Experimental study on crack development of subgrade soil under rainfall and polymer material repair
Year: 2025
Type: article
Abstract: • When the pavement structure layer is intact and free of cracks, the wetting front of the sample permeates downward in a horizontal annular pattern following water infiltration. When cracks are present in the pavement structure layer, the wetting front of the samples infiltrates in a V-shaped pattern following rainfall water infiltration, resulting in a clearly defined preferential flow state. The test data indicate that the water infiltration rate under cracked conditions is approximately 40 % faster compared to the intact structure, while the compressive strength of the soil in the cracked area decreases by 25 % to 30 %. • The impact of the dry-wet cycle on soil strength is a significant weakening factor. The dry-wet cycle has a substantial impact on the mechanical properties of soil, leading to a noticeable reduction. After 5 cycles, the compressive strength of the soil reduced from 134.7 kPa to 82.9 kPa, representing a 38.5 % decrease. Similarly, the shear strength decreased from 50.4 kPa to 24.5 kPa, reflecting a 51.4 % reduction. As the number of cycles increases, the fracture propagation rate accelerates. After the third cycle, the fracture width expands by approximately 50 %, and following the fifth cycle, the fracture depth reaches up to 60 % of the specimen height. • Select an appropriate solution formula to conduct crack resistance testing on subgrade topsoil. We explore the evolution law of cracks under dry-wet cycles and the principle of controlling crack evolution through water blocking using polymer materials. ① The polymer solution can modify the physical properties of soil on both sides of cracks through material enhancement, thereby slowing down crack development in a more effective manner. When the acrylamide solution content is 10 %, the effect is optimal, extending the sample's disintegration time from 30 s to 180 s—a delay of up to 500 %. Additionally, the shear strength increases to 59.9 kPa, representing an improvement of 18.8 %. The magnesium acrylate solution demonstrated superior water resistance and stability. During the dry-wet cycle, the number of secondary cracks was reduced by 50 %, and the crack depth was successfully controlled to within 20 % of the sample height. Both materials can effectively slow down the development of cracks and block the water migration path by filling cracks and enhancing the physical properties of soil, such as increasing cohesion to 28.7 kPa and the friction angle to 35.5° ② Polymer materials form a water barrier by plugging cracks through water absorption and expansion (acrylamide) or curing and filling (magnesium acrylate). The moisture distribution in the modified soil becomes more uniform, and the stress distribution gradually balances during the dry-wet cycle, effectively inhibiting further crack expansion. With how fast highways are developing in China, road cracks are becoming a bigger and bigger issue. Especially when it rains, the cracks get worse and the soil gets damaged, which leads to more problems for the roads. In this paper, we look at how rainfall soaking and dry-wet cycles affect soil cracks in the road base through lab tests. We also talk about how well polymer materials work for fixing those cracks. The test results show that: (1) If the pavement structure is intact, water seeps in horizontally in a ring-like pattern. But when cracks are present, the water moves in a V-shape, creating a clear preferential flow. (2) The dry-wet cycles really lower the soil's compressive and shear strength, and make crack spreading worse. (3) By tweaking the polymer material formula with an orthogonal test, a solution of acrylamide and magnesium acrylate can slow down crack spreading and boost the soil's shear strength. Among these, the 10 % acrylamide solution works the best. It really slows down how fast the samples break apart and boosts their shear strength. The way polymer materials fix cracks includes: changing the physical properties of the soil around the cracks to slow down their growth, and filling in the cracks to create a water barrier that keeps the water balance on both sides. This study provides effective materials and technical support for subgrade crack repair.
Source: Results in Engineering
Institutions: Tianjin University, Henan University
Language: English
Subfield: Civil and Structural Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,940
OpenAlex ID: W4409716601