Imperfections in waterproofing board cutting and second lining seriously threaten driving safety

In the section where the second lining is plain concrete, due to improper construction of the purchase high quality HDPE liner and poor joint construction quality, when pouring the second lining, the concrete penetrates between the waterproof board and the main support through the joint gap of the waterproof board, the waterproof board is loose, resulting in waterproofing The slab is embedded in the second lining, forming the phenomenon of cutting the second lining concrete, so that the second lining concrete forms the inner and outer layers.

The defect of "secondary lining of wholesale HDPE Liner made in China cutting" seriously threatens driving safety and must be treated. In order to judge the safety of the tunnel structure and provide a basis for the treatment design, the test data should be detailed and reliable.

Combined with actual work experience, for such defects, the crack distribution area should be mainly checked during visual inspection, because the crack part may be the weak part of the outer concrete. From the crack distribution, the defect range can be initially determined. For the selection of "rebound strength and drilling Provide a reference for the location of the "core inspection". In order to facilitate inspection and observation, the convex part is generally cleaned locally, but it is not suitable for large-scale cleaning. Large-scale cleaning may cause large-scale peeling of the raised parts, accelerate structural damage, further threaten driving safety, and bring hidden safety hazards to on-site inspection work. If the lining part of the same mold has the same repair marks as the defect, and there is no high quality aquaculture geomembrane exposed in appearance, it is likely to be a similar defect problem. The repair position and the surrounding core can be verified.

Ground penetrating radar is usually used to detect the thickness, voids and voids of the second lining. The thickness, voids and voids of the second lining are detected in detail through encrypted survey lines (the line spacing at the arch is 1m). Provide the basis for the selection of the later reinforcement treatment design plan.

When using the rebound method to detect the strength of the secondary lining, the results of the visual inspection should be used as the basis to avoid the rebound value of the weak parts of the secondary lining. The core sample of the coring test should consider the compressive strength test.

When dealing with defects, reinforcement measures such as planting bars, hanging nets, and vertical arches can be taken on the surface of the original lining. Considering that planting steel bars, hanging nets and setting arches may invade the tunnel construction area plastic geocells factory price, it is necessary to measure the clearance of the tunnel section. When measuring, you need to find the center line of the tunnel. The circumferential distance between the measuring points is generally 1m. Compare the measurement results with the tunnel design parameters for reference in the processing design.

The main purpose of drilling and coring is to finalize the defect scope in detail. Ground penetrating radar detection cannot quickly and accurately determine the defect range, and can only be determined initially by visual inspection. If it is verified by large-scale coring, it is necessary to drill many holes in the secondary lining structure. Excessive holes will not only affect the stability of the original structure, but also make it difficult to deal with the waterproofing and drainage of the tunnel in the leaky section.