior can be identified by uniaxial and triple-axis crawling tests. In some cases, the primary creep curve approaches a constant rate of stress called secondary creep. In high-stress specimens, secondary crawl may turn up in higher creep, which is characterized by an increased stress rate until crawl failure occurs suddenly. In the last two stages, the thin vertical cracking begins, accompanied by hardening, and only near failure, large cracks spread rapidly and lead to a sudden collapse. Long-term tests were performed on a secondary creep sample showing even at 40% of estimated strength.

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