Common Construction Mistakes of Geosynthetics and Standardized Construction Optimization Plan

Most quality problems such as leakage, settlement, cracking and landslide in geotechnical, anti-seepage and reinforcement projects do not all stem from product quality problems, but are mostly caused by non-standard construction and operation misunderstandings of geosynthetics. Many construction teams adopt traditional extensive construction methods, ignoring key details such as base surface treatment, laying process, lap welding and finished product protection. Even if high-quality national standard materials are selected, problems such as unqualified project quality, failed acceptance and later rework will occur. This article sorts out five high-frequency misunderstandings in geosynthetics construction, and provides optimization schemes combined with standardized construction processes to help construction teams standardize operations and improve project quality.

1. Misunderstanding 1: Ignore base surface treatment and lay materials directly

Many constructors lay geotextile, geomembrane, waterproof blanket and other materials directly on the base surface with unevenness, gravel, weeds and sharp debris without cleaning and leveling the base surface to save construction period, which is the most common construction misunderstanding. Sharp gravel and debris will directly pierce and scratch geosynthetics, causing invisible damage, which is easy to lead to leakage and cracking in the later stage; uneven base surface will lead to hollowing, wrinkles and uneven stress after material laying, and local damage and shedding will occur after long-term soil extrusion.

Standardized optimization plan: Before construction, comprehensively clean the base surface, remove gravel, weeds, tree roots and sharp hard objects, level and compact the soil to ensure that the base surface is flat, solid, free of impurities, protrusions and depressions. For areas with soft soil, complete compaction and reinforcement in advance to avoid pulling materials due to later settlement, provide a flat and stable construction base for geosynthetics laying, and avoid hidden dangers of material damage from the source.

2. Misunderstanding 2: Insufficient lap width and non-standard welding/splicing

The lapping and welding process of geosynthetics laying is the core key to project quality and also the most error-prone link. Some construction teams arbitrarily reduce the lap width to save materials and speed up construction. The lap width of geotextile and waterproof blanket is less than 10cm, and the lap width of geomembrane welding is less than 8cm, resulting in excessive gaps at material joints and water seepage and delamination. At the same time, hot melt welding of geomembrane has problems such as virtual welding, missing welding and uneven weld joints. The splicing place becomes the weak point of the project, and leakage is easy to occur.

Standardized optimization plan: Strictly implement national standard lapping standards. The conventional lap width of geotextile and bentonite waterproof blanket shall be ≥15cm, and the lap width in slope and deep water areas shall be ≥20cm; the lap width of HDPE geomembrane hot melt welding shall be ≥10cm, and double-track hot melt welding process shall be adopted to ensure flat and firm weld joints without missing welding and virtual welding. After welding, air pressure test and tensile test shall be carried out to ensure that the splicing strength and anti-seepage performance meet the standard and eliminate hidden dangers of gap leakage.

3. Misunderstanding 3: Laying too tight or too loose without expansion allowance

The tightness of geosynthetics laying directly affects the service life of the project. Many constructors cannot control it properly. Either lay it too tight and fully stretched without any expansion allowance; or lay it too loose with accumulated wrinkles. When laid too tight, soil settlement and temperature difference expansion and contraction will directly pull the material, resulting in cracking and fracture; too loose laying will cause material accumulation and hollowing, and uneven stress will lead to local damage and displacement, affecting reinforcement and anti-seepage effect.

Standardized optimization plan: Reserve reasonable expansion allowance according to the construction environment. The relaxation degree during laying at room temperature is controlled at 3%-5%. Appropriately increase the relaxation degree for construction in high-temperature summer, and reduce the stretching force for construction in low-temperature winter to ensure that the material fits the base surface, flat without wrinkles and excessive tension. Lay the material from top to bottom on the slope at a constant speed to avoid local pulling and accumulation, ensure uniform stress of the material and adapt to soil settlement and temperature difference deformation.

4. Misunderstanding 4: Lack of finished product protection and material damage in later construction

After the laying of geosynthetics is completed, many construction teams directly carry out the next process of soil covering, pouring and rolling, ignoring finished product protection, which is easy to cause secondary damage. Treading by constructors, rolling by construction machinery and falling of sharp materials will cause invisible damage to the laid geomembrane and geotextile; long-term open-air exposure and rain erosion will also accelerate material aging and displacement and reduce service life.

Standardized optimization plan: After the acceptance of material laying, carry out soil covering protection and protective layer construction in a timely manner to avoid long-term open-air exposure. During construction, heavy machinery is prohibited from directly rolling unprotected geosynthetics. Constructors wear soft-soled shoes to work to prevent sharp tools from scratching materials. Make protective shielding during construction intervals to avoid rain erosion and wind pulling, and comprehensively protect the integrity of finished materials.

5. Misunderstanding 5: Ignore detailed acceptance and leave quality hidden dangers

Many projects only carry out overall appearance acceptance, ignoring the acceptance of details such as corners, lap joints, internal and external corners and pipeline interfaces. These concealed parts are high-incidence areas of leakage and damage, which are easy to leave hidden quality dangers. At the same time, some teams do not carry out water test and compression test, and deliver directly after completion, which is easy to have quality problems in later use and cause rework losses.

Standardized optimization plan: Project acceptance implements dual standards of comprehensive acceptance + detail verification. Focus on checking concealed parts such as corner lap joints, welding interfaces, internal and external corner treatment and pipeline wrapping to ensure no damage, missing welding and qualified lap. For anti-seepage projects, carry out a closed water test for more than 48 hours after completion, and carry out load test for reinforcement projects. The next process can only be carried out after acceptance to completely eliminate hidden dangers of project quality.