cccp技术修复钢筋混凝土排水管道-武汉中地大非开挖研究院有限公司

CCCP技术修复钢筋混凝土排水管道
在加利福尼亚州汉密尔顿市亨廷顿海滩附近的路口，有路人报告奇怪的气味，经过检查发现来源不是下水道，推测为周围的沼泽地带有机物分解产生的。

检查发现高浓度硫化氢气体，足够使硫杆菌的细菌菌落生长并排泄硫酸。

氧化亚铁硫杆菌的某些菌株可在酸浓度高达7％的环境里大量繁殖，从而产生足以对混凝土管到造成腐蚀的硫酸，由此形成的微生物腐蚀（MIC）可在几个月破坏混凝土管道的完整性。

而硫化氢集中区域正好有一条埋深16ft，直径48in、长515m的钢筋混凝土（RCP）管，其原始壁厚为5in，但目前该管道仅剩下1in厚度的管壁保持完好，剩下部分都十分松散易碎。

对该RCP管道进行修复变得十分迫切，但是16ft的埋深及5ft深的地下水，使得采用非开挖修复成为必然选择。

通过对几个不同方法的对比，业主最终选择用CCCP技术对主管进行修复，而用CIPP技术对支管进行修复；同时，考虑到该地区存在大量的H2S气体，在CCCP内衬修复材料PL-8,000中添加一定量的Con mic shield®抗微生物腐蚀（MIC）添加剂，从而彻底消除H2S的隐患。

根据设计，CCCP内衬管有1in厚就足够，但业主出于保守起见，在一些部位仍使用了2in的厚度。

实践表明，CCCP内衬管就有结构强度高、整体性好、过流断面减小量小、一次性施工长度大、特别适合大管道修复等优点，且与CIPP技术相比，施工成本更低。

武汉中地管通非开挖科技有限公司
电话：138****9445联系人：孔耀祖（博士）
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武汉市东湖高新技术开发区光谷创业街 12 栋 A4-901 室
Angus W. Stocking, L.S.
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214 Box Elder Avenue (other shipping)
Paonia CO 81428
270.363.0033 cell
970.527.4326 home/office
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Wednesday; October 23, 2013
1,400 words
When It Smells Like Sewage, But Isn’t: Huntington Beach Gets Innovative to Solve
Puzzling Storm Drain Failure
by Angus W. Stocking, L.S.
When passersby reported strange smells near the intersection of Brookhurst and Hamilton in Huntington Beach, California, city officials looked into the matter. What they found was puzzling; though the odors were definitely ‘sewage-like’, analysis of the drain layout and testing of the surrounding soil and groundwater showed conclusively that actual sanitary waste and/or infiltra tion wasn’t the culprit. In fact, the source of the odor is still something of a mystery; the best guess is that surrounding marshy areas contribute enough organic matter to cause the smell.
But more importantly, testing revealed high levels of hydrogen sulfide gas—enough, apparently, to foster colonies of Thiobacillus bacteria that consume the gas and excrete sulfuric acid. Some strains of Thiobacillus can thrive in acid concentrations as high as 7-percent. This was bad news; the acid had attacked the concrete sewer, turning it much of it into crumbly calcium sulfate (gypsum). Once established, microbiologically induced corrosion (MIC) can work from the inside out to destroy concrete integrity in a few months.
Chemical grouting was considered as a repair solution, but in this case the pipe was just too fragile. “This was a 48-inch, reinforced concrete pipe (RCP) sewer, about five inches thick,” says Chuck Parsons, general manager at Sancon Engineering, the city’s contractor for the rehabilitation project. “But in places, the good solid concrete was only an inch thick—the rest was almost entirely crumbly and compromised.”
So the city had two challenges: How to make a cost-effective, emergency repair on 515 feet of very fragile storm sewer, under 16 feet of soil and five feet of groundwater and, how to prevent further MIC destruction? The solution proposed by Sancon ultimately included four different trenchless technologies, and a very innovative dewatering method.
Mixing and Matching Methods
Sancon Engineering has specialized in trenchless pipe and sewer repair for over 30 years and they had, basically, every available trenchless technology to work with. CIPP, Danby Rehabilitation, and centrifugally cast concrete pipe (CCCP) were all considered. Eventually, for this project, CCCP was used for the main pipe rehabilitation and CIPP was used to repair two compromised laterals. To prevent further MIC damage and groundwater infiltration, two admixtures from ConShield Technologies were used in the centrifugally cast concrete: ConShield, which prevents MIC by making concrete permanently anti-microbial and Crystal-X, which makes concrete watertight by filling voids in the cured product. “We usually just use ConShield in sanitary sewers,” says Parsons. “But these were ‘sewer-like’ conditions, if you will, and there was certainly MIC damage, so we’re glad ConShield was available. And given the soil conditions and relatively high groundwater, the Crystal-X was also essential in this proj ect.”
The CCCP process used, CentriPipe, from AP/M Permaform and is relatively new. CentriPipe CCCP rehabilitation is built around a precisely controlled spincaster that is inserted into a pipe and withdrawn at calculated speeds. As it’s withdrawn, the spincaster sprays thin layers of high-strength cementitious grout that adhere tightly to most substrates. Essentially, CentriPipe casts a new concrete pipe within the failing pipe that is completely sound structurally, with no seams or joints.
The process was ideal for the Huntington Beach project for several reasons, the most important of which was structural integrity—since the original pipe was failing badly, it couldn’t be relied on to contribute any structural capacity to the final rehabilitation. Moreover, its very fragility ruled out some repair methods; collapsing pipe would make CIPP difficult, and the Danby method is not inherently structural. So CentriPipe emerges as an excellent rehabilitation solution where original pipes are structurally compromised; since the new pipe is cast in thin layers, impact is low during each pass, and since the final casting creates a structurally sound pipe with engineered thickness, the failing pipe is not needed for support. It worked out well in Huntington Beach; during the CentriPipe application on this project, no old cement pulled away during spincasting, and there were no collapses.
It’s also advantageous that the new concrete adheres tightly to the original pipe. This
means no annular space is created for water flow outside the rehabilitation, and since CentriPipe installations are usually quite thin—usually less than two inches—flow capacity is not significantly affected. And CCCP is extremely cost effective, compared to CIPP, especially for large diameter pipe.
B ut CentriPipe is not usually used to fill irregular spaces, and that’s why CIPP was used to line the laterals. “Big earth voids had formed around the lateral entrances,” Parsons explains. “They were large, irregular cavities, and we weren’t sure how to fil l those areas effectively.” So, new CIPP was placed in the laterals, and allowed to project well into the main storm sewer. After curing, conventional spraycasting was used to fill and stabilize the voids around the projecting ends, and the CIPP was trimmed. This left a stable, round pipe, ready for CentriPipe.
This combination of several trenchless solutions is fairly common in large rehabilitation projects; no one method can handle every particular challenge when working underground. “Once we were actuall y prepared to do the CentriPipe, it went very quickly,” says Parsons “just a couple of weeks in fact. But, it took us several weeks to get to that point. Dewatering, in particular, was a significant challenge.”
In fact, the first dewatering method employed, a series of well points installed along the pipe, wasn’t really successful. Sancon ended up devising a method that was new in their experience.
One Way. Or Another.
The first dewatering method used was a series of about 30 well points, drilled into concrete sidewalk at regular intervals along the pipe and ending near the pipe midline. In ordinary conditions, these well points could be used to pull out enough groundwater to allow CIPP and CCCP work—PL-8000, the grout typically used in CentriPipe applications, adheres well even in moist conditions, but standing water does have to be removed.
Unfortunately, these weren’t ordinary conditions. “This was very heavy clay soil, and the original pipe was laid in rock bedding,” Parsons explains. “We just couldn’t g et enough water to come up out of the bedding and into the wells.”
So something new was tried. Sancon drilled three two-inch holes along the old sewer invert to get at the rock bed directly. The results were remarkable. “There was so much groundwater press ure that jets of water shot up through the holes,” says Parsons. “They were like little geysers, 15 inches high.”
To take advantage of that direct access, pumps were used to suck water out of the bedding, and CentriPipe was applied in two phases; first the upstream half of the pipe
was dewatered and CCCP applied, then the downstream half was rehabilitated the same way. This, incidentally, highlights another advantage of CentriPipe; since the cement layers bond well, work can be done in phases without leaving seams or joints. In this case, third party engineers said that a total CCCP thickness of less than an inch would have been sufficient, but Parsons chose to go thicker—nearly two inches in some parts of the pipe—in several passes for extra strength and security.
Whatever it Takes
There were a few other challenges associated with this project—a bus stop had to be moved, for example, and a lot of driveways had to repaired when work was done—but in fact it went extremely well when one considers the possibilities; after all, MIC damage can often lead to chronic weaknesses in sewers, and working trenchlessly, in heavy soils, is typically slow and expensive. And also, this work wasn’t planned for as part of a comprehensive maintenance scheme—MIC damage to a storm sewer is not an expected source of failure in Huntington Beach.
But in this case, Sancon was able to use primarily CentriPipe, complemented by several other relatively new technologies, to efficiently and cost-effectively make a near-emergency repair. The newly rehabilitated storm sewer is completely sound, structurally, and thanks to ConShield and Crystal-X it’s also permanently and intrinsically watertight, ant-microbial, and MIC-resistant. Post-project video inspection confirms that the new pipe is sea mless and sound. Thanks to Sancon’s innovative thinking, this is one storm sewer that city officials shouldn’t have to worry about for many decades.
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Angus W. Stocking, L.S. is a licensed land surveyor who has been writing full time on infrastructure topics since 2002. 。