Depth Of Specimen Research Articles

Determination of crack extension resistance of concrete from boundary effect model

The fracture behavior of concrete can be described by an R-curve, which represents the ability of concrete to resist crack propagation. In this study, the R-curve is defined as the envelope of the energy release rates in the critical state and is constructed on the basis of the boundary effect model. Two fracture parameters are introduced for constructing the R-curve, namely, the fracture energy Gf and the equivalent crack extension cf in an infinitely large specimen, and these two vital parameters can be obtained from testing specimens of different sizes. One of the greatest features of the proposed R-curve is that the influence of concrete aggregate is explicitly manifested in the R-curve expression in terms of the maximum aggregate size. The theoretically derived ascending branch of the R-curve is fitted using a unified function for three-point bending specimens with varying values of the initial crack length relative to the specimen depth (between 0.2 and 0.9). The developed R-curve approach is applied to the tested three-point bending notched concrete beams, and the predicted load-displacement responses are found to agree with the experimental curves. It is also shown that the results are not sensitive to the choice of the discrete number β, which is included in the R-curve expression to address the linkage between the fictitious crack growth and coarse aggregate structures of concrete.

Experimental and numerical investigation of bubble oscillation and jet impact near a solid boundary

This paper aims at introducing a novel forming technology named Cavitation Shotless Forming (CSF) and simulating the dynamics of cavitation bubble from initial expansion to collapse stages. The plasma shock wave and bubble collapse shock wave were detected under different laser energies. A wall reflection shock wave was detected by a hydrophone, which is consistent with the simulation result. The trajectory of the bubble was captured by Matlab software. The bubble moves towards the solid wall due to the Bjerknes force. The bubble shape, pressure field and velocity field distributions under different standoff distances were compared. The impinging time of micro-jet was prolonged when the standoff distance was small, and the jet speed and maximum pressure increases with the increasing of standoff distances. In addition, the water hammer pressure under different standoff distances and initial bubble pressures were analyzed. It increases with the increase of initial bubble pressure but decreases with the standoff distance. Finally, the experiments of CSF were carried out, and the specimens show typical morphologies under different standoff distances and the forming depth of specimen decreases with the increase in standoff distances.

Enhanced transport properties of graphene oxide based cement composite material

This study is aimed to evaluate the transport properties of a cement composite incorporated with graphene oxide (GO). GO is a 2-dimensional nano material, enriched with reactive oxygen functional groups which made it as a suitable reactive material with cementitious materials. The GO-cement composite was prepared by adding GO in four different proportions such as 0.01%, 0.02%, 0.03%, and 0.04% by weight of cement. In the durability aspect water absorption, water sorptivity, resistance to acid attack, mechanical properties, thermal analysis, chloride migration coefficient, and chloride penetration depth were examined experimentally for GO-cement composite specimens and compared with plane cement composite specimens. Experimental results indicated that 14.5%, 30%, and 40.47% degradation in water absorption capacity, chloride migration coefficient, and chloride penetration depth of cement composite specimens with 0.03% addition of graphene oxide than normal cement composite specimens at 28 days of curing. Additionally, significant decrement in the sorptivity coefficient of cement composite was also achieved at 0.03% of GO addition. Mechanical properties were enhanced by 77.70% in flexural strength at 0.03% of GO addition and 47.61% in compressive strength at 0.04% of GO addition in cement composite at 28 days of curing. SEM analysis of the test samples exhibited the pore filled structure of the cement composites with GO addition. In addition, all GO-cement composite specimens exhibited greater resistance to an acidic environment and negligible loss in strength and weight was observed than normal cement composite specimens at 28 days immersion in 2% and 5% concentrations of both H2SO4 and HCl acidic solutions. Thermal resistance was increased in the terms of compressive strength in all GO-cement composite mixes gradually by increasing the concentration of GO content from 0.01% to 0.04% by weight of cement. It can be concluded that an effective improvement in transport properties of cement composite was achieved by the incorporation of graphene oxide nano material.

Visualization and quantification of aggregate and fiber in self-compacting concrete using computed tomography for wedge splitting test

Wedge splitting test gained popularity as a stable and simple method to predict the fracture mechanism properties of concrete specimens. The present research focuses on understanding the behavior of self-compacting concrete specimens made with and without steel fibers tested using wedge splitting test, later scanned under high resolution computed tomography. The contribution of hooked end steel fiber and coarse aggregates in fiber reinforced specimens was compared without steel fiber reinforced concrete specimens using high resolution computed tomography. As fracture takes place across the plane perpendicular to the splitting force, i.e. along the depth of specimens. High resolution computed tomography technique was adopted in visualizing the changes taking place across the matrix, coarse aggregate and steel fibers, along with the specimen’s depth. Datasets of the images, obtained from computed tomography, after images analysis and volume reconstruction, revealed a higher coarse aggregate and steel fiber participation in the failure region of without and with fibers specimens. Computed tomography investigation indicated a total of 23 coarse aggregate and 64 steel fibers participated in resisting the failure, during wedge splitting test of without and with fibers specimens. Therefore, high resolution computed tomography can be used in understanding, quantifying the participation of coarse aggregate and steel fiber in the failure plane, under fracture loads.

Influence of Exposure to Environment on Degradation of a Friction Stir Welded Aluminum Alloy

We carried out a comparative study on both the stress corrosion response and corrosion damage characteristics of aluminum alloy 2219, both the base material and a friction stir welding (FSW) counterpart upon exposure to exfoliation corrosion (EXCO) solution. The results reveal that the test specimen containing an FSW joint reveals better electrochemical corrosion resistance than that taken from the base metal. When test specimens upon exposure to EXCO solution are concurrently subjected to a tensile stress, since the mechanical properties of the FSW joint are lower than the base metal, a test specimen containing an FSW joint is more easily prone to the early initiation of fine microscopic cracks. This makes the test specimen containing the FSW joint to be less resistant to stress corrosion damage than that taken from the base metal for the various levels of applied stress and exposure time to EXCO solution. The average corrosion depth of the test specimen containing the FSW joint is less than that of the base metal, while the maximum corrosion depth of it is greater than that of the base metal. This reveals that test specimen containing the FSW joint is more susceptible to damage and degradation than test specimen taken from the base metal.

Mini-laparoscopic adrenalectomy with transgastric specimen extraction.

We aimed to describe the initial experience of mini-laparoscopic adrenalectomy combined with transgastric specimen extraction and to assess its safety and feasibility. We used only 5-mm trocars, three ports for left adrenalectomy and four for right. Intraoperative gastroscopy was performed for specimen extraction through the mouth via an endoscopic snare. The gastrotomy was closed intracorporeally. Demographic, perioperative and pathological data were analyzed. There were 16 patients (12 females) with the mean ageof 46.5 ± 11.3years and half of them had previous abdominal surgeries. The median operative time was 150 (45-432) min with a median blood loss of 88 (0-350) ml. The median oral intake time was 2 (1-4) days and themedian length of hospital stay was 2 (2-5) days. There was no mortality and extraction-related complication. Histopathological median tumor length, width and depth were 3cm, 2.15cm, and 1.9cm, respectively. The median specimen length, width and depth were 6.25cm, 4cm, and 2.2cm, respectively. Mini-laparoscopic adrenalectomy combined with transgastric specimen extraction is a safe and feasible surgical technique. It provides a less invasive surgery and may also have some benefits on wound-related complications and cosmesis.

Corrosion of 304 stainless steel in static liquid lithium under high vacuum

• Corrosion behaviors of 304SS exposed to liquid Li at 700 K for 1320 h under high vacuum were investigated. • Corrosion of 304 SS in liquid Li at 700 K was compared to at 600 K and 640 K. • Cu of sealing gasket was deposited on the wall of test vessel. To study the compatibility especially the corrosion characteristic of structural material stainless steel (SS) with liquid lithium (Li) is an important factor for the simultaneous application of liquid Li and SS as a blanket material or potential plasma facing material (PFM) in future fusion devices. The corrosion behaviors of 304SS exposed to liquid Li at 700 K for 1320 hr under high vacuum were investigated. After exposure to liquid Li, 304SS produces non-uniform corrosion which includes corrosion products and grain boundary corrosion. Compared with the corrosion behaviors at 600 K and 640 K, temperature plays an important role in the corrosion behaviors of 304SS in static liquid Li. The weight loss, corrosion depth and corrosion products of 304SS specimens increase with the corrosion temperature. In general, the compatibility between 304SS and static liquid Li is relatively good under the experimental conditions. And besides, it is unexpectedly found that the compatibility of copper with Li is not good.

Experimental Investigation of the Flexural Behavior of Steel Fiber Reinforced Concrete

This research study is conducted to investigate the flexural behaviour of steel fiber reinforced concrete (SFRC) prisms incorporating different types and volume fractions of steel fibers, various grades of concrete, and different specimen depths, all tested under displacement control mode using four-point loading configuration. Two types of steel fibers (hooked end and straight) were incorporated into the concrete mixes at two different dosages (1% and 2%). Concrete mixes with compressive strengths of 40, 50, and 70 MPa were used to cast the samples. Specimen depth was also among the test variables, where prisms of depth 100, 150 and 200 mm were tested to study the size effect on the flexural behaviour of SFRC. Test results indicated that for the straight-end steel fibers, the increase in the fiber volume fraction from 1 to 2% had a noticeable effect on both flexural strength (or Modulus of Rupture, MOR) and associated prism mid-span deflection. However, for the hooked end steel fibers, there was only a limited increase in the same measured values due to reduced workability of the SFRC fresh mix. The test results also have shown that the increase in the concrete compressive strength had only a modest effect on the average MOR value, but a noticeable effect on average mid-span deflection at peak load. The latter was attributed to the relatively long length and the hooked end geometry of the steel fibers. Finally, test results revealed that specimen depth had an impact on the measured flexural strength, where increase in specimen depth was associated with reduced MOR values, a phenomenon that is commonly referred to in the literature as size effect.

Size effect on double-K fracture parameters of concrete based on fracture extreme theory

Based on fracture extreme theory (FET), the size effect on initial fracture toughness $$K_{\mathrm{I}}^{\mathrm{ini}}$$ and unstable fracture toughness $$K_{\mathrm{I}}^{\mathrm{un}}$$ of concrete for three-point bending beam was investigated. Nine groups of geometrically similar specimen were simulated to obtain peak load and critical crack mouth opening displacement, of which specimen depth was from 200 to 1000 mm and initial crack length-to-depth ratios were from 0.1 to 0.6. The $$K_{\mathrm{I}}^{\mathrm{ini}}$$ and $$K_{\mathrm{I}}^{\mathrm{un}}$$ were calculated by FET and double-K method, in which FET adopted the linear, bilinear, and trilinear cohesive stress distribution assumptions and double-K method only used the linear cohesive stress distribution assumption. With linear cohesive stress distribution assumption, $$K_{\mathrm{I}}^{\mathrm{ini}}$$ and $$K_{\mathrm{I}}^{\mathrm{un}}$$ determined by FET and double- K method were compared. Then, the influence of specimen depth on $$K_{\mathrm{I}}^{\mathrm{ini}}$$ and $$K_{\mathrm{I}}^{\mathrm{un}}$$ was discussed. In addition, $$K_{\mathrm{I}}^{\mathrm{ini}}/K_{\mathrm{I}}^{\mathrm{un}}$$ calculated via FET using different cohesive stress distribution assumptions were analyzed.

Carburizing Behavior of AISI 4115 Steel According to the Flow Rates of Acetylene in Vacuum Carburizing

The vacuum carburizing behavior of AISI 4115 steel according to acetylene flow rates (1, 5, 10, 20, 30, 40, and 50 sccm) and temperatures (900, 950, and 1000 <sup>o</sup>C) was quantitatively investigated through microstructure, carbon concentration and hardness analyses. As the acetylene flow rate increased, the penetration rate of carbon into the surface of the samples (surface-carbon flux) increased, resulting in an increase in the solute carbon concentration at the surface up to the solubility of carbon in austenite. At the same time, the amount of carbon diffusion into the interior of the specimen and overall carburizing depth increased. When the carbon concentration in the surface of the carburized specimen exceeded the solubility of carbon in the austenite above a certain flow rate, cementite precipitated in the austenite grain boundaries. Accordingly, the surface hardness decreased and the amount of carbon diffusion into the specimen became constant as the solute carbon concentration in the austenite matrix at the surface of the specimen became constant. As a result, the overall solute carbon concentration and the effective case depth no longer increased. Meanwhile, the tendency of vacuum carburizing behavior according to temperature was the same, but as temperature increased, the surface-carbon flux and rate of carbon diffusion into the interior of the sample increased, resulting in increased carburizing depth. The appropriate flow rates (10, 20, and 30 sccm) and the corresponding surface-carbon fluxes (62.3, 135.7, and 216.7 g/m<sup>2</sup>h) were derived according to carburizing temperatures (900, 950, and 1000 <sup>o</sup>C), respectively.

Effects of concrete flow on the distribution and orientation of fibers and flexural behavior of steel fiber-reinforced self-compacting concrete beams

Several parameters during the fabrication process cause segregation and poor orientation of the fibers in steel fiber-reinforced concrete (SFRC) members. With its high flowability and compactability, self-compacting fiber-reinforced concrete (SCFRC) can be used as an alternative to conventional SFRC, as it exhibits improved orientation and lesser fiber segregation. This study aims to investigate (1) the effects of concrete type (i.e., SCFRC versus SFRC), fiber content, and specimen depth on the fiber distribution and orientation and (2) the structural performance of SCFRC and SFRC beams considering their fiber distribution and orientation using X-ray images. The X-ray images showed that owing to the high-flow properties, the SCFRC beams exhibited a lower fiber segregation and better fiber alignment than the SFRC beams. The bending test results demonstrated that the SCFRC beams exhibited better flexural performance than the SFRC beams owing to the improved distribution and orientation of the fibers. Moreover, a finite element (FE) analysis was performed to evaluate the structural performance of the beams considering the varying fiber distribution properties observed in the X-ray images. The FE method could differentiate the superior structural performance of the SCFRC beam from that of the SFRC beam.

Performance of High-strength Concrete Made with Recycled Ceramic Aggregates (Research Note)

Recent scientific concerns to achieve sustainability in construction have suggested the implementation of using recycled aggregate in concrete; because it has the potential to reduce the demand for extraction of natural raw materials and decrease the volume of wastes landfilled. In this respect, this study aims to investigate the suitability of using ceramic tile (CT) and ceramic sanitary (CS) wastes as coarse aggregate in production of high-strength concrete (HSC). Different concrete mixes were produced by partial replacement of 10, 20 and 30% of natural coarse aggregate with recycled aggregates. Besides investigating the characteristics of recycled aggregate, slump, compressive strength, initial and final absorption and chloride ion penetration depth of HSC specimens were evaluated and compared with that of plain HSC. Results showed that using recycled ceramic aggregates increased the superplasticizer dosage to maintain the target slump. Although by incorporation of high percentage of CT or CS aggregate, compressive strength of HSCs was reduced compared with reference HSC, it is possible to produce HSC with 28-days compressive strength higher than 60.7 MPa. Moreover, the absorption and chloride ion penetration depth of recycled aggregate incorporated HSC were higher than those of estimated for plain concrete. Generally, waste ceramic aggregate at optimum replacement ratio can be used in the sustainable development of HSC.

Hybrid multifocal structured illumination microscopy with enhanced lateral resolution and axial localization capability.

Super-resolution (SR) fluorescence microscopy that breaks through the diffraction barrier has drawn great interest in biomedical research. However, obtaining a high precision three-dimensional distribution of the specimen in a short time still remains a challenging task for existing techniques. In this paper, we propose a super-resolution fluorescence microscopy with axial localization capability by combining multifocal structured illumination microscopy with a hybrid detection PSF composed of a Gaussian PSF and a double-helix PSF. A modified reconstruction scheme is presented to accommodate the new hybrid PSF. This method can not only recover the lateral super-resolution image of the specimen but also retain the specimen's depth map within a range of 600 nm with an axial localization precision of 20.8 nm. The performance of this approach is verified by testing fluorescent beads and tubulin in 293-cells. The developed microscope is well suited for observing the precise 3D distribution of thin specimens.

Experimental and Numerical Studies on the Evolution of Shear Behaviour and Damage of Natural Discontinuities at the Interface Between Different Rock Types

Recent research has paid little attention to the shear damage of discontinuities with different joint wall material (DDJM). In this paper, we present an investigation on the evolution of the shear behaviour and the damage of three typical types of natural DDJM in a sliding-prone stratum of China. Experimental direct shear tests were performed on 14 pairs of natural DDJM specimens to examine the changes in the shear strengths and surface damages of the DDJM with increasing normal stresses and an increasing number of shear cycles by evaluating surface damages via damage zone distribution, damage area percentage, and variation of joint roughness coefficient (JRC). The results indicate that the differences in the shear damage between the two halves are closely related to the difference in strength of the two joint walls of the DDJM specimens with similar initial JRC values of the two joint surfaces. Simultaneously, parallel numerical direct shear tests were conducted in PFC3D. The performance of the numerical modeling was examined by comparing the parameters of shear strength, damage area and damage depth of DDJM specimens with those obtained in the experimental direct shear tests. Then the validated models were used to explore the evolution of the damage depth of DDJM specimens during the shearing process. The results demonstrate that the proposed numerical approach has the ability to reproduce the shear behavior and damage of DDJM reasonably and could be used to examine the internal damage of DDJM which are not easy to investigate via laboratory experiments.

Tangential X-Ray Radiography for Pitting Geometry Analysis of Outside Wall of Insulated Steel Pipes

The piping systems used for the transportation of liquids and gases in power stations, petroleum petrochemical facilities, and chemical plants are significantly impacted by corrosive processes. One of the most destructive forms of corrosion is pitting corrosion, which produces holes on piping metal surfaces. Monitoring pit depth is necessary in order to prevent leakage in the piping system, especially during operation. However, measuring pit depth as a part of periodical inspections is complicated since the pit depth on the outside wall of a pipe may vary. Non-destructive testing (NDT) methods such as ultrasonic, liquid penetrants, and magnetic particles are used to detect defects in industrial components; however, they first require the removal of insulation and the shutdown of the pipe system. Another alternative NDT technique, tangential radiography technique (TRT), offers a solution to this problem as tests can be conducted without removing piping insulation, allowing testing while the piping system is online. In this study, we tested TRT using an X-ray radiation source, which has good controllability (i.e., intensity and exposure time) and a lower impact on the human body than do γ-ray sources. We focused on the comparison of film density measurements using a density meter and a light meter. The magnification of pit diameter was used to obtain an equation for small-diameter pipes (i.e., diameter of less than 50 mm). The working voltage was varied (200, 230, and 260 kV) in order to generate appropriate X-ray energies to measure various pit depth (20, 40, and 60%, receptively) of a stepped steel pipe specimen. Film density measurements using the density and light meters showed similar results; however, the film density result using the density meter was more accurate. All tangential side edges of the specimen burned off for film densities above 3.5. Degrees of magnification (1.0123, 1.0254, and 1.0379) varied as a function of distance from the midpoint of the X-ray target (30, 60, or 90 mm, respectively). Using the results, a linear equation with three variables was obtained to determine the actual diameter of pitting: 0.000385436a + 0.038350128b + 0.000467083c = d; where the actual diameter = film diameter/d. High working voltage produced low film contrast, high film definition, and low scatter. Low working voltage produced high film contrast, low film definition, and high scatter. Based on our results, a working voltage of 260 kV is most appropriate for effective analysis.

Hardness and tensile properties of metals subjected to aging conditions

Many metals used in engineering applications are exposed to aging conditions such as ultraviolet radiation and moisture. Aged metals are expected to lose their designed mechanical properties, and it was desired to relate a degraded local property to other homogenous properties. To study the aging effect, steel and aluminum were tested with reproduced variables in an accelerated weather testing chamber. Multiple tensile specimens of steel and aluminum were created to undergo accelerated Q-Lab Ultraviolet testing in the presence of radiation, heat and moisture. Accelerated aging resulted in decreasing surface hardness correlating with the tensile strength and elastic modulus for both steel and aluminum. The study also investigated the change in hardness through the depth of specimens resulting from aging, exhibited more consistently in steels. The overall strongest correlations existed in steels, between surface hardness and tensile strength, analogous to other studies. Modeling linear relationships for metal lifetime forecasts from hardness has been supported by this study. Outcomes can be expanded upon with more elaborate finite element analysis if desired in future experimentation.

The Structure of Oxide Film on the Porous Silicon Surface

A prolonged stay of porous silicon in the air environment gives rise to structural changes in its surface layer, and the standard single-layer model is not sufficiently accurate to describe them. In this work, the structure of the near-surface layer in porous silicon is studied using the polygonal ellipsometry method. A combined approach is proposed to analyze the angular ellipsometry data for the parameters ф and Δ. It consists in the application of the multilayer medium model and the matrix method, while simulating the propagation of optical radiation in this medium in order to obtain the theoretical angular dependences of tan ф and cosΔ. In this method, the dependence of the sought optical profile on the specimen depth is an additional condition imposed on the multilayer model. Evolutionary numerical methods are used for finding the global minimum of the mean squared error (MSE) between the corresponding theoretical and experimental dependences, and the parameters of an optical profile are determined. A model in which the inner non-oxidized layer of porous silicon is homogeneous, whereas the refractive index in the outer oxidized layer has a linear profile, is analyzed. It is shown that the linear and two-step models for the refractive index of an oxidized film provided the best agreement with the experimental ellipsometric functions. The adequacy of the theoretical model is also confirmed by determining the color coordinates of the specimen.

Investigation of three‐body wear behavior and hardness of experimental titanium alloys for dental applications in oral environment

AbstractThe aim of this study was to investigate the three‐body wear resistance and hardness of commercially pure titanium and titanium alloys containing zirconium and tantalum (cp‐Ti, Ti‐5Zr and Ti‐5Ta). Each titanium test group, were subjected to wear tests under 105 wear cycles, 50 N mechanical force, 2.0 Hz wear frequency, 6 mm diameter Al2O3 antagonist ball, 5 °C/55 °C thermal change conditions immersed in poppy seed slurry as third‐body medium. The mean wear volume loss and depth of all test specimens after the three‐body wear tests was determined with use non‐contact 3D profilometer and also Vicker's hardness was measured. Wear area of microstructures were evaluated using scanning electron microscopy (SEM) and x‐ray diffraction (XRD) analysis. The hardness of Ti‐5Zr material was significantly greater than the other alloy material and cp‐Ti. However, for the test materials in this study considered, correlations between the three‐body wear resistance and hardness were found to be insignificant. It was concluded, the three‐body wear resistance of the alloy formed with the adding of zirconium and tantalum to the pure titanium is increased after wear tests.

Scaling melt pool geometry over a wide range of laser scanning speeds during laser-based Powder Bed Fusion

Generating dense parts from laser-based Powder Bed Fusion of metals often requires the adaption of laser scanning speed. Thereby, scanning speed is lost as a degree of freedom for tailoring the microstructure. This paper addresses this issue by using an analytical model from literature to achieve equal melt pool width and depth for a range of factor 12 for laser scanning speeds and by examining the resulting specimen densities for this range of scanning speeds. The melt pool width and the melt pool depth of a dense reference specimen are measured. The measured melt pool width and melt pool depth are defined as the target sizes of the melt pool for all examined scanning speeds, as this is expected to result in dense specimens from a geometrical point of view. The target size shall be achieved by using an analytical model from the literature. This strategy is chosen to estimate the necessary energy input for creating dense specimens while avoiding incomplete fusion and keyholing. Defects mechanisms like splatters and cracks are excluded from this initial examination.

Mechanical property of granite from different buried depths under uniaxial compression and dynamic impact: An energy-based investigation

Mechanical properties of rock play a basic and important role in rock dynamic disaster prevention and control as well as rock engineering design and construction. Buried depth is one of the vital factors affecting rock mechanical properties. To study the energy evolution rules during rock failure at different buried depth, static loading experiments under uniaxial compression and dynamic impact experiments at different strain rates and confining pressures were carried out on six groups of granite specimens with different buried depth. Meanwhile, fractal characteristics of rock specimens crushed at different strain rates were also described in the paper. The results indicate that in uniaxial compression experiments, the dissipation energy and energy dissipation rate of rocks show a quadratic curve with the increase of the depth. Moreover, the amount of the dissipation energy during the rock failure is closely related to the buried depth of the rock specimens. In dynamic loading impact experiments, the incident energy, transmitted energy, dissipation energy and absorption energy increase with the rising strain rate and confining pressure. The reflected energy of rock specimens goes up with the increase of the strain rate, while they decrease with the rising confining pressure. As the strain rate gets larger and larger, the fractal dimension increases gradually. The growth amplitude of fractal dimension for the deep rock specimen is significantly greater than that for the shallow one. The specimen fragmentation degree is smaller and smaller, and the fragment particle size gets more and more uniform. From the relationship between various energy and fractal dimension for rock specimens from different buried depth, it can be known that within the buried depth of 750 m~950 m, the k value of incident energy density, transmitted energy density, dissipation energy density and unit absorption energy gradually decrease with the increase of the buried depth. However, within the buried depth ranging from 950 m to 1250 m, the k value of the above energy increases as the buried depth grows.