Datasets of various geotechnical surveys in several arrays in the Taipei Basin

The standard penetration test (SPT), seismic cone penetration test (SCPT), and various in-situ seismic tests are commonly utilized for geotechnical site investigations. The investigated data via these tests are widely adopted to capture site characteristics for geotechnical engineering design. However, site characterizations vary in the above in-situ tests, which leads to uncertainties in the corresponding engineering analysis and design. To address these variabilities, this paper meticulously carried out the above-mentioned geotechnical in-situ tests with rigorous supervision at 13 selected sites in the Taipei Basin, yielding several valuable datasets. The datasets consist of digital investigation data including SPT-N, soil classification, CPT-qc and -fs, and the shear wave velocities (Vs) obtained from different measurements. We believe that these datasets will be beneficial for conducting various calibration studies for different geotechnical investigation methods and the corresponding geotechnical parameters.


Subject
Earth and Planetary Sciences Specific subject area Geotechnical Engineering, Geophysics

Data format
Seismic cone penetration test (SCPT) data, Standard penetration test (SPT) data (including index properties of split-samples): Raw Shear wave velocity (V S ): Analyzed Type of data Table Data collection Except for V S data collected via the multichannel analysis of surface waves (MASW) tests, all data were acquired based on the following corresponding international standards: • CPT data: ASTM D5778 (2012) • SPT data: ASTM D1586 (2018) & ASTM D4633 (2010) • V S via cross-hole seismic tests: ASTM D4 428/D4 428M (2016) • V S via down-hole seismic tests: ASTM D7400 (2019) • V S via suspension PS-logging: JGS 1122 (2012) For MASW measurements, all test lines were over 60 m long, and 23 geophones (4.5 Hz) at 3 m intervals were used to receive the signals generated by an active source in each line.The SeisImager/SW software was used to derive a dispersion curve by selecting the maximum amplitudes.The deterministic inversion of dispersion curves was adopted to derive the V S values according to the procedures recommended in the SeisImager manual [9] .

Data source location
The dataset was obtained from alluvium sites along the Tamsui River and the Keelung River in the Taipei Basin in Taiwan.The map of these sites is shown in the manuscript.Data

Value of the data
• Multiple prevalent in-situ tests, including the standard penetration test (SPT), seismic cone penetration test (SCPT), and various other seismic tests (e.g., cross-hole seismic tests and suspension PS-logging methods), were meticulously implemented at each of 13 sites in the Taipei Basin.The multiplicity of in-situ tests at one site benefits studies on the correlation of geotechnical parameters and calibration of their transformation variability.Moreover, the consistency studies of V s measurements via different seismic tests is also enhanced by these datasets.• The datasets contain the subsurface geo-information (reaching 30 m in depth) for each site, which provides information for soil liquefaction risk evaluation and site classification.• This database contains two-or three-dimensional underground information for each site, which enhances studies on spatial variability and provides actual case data for numerical studies on modeling geo-formations.• Data-centric geotechnics play an important role in response to digital transformation.However, corruption of geotechnical investigation data commonly poses a challenge.While it is time-consuming and labor-intensive to clean and organize corrupted data from legacy systems, these in-situ investigation records help eliminate this problem since data acquisition was supervised by doctoral fellows from the National Center for Research on Earthquake Engineering (NCREE), which ensures the quality of output results.

Background
The 2016 Meinong earthquake in Southern Taiwan highlighted the urgency of addressing soil liquefaction risks, particularly in urban settings.In response, the Taipei City Government launched the 'Home Security Plan.'This project was a concerted effort to assess and strategize soil liquefaction potential in anticipation of future seismic events.Collaborating with the NCREE  as the main consultant and CECI Engineering Consultants as the executing agency, the project involved comprehensive geological surveys in over ten sites across the Taipei Basin.These surveys aimed to identify and analyze key factors in liquefaction assessment, including various testing and evaluation methodologies.
The NCREE oversaw the execution of these on-site investigations, conducted by CECI Engineering Consultants, to guarantee the data reliability and quality.The collected data are expected to significantly contribute to geotechnical research, particularly in understanding the uncertainties of simplified soil liquefaction assessment methods, shear wave velocity measurements, and correlation of different geotechnical parameters.

Data Description
The datasets include the data of SPTs, SCPTs, and a series of in-situ V s measurements conducted at 13 chosen Holocene alluvium sites in the Taipei Basin.Table 1 provides a list of site labels, coordinates, and layout indices.At each of the 13 sites, two or three boreholes were drilled, and two SCPTs, traditional invasive seismic measurements (using cross-hole, down-hole, and suspension methods), and non-invasive MASW (multichannel analysis of surface waves) tests were conducted.Data from each site were compiled into a single Microsoft EXCEL spreadsheet for the 13 files.Each file comprises two or three worksheets, corresponding to the number of boreholes.Fig. 1 shows the sample data for a site in an EXCEL spreadsheet with three worksheets (three SPT boreholes).The first two characters of the worksheet title correspond to the site label given in Table 1 , while the remaining characters refer to the number of the grouped data.So, please refer to Fig. 2 ."0 0 01" in the spreadsheet title refers to the data from borehole BH-1 and V s measurements or soundings at or close to the borehole (i.e., at C-1).Similarly, "0 0 02" refers to data from BH-2 and associated V s measurements at or close to the borehole (i.e., C2), and "0 0 03" to the data from BH-3 and associated V s measurements.Note that some sites did not have a third borehole and therefore do not have a third worksheet.Each site has a similar plan.Fig. 2 shows the borehole and sounding layout at a typical site, providing a general plan for each location.The example in Figs. 1 and 2 demonstrates that each worksheet captures data for the SPT borehole, SCPT soundings, the V s measurements near the borehole, and MASW test results.Cross-hole V s measurements were repeated and appear in two worksheets when only one of the boreholes was used for cross-hole V s measurements.The V s measurements obtained by the MASW method cover the entire area of the site and therefore appear repeatedly throughout the worksheets.Table 2 shows the SPT data in the CM0 0 02 worksheet and indicates sample number, testing range, SPT-N value, plasticity index (PI), unit weight, soil classification in the Unified Soil Classification System (USCS), soil content, averaged energy ratio, and ground water level during the drilling.Table 3 lists the SCPT data in the worksheet of CM0 0 02 and contains the cone resistance (q c ), the sleeve friction resistance (f s ), pore pressure (u), and shear wave velocity (V s ).Note that the shear wave velocity was only measured every 1 m, so the accuracy is not as high as that for other outputs.Fig. 2 shows the profiles of the SPT boreholes and SCPT soundings at site CM as an example.Table 4 shows the seismic wave velocity measurement results in the worksheet of CM0 0 02.This table includes the derived shear wave velocities (V s ) and compressional wave velocities (V p ) obtained using different methods.Note that the V s measurements obtained by the cross-hole method have two records for each measurement depth.The reason for this is that the V s measurements by the cross-hole method were cross-validated by exchanging receivers and sources, thus generating two different survey paths at the same depth, further enhancing their reliability.Fig. 3 shows the profiles of the V s measurements using different methods at site CM as an example.

Experimental Design, Materials, and Methods
All tests were conducted over the period 27 December, 2018 to 9 April, 2019.All tests including SPT, SCPT, and a series of in-situ V s measurements were meticulously planned at 13  selected Holocene alluvium sites in the Taipei Basin, with a primary focus on the Song-Shan layer.This layer is the youngest Holocene alluvium in the Taipei Basin and consists of interbedded sands, clays, and silts.To reduce interference from environmental vibrations, and to avoid underground pipeline obstacles during geological drilling, the selected testing sites were primarily chosen along banks of the Keelung and Tamsui Rivers.A map of the site locations is shown in Fig. 4 .

Methods and standards
Fig. 2 displays the typical layout of the boreholes and soundings at each site.At each of the thirteen sites, two boreholes (BH-1 and BH-2) were drilled in accordance with international standard [1] and drilled by automatic and donut hammers, respectively.The two boreholes were cased with PVC tubes and backfilled with different materials.BH-1 was filled with pervious sandy gravel with an average grain size of 1 cm, while BH-2 was filled with cement-bentonite grout (with a bentonite to cement and water weight ratio of 1:2:15).These two materials are commonly adopted for backfilling after drilling.To better understand the influence of backfill and casing on V s measurements, one extra borehole (BH-3), placed between the other two holes, was drilled at five of the 13 sites.At each site BH-3 was drilled with a donut hammer according to international standard [1] but it was not cased and backfilled until the suspension tests had been completed.While drilling the boreholes, energy ratio measurements were conducted in accordance with international standard [2] .Other than the boreholes, two SCPTs were conducted in accordance with international standard [3] .The corresponding borehole and SCPT were lo-  cated within approximately 1 m of each other.Fig. 2 shows a typical layout of a site with three boreholes and two SCPT soundings.The boreholes were used for traditional invasive seismic measurement (i.e., cross-hole, downhole, and suspension methods).The depths of all the boreholes and SCPTs were approximately 30 m.The V s measurement interval depth was 1 m, and measurements were made by professionals.To reduce potential interference due to drilling and effects of seismic tests on subsequent measurements, the time interval between drilling and the seismic testing was set to one week.

Data interpretation
In addition to these invasive seismic methods, non-invasive MASW tests were conducted at each site, covering the same horizontal ranges as the other seismic tests.The different seismic tests at each site were sufficiently close to one another such that measurements from these methods can be regarded as being conducted at an identical location.All seismic tests were carried out in accordance with international standards [4][5][6][7][8] , except for MASW.For the MASW measurement, all test lines were over 60 m long and 23 geophones (4.5 Hz) placed at 3 m intervals were used to receive the signals generated by an active source in each line.The SeisImager/SW software was used to derive a dispersion curve by selecting the maximum amplitudes, and deterministic inversion of the dispersion curves was adopted.The MASW procedure was carried out according to the SeisImager manual [9] .
To ensure data quality, drilling and V s measurement operations were supervised by professional engineers from the NCREE throughout the process, and experienced geotechnical experts irregularly inspected the implementation procedures.Moreover, the data processing procedure (e.g., picking arrival times) and the final measurement results were examined by a committee comprised of geotechnical engineering and geophysical science scholars and engineers from Taiwan.Fig. 5 shows photographs of supervision for each test.

Fig. 1 .
Fig. 1.A typical example of a spreadsheet and worksheet (from sample data of site CM).

Fig. 2 .
Fig. 2. Layout and results of SPT and SCPT at site CM.

Fig. 3 .
Fig. 3. V S profiles obtained using different methods at site CM.

Fig. 5 .
Fig. 5. Photographs of methods employed at each test.

Table 1
Abbreviation of the sites and their coordinates.

Table 2
Data example of SPT.

Table 3
Data example of SCPT.

Table 4
Data example of Vs measurements.
Fig. 4. Locations of the thirteen test sites.