Experimental data on the temperature dependence of P-wave velocities in rocks of various genesis
Description
This dataset contains the raw and processed experimental results supporting the findings of the manuscript " Inversion of the Temperature Dependence of Longitudinal Elastic Wave Velocities in Rocks of Various Genesis: Experimental Observations and Physical Mechanisms". The study investigates the thermal behavior of longitudinal (P-wave) velocities in four rock types – limestone, marble, granite, and volcanic tuff – across a temperature range of 30 °C to 100 °C. Measurements were conducted using the pulse ultrasonic method with a temperature step of 10 °C. The data reveals a fundamental inversion in thermal behavior depending on rock origin. Dense crystalline (granite, marble) and sedimentary (limestone) rocks exhibit a monotonic decrease in velocity due to thermoelastic lattice softening. In contrast, highly porous volcanic tuff displays an anomalous velocity increase driven by thermal compaction and microcrack closure within its amorphous glassy matrix. The dataset includes absolute velocity values (Vp), time delays (Delta t), specimen dimensions, and calculated relative changes in velocity (Delta V and delta) with respect to the baseline at 30 °C. These results provide a physical basis for origin-differentiated approaches in geomechanics and highlight the invalidity of simplified empirical models for thermally affected porous media. Methodology: • Specimens: Cylindrical samples (20 mm diameter, 120 mm length) of limestone (Domodedovo quarry), marble (Koelga deposit), granite (Vozrozhdenie deposit), and volcanic tuff (Akhaltsikhe deposit). • Apparatus: Pulse ultrasonic flaw detector (UD2-70) with 1 mm piezoelectric transducers; Nabertherm tubular furnace with P320 controller; Testo electronic thermometer. • Procedure: Air-dry samples were heated from 30 °C to 100 °C in increments of 10 °C. P-wave velocity (Vp) was calculated based on the specimen length (L) and the two-way travel time (Delta t) of ultrasonic pulses reflected from the end faces. • Calculated parameters: The dataset includes the mean velocity of three measurements per step (VpMean), absolute change (Delta V = V - V0), and relative change (delta) with respect to the baseline at 30 °C. File Structure: The dataset is provided in an Excel file (.xlsx) containing data: 1. Specimen length (L) and temperature step parameters. 2. Experimental measurements contain 96 records of time-domain and velocity-domain measurements for all rock groups (L1a, L2a, G3a, etc.). Columns include temperature (Temp. [C]), time delays (Delta t [microseconds], Delta t [s]), absolute velocities (Vp [m/s]), mean velocities (VpMean), and relative variations (delta). 3. Raw time data contains the raw time interval values (tmin, tmax) in microseconds for each ultrasonic pulse measurement. 4. Plots of temperature dependences of Vp velocities for individual specimens, as well as averaged dependences of Vp, ΔV, and δ(T).
Files
Steps to reproduce
the step-by-step procedure for obtaining the dataset was as follows: 1. Sample Preparation Four groups of rocks representing different genesis were selected: sedimentary (limestone), metamorphic (marble), igneous plutonic (granite), and igneous volcanic (tuff). From each rock type, three cylindrical core specimens were prepared with a diameter of 20 mm and a length of 120 mm. 2. Experimental Setup Each specimen was placed horizontally in a central holder inside a tubular furnace. A Testo electronic thermometer with a thermocouple was attached directly to the sample surface to monitor the actual rock temperature. For ultrasonic measurements, two 1 mm piezoelectric transducers were bonded to the opposite end faces of the specimen. 3. Temperature Regime The samples were heated from an initial temperature of 30 °C to a maximum of 100 °C. The temperature was increased in discrete steps of 10 °C. At each step, the furnace temperature was stabilized to ensure a uniform thermal field within the specimen before taking measurements. 4. Time Delay Measurement. At each temperature point (30 °C, 40 °C, ..., 100 °C), a series of ultrasonic pulses was transmitted through the rock. The instrument recorded the time delay of the elastic wave. To minimize systematic errors caused by electronic delays in the instrument's circuitry, a pulse-echo scheme was used: the velocity was calculated based on the time interval between two consecutive echo pulses (the two-way travel time). These raw time values are recorded in the "Raw time data" sheet of the Data file (columns tmin and tmax, with the difference calculated in columns Delta t [mks] and Delta t [s]). 5. Velocity Calculation The P-wave velocity Vp for each individual measurement was calculated using the known length of the specimen L and the measured two-way travel time. The resulting values in meters per second are listed in the column Vp [m/s] of the "Experimental measurements" sheet.