Decrease In Wave Velocity Research Articles

2Pb1-5 Decrease of longitudinal wave velocity in glycated collagen

2Pb1-5 Decrease of longitudinal wave velocity in glycated collagen

Experimental investigation of thermal cycling effect on physical and mechanical properties of heated granite after water cooling

Geothermal energy is recommended as a clean and renewable energy resource. During the exploitation process, hot rocks in a geothermal reservoir will be subjected to cyclic water cooling. Laboratory tests were conducted to investigate the physical and mechanical behaviors of water-cooled granite specimens subjected to various thermal cycles with temperatures ranging from 20 °C to 500 °C. Meanwhile, scanning electron microscope (SEM) images were used to capture the development of the microcracks within the specimens. It was found that volume increases with thermal cycle and mass, that density and P wave velocity decrease with thermal cycle, especially after the first thermal cycling, and their change rates diminish with increasing thermal cycle. Both uniaxial compressive strength (UCS) and elastic modulus (E) of granite decrease with thermal cycle. The decreasing extents gradually tend to constant with thermal cycle, and they remain almost unchanged once the thermal cycle reaches 20 iterations. The deterioration mechanisms of the physical and mechanical behaviors of granite are mainly caused by the generation and propagation of microcracks. Microcrack density increases slowly with the thermal cycle rising from 10 to 30, corresponding to the decrease of the physical and mechanical properties. The results are expected to provide an important contribution to the stability of well boreholes during the exploitation of deep geothermal energy.

Successful use of ultrasound elastography in the preliminary intermediate evaluation of therapeutic response in patients with Hodgkin’s lymphoma

Objective. The possibilities of ultrasound elastography of the lymph nodes as an additional technique for the intermediate control of treatment of patients with Hodgkin’s lymphoma are determined. Materials and methods. A prospective study included patients with a diagnosis of classical Hodgkin’s lymphoma with affected superficial lymph nodes. Patients underwent ultrasound elastography (compression elastography and shear wave elastography) of the enlarged lymph nodes before treatment and after two cycles of chemotherapy. The reasons for the ultrasound examination of superficial lymph nodes after the second chemotherapy cycle were: an earlier ultrasound examination with revealed changes in the superficial lymph nodes (in 100% of cases), preservation of the palpable formation in the projection of the superficial lymph nodes (in 56.9% of cases). Before ultrasound elastography of the studied group of patients, the positive dynamics after two cycles of chemotherapy was confirmed by PET/CT (Deauville scale 2—3). Results and conclusion. According to strain elastography, stiff heterogeneous (third type of elastogram) and stiff structure (fourth type of elastogram) of affected lymph nodes were noted in 53.5 and 42.3% of cases, respectively, before treatment. After two cycles of chemotherapy, these types of elastogram were 52.1 and 43.7% of cases, respectively. According to the results of shear wave elastography before and after treatment, a decrease in the average shear wave velocity in the affected lymph nodes from 2.67 + 0.69 to 2.21 + 0.40m/s (p = 0.000003) was revealed.

Increased Brachial Artery Compliance After Arteriovenous Fistula Creation as Measured by Shear Wave Elastography: Results From a Feasibility Study.

Arterial stiffness has been proposed as a marker of arteriovenous fistula failure and can be measured locally by using ultrasound shear wave elastography (SWE). This preliminary study aimed to assess whether SWE measurements of the brachial artery were associated with arteriovenous fistula failure. Data were collected on patients who were indicated for fistula creation. Preoperative and postoperative vessel diameters from B-mode ultrasound, brachial artery SWE maps, and demographic data were collected. Logistic and linear regression analyses were used to determine whether any of these variables were related to the outcome of the fistula 3 months after creation. Data were acquired for 33 patients. Shear wave velocity values decreased after fistula creation (mean ± SD, -1.2 ± 1 m/s; P < .05). No parameters were associated with failure of the fistula in the logistic regression analysis. No markers were related to fistula failure, but a decrease in the shear wave velocity was observed in the brachial arteries after fistula creation, indicating increased compliance.

Low-velocity layers in the northwestern margin of the South China Sea: Evidence from receiver functions of ocean-bottom seismometer data

The receiver function method was applied to teleseismic recordings of an active-source ocean-bottom seismometer array in the northwestern margin of the South China Sea. Forward modeling of the receiver functions was used to derive velocity interfaces beneath the stations. Two main groups of low-velocity layers were imaged. The first group in the reef area, with a thickness of 7–10 km, exhibits a seaward uptrend of the buried depth but poor continuity. The second group, with a thickness of 3–4 km, is more continuous along the Zhongsha Trough; the buried depth decreases asymmetrically from the flanks to the rift center. A high shear wave velocity layer of ~4.0 km/s is imaged at the crust bottom beneath the Zhongsha Trough, with thickness of ~3 km. The average Vp/Vs in the Cenozoic sediment is 2.0–3.0 and was affected by high fluid activity induced by intensive faults. The Vp/Vs of the crust varies between 1.77 and 1.88, suggesting an intermediate to basic composition under the continental extension. Together, these results suggest a two-stage evolution model of the continental crust. In the first stage, the crust deformed in a ductile manner and thus created considerable shearing structures with high anisotropy that caused the obvious decrease of the shear wave velocity. In the second stage, the shearing structures connected asymmetrically, driven by detachment faults in the upper crust and upwelling of the lower crust. The Zhongsha Trough then formed, probably with magmatic underplating due to lithospheric extension or rising of hot mantle materials.

Digital Rock Approach to Model the Permeability in an Artificially Heated and Fractured Granodiorite from the Liquiñe Geothermal System (39°S)

The Southern Volcanic Zone of the Andes has a high potential in terms of geothermal resources and is an exceptional and poorly explored natural laboratory to study the interplay between tectonic stresses, thermal damage, low-permeable crystalline rocks, and fluid flow. Permeability is mostly related to the damage zones associated with the faults controlling regional tectonics, namely, the Liquine–Ofqui Fault System and Andean Transverse Faults. This research presents a laboratory approach comprising a characterization of the analogue host rock from a shallow, low-to-medium temperature geothermal system surrounding the Liquine area in Southern Chile (39°S) to better constrain intrinsic and extrinsic factors which allow permeable pathways to exist. We analyse the effect of thermal stress at 25, 150, and 210 °C in a granodiorite, measuring some petrophysical properties before and after applying thermal damage, and then loaded the samples until failure. We also compared petrophysical properties with the fracture network characterization using X-ray microcomputed tomography imaging, segmentation, and fluid flow computational simulations. The results show that thermal stress produces intercrystalline microcracks, which result in: (1) an increase in capillary absorption; (2) a decrease in ultrasonic wave velocities; (3) a decrease in compressive strength; (4) a decrease in fracture aperture, and (5) fluid flow simulations indicate that permeability is similar at different temperatures. We conclude that for the granodiorite host rock of the Liquine geothermal system, the combined effect of thermal stress, even at low temperature, may constitute an effective mechanism for sustaining permeability at shallowest depths.

Melting at the Edge of a Slab in the Deepest Mantle

AbstractWe analyzed new recordings of SPdKS seismic waveforms from a global set of broadband seismograms and horizontal tiltmeters from the Hi‐net array in Japan from 26 earthquakes in the Central American region. The anomalous waveforms are consistent with the presence of at least three ultralow‐velocity zones (ULVZs), on the core‐mantle boundary beneath northern Mexico and the southeastern United States. These ULVZs ring an area of high seismic wave speeds observed in tomographic models that has long been associated with past subduction. Waveform modeling using the PSVaxi method suggests that the ULVZs have S and P wave velocity decreases of 40% and 10%, respectively. These velocity decreases are likely best explained by a partially molten origin where the melt is generated through melting of mid‐ocean ridge basalt atop the subducted slab.

Coseismic changes in subsurface structure associated with the 2018 Hokkaido Eastern Iburi Earthquake detected using autocorrelation analysis of ambient seismic noise

Autocorrelation analysis using ambient noise is a useful method to detect temporal changes in wave velocity and scattering property. In this study, we investigated the temporal changes in seismic wave velocity and scattering property in the focal region of the 2018 Hokkaido Eastern Iburi Earthquake. The autocorrelation function (ACF) was calculated by processing with bandpass filters to enhance 1–2 Hz frequency range, with aftershock removal, and applying the one-bit correlation technique. The stretching method was used to detect the seismic wave velocity change. After the mainshock, seismic velocity reductions were observed at many stations. At N.AMAH and ATSUMA, which are located close to the mainshock, we detected 2–3% decreases in seismic wave velocity. We compared parameters indicating strong ground motion and showed the possibility of correlations with peak dynamic strain and seismic velocity reduction. We also investigated the relationship between waveform correlation and lag time, using ACFs from before and after the mainshock, and detected distortion of the ACF waveform. The source of the waveform decorrelation was estimated to be located near the maximum coseismic slip, at around 30 km depth. Thus, distortion of the ACF waveform may reflect the formation of cracks, due to faulting at approximately 30 km depth.

Effect of viscoelastic medium on wave propagation along protein microtubules

An Orthotropic Kelvin-like model is developed here to study wave dispersion relation along microtubules when they are embedded in viscoelastic material. Owing anisotropicity of elastic shell like microtubules, an orthotropic elastic shell model is derived while the surrounding environment of microtubules is modeled as Kelvin like material. Symmetrical and asymmetrical waves are studied in embedded microtubules. We compared the wave velocities for embedded and free microtubules as well as the comparison of wave velocities for isotropic and orthotropic microtubules are also given. Longitudinal, Torsional and Radial wave velocities are obtained, noticing that torsional and radial wave velocities are lower in embedded microtubules as compared to longitudinal wave velocities in embedded microtubules. The radial wave frequency is considerably low because in cylindrical microtubules, pressure is exerted from the surroundings. The decrease in wave velocities is due to strong mechanical coupling of microtubules with surrounding medium and this decrement is more obvious when the wave length is long.

Change in the physical­mechanical and decorative properties of labradorite under thermal exposure

We have experimentally investigated samples from the four fields of coarse-grained labradorite, which is extracted in Ukraine. The samples of labradorite were tested at high temperatures of 200, 300, 400, 500, 600, 700, 800, 900 °С. Red spots at the surface of samples is the result of oxidation of the metal Fe 2+ : at different fields of labradorite they cover a different area of the sample's surface of natural stone: it ranges from 39 to 60 %. An analysis of the polished labradorite surface after heating revealed that red inclusions are evenly distributed over the surface of labradorite samples. Oxidation of minerals, which is visually observed on all the samples of labradorite, starts at a temperature of 300 °С. One of the features in the research described in this paper is the application of digital image processing in order to quantitatively assess the Fe oxidation area (red spots) at the polished surface of labradorite samples. To a temperature of 500‒600 °С, there is a gradual increase in the oxidized area of the samples' surface. At temperatures above 700 °С, there is a sharp increase in the oxidized area at the samples' surface. In general, the oxidized spots of metals cover between 40 to 60 % of the surface of labradorite samples. When heated, the labradorite samples become 50 % brighter than the original value for indicator L in the color system Lab. A decrease in the velocity of ultrasonic wave propagation in labradorite samples occurs evenly, without surges. The reason for a decrease in the ultrasonic wave velocity is the formation of defects and cracks in labradorite samples due to an uneven thermal expansion of minerals. At a temperature of 700 °С ° or higher, there is a decrease in the velocity of ultrasound wave propagation in the samples of natural stone. At heating, there is a decrease in the indicators for gloss in all labradorite samples. In general, when labradorite was heated up to 900 °С, the samples from the Ocheretyansky deposit lost 11.21 % of their gloss, from the Neviryvsky deposit ‒ 4.03 %, from the Osnikivske deposit ‒ 33.57 %, from the Katerinovsky deposit ‒ 15.3 %.

Simultaneous measurements of electrical conductivity and seismic wave velocity of partially molten geological materials: effect of evolving melt texture

Comparison between geophysical observations and laboratory measurements yields contradicting estimations of the melt fraction for the partially molten regions of the Earth, highlighting potential disagreements between laboratory-based electrical conductivity and seismic wave velocity measurement techniques. In this study, we performed simultaneous acoustic wave velocity and electrical conductivity measurements on a simplified partial melt analogue (olivine + mid oceanic ridge basalt, MORB) at 2.5 GPa and up to 1650 K. We aim to investigate the effect of ongoing textural modification of partially molten peridotite analog on both electrical conductivity and sound wave velocity. Acoustic wave velocity (Vp and Vs) and EC are measured on an identical sample presenting the same melt texture, temperature gradient, stress field and chemical impurities. We observe a sharp decrease of acoustic wave velocities and increase of electrical conductivity in response to melting of MORB component. At constant temperature of 1650 K, electrical conductivity gradually increases, whereas acoustic velocities remain relatively constant. While the total MORB components melt instantaneously above the melting temperature, the melt interconnectivity and the melt distribution should evolve with time, affecting the electrical conduction. Consequently, our experimental observations suggest that acoustic velocities respond spontaneously to the melt volume fraction for melt with high wetting properties, whereas electrical conduction is significantly affected by subsequent melt texture modifications. We find that acoustic velocity measurements are thus better suited to the determination of the melt fraction of a partially molten sample at the laboratory time scale (~ h). Based on our estimations, the reduced Vs velocity in the major part of the low velocity zone away from spreading ridges can be explained by 0.3–0.8 vol% volatile-bearing melt and the high Vp/Vs ratio obtained for these melt fractions (1.82–1.87) are compatible with geophysical observations.

Physiotherapeutic correction of arterial stiffness at the comorbidity of arterial hypertension and hyperuricemia

Hyperuricaemia is included in the risk factors for arterial hypertension. Arterial stiffness is one of the risk factors for arterial hypertension. The purpose of the study: to evaluate the effectiveness of low level laser therapy for the correction of hyperuricaemia and stiffness of the arterial wall at the comorbidity of hyperuricaemia with arterial hypertension. The study included 92 patients: 1st group — 42 patients with arterial hypertension, 2nd group — 50 patients with arterial hypertension in combination with hyperuricaemia. The low level laser therapy was performed by the Mustang 2000 apparatus with a wavelength of 635 nm. Correlation relationship between the level of uric acid and pulse wave velocity. After low level laser therapy, the level of uric acid decreased in the 1st group by 3.4 %, in the 2nd — by 19.1 %. In the 2nd group, the decrease in uric acid after low level laser therapy was 15.7 % more intense than in the 1st group. After low level laser therapy there was a pulse wave velocity decrease in both groups. Thus, the effectiveness of low level laser therapy for the correction of arterial hypertension and the reduction of arterial wall stiffness with arterial hypertension comorbidity with hyperuricaemia are proved.

Effects of debonding on Lamb wave propagation in a bonded composite structure under variable temperature conditions

Bonded composite structures are a special type of sandwich-like structures in which multiple carbon-fibre laminates are bonded with adhesives, and debonding can appear at the bond layer due to variable loading and uncertain operating conditions. This study aims to investigate the debonding effects on Lamb wave propagation in a bonded composite structure under variable ambient temperature conditions. In the process, a combined theoretical analysis, time-domain spectral element simulation and experimental analysis of elastic wave propagation in a carbon-fibre reinforced adhesively-bonded composite structure have been carried out. It is shown that theoretical analysis and spectral formulation are effectively able to capture the behaviour of Lamb modes in the healthy structure due to variations in ambient temperature. It is found that the primary anti-symmetric Lamb wave mode amplitude and velocity decrease with an increase in ambient temperature. Furthermore, the spectral formulation accurately captures the effects of debonding on the Lamb wave signals under variable temperature conditions that are consistent with the experimental results. Finally, temperature correction factors are proposed for the primary anti-symmetric mode velocity and amplitude difference calculations and the effectiveness of the factors is successfully verified for selected study cases.

Time and Temperature Dependent Creep in Tournemire Shale

AbstractWe conducted a series of triaxial creep experiments on shale specimens coming from Tournemire, France, using the stress‐stepping method up to failure, at a confining pressure of 80 MPa, on two orientations (parallel and perpendicular to bedding), and at temperatures of 26 and 75 °C. In these week‐long experiments, stress, strains, and P wave ultrasonic velocities were recorded (quasi‐) continuously. The strength at creep failure of Tournemire shale was ~70% higher than the peak strength measured during constant strain rate (~10−7/s) experiments, and failure was reached at larger strains. An overall transition from P wave velocity increase at moderate differential stress to P wave velocity decrease closer to brittle failure was also observed. At a smaller timescale, P wave velocities initially decreased and then increased gradually during each step of creep deformation. The magnitude of these variations showed important (i) stress, (ii) orientation, and (iii) temperature dependences: larger increase was observed for P wave propagating along the main compressive stress orientation, larger decrease for P wave propagating perpendicular to it, and a changing behavior enhanced at a higher temperature. Scanning electron microscopy performed postmortem revealed evidence of time‐dependent pressure solution, localized compaction, crack growth, and sealing/healing. Our data reveal that shale deformation is highly stress sensitive only in a narrow stress domain where stress corrosion cracking‐induced brittle dilatant creep deformation is dominant. At stresses below, pressure solution compaction creep dominates the deformation and shales compact, consolidate, and heal. This has important implications for the mechanics of shallow fault zones and accretionary prisms.

The effect of intensive therapy of atorvastatin on vascular rigidity and lipid profile in patients with ST-segment elevation myocardial infarction

Objective. To evaluate the effect of 24-week atorvastatin therapy on the lipid profile, structure and functions of the large arteries in patients with ST-elevation myocardial infarction (STEMI) with single-vessel hemodynamically significant stenosis of the coronary arteries.Design and methods. We enrolled 85 patients with STEMI aged 33 to 66 years (51,9 ± 9,3 years), 75 men (88 %), and 10 women (12 %). Inclusion criteria were: age from 30 years to 70 years, STEMI confirmed by electrocardiogram and increased troponin I and creatine kinase-MB, the presence of a significant stenosis of the infarct-related artery, stenosis of other arteries less than 50 %, and the stenosis of the trunk of the left coronary artery less than 30 %. Patients underwent laboratory (lipids) and instrumental examination at baseline (7–9 days from the symptoms onset) and 24 weeks after the therapy was started. We assessed carotid atherosclerosis by the ultrasound scanner MyLab 90 (“Esaote”, Italy). Central pressure parameters and arterial stiffness were evaluated using the applanation tonometry (SphygmoCor, “AtCorMedical”, Australia).Results. After 24 weeks of treatment patients from the control group demonstrated a decrease in total cholesterol by 26 %, low density lipoproteins — by 40,5 % and high density lipoproteins — by 3 %. Patients receiving atorvastatin 80 mg/day showed similar reduction of the parameters: by 45 %, 55 % and 14 %, respectively. Patients who took lower dose of atorvastatin showed no change in intima-media thickness (IMT), but there was a positive change of the coefficient of transverse extensibility — DC, which increased by 25 % (p &lt; 0,05). In the same cohort of patients, locPsys and locPdia increased by 5,4 and 3,6 mm Hg, respectively, and there was a 3,5-fold increase in the augmentation index (p &lt; 0,05). In the group of high-dose atorvastatin therapy carotid IMT decreased by 11 % after 24 weeks (p &lt; 0,05). The coefficient of transverse compliance (CC) increased by 11 % (p &lt; 0,05), the stiffness indices α and β significantly decreased by 11 % and 13 %, respectively (p &lt; 0,05). There was also a decrease in pulse wave velocity (PWV) measured locally in the carotid arteries by 6 % (p &lt; 0,05). We found a 3-fold increase in augmentation pressure (AP) and augmentation index (Aix) after 6 months of therapy (p &lt; 0,05).Conclusions. Patients who receive the maximum daily dose of atorvastatin develop a more significant improvement of lipid profile compared to the control group. Our results are consistent with the statement of the American Association of Cardiologists proving that high-dose statin therapy can reduce the level of low density lipids by more than 50 % compared to the baseline values. Using the radiofrequency analysis of the ultrasound signal (echotracking), we analyzed the stiffness parameters α and β, the compliance and distensibility coefficients, which reflect the vascular wall rigidity, regardless of the arterial pressure level. When comparing two schemes of atorvastatin therapy, intensive therapy showed a more evident favourable effect on carotid stiffness.

Urbanization as a risk factor for aortic stiffness in a cohort in India.

Urbanization is associated with higher prevalence of cardiovascular disease worldwide. Aortic stiffness, as measured by carotid-femoral pulse wave velocity is a validated predictor of cardiovascular disease. Our objective was to determine the association between urbanization and carotid-femoral pulse wave velocity. The analysis included 6166 participants enrolled in an ongoing population-based study (mean age 42 years; 58% female) who live in an 80 × 80 km region of southern India. Multiple measures of urbanization were used and compared: 1) census designations, 2) satellite derived land cover (crops, grass, shrubs or trees as rural; built-up areas as urban), and 3) distance categories based on proximity to an urban center. The association between urbanization and carotid-femoral pulse wave velocity was tested in sex-stratified linear regression models. People residing in urban areas had significantly (p < 0.05) elevated mean carotid-femoral pulse wave velocity compared to non-urban populations after adjustment for other risk factors. There was also an inverse association between distance from the urban center and mean carotid-femoral pulse wave velocity: each 10 km increase in distance was associated with a decrease in mean carotid-femoral pulse wave velocity of 0.07 m/s (95% CI: -0.09, -0.06 m/s). The association was stronger among older participants, among smokers, and among those with other cardiovascular risk factors. Further research is needed to determine which components in the urban environment are associated with higher carotid-femoral pulse wave velocity.

Does Obstructive Sleep Apnea Influence Blood Pressure and Arterial Stiffness in Response to Antihypertensive Treatment?

Untreated obstructive sleep apnea (OSA) is common in patients with hypertension and may impair blood pressure (BP) and target-organ damage responses to antihypertensive therapy. In this study, we recruited hypertensive patients who underwent treatment with a 30-day regimen of hydrochlorothiazide 25 mg plus enalapril (20 mg BID) or losartan (50 mg BID) and were assessed with a baseline clinical evaluation, polysomnography, 24-hour ambulatory BP monitoring, and carotid-femoral pulse wave velocity. All the examinations except for polysomnography were repeated at 6 and 18 months of follow-up. We studied 94 hypertensive patients (mean age, 55±9 years). The frequency of OSA was 55%. Compared with baseline, we did not observe significant differences between groups in 24-hour BP, daytime systolic and diastolic BPs, or night-time systolic BP at 6 and 18 months. The BP control rate at 24 hours (<130/80 mm Hg) was similar between the groups (baseline, 42.3% versus 45.2%; 6 months, 46.9% versus 57.5%; 18 months, 66.7% versus 61.5%). However, patients with OSA had higher night-time diastolic BP decrease than did the non-OSA group (6 months, -4.9±11.8 versus -0.3±10.3 mm Hg; 18 months, -6.7±11.1 versus -1.2±10.6 mm Hg; P=0.027). There were no differences in the number and class of antihypertensive medications prescribed during follow-up. In terms of arterial stiffness, patients with OSA had higher pulse wave velocity than did patients without OSA at baseline (10.3±1.9 versus 9.2±1.7 m/s; P=0.024), but both groups had similar decreases in pulse wave velocity during follow-up. In conclusion, with combined antihypertensive treatment aimed at controlling BP, hypertensive patients with OSA had similar 24-hour BP and arterial stiffness to those without OSA.

Effects of quenching cycle on tensile strength of granite

Quenching cycle has practical significance in the study of rock properties with regard to the cooling of the drilling fluid, development of geothermal resources and tunnel fire rescue. In this study, a Brazil splitting experiment was conducted with granite that is subjected to different temperatures up to 650°C and quenching times of 1–20. The results indicate that the tensile strength of granite is negatively correlated with the temperature and the number of quenching cycles. The tensile strength and wave velocity decrease as the temperature increases for the same quenching cycle. When the number of quenching cycles is &gt;5, the influence of the number of quenching cycles on the tensile strength and wave velocity is relatively small. A faster rate of decline of tensile strength occurs at temperatures higher than 450°C. In addition, it is concluded that the changes in the tensile strength and wave velocity are similar for the tested temperature range and number of quenching cycles.

Investigation of viscoelastic effects on transient flow in a relatively long PE100 pipe

In this paper, the dynamic effect of the viscoelastic behavior of PE100 material, on the transient flow in a relatively long pipe, has been studied. At first, to study the transient flow in pipes with fluid structure interaction (FSI), two mathematical models, i.e., fully coupled four equation model and simplified two equation model, have been developed. The method of characteristics has been used to solve the model. Then, we have demonstrated that the viscoelastic behavior of PE100 plays a primordial role in the damping of the water hammer phenomenon. It has a dynamic effect to cause the decrease of pressure wave velocity with increase of pressure along the wave front. At the end of the paper, It has been shown that the coupled model with FSI does not introduce many changes from the simplified viscoelastic model.

Porosity and wave velocity evolution of granite after high-temperature treatment: a review

The evolution of porosity and changes in wave velocity in granite after high-temperature treatment has been experimentally investigated in different studies. Statistical analysis of the test results shows that there is a temperature threshold value that leads to variations in porosity and wave velocity. At a temperature that is less than 200 °C, the porosity of granite slowly increases with increases in temperature, while the wave velocity decreases. When the temperature is greater than 200 °C (especially between 400 and 600 °C), the porosity quickly increases, while the wave velocity substantially decreases. The temperature ranges of room temperature to 200 and 200–400 °C correspond to the undamaged state and the micro-damage state, respectively. The results confirm that there is an important link between the variations of physical and mechanical properties in response to thermal treatment. By studying the relationships among rock porosity, wave velocity and temperature, this provides the basis for solving multi-variable coupling problems under high temperatures for the thermal exploitation of petroleum and safe disposal of nuclear waste.