Mechanical Index Research Articles

Determination of thermal and mechanical indices of an ultrasound probe with an inclined beam-axis in accordance with the new JIS (or IEC Standards)

According to the new JIS (or IEC Standards), it is necessary to measure the bounded-square output power (P 1×1) for the determination of the soft tissue thermal index (TIS) for both scanning and non-scanning modes of an ultrasonic diagnostic equipment. However, there is no report about how to measure P 1x1 for an ultrasound probe with an inclined beam-axis (UPIB). We designed an angle-corrected 1 cm × 1 cm absorbing mask in accordance with the spirit of IEC 62359 Ed. 2.0 and established a reasonable process for the measurement of TIS and mechanical index (MI) of a paste type probe (PTP), which is a specially designed UPIB for examination of the blood flow in a carotid artery more conveniently and efficiently. Both the TIS and MI of the PTP were much less than 1.0 at all selectable presettings of the blood flow monitor, the FURUHATA device, suggesting it is as safe as a common ultrasonic Doppler diagnostic device.

Machine learning models for predicting unconfined compressive strength: A case study for Precambrian basement complex rocks from Ado-Ekiti, Southwestern Nigeria

This study investigates the applicability of four distinct machine learning (ML) models – Random Forest (RF), Relevance Vector Machine (RVM), Support Vector Machine (SVM), and Artificial Neural Network (ANN) - for predicting the unconfined compressive strength (UCS) values of Precambrian basement rocks. The models employ input parameters such as rock aggregate index (Aggregate Crushing Value (ACV), Aggregate Impact Value (AIV), and Los Angeles Aggregate Value (LAAV)) and mechanical test index values (Schmidt Hammer Rebound Number (SHR) and Point Load Strength Index (IS(50)) for prediction purposes. Additionally, a multilinear regression (MLR) model was implemented to compare the predictive performance of the ML models against the traditional linear regression model. The developed models were validated using performance metrics such as Mean Absolute Error (MAE), Root Mean Squared Error (RMSE), and Adjusted R-Squared (Adj.R2). The Friedman statistical test was also employed to investigate the significance of the differences in the performance of the models. The results indicate that all the models performed well and showed better predictive performance compared to the MLR model during both the training and testing phases, except for the ANN model, which exhibited slightly poorer performance than the MLR model in the testing phase. However, the SVM model demonstrated the best predictive accuracy among all the models with MAE, RMSE, and Adj.R2 scores of 0.76 and 1.45; 1.16 and 1.8; 0.98 and 0.90, respectively, for the training and testing phases. The difference in the performance of the predictive models was statistically significant, as revealed by the Friedman statistical test. A feature importance analysis was conducted to verify the significance of each input parameter, revealing that all input features had a positive effect on the output of all the models. However, IS(50) had the most significant impact on the models.

An investigation on the respiratory mechanics of mechanically ventilated patients during spontaneous breathing trials with enhanced low-level pressure support ventilation.

Low-level pressure support ventilation (PSV) is most commonly adopted in spontaneous breathing trials (SBTs), and some have proposed setting the positive end-expiratory pressure (PEEP) to 0cmH2 O in order to shorten the observation time of SBTs. This study aims to investigate the effects of two PSV protocols on the patients' respiratory mechanics. A prospective randomized self-controlled crossover design was adopted in this study, which involved enrolling 30 difficult-to-wean patients who were admitted to the intensive care unit of the First Affiliated Hospital of Guangzhou Medical University between July 2019 and September 2021. Patients were subjected to the S group (pressure support: 8cmH2 O, PEEP: 5cmH2 O) and S1 group (PS: 8cmH2 O, PEEP: 0cmH2 O) for 30 min in a random order, and respiratory mechanics indices were dynamically monitored via a four-lumen multi-functional catheter with an integrated gastric tube. Among the 30 enrolled patients, 27 were successfully weaned. The S group showed higher airway pressure (Paw), intragastric pressure (Pga) and airway pressure-time product (PTP) than the S1 group. The S group also showed a shorter inspiratory trigger delay, (93.80 ± 47.85) versus (137.33 ± 85.66) ms (P = 0.004); and fewer abnormal triggers, (0.97 ± 2.65) versus (2.67 ± 4.48) (P = 0.042) compared with the S1 group. Stratification based on the causes of mechanical ventilation revealed that under the S1 protocol, patients with chronic obstructive pulmonary disease (COPD) had a longer inspiratory trigger delay compared to both post-thoracic surgery (PTS) patients and patients with acute respiratory distress syndrome. Despite providing greater respiratory support, S group led to significant reductions in inspiratory trigger delay and less abnormal triggers compared to S1 group, especially among patients with chronic obstructive pulmonary disease. These findings suggest that the zero PEEP group was more likely to induce a higher number of patient-ventilator asynchronies in difficult-to-wean patients.

An experimental and numerical investigation on the load transfer efficiency of a novel prefabricated cement concrete pavement

Prefabricated cement concrete pavement (PCCP) is utilized more frequently in airport projects. Load transfer efficiency (LTE) is an essential mechanical index of PCCP. This study proposes a novel PCCP surrounded by tongue and groove joints. It uses both physical and numerical modeling to perform the investigation, and the mechanical responses and the LTE of the novel PCCP are presented in the experiments. The experimental results showed that the presence of tenon and mortise causes a difference in the stresses of two longitudinal and two transverse joints. Subsequently, a finite element model is developed to simulate the PCCP with and without transverse tongue and groove joint. In addition, the influence of different slab thicknesses, joint rigidity, and base elastic modulus on LTE is also discussed. The findings demonstrated that the transverse joints change the pavement slab's stress state. The LTE of the slab without a transverse joint is slightly larger than that with a transverse joint, while the maximum horizontal tensile stress of the slab without a transverse joint is 395% higher than that with a transverse joint on average. It is also observed that increasing the joint rigidity improves the LTE, whereas increasing the slab thickness decreases the LTE, and increasing the base modulus has no discernible effect on the LTE. Comparing the experimental and numerical results reveals a good agreement.

Motion Measurement and Analysis for Functional Independence Measure

An appropriate physical functionality status assessment is necessary after rehabilitation to determine the level of assistance required by the patient and the efficacy of rehabilitation. The effectiveness of rehabilitation can be determined by computing a functional independence measure (FIM) score. The FIM score measurement process evaluates the amount of assistance associated with activities of daily living; however, it is influenced by evaluator subjectivity and can vary for the same patient assessed by different evaluators. Furthermore, it is time-consuming and laborious because of the large number of component items. Therefore, a new evaluation system that is easily implementable and based on objective criteria is needed. Several machine learning techniques have been suggested for evaluating the progress of rehabilitation in an objective manner, and their efficacy has been proven. However, the FIM score includes complex movement items, necessitating the evaluation of factors from multiple angles. In this study, a method for estimating FIM values using machine learning was investigated to evaluate the effectiveness of rehabilitation objectively. A simple exercise measurement experiment was conducted, and a musculoskeletal model was used to analyze the data to obtain movement and other mechanical indices, and these were subsequently used as features of machine learning. Based on the FIM values, an estimation experiment was conducted in three groups: independent, modified independent, and assisted groups. The statistical approaches of random forest and logistic regression were used in conjunction with a support vector machine for FIM estimation. The highest accuracy was estimated to be approximately 0.9. However, the accuracy varied with each method and item; the lowest accuracy was approximately 0.3. Statistical analysis showed clear differences in the indicators, with significant differences between the groups. These differences were considered to increase the accuracy of FIM estimation. Additionally, the accuracy of some items was improved by changing the feature values used. The best results were obtained when only the joint angle was used for two items, joint torque and muscle strength were used for seven items, and all indicators were used for two items. This suggests that a comprehensive evaluation, including that of joint torque and muscle strength, is effective for estimating FIM score.

New calibration setup for quantitative DCE-US imaging protocol: Toward standardization.

The DCE-US (Dynamic Contrast-Enhanced Ultrasonography) imaging protocol predicts the vascular modifications compared with Response Evaluation Criteria in Solid Tumors (RECIST) based mainly on morphological changes. A quantitative biomarker has been validated through the DCE-US multi-centric study for early monitoring of the efficiency of anti-angiogenic cancer treatments. In this context, the question of transposing the use of this biomarker to other types of ultrasound scanners, probes and settings has arisen to maintain the follow-up of patients under anti-angiogenic treatments. As a consequence, radiologists encounter standardization issues between the different generations of ultrasound scanners to perform quantitative imaging protocols. The aim of this study was to develop a new calibration setup to transpose the DCE-US imaging protocol to the new generation of ultrasound scanners using both abdominal and linear probes. This calibration method has been designed to be easily reproducible and optimized, reducing the time required and cost incurred. It is based on an original set-up that includes using a concentration splitter to measure the variation of the harmonic signal intensity, obtained from the Area Under the time-intensity Curve (AUC) as a function of various contrast-agent concentrations. The splitter provided four different concentrations simultaneously ranging from 12.5% to 100% of the initial concentration of the SonoVue contrast agent (Bracco Imaging S.p.A., Milan, Italy), therefore, measuring four AUCs in a single injection. The plot of the AUC as a function of the four contrast agent concentrations represents the intensity variation of the harmonic signal: the slope being the calibration parameter. The standardization through this method implied that both generations of ultrasound scanners had to have the same slopes to be considered as calibrated. This method was tested on two ultrasound scanners from the same manufacturer (Aplio500, Aplioi900, Canon Medical Systems, Tokyo, Japan). The Aplio500 used the settings defined by the initial multicenter DCE-US study. The Mechanical Index (MI) and the Color Gain (CG) of the Aplioi900 have been adjusted to match those of the Aplio500. The reliability of the new setup was evaluated in terms of measurement repeatability, and reproducibility with the agreement between the measurements obtained once the two ultrasound scanners were calibrated. The new setup provided excellent repeatability measurements with a value of 96.8%. Once the two ultrasound scanners have been calibrated for both types of probes, the reproducibility was excellent with the agreement between their respective quantitative measurement was at the lowest 95.4% and at the best 98.8%. The settings of the Aplioi900 (Canon Medical Systems) were adjusted to match those of the Aplio500 (Canon Medical Systems) and these validated settings were for the abdominal probe: MI=0.13 and CG=34dB; and for the linear probe: MI=0.10 and CG=38dB. This new calibration setup provided reliable measurements and enabled the rapid transfer and the use of the DCE-US imaging protocol on new ultrasound scanners, thus permitting a continuation of the therapeutic evaluation of patients through quantitative imaging.

Vessel Rupture Thresholds for Vessel-Bubble Interactions Using an Earthworm Vasculature Model.

Intravenous microbubble oscillation in the presence of ultrasound has the potential to yield a wide range of therapeutic benefits. However, the likelihood of vessel damage caused by mechanical effects has not been quantified as a function of the numerous important parameters in therapeutic ultrasound procedures. In this study, we examined the effects of microbubbles injected into the vasculature of the earthworm. It was found that the elastic properties of earthworm blood vessels are similar to those of arteries in older humans, and that earthworms are well suited to the large number of experiments necessary to investigate safety of procedures involving microbubble oscillation in sonicated vessels. Microbubbles were infused into earthworm vessels, and the rupture time during sonication was recorded as a function of ultrasound frequency, pulse repetition frequency and acoustic pressure. A modified mechanical index (MMI) was defined that successfully captured the trends in rupture probability and rupture time for the different parameter values, creating a database of vessel rupture thresholds. In the absence of bubbles, the product of MMI squared and rupture time was approximately constant, indicating a possible radiation-force effect. The MMI was an effective correlating parameter in the presence of bubbles, though the mathematical dependence is not yet apparent. The results of the study are expected to be valuable in designing more refined studies in vertebrate models, as well as informing computational models.

A unified section-based restoring force model for reinforced concrete coupling beams based on the XGBoost model: Establishment, validation and application

To enhance the seismic performance of reinforced concrete (RC) coupling beams, improved reinforcement details such as diagonal layout and high-performance concrete including fiber reinforced concrete (FRC) as well as engineered cementitious composites (ECC) are widely investigated and applied. Despite the numerous experimental studies on various reinforced concrete coupling beams, there is still a lack of unified, efficient and accurate numerical model applicable to all kinds of concrete and reinforcement layouts, leading to difficulty in numerical study and proper design of coupling beams and coupled shear walls. In this study, a database containing 180 reinforced concrete coupling beam specimens is first set up. Then the key mechanical indexes of test curves including the peak load, peak beam rotation, yielding beam rotation and softening beam rotation are predicted using the trained XGBoost models. The feature importance and partial dependence of different independent variables are analyzed. Based on the predicted results, the skeleton curves of the section-based restoring force model can be obtained. Besides, a new hysteretic rule for the restoring force model which can account for the pinching effect, strength and stiffness degradation is proposed. The proposed model is then implemented in ABAQUS 2017 software, of which the accuracy and applicability are validated by twelve coupling beam specimens with different concrete materials and reinforcement layouts. Finally, a coupled shear wall specimen is simulated to quantitatively and thoroughly evaluate the effects of key indexes of the coupling beams on the seismic performance of the coupled shear wall structures.

Correlation Analysis of Loess Collapsibility Coefficient with Its Physical and Mechanical Properties in Weibei Area

Based on a large number of drilling and laboratory test data in Weibei loess tableland area, the correlation of three conventional physical and mechanical indexes of loess in this area, such as void ratio, compression coefficient and collapsibility coefficient, was analyzed and studied. The results show that void ratio is positively correlated with compression coefficient and collapsibility coefficient, and the correlation between void ratio and collapsibility coefficient is higher. The correlation between compression coefficient and collapsibility coefficient is obvious when the compressibility of soil is small, but there is no obvious correlation between collapsibility coefficient and compression coefficient when the compression coefficient is large.

Multi-Objective Optimization of Epoxy Resin Adhesive for Pavement Toughened by Self-Made Toughening Agent.

Epoxy resin adhesive for pavement is often insufficient in flexibility and toughness. Therefore, a new type of toughening agent was prepared to overcome this shortcoming. To achieve the best toughening effect of a self-made toughening agent on an epoxy resin adhesive, its ratio to the epoxy resin needs to be optimally selected. A curing agent, a toughening agent, and an accelerator dosage were chosen as independent variables. The epoxy resin's adhesive tensile strength, elongation at break, flexural strength, and flexural deflection were used as response values to establish a single-objective prediction model of epoxy resin mechanical property indexes. Response surface methodology (RSM) was used to determine the single-objective optimal ratio and analyze the effect of factor interaction on epoxy resin adhesive's performance indexes. Based on principal component analysis (PCA), multi-objective optimization was performed using gray relational analysis (GRA) to construct a second-order regression prediction model between the ratio and gray relational grade (GRG) to determine the optimal ratio and to validate it. The results showed that the multi-objective optimization using response surface methodology and gray relational analysis (RSM-GRA) was more effective than the single-objective optimization model. The optimal ratio of epoxy resin adhesive was 100 parts of epoxy resin, 160.7 parts curing agent, 16.1 parts toughening agent, and 3.0 parts accelerator. The measured tensile strength was 10.75 MPa, elongation at break was 23.54%, the bending strength was 6.16 MPa, and the bending deflection was 7.15 mm. RSM-GRA has excellent accuracy for epoxy resin adhesive ratio optimization and can provide a reference for the epoxy resin system ratio optimization design of complex components.

Velocity field estimation in transcranial small vessel using super-resolution ultrasound imaging velocimetry

Based on the diameter and position information of small vessels obtained by transcranial super-resolution imaging using 3 MHz low-frequency chirp plane waves, a Gaussian-like non-linear compression was adopted to compress the blood flow signals in spatiotemporal filtering (STF) data to a precise region, and then estimate the blood flow velocity field inside the region over the adjacent time intervals using ultrasound imaging velocimetry (UIV). Imaging parameters, such as the mechanical index (MI), frame rate, and microbubble (MB) concentration, are critical during the estimation of velocity fields over a short time at high MB contrast agent concentrations. These were optimized through experiments and algorithms, in which dividing the connected domain was proposed to calculate MB cluster spot centroid spacing (SCS) and the spot-to-flow area ratio (SFAR) to determine the suitable MB concentration. The results of the in vitro experiments showed that the estimation of the small vessel flow velocity field was consistent with the theoretical results; the velocity field resolution for vessels with diameters of 0.5 mm and 0.3 mm was 36 μm and 21 μm, and the error between the mean velocity and the theoretical value was 0.7 % and 0.67 %, respectively.

Microbubble-Assisted Ultrasound for Drug Delivery to the Retina in an Ex Vivo Eye Model.

Drug delivery to the retina is one of the major challenges in ophthalmology due to the biological barriers that protect it from harmful substances in the body. Despite the advancement in ocular therapeutics, there are many unmet needs for the treatment of retinal diseases. Ultrasound combined with microbubbles (USMB) was proposed as a minimally invasive method for improving delivery of drugs in the retina from the blood circulation. This study aimed to investigate the applicability of USMB for the delivery of model drugs (molecular weight varying from 600 Da to 20 kDa) in the retina of ex vivo porcine eyes. A clinical ultrasound system, in combination with microbubbles approved for clinical ultrasound imaging, was used for the treatment. Intracellular accumulation of model drugs was observed in the cells lining blood vessels in the retina and choroid of eyes treated with USMB but not in eyes that received ultrasound only. Specifically, 25.6 ± 2.9% of cells had intracellular uptake at mechanical index (MI) 0.2 and 34.5 ± 6.0% at MI 0.4. Histological examination of retinal and choroid tissues revealed that at these USMB conditions, no irreversible alterations were induced at the USMB conditions used. These results indicate that USMB can be used as a minimally invasive targeted means to induce intracellular accumulation of drugs for the treatment of retinal diseases.

Mechanical damage model and brittleness index of frozen rocks based on statistical damage theory

Mechanical damage model and brittleness index of frozen rocks based on statistical damage theory

Physicochemical and pozzolanic properties of municipal solid waste incineration fly ash with different pretreatments.

Swelling caused by gas generated from municipal solid waste incineration fly ash (MSWIFA) when it is mixed with alkali limits its uses. Besides, the leaching of anion salts and heavy metals contained in MSWIFA poses a high risk to environment. This study presents the feasibility of a one-step alkaline washing, one-step thermal quenching and two-step combination of alkaline washing and thermal quenching pretreatment methods in altering the key properties of MSWIFA for promoting its reusability. It was found that apart from H2(gas), NH3(gas) was also generated during the alkaline washing of the MSWIFA. Besides, pretreatments led to the reduction in particle size, the increase in pore volume and specific surface area of the MSWIFA, as well as the removal of chloride and sulfate anions. All the pretreatment methods were effective in reducing leaching of heavy metals to below levels of nonhazardous waste except Cd and Pb with alkaline washing. Furthermore, both the chemical Frattini test and the mechanical activity index test showed improvement in pozzolanic activities of the MSWIFA after the pretreatments. Overall, the combined pretreatment method was most effective in eliminating gas emission, and reducing leaching of metal ions and anions from the ash, while enhancing the pozzolanic activity of the ash.

Fast and Selective Super-Resolution Ultrasound In Vivo With Acoustically Activated Nanodroplets.

Perfusion by the microcirculation is key to the development, maintenance and pathology of tissue. Its measurement with high spatiotemporal resolution is consequently valuable but remains a challenge in deep tissue. Ultrasound Localization Microscopy (ULM) provides very high spatiotemporal resolution but the use of microbubbles requires low contrast agent concentrations, a long acquisition time, and gives little control over the spatial and temporal distribution of the microbubbles. The present study is the first to demonstrate Acoustic Wave Sparsely-Activated Localization Microscopy (AWSALM) and fast-AWSALM for in vivo super-resolution ultrasound imaging, offering contrast on demand and vascular selectivity. Three different formulations of acoustically activatable contrast agents were used. We demonstrate their use with ultrasound mechanical indices well within recommended safety limits to enable fast on-demand sparse activation and destruction at very high agent concentrations. We produce super-localization maps of the rabbit renal vasculature with acquisition times between 5.5 s and 0.25 s, and a 4-fold improvement in spatial resolution. We present the unique selectivity of AWSALM in visualizing specific vascular branches and downstream microvasculature, and we show super-localized kidney structures in systole (0.25 s) and diastole (0.25 s) with fast-AWSALM outperforming microbubble based ULM. In conclusion, we demonstrate the feasibility of fast and selective imaging of microvascular dynamics in vivo with subwavelength resolution using ultrasound and acoustically activatable nanodroplet contrast agents.

INFLUENCE OF TEMPERING TEMPERATURE ON THE ABRASIVEWEAR OF HIGH-STRENGTH, MARTENSITIC BORON STEELHARDOX EXTREME

The article discusses the microstructural and wear aspects of high-strength, martensitic boron steel HardoxExtreme. It is characterised by a hardness well in excess of 600 HBW and a static tensile strength Rm over2000 MPa, which provides high resistance under abrasive wear conditions. However, such high mechanicalproperties reduce the steel's ductility parameters, including impact strength, elongation and area reduction.Examples of components exposed to abrasive wear, including ploughshares, cultivator teeth, excavatorbuckets or chutes, also require satisfactory resistance to impact wear. Subjecting Hardox Extreme steel totempering treatments can enhance its performance characteristics by increasing its plastic properties whilemaintaining satisfactory mechanical indices. Therefore, it was decided to study the tribological properties ofHardox Extreme steel after stress-relieving and low-temperature tempering treatments. In the course of thework carried out, it was shown that with a reduction in hardness from 644 HBW to 508 HBW, it is possibleto achieve satisfactory wear indices. The value of the coefficient of relative abrasion resistance kb is equal to1.36 1.12, respectively, for the as-delivered condition and after tempering treatments at 250 C.

Status of Mechanization in Kadapa District of Andhra Pradesh

Indian Agriculture is undergoing a gradual shift from dependence on human power and animal power to mechanical power. Mechanical power is largely consumed in big land holdings asunder their economic condition, the small and marginal farmers are unable to own farm machinery on their own. Andhra Pradesh State is typically an agrarian State with 80.96 lakh ha of the net sown area and has about 65.39 lakh ha operational holdings and 34.35 lakh ha are small and marginal holdings. Some of the initial problems in farm mechanization had been the small and scattered size of farm holdings, financially challenged farmers, lack of awareness among the marginal farmers, and the issue of dry land agriculture. In Andhra Pradesh at present, the Farm power availability is below 2.00Kw/ha. Which is low and there is a lot of scope for improvement. The mechanization index very low SC and ST category because of that is staying away from the municipal areas, small land holding, less annual income, and repair and Maintenance Lake of non-availability of workshops in rural areas. The economic status of the farmers is greatly affected by the farm mechanization index less mechanization formed in less than 25,000 Rs of the annual income of the farmers.

Performance Analysis of Short-Span Simply Supported Bridges for Heavy-Haul Railways with A Novel Prefabricated Strengthening Structure

A novel prefabricated strengthening structure (NPSS) is proposed to improve the vertical stiffness and load-bearing capacity of existing short-span bridges for heavier axle-load trains passing through. The strengthening principle of the NPSS is revealed through theoretical derivation. A refined calculation model is prepared to investigate the effects of two important parameters on the structural behavior of the bridge, including the support stiffness and the installation location of the NPSS. The calculation model is also verified with four-point bending test of a bridge removed from a heavy-haul railway. With the calculation model and the response surface methodology (RSM), the functional relationships among the crucial mechanical indexes of the bridge and the two parameters of the NPSS are methodically established. Thus, the optimal values of the parameters are determined via a multi-objective optimization model and the analysis hierarchy process-fuzzy comprehensive evaluation method. Furthermore, the feasibility of the optimal parameters is appropriately verified based on simulations of the vehicle–track–bridge dynamics. The existence of the NPSS with optimal parameters could enhance the vertical stiffness of the bridge by 21.0% and bearing capacity by 19.5%. In addition, it could reduce the midspan dynamic deflection amplitude by 23.4% and vertical vibration acceleration amplitude of the bridge by 25.2%. The results of the study are expected to contribute to the capacity development and rehabilitation of existing heavy-haul railways with low cost and convenient construction without railway outage.

Correlation analysis of physical and mechanical parameters of inland fluvial-lacustrine soft soil based on different survey techniques

Abstract Based on the collected soil property index test data of more than 2,500 groups of inland fluvial-lacustrine soft soil, the correlation of physical and mechanical parameters of this soft soil was systematically analyzed. The results show that the physical indexes of inland fluvial-lacustrine soft soil are close to that of marine soft soil, while its mechanical indexes are higher. However, the variation coefficient of its mechanical indexes is much larger than that of the physical indexes. In addition, it is found that the cone penetration parameters of this soft soil are significantly correlated with its physical and mechanical indexes by establishing a series of empirical relationships between the static point resistance and the natural unit weight, the liquidity index, the quick shear cohesion, and vane shear strength. On the basis of the previous research results, the disturbance strength of inland fluvial-lacustrine soft soil can be converted into in situ strength by deriving the theoretical formula between the vane shear strength and the disturbance degree. The calculation process of the above conversion relation is explained in detail through an engineering case, which indicates that the theoretical formulas have good applicability for inland fluvial-lacustrine soft soil.

Mechanical Properties under Compression and Microscopy Analysis of Basalt Fiber Reinforced Recycled Aggregate Concrete

In this study, the basalt fiber content (0%, 0.075%, and 0.15%) and replacement ratio of recycled coarse aggregate (0%, 50%, and 100%) were used as parameters, and the compressive strength of 15 cubes and 15 prisms was analyzed. The failure morphology of the specimens was characterized, and the cubic compressive strength, axial compressive strength, elastic modulus, Poisson's ratio, and other mechanical property indices of the specimens were measured. Upon increasing the replacement ratio, the degree of damage of the specimens gradually increased, whereas the cubic compressive strength, axial compressive strength, and elastic modulus gradually decreased. As the replacement ratio was increased from 50% to 100%, the cubic compressive strength and elastic modulus were noted to decrease the most by about 9.07% and 9.87%, respectively. On the other hand, the Poisson's ratio first decreased, followed by an increase. Upon increasing the fiber content, the degree of damage of the specimens was gradually reduced, whereas the cubic compressive strength, axial compressive strength, and elastic modulus gradually increased. As the fiber content increased from 0.075% to 0.15%, the axial compressive strength and elastic modulus increased the most by about 6.65% and 10.19%, respectively. On the other hand, the Poisson's ratio gradually decreased. Based on the test data, the functional relationships between the strength indices and different variables, as well as the conversion value of each strength index and different variables were established; after comparison and verification, the formula calculation results were found to be in good agreement with the test results. The microstructural changes in the basalt fiber reinforced recycled aggregate concrete were characterized by scanning electron microscopy (SEM), and the changes in the mechanical properties of the basalt fiber reinforced recycled aggregate concrete as well as the mechanism of fiber modification and reinforcement were explained from a micro perspective.