LITERATURE REVIEW

followed, they slowly carved the mine into a warren of galleries and tunnels that extended more than 1,000 feet underground.

When they were not digging for “white gold,” the workers also used the mine’s salt crystal deposits to build a stunning collection of chapels, chandeliers, statues, and bas reliefs, including a detailed replica of Da Vinci’s “The Last Supper.” The Wieliczka mine stopped producing salt in 2007 after some seven hundred years in operation, but it remains a popular tourist attraction in Poland. It is also home to a health spa that touts the therapeutic properties of the mine’s salt-rich microclimate.

The Italian hilltop town of Orvieto is known for its white wines and picturesque architecture, but its most mysterious wonders lie underground. Beginning with the ancient Etruscans, generations of locals burrowed their way deep into the volcanic rock bluff on which the city was originally built. The subterranean maze was first carved to build wells and cisterns, but over the centuries it grew to include more than 1,200 interlocking tunnels, grottoes, and galleries. Some chambers include the remnants of Etruscan-era sanctuaries and medieval olive presses, while others show signs of having been used as storage places for wine or roosts for pigeons—a common local delicacy. Orvieto’s underground city was also frequently employed as a hiding place during times of strife. As recently as World War II, people were still using certain sections as bomb shelters. (Andrews, n.d.)

The history of the Paris Catacombs starts in the late eighteenth century, when major public health problems tied to the city’s cemeteries led to a decision to transfer their contents to an underground site During the Gallo-Roman period, the inhabitants of Lutetia, the forerunner of present-day Paris, used the limestone peculiar to that area to construct their buildings. In later years this stone built much of the city. The mining utilized the technique of extracting horizontally along the vein, a process which Figure 1.10. Catacombs of Paris left a honeycomb of tunnels as Paris grew. Meanwhile, many cemeteries within the city limits had become filled to overflowing, resulting in unsanitary and unpleasant living conditions for those dwelling adjacent to them. The problem grew so acute that by 1786, these cemeteries were being emptied for reasons of public safety. With the remains of some six million people requiring reburial, the only location with sufficient room to inter them all was the former mine tunnels twenty meters beneath the city. Thus, the former limestone mines of Paris became a municipal ossuary referred to as the ‘catacombs,’ as they bore a similarity to the subterranean necropolis of ancient Rome, even though the tunnels were not originally intended to serve as a tomb.

.2.3. Why there is a need of underground space in present day:

As the world faces an uncertain future fraught with the dangers of rising sea levels and unpredictable weather patterns it becomes important to take steps to create resilient cities which can withstand these changes. Rapid urbanization is making people more vulnerable to the impacts of climate

Figure 1.11

Statistics of global urbanization

change, according to a new UN report that highlights diverse initiatives worldwide that are bolstering the resilience of cities, towns, and villages. More than half the world’s population today lives in cities, and another 2.5 billion people are expected to join them by 2050. The frequency of torrential rain and storm surges is on the rise in big, densely populated cities like New York, Mumbai, and Jakarta, hitting those living in marginalized, informal settlements like slums the hardest. Desertification swallows arable land needed to feed swelling urban populations. And sea-level rise threatens everyone living in coastal areas, delta regions, and small-island countries. To combat these threats to sustainable development, numerous cities have taken steps to build resilience and address the growing climate-related risks posed to inhabited areas. Through initiatives such as 100 Resilient Cities and the Global Covenant of Mayors, leaders of cities have shown commitment to working together to address climate change and its impacts.

2.3.1. Some of the benefits of underground cities are:

1 Safety considerations – In current circumstances against nuclear or bombing attacks.

2. Reducing occupation of surface areas.

3. Reducing the need for heating and cooling energy.

4. Reducing noise pollution.

5. Reducing dust loads.

6. Reducing environmental load.

7 Reduces demand for transportation.

8. Help is to preserve existing, historical, cultural, architectural values and buildings.

2.4. The Building Concepts concerning spaces:

A wide variety of approaches exists within the concept of the underground building. At one extreme, a building can be erected on the original surface of the ground (i.e., at grade) and then be covered by earth to shelter the building partially or completely. At the other extreme, the building is constructed in a completely excavated site (i.e., Below grade). In between there are several different other types of underground building concepts that can be distinguished, does not include every design possible, but gives a typological overview.

2.4.1 Fully underground spaces

These spaces have little or no contact with the above world. These are the spaces below the ground completely. Only the entrance will be above the ground. So, these spaces have a supply of light and air. The absence of natural light and views makes prolonged stays underground less appealing.

Figure 1.12.underground space

2.4.2 Submerged Spaces:

Submerge spaces are the ones lying just under the surface of the ground. They possess the ability to extend deep into the ground, but they always have direct contact with the aboveground world and with natural light. To admit daylight, the