In the ever-evolving tapestry of our lives, change often arrives subtly, and we're left with a little note - a precursor to the transformation that awaits us.
Picture this: the building next door is slated for demolition and excavation, heralding the arrival of yet another residential block. This transformation will inevitably alter the streetscape you've grown to call home. With this transformation comes the uncertainty of potential harm to your property, sparking concerns about becoming part of a concerning statistic.
Regrettably, the construction industry in the Maltese Islands has not always upheld a spotless reputation. Demolition, excavation, and construction methods have remained largely unregulated. The existing police laws, drafted over a century ago, stipulate that a mere two feet and six inches of unexcavated rock must remain along the party wall, a blanket guideline applied irrespective of excavation depth or ground conditions.
This one-size-fits-all approach frequently leads to disputes, inefficiencies, and wasted time, often proving ineffective.
Comparatively, other European nations have adopted established, enforced regulations, prioritising the protection of homeowners' peace and property. These regulations draw upon science, knowledge, and experience, as opposed to rigid standards.
Locally, our approach typically involves using a standard method statement file at the (BCA). These methods, while celebrated as innovations, often involve unorthodox techniques, such as using a giant chainsaw to reduce vibrations near party walls, during excavation.
However, these innovations have inadvertently revealed a more ominous issue lurking deep underground. Our bedrock, though fractured, still bears the weight of our structures. A single fissure in the wrong direction can cause havoc as adjacent materials are excavated. A chainsaw cut, reducing confinement, can trigger an uncontrolled shift.
Figure 1- Diagram of how rock fissures may lead to dislocation of rock when confinement is removed.
Figure 2 – Fissures as seen in locally excavated sites.
Ideally, civil engineers, architects and contractors should have insight into the number and orientation of these fissures. However, inspecting fissures from the face of an excavation is often too late to make necessary corrections. By then, a wedge of rock may have already shifted foundations, leading to millimeter-level drops and wall cracks, causing once-sturdy bathroom tiles to sound hollow and making internal doors difficult to close.
In today's world, is it acceptable to allow such situations to occur?
The challenge lies in comprehending the organisation of these underground fissures, quite a puzzle when these are buried and invisible. A group of engineers from the Department of Electronic Systems, geo-technical engineers from the Department of Civil and Structural Engineering at the University of Malta and local geotechnical investigations and consolidation company, , has taken up this daunting task, aiming to develop an innovative instrument capable of retrieving this essential information.
Solidbase has frequently been called upon to assess ground conditions before construction commences. Their role is to provide architects with insights into ground characteristics, ensuring safe excavation and the addition of new floors on existing foundations. However, evaluating the ground beneath a third-party property, sometimes owned by uncooperative owners, presents a unique challenge. Traditional investigative techniques often involve wet drilling processes by large, track-mounted equipment, an impossibility to conduct within a finished living room or maintained backyard.
Breaking away from the conventional approach, the team opted to drill a narrow hole and, rather than scrutinising the extracted fractured rock, proceed to explore the wall of the hole itself. The question arose: why not conduct an internal scan of the borehole to generate a three-dimensional computer model of the rock features and cavities?
This innovative concept has evolved into an extensive research and development endeavour within the previously mentioned university departments. The primary goal is to design an instrument and corresponding scientific methodologies aimed at collecting data on fissure dimensions and orientations. This ongoing development strives to enhance the sophistication of these techniques, particularly in addressing the challenges posed by deep, small-diameter boreholes. Promisingly, the team has already successfully retrieved the initial dataset from a university borehole. The forthcoming steps entail fine-tuning the scanning process for greater speed and precision, along with the creation of mathematical models to accurately determine the positions and angles of fissures within three-dimensional space. This invaluable data equips geotechnical engineers with the means to proactively assess potential excavation-related issues as per the permit drawings even before ground is broken.
The significant advantage of this approach is that only a handful of hand-held coring machine-drilled holes have been necessary. This methodology starkly contrasts with the traditional practice of assessing the excavation's face after adjacent buildings have already sustained damage. It enables early discussions and proactive planning for any required shoring or underpinning work, ultimately ensuring safer and more informed construction practices.
This idea is gaining momentum, with support from institutions and funding agencies that recognise its potential. Funding to develop the prototype has recently been granted by the (MCST) through the FUSION Technology Development Programme. The team is eager to refine the prototype and introduce it into the mainstream geotechnical investigations, paving the way for safer and more informed construction practices in the Maltese Islands.
Research Team:
From the Department of Electronic Systems Engineering
From the Department of Civil and Structural Engineering
From Solidbase Laboratory Ltd
