Data on manmade sinkholes due to leakage in underground pipelines in different subsurface soil profiles

This paper provides simulated datasets for different versions of small-scale physical sinkhole models that are essential to understand the sinkhole formation rate. These 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 subsurface soil profile, pattern of water flow, and leakage position in the pipeline. The experimental results and statistical analysis showed that the subsurface soil strata conditions dominated the sinkhole occurrence mechanism, although other factors also contributed to the settlement. The results also showed that the subsurface soil comprising strata sandy clay, limestone, and bedrock (SC-LS-BR) dominates the sinkhole mechanism. The data are organized and formated in a useful structure. Specifically, the dataset is presented in terms of tables to illustrate the settlements in different soil profiles under various conditions. This analysis was then used to predict the sinkhole risk level under different conditions. The formulated dataset and the results can be considered in developing a sinkhole risk index (SRI) and identifying sinkhole risk areas.


Specifications
Civil

Value of the Data
• A dataset of manmade sinkholes (see [2] ) generated from leaking pipelines in different subsurface soil profiles can be useful for predicting the sinkhole risk in urban areas. • This dataset can help public and private maintenance authorities, such as urban water management authorities and geological departments, to take action as soon as possible to prevent accidents due to leaking underground sewers and/or water pipelines. • Researchers in the area of urban disaster risk prediction and urban infrastructure development can use the data to develop a Sinkhole Risk Index (SRI).

Data Description
The presented data (see [2] ) were obtained from a systematic experimental investigation of manmade sinkholes due to leakage in underground water pipelines in different subsurface soil profiles. Two different types of water flow, continuous and non-continuous flows, were considered. The subsurface soil profiles under consideration were: 1. Sandy clay (SC) 2. Sandy clay and Bedrock (SC-BR) 3. Sandy clay, Limestone, and Bedrock (SC-LS-BR) 4. Sandy clay, Cavity, and Bedrock (SC-C-BR) Table 1 outlines the settlement data for four different soil profiles when the flow inside the pipeline was continuous. Table 2 shows the settlement data for four different soil profiles when the flow inside the pipeline was non-continuous (30 s cyclic time interval). Table 3 shows the settlement data for four different soil profiles when the flow inside the pipeline was non-continuous (5 s cyclic time interval).

Data simulation setup
The software architecture for our data analysis was implemented using the R programming language. The R language has many benefits, such as compatibility with many operating systems and real-time implementation. The Origin Pro-tool was also used to cross-check the results of our analysis. In our study, the dataset has been re-organized and re-formated. The data is represented in different tables in order to illustrate the sinkhole mechanism under various subsurface soil profiles for different water flow conditions and time periods.

Experimental design and materials
The first stage of the experiment was to design the architecture in the laboratory. The overall architecture of the experimental setup is shown in [1] . Water was supplied to the system from a water tank (Tank 2) with a capacity of 227 L. The water passing through the pipeline was collected at the outlet, allowing measurement of the quantity of water seeping into the model box due to leakage. In total, 200 L of water was placed into the water tank for each case. As the pressure of the water flow at the inlet declines steadily with the water level inside the water tank, another water tank (Tank 1) was used to maintain the water level in Tank 2 to control the drop in water pressure, as shown by [1] . A solenoid valve was fixed at the bottom of each water Table 2 Settlement values for non-continuous water flow with 30 s cyclic time interval through four different soil profiles.  12  17  30  117  960  13  20  34  119  1020  14  23  145  121  1080  15  27  147  125  1140  16  32  149  127  1200  17  36  151  131  1260  19  40  154  135  1320  21  44  156  138  1380  22  48  158  139  1440  23  51  159  142  1500  24  54  163  144  1560  25  56  166  146  1620  27  58  169  147  1680  28  60  173  148  1740  29  61  174  149  1800  30  62  175  150 tank to manually control the flow of water inside the pipeline. A PVC pipeline with an external diameter of 40 mm and an internal diameter of 36 mm was used. Artificial leakage was created by creating a hole in the pipeline, as shown by [1] . 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 combinations of bedrock, carbonate rock, cavities, sand, and clay.
Step 6 was repeated for a non-continuous flow of water with two different time intervals of 30 s and 5 s. 8. A camera was used to capture images of the experiment at the beginning and end of each case.
From the extracted dataset, the subsurface soil strata consisting of sandy clay, limestone, and bedrock (SC-LS-BR) are seen to dominate the sinkhole mechanism.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships which have or could be perceived to have influenced the work reported in this article.