The shape effects of prefabricated vertical drains and smear zones on consolidation
HUANG Chaoxuan1*, LEI Guohui2, WANG Jun1, GU Tingwei1, DENG Yuebao3
(1. Zhejiang Design Institute of Water Conservancy and Hydroelectric Power, Hangzhou, Zhejiang 310002, China; 2. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing, Jiangsu 210024, China;
3. Collaborative Innovation Centre of Coastal Urban Rail Transit, Ningbo University, Ningbo, Zhejiang 315211, China)
Abstract：The smear zone created by the installation of a prefabricated vertical drain (PVD) is typically considered elliptical in practice, whereas current theoretical methods assume it to be circular. This assumption impacts the accuracy of consolidation calculations. Utilizing the consolidation theory of equal strain for a vertical drain foundation and the assumption of an elliptical cylinder for both the PVD and smear zones, analytical solutions for excess pore water pressure and the average degree of consolidation under complex loads are derived. An example analysis is conducted using finite element numerical simulations and laboratory test data to validate this method. The results indicate that the ratio of the equivalent diameter of the elliptical smear zone to the equivalent diameter of the area equivalence decreases as the oblateness of the elliptical smear zone increases. When the elliptical oblateness is substantial, the ratio gradually diminishes. Conversely, the equivalent diameter ratio increases with an increase in the width of the PVD. Under conditions of equal smear zone areas, a flatter smear zone results in a smaller adverse effect and a faster consolidation rate of the foundation soil. A fitting formula for the equivalent diameter of the oblate elliptical smear zone is provided for commonly used prefabricated vertical drains in engineering applications, offering a technical reference for related engineering design and research.
黄朝煊1*，雷国辉2，王 军1，顾霆威1，邓岳保3 . 排水板及涂抹区形状效应对竖井地基固结影响研究[J]. 岩石力学与工程学报, 2026, 45(S1): 423-436.
HUANG Chaoxuan1*, LEI Guohui2, WANG Jun1, GU Tingwei1, DENG Yuebao3. The shape effects of prefabricated vertical drains and smear zones on consolidation. , 2026, 45(S1): 423-436.
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2026, Vol. 45 
