Data on man-made sinkholes due to leakage in underground pipelines in different subsurface soil profiles
Description
Jae-ho Choia* (jaehochoi@dau.ac.kr) Abstract A sinkhole is a ground surface depression that may occur with or without any indications on the surface and often pose danger to both properties and people. Leakage from underground pipe mains in urban areas may cause sudden ground subsidence or sinkholes. For a long time, researchers have been working on hazard and risk assessment of sinkhole formation, especially natural sinkholes. However, much less work has been done on risk prediction and the mechanism of manmade sinkholes. In this study, different versions of small-scale sinkhole physical models were used in experiments to monitor ground settlement or collapse due to leakage from an underground pipeline. The factors under consideration were the type of subsurface soil profile, type of water flow, and leakage position in the pipeline. The ultimate goal was to use this information to predict the risk of sinkhole occurrence due to leakage from sewer or water pipelines under different subsurface soil conditions. The experimental results and statistical analysis showed that the subsurface soil strata conditions dominated the mechanism of sinkhole occurrence, although other factors also have contributed to the settlement. This analysis was then used to predict the sinkhole risk level under different conditions. The development of a reliable sinkhole risk prediction system can potentially minimize the risk to human lives and infrastructure. These findings can be applied to the development of a sinkhole risk index (SRI) that considers various other factors influencing sinkhole occurrence.
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Steps to reproduce
The first stage of the experiment was to design the architecture in the laboratory. The overall architecture of the experimental setup is showed by (Ali and Choi, 2019). Water was supplied to the system from a water tank (Tank 2) with a capacity of 227 liters. The water passing through the pipeline was collected at the other end (outlet). The collected water at the outlet lets the authors know about the quantity of water which is seeped into the model box through the leakage. In total 200 liters of water was inside the water tank for each case. As the pressure of the water flow declines steadily with the water level inside the water tank (inlet), so another water tank (Tank 1) was used to maintain the water level in Tank 2 to control the drop in water pressure, as showed by (Ali and Choi, 2019). A solenoid valve was fixed at the bottom of each water tank to manually control the flow of water inside the pipeline. A PVC pipeline with an external diameter of 40 mm and internal diameter of 36 mm was used. Artificial leakage was created by making a hole in the pipeline, as showed by (Ali and Choi, 2019). The model box used for the experiment had dimensions of 700 mm (width) × 600 mm (length) × 330 mm (height) with a hole at the center of the bottom for drainage. The different subsurface soil profiles considered in this study comprised bedrock, carbonate rock, cavities, sand, and clay. Four soil profiles were considered: sandy clay (SC), sandy clay-bedrock (SC-BR), sandy clay-cavity-bedrock (SC-C-BR), and sandy clay-limestone-bedrock (SC-LS-BR). In addition, two water flows in the pipeline were considered: continuous and cyclic. The materials adopted for the 13 different soil profile models in the laboratory included sandy clay, limestone, sugar cubes, and gravel. Coarse aggregate (gravel) was used to represent bedrock, limestone powder was used to represent limestone, and sugar cubes were used to represent artificial cavities as showed by (Ali and Choi, 2019). Ali and Choi, (2019) showed that the four different soil profiles under consideration in this study are represented as A, B, C, and D. In each of the 13 cases, the soil was compacted in two layers that were each 160 mm in thickness. The soil was compacted manually with a brick having dimensions of 20 cm × 6.3 cm × 5 cm, and 20 vertical blows were used for each case. To measure the settlement in each case, a meter tape was attached vertically to the center of each model box, and the reading was recorded in millimeters (Ali and Choi, 2019). A camera was used to capture images of the experiment at the beginning and end of each case.