**3. Digital examples of recording**

For digital examples it is important to note and record what was learnt from the archive searches, how we arrived at a solution and then how it was made to work successfully on site. In this electronic archive way the methods used can be made available to various bodies of engineers and conservation societies that need such data examples and who would find it useful in the future because having worked visual examples is both very informative as well as helpful and reassuring. In the United Kingdom these worked examples and papers have been for the Institute of Civil Engineers 'Structural Faults' and 'Concrete Solutions' conferences in the main. A list of references for these is in the Citing Sources section of the Appendices, as are the selection of video material referred to in the text [2].

Most Heritage monuments are subjected to the destructive forces of nature and in particular old sea walls and breakwaters to an increase of storm duration and intensity, due to sea level rise through climate change. Also, many land-based Heritage masonry walls are subject to chemical attack from pollutants in the atmosphere, floods, and heavy rainfall. More direct human intervention forces, quite often from developers changing the surrounding environment of the building or wall is another frequent source of destructive intervention. Usually unrecognised, manmade influence is often the lack of finance leading to greatly reduced or even zero maintenance for the structure and its environment. Another more recent threat to the structures is when the personnel or custodians of such monuments change from different departments, or different governments take over responsibility and they do not provide an effective 'hand over' of knowledge for preserving the Heritage monument. Therefore, it is important to ensure that the organisation or society responsible for the upkeep of the asset has a 'virtual' record of what is currently in existence in case some future disaster should happen i.e. earthquakes, wars etc. The new custodians need an understanding of the behaviour of the structure and the strengths and weaknesses of it as well as having access to the store of archive data.

This chapter gives practical examples of using digital capture of Heritage masonry structures that can be used by those responsible for the future conversation of similar types of asset. This philosophy of digital access will also enable those who have to take over responsibility for the various, sometimes iconic, structures to be able to see what was done and where it was done in a previous similar example which was invariably under great pressures to expend a minimal cost for the maximum advantage gained for the preservation i.e. the constraints of most custodian's budgets. There are several examples where the use of digital models have helped to procure the funding for major and significant civil and marine engineering repairs such as St. Aubins breakwater, Gorey Pierhead and St. St. Catherine's Breakwater in the UK Channel Island of Jersey which has an aggressive 11 m tidal range and faces the storms from the Western Atlantic Ocean.

### **4. LiDAR examples of recording**

This chapter therefore provides examples of how digitally capturing the whole external shape, surface and geometry of the structure was applied to examples at St. Aubins Harbour piers and Gorey Pier in Jersey where LiDAR (Light Detection and Ranging) was used to great effect. The use of LiDAR again, together with drone surveys and photo model enhancement, was used at St. Catherine's breakwater at a different part of the coast of the island of Jersey. The use of this data proved

#### *Heritage - New Paradigm*

essential in illustrating to the Government funding bodies of the Island that emergency finance was essential to save these assets for the Island of Jersey's Heritage.

From the archives search the failure of the inner face of the breakwater wall (**Figure 2**), Ref. [3] was seen to be the result of wave impact on the outside face of the breakwater causing, through 'stress propagation', the wall on the inner face of the breakwater to be forced outwards resulting in a partial collapse. The inner wall had also settled because it was originally built on the beach sand using large, loose blocks of granite stones with no foundations in 1640 by a young king Charles II. The solution shown in the model, in **Figure 3** (Ref. [3] Vid [1]), was for 'mini-piles' and 'secret fix ties' across the two granite walls of the structure which are designed to arrest any further movement.

The North Pier of the harbour at St. Aubins was also suffering from the same defects common to these old marine structures of inner wall settlement on no existing foundations that was resulting in a significant rotation inwards of the inner wall of the structure getting worse and more vertical towards the end of the breakwater [5–8]. The LiDAR survey produced the accurate model of the loose stone structure that was able to be assessed (**Figure 4**, Ref. [3] Vid [1]).

Of particular interest here was that the model moved graphically with the blue curser moving along the wall in plan with an imbedded graphic which showed the verticality of the inside loose stone wall becoming more vertical as the curser approached the end of the breakwater (**Figure 5**, Ref. [3], Vid Ref. [1]). As the original loose granite stone breakwater slopes inwards (called a 'batter'), the graphic was able to show dramatically that the further along the breakwater the inner face of the loose stones had reached vertical towards its end and was about to fail in a similar manner to the St. Aubins Fort breakwater seen in **Figure 2**. This demonstrated to everybody concerned with the maintenance of the structure that there was an urgent need to 'pin' and 'support' the inner stone wall at the end of the breakwater and tie the two masonry walls together with a 'secret fix'.

**Figure 2.** *St Aubin's fort breakwater failure 1972 (archives).*

#### **Figure 3.**

*St. Aubins N. pier LiDAR 3D model. (video Fly through and model Ref. [4]). (Link to video materials is available at the end of the chapter).*

*Digital Technology to Preserve Heritage Structures DOI: http://dx.doi.org/10.5772/intechopen.99023*

**Figure 4.** *North pier St. Aubins harbour LiDAR screenshot.*

**Figure 5.**

*Model used to demonstrate inner wall rotation of north pier. (Video of curser in moving blue cross section, Ref. [4]).*
