As well as charting development of grouting techniques in his John Mitchell Lecture, Clif Kettle will also call the industry to put more into learning the craft of geotechnics.
Independent consultant Clif Kettle says he was “thrilled to bits” to be invited to deliver the 2019 John Mitchell Lecture on 23 January at the Institution of Civil Engineers in London. “I was stunned to be invited to deliver the lecture – there are so many great engineers out there,” he says.
Kettle has been active in contracting since 1973 and has had some involvement in the grouting work on most big infrastructure projects in the UK, as well as a number of international schemes. With this background there was no doubt in his mind as to the focus of his lecture. “There is a need to focus on ground treatment technology,” he said.
However, Kettle plans to use the lecture to bring home another issue that his is concerned about – loss of focus within large organisations in the ground engineering industry. “The industry is losing lots of specialists, which is partly due to their structure and this is leading to less understanding of processes,” he says. Kettle says he is seeing the trend in the grouting sector and said it is a common problem across other specialist areas of ground engineering.
“You need to know how far we’ve come and the dangers of regression, as well as the nuts and bolts of where we are,” he says.
Kettle says he want to appeal to his lecture audience who can change this trend. But what does he believe the industry needs to do? “The word that comes to mind is patience,” he explains.
“There is a growing issue with people having the patience to stop and learn.”
Kettle says that there is a trend for engineers to move too quickly from one specialism to another without actually becoming a specialist in those areas but with the aim of amassing industry experience in lots of areas to move into project management.
“It’s not like this in Italy, Germany or France – where there is a strong technician class and you can stay as a specialist and be financially rewarded for doing so for your whole career,” he says. “In the UK, companies don’t recognise technical specialists well and push people towards management to reward staff.
“Many young engineers don’t stick with the subject for long enough to learn about it and try to clock up a grouting job, a piling job, a diaphragm wall job – once they get all the badges they can move into management.
“That’s great for people who are skilled as managers, but many engineers are more technically minded and there is less chance for them to progress within that.
“Companies need to leave people to learn and engineers need to be patient to learn the technical aspects of the work they want to manage. Every site is different and just working on one or two schemes in a specialist area is not enough to fully appreciate the challenges and potential issues.”
While Kettle will use the lecture as a sounding board for his concerns, the main focus of the lecture will be all the development that he has seen in the grouting sector over the course of his career and a look at the capabilities, techniques, materials and equipment that now exists. “The scale of development has been tremendous,” he says. “But we still need to be sure that we are focused on maintaining this momentum.”
Kettle believes that this preserving this pace calls for the industry to be more collaborative and share more.
“The US has a more open attitude to technological development,” he says. “They do more sharing through specialist conferences and the grouting sector there is advancing rapidly. If Europe and the UK is not careful, then the lead we have will be eroded so we need to emulate the US approach.”
Kettle points to his time working with Stuart Littlejohn at Colcrete where Littlejohn encouraged staff to “publish everything they know”. According to Kettle, this helps to synthesise the knowledge, improve self-confidence and intimidate colleagues, as well as raise the bar.
“Littlejohn believed that there was no commercial disadvantage to sharing so much as by the time others have read and applied your knowledge, you’ve moved on,” explains Kettle.
Kettle says that he and many past colleagues still refer to the technical memos put out by Littlejohn. “He used to share the developments with everyone in the business,” says Kettle. “It helped you to understand how the company’s capabilities were developing outside of your own specialism and was also gave important insight for when talking to clients.”
Kettle laments that he has not published enough papers during his career – he estimates the number to be around 20 – and regrets that he has been too busy to share the knowledge that he feels he should have done.
Kettle believes that a reluctance to publish across the industry did little to dispel the perception that grouting was a black art. “It was not well documents, so was not well understood,” he says.
In the early days of working on grouting projects, Kettle admits that the techniques were crude but much has changed for the better. “Now every second of every injection can be recorded graphically,” he says.
“On early projects we were working on the backfilling of coal workings and shafts with grout and the grout was mixed by tipping pulverised fuel ash onto the ground and shovelling it into the mixer by hand. It was poorly controlled in terms of safety and in terms of quality – the technical control was weak or non-existent.
“Then it was not seen as an engineering or scientific technique and records were limited to pocket books.”
One of the last projects Kettle was involved in before leaving Bachy Soletanche highlights the advances in grouting techniques, materials and equipment, as well as the integration of the work with the main construction. “The work on the compensation grouting for Crossrail’s Liverpool Street station had total integration with the project team,” he says.
“The process was entirely engineered from start to finish. There was integration between the soil instrumentation and the tunnellers knew exactly what face loss was expected with each advance and we had software to precisely replace this loss with grout on a millimetric basis.
“There was total control of the injections in real time and it could be done remotely too. The project demonstrated the extraordinary capabilities of grouting techniques.”
According to Kettle, other milestone projects for the grouting sector include the Thames Barrier, where chemical grouts were developed to overcome difficult ground conditions and tight deadlines; the Tarbela Dam in Pakistan – which was the largest dam in the world at the time – which took grouting to a new scale; and the metro lines in Paris and Rome where the scale of the work meant that the “pocket book” approach was just not feasible.
“There has been a huge step change in equipment, injection control and materials,” says Kettle.
Nonetheless, Kettle believes that further evolution is possible in terms of both materials and equipment. “Cements are becoming finer but there is also the development of biocalcification which has fantastic potential,” he says.
“A lot of the development has been driven by contractors who are conscientious in trying to improve and we need to keep that mentality.
Training and sharing
Kettle says that there is a need for more grouting-specific training and will call on the industry to respond and develop industry-wide courses.
“In the UK, Soil Mechanics used to offer training courses including one on grouting but now it’s gone and that is a terrible shame,” he says.
“The lack of skills and knowledge means that there is a tendency to cut and paste specifications for grouting, even where the ground conditions are different. There is a both a decline and dilution of skills across the industry and there are almost no external training courses for grouting. The only one I’m aware of is in the US.”
At a recent Deep Foundations Institute meeting there was an ambition to try and bring a course to Europe in 2019 to harmonise practice in the US and Europe.
Kettle says that it was development of skills and a more professional approach to grouting that helped it become an accepted technique and be used in more extreme ground conditions.
Without appropriate training, Kettle fears that skills will be lost.
“The construction industry is very cyclical,” he says. “There is a build up of expertise for major projects, such as the Jubilee Line Extension, but then it becomes dispersed at the end of the work. The next major project then calls for another build up.
“We’ve seen it time and again with the Jubilee Line Extension, the Channel Tunnel Rail Link, Crossrail, Tideway and HS2. The gaps between each project have been sufficient for skills to be lost each time and this causes enormous issues for contractors.
“The pressure of working like this means that we have to reinvent the wheel each time. We need to invest in research and development.
“Development of a standard training course would go a long way to ensuring staff maintain knowledge of best practice and are ready to deliver these major schemes.”