Effect Of Penetration Rate Research Articles

Mixed traffic capacity estimation of autonomous vehicles impact based on empirical data

This study refined the composite headway distribution model to estimate the mixed traffic capacity by utilizing extensive empirical mixed traffic data. The enhanced model integrated an automatic iterative algorithm into the stochastic process to capture the headway distributions of autonomous and human-driven vehicles in five types of car-following pair combinations. The proposed iterative algorithm automatically fitted the free-flow headway distribution and dynamically determined the threshold for distinguishing the car-following and free-flow states of autonomous and human-driven vehicles based on extensive trajectory data. Quantitative analysis was carried out to assess the impact of time period and vehicle type on the headway distributions of following vehicles in the five car-following pairs. The mixed traffic capacity was estimated using the overall composite headway distribution model, considering the effects of penetration rate, platoon intensity, and maximum platoon size of the autonomous vehicle. The findings indicated that autonomous vehicles showed more cautious and sensitive car-following behaviors compared to human-driven vehicles. Compared to the daytime, autonomous vehicles showed more cautious car-following behaviors at night. When following heavy vehicles, autonomous vehicles typically adapt conservative and stable car-following behaviors. In addition, the results also showed that the penetration rate, platoon intensity, and maximum platoon size significantly affected the capacity of mixed traffic flow. These results of this study can assist traffic management authorities in formulating rules or policies that take into consideration the growing prevalence of autonomous vehicles.

Influence of Penetration Rate on Full-Flow Penetrometer Resistance in Underconsolidated Clay

In the past few years, offshore site investigations have extensively utilized full-flow penetrometers like the Ball and T-bar penetrometers to assess penetration resistance and subsequently analyze the strength characteristics of marine clay. The relationship between penetration rate and the measured resistance to penetration and shear strength in clays has been extensively documented through full-flow penetration tests. Although previous studies have shown empirical correlations between undrained shear strength and penetration resistance, the resistance factor utilized in these correlations is typically suggested for cohesive soils that are overconsolidated or normally consolidated, rather than underconsolidated soils. The effects of penetration rate undrained penetration resistances in underconsolidated marine clay are investigated in this study by considering the outcomes of variable rate penetration testing and twitch penetration testing using full-flow penetrometers in laboratory model tests. The discussion focuses on penetration resistances depending on the normalized velocity of the full-flow penetrometers (Ball and T-bar).

Study of cone penetration rate effects in the Yellow River Delta silty soils with different clay contents and state parameters

The penetration rate effect is a critical factor in the properties assessment of silty soils in the Yellow River Delta using CPTu. This paper discussed the factors affecting penetration rate effect of silty soils in the Yellow River Delta through variable penetration rate tests in a pressure chamber, a series of supplementary soil element tests and FE calculations. Samples, consisting of varying proportions of Yellow River Delta silt and kaolin clay that produce three clay contents of 13%, 20% and 30%, are mixed as slurry and consolidated to five state parameters of −0.27, −0.17, −0.1, 0 and 0.03. In the Yellow River Delta silty soil layers, clay content has a significant effect on the soil's drainage characteristics, and state parameters have a significant effect on viscous effects. With the increase of clay content, the Bq value increases, and a Bq value of close to zero at any penetration rate is a sign of silt. A normalized partial drainage influence equation is proposed. A practical recommendation is that Nkt(u) in the shallow silty soil is 9.5–9.9, and Bq can be used to judge drainage conditions. The partial drainage equation and Nkt(u) provide insight into the inversion of silty clay strength.

A simplified approach to normalisation of piezocone penetration rate effects

The influence of factors controlling the rate of penetration during piezocone tests (CPTU) is addressed in the present paper, including a critical appraisal of measurements adopted as input in existing dimensionless analysis. From a heuristic approach, a method is proposed to identify possible consolidation effects taking place during penetration using the velocity factor, [Formula: see text]. Defined as a direct function of probe size, d, penetration rate, v, and dissipation time, t50, the dimensionless velocity factor [Formula: see text] is used to demonstrate that normalisation of cone penetration velocity is an important step for assessment of soil properties and for comparative performance of data from different geomaterials. An application is reported to illustrate the normalisation of measured data in soils within the permeability range from 10−5 to 10−8 m/s.

Experimental Validation of String Stability for Connected Vehicles Subject to Information Delay

In this paper, we investigate the performance of communication-based controller design in connected vehicle networks. A testbed consisting of a group of ground robots that can mimic the dynamics of personal vehicles is built. We show that when incorporating time delays in the modeling equations, which arise due to digital implementation and intermittent vehicle-to-vehicle (V2V) communication, the experimental results have a very good correspondence with the theoretical ones. Moreover, we demonstrate that by designing a controller for each individual vehicle in the chain plant stability and string stability can be guaranteed despite the time delays in the control loop. Then, a series of experiments is conducted for a mixture of string stable and string unstable vehicles and the effects of penetration rate of string stable vehicles in maintaining smooth traffic are evaluated. The results lay a foundation for connected vehicle system design with flexible connectivity topologies.

Observation of sand movement during bucket installation

The occurrence of soil-plug heave during bucket installation is one of the major problems in successful installation of bucket foundation at a desired depth. It is usually caused by the upward seepage flow created by continuous pumping out of water from inside the bucket as well as due to shear failure of the soil along the skirt wall during skirt penetration. This soil-plug heave eventually hinders the bucket to be installed at a targeted depth and hence affects its performance. This paper, therefore, presents the result of a series of bucket installation tests using half-bucket foundation performed in a box equipped with a transparent window for directly observing the soil movement around the bucket during installation. Continuous images were captured simultaneously during the entire suction installation process and subsequently analysed by particle image velocimetry to quantify the soil movement. The results provide: (a) the trend of suction pressure with wall embedment; (b) soil-displacement pattern and (c) the effects of penetration rate (i.e. water-pumping rate) and wall thickness on the soil displacement. The results also provide comprehensive insights into the mechanism of soil disturbance, including soil-heave formation, during suction installation.

Mechanics and Energetics of Soil Penetration by Earthworms and Plant Roots: Higher Rates Cost More

Core Ideas We quantified mechanical differences between earthworms and roots using penetration rates. Mechanical modeling was justified by direct imaging of both plant roots and earthworms. We validated model predictions with rate‐controlled miniature cone penetrometer experiments. Earthworm burrows are dominantly formed through mechanical processes, not ingestion. We outline mechanical and energetic limitations for a range of water contents. We quantified the mechanics and energetics of soil penetration by burrowing earthworms and growing plant roots considering different penetration rates and soil mechanical properties. The mechanical model considers cavity expansion by cone‐like penetration into a viscoelastic soil material in which penetration rates affect the resulting forces and hence the mechanical energy required. To test the predicted penetration rate effects on forces and energetics, we conducted rate‐controlled cone penetration experiments across rates ranging from 1 to 200 μm s−1 to determine the mechanical resistance forces for cone geometries similar to plant roots and earthworms. These measurements also enabled inverse estimation of soil rheological parameters that were in good agreement with literature values for similar soils and water contents. The results suggest that higher soil penetration rates typical for earthworm activity (about 200 μm s−1) may significantly increase resistance forces and energy expenditure by up to threefold relative to slower penetration rates of plant roots (0.2 μm s−1) for similar soil properties and geometries. Another important mechanical difference between earthworms and roots is the radial pressures that earthworms' hydro‐skeleton exerts (<230 kPa), whereas plant roots may exert radial pressures exceeding 1 MPa. These inherent differences in burrowing rates and expansion pressures may significantly extend the range of conditions suitable for root growth in drier and compacted soil compared to earthworm activity. Results suggest that the mechanical energy costs of soil bioturbation under agricultural intensification and drier climate could greatly increase the energetic costs of these ecologically important soil structure‐forming bioprocesses.

Simulation Study on Influences of Wellbore Tortuosity on Hole Cleaning in Extended-Reach Drilling

Summary Wellbore tortuosity or spiraling can lead to the trapping of a cuttings bed in a trough of a tortuous hole, thereby leading to poor hole cleaning in extended-reach drilling. The objectives of this study included quantitatively evaluating the influences of wellbore tortuosity on hole cleaning and cuttings-transport behavior in extended-reach drilling. In addition, the study provided a recommendation of effective drilling practices. The study involved performing hole-cleaning-optimization studies for an extended-reach well with a long horizontal section aiming for maximum reservoir contact, by use of a transient cuttings-transport simulator. The planned trajectory of the well was assumed to have a certain degree of wellbore tortuosity in the horizontal section. The pump rate and bottoms-up circulation operation were optimized on the basis of parameter studies and additional transient simulations by considering the effects of penetration rate and variation in cuttings size. Simulation results indicated the formation of a considerably high cuttings bed, particularly in the downdip intervals (updip in mud-flow direction) at an insufficient pump rate; one-third to one-half of the drillpipe diameter could be potentially buried in a cuttings-deposit bed, and this can result in a packed-off hole or stuck pipe. A higher rate of penetration (ROP) can also cause insufficient hole cleaning. In this case, controlled drilling that maintains a reasonably low penetration rate may be effective. Furthermore, borehole breakout may enlarge hole diameter and generate large-sized cuttings. Both of these can have negative impacts on hole cleaning, and, thus, borehole stability and smooth wellbore-trajectory controls should be carefully considered. To clean these holes, frequent bottoms-up circulations were effective at each stand of drilling even if the optimization of other drilling parameters was limited. The findings also revealed that accumulated cuttings in a tortuous wellbore were trapped in the trough of the hole, and that the bed height of locally trapped cuttings in the downdip intervals could be much higher than that indicated by previous studies.

Detector-Free Signal Offset Optimization with Limited Connected Vehicle Market Penetration: Proof-of-Concept Study

Connected vehicle (CV) data have the potential to transform traffic signal operations, but the success of control methods that are based on CV data depends on the level of market penetration. Recent studies of real-time operational strategies in CV environments suggest that penetrations exceeding 20% is required. This study explored the feasibility of using CV data to generate arrival profiles for optimizing arterial progression. Applications to offline (3-h analysis period) and online (15-min analysis period) offset optimization were considered. Vehicle arrival profiles obtained from real-world measurement were used as a basis for comparison. Subsampled distributions were used to estimate the potential distributions that might be obtained from CVs, and these distributions were statistically analyzed to explore the effects of penetration rate, analysis period, and traffic volume. For selected penetration rates ranging from 0.1% to 50%, the subsampled distributions were used to optimize the corridor, and the results were evaluated in the complete data model. The results show that over a 3-h window, successful offline optimization can be achieved with a CV penetration rate as low as 1%. Layering multiple days of data might allow offline optimization with penetration rates as low as 0.1%. Online optimization with 15-min windows requires somewhat higher penetration rates of at least 5%. The results suggest that early applications of CV data may be possible at very low levels of market penetration. In corridors with a high penetration rate of connected mobile devices, some private-sector probe data services may be on the cusp of providing the necessary data to facilitate detector-free optimization.

Shearing Rate Effects on Research Centre for Soft Soils (Recess) Clay Using Cone Penetration Test (CPT)

A wide range of industrial applications, on land and offshore, require the solution of time domain problems and an associated understanding of rate effects in clay soils. In recent decades many researchers have examined the correlation between shear strength of soils and variation of shear strain rate and it is generally accepted that the strength increases by 1-5% for each order of magnitude increase in shear strain rate. This paper discusses the effects of penetration rate on the penetration resistance (qc) by using cone penetration test (CPT) test setup. The research had been conducted at RECESS and cone penetration test were used in three selected range of rate which were 0.5 cm/s, 1cm/s and 5cm/s. In addition, Mackintosh probe testhad been considered as comparison with CPT test for the unconfined compressive strength. The result shows different penetration rate influenced the soil shear strength. For the slowest rate (0.5 cm/s), the shear strength was approximately 0.15% less compared to the standard rate (2 cm/s). However, for the highest rate (5 cm/s), the shear strength was 0.22% more than the reference rate (0.5 cm/s). In conclusion, it is suggested that the RECESS clay soil influenced by the rate effect and in agreement with previous research findings.

Penetration Rate Effects on Cone Resistance: Insights From Calibration Chamber and Field Testing

Cone penetration in mixed or intermediate soils (soils containing mixtures of sand, silt and clay) is neither fully drained nor fully undrained at the standard cone penetration rate of 20 mm/s. Considerable research, mainly relying on centrifuge tests, has been undertaken to quantify the effects of penetration rate (and thus partial drainage) on cone resistance. In this paper, the effects of penetration rate on cone resistance in saturated clayey soils were investigated by performing field tests and miniature cone penetration tests in a calibration chamber. The field tests were performed at sites especially selected to span the range of drainage conditions from fully drained to fully undrained. The calibration chamber tests, using both conical and flat-tip penetrometers, were performed at different penetration rates in two specimens prepared by mixing kaolin clay and sand with different mixing ratios and one-dimensionally consolidateding the mixtures. A correlation between cone resistance and drainage conditions is established based on the cone penetration test results. The transitions from no drainage to partial drainage and from partial drainage to full drainage are defined as a function of penetration rate normalized with respect to the penetrometer diameter and the coefficient of consolidation.

Penetration resistance according to penetration rate, cone base size and different soil conditions

This study aimed to evaluate the effect of penetration rate and the size of the cone base on the resistance to penetration under different soil moistures and soil bulk density. The experimental design was completely randomized in a 4x2x2x2 factorial arrangement, with the factors, soil bulk density of 1.0; 1.2; 1.4 and 1.6 Mg m-3, soil moisture at the evaluation of 0.16 and 0.22 kg kg-1, penetration rates of 0.166 and 30 mm s-1 and areas of the cone base of 10.98 and 129.28 mm² resulting in 32 treatments with 8 replicates. To ensure greater uniformity and similarity to field conditions, samples passed through cycles of wetting and drying. Only the interaction of the four factors was not significant. Resistance values varied with the density of the soil, regardless of moisture and penetration rate. Soil penetration resistance was influenced by the size of the cone base, with higher values for the smallest base independent of moisture and soil bulk density. The relationship between resistance to penetration and moisture is not always linear, once it is influenced by soil bulk density. Reduction in the area of the cone leads to an increase in the soil resistance to penetration.

Needle penetration test: Evaluation of its performance and possible uses in predicting strength of weak and soft rocks

High quality core samples recommended by testing standards or suggested methods for uniaxial compressive strength (UCS) determinations cannot always be obtained particularly from soft, weak-to-very weak and clay-bearing rocks. Due to this difficulty, some simple and cheap index test methods have been developed in order to indirectly estimate the UCS. However, preparation of smaller samples from such rocks even for some index tests is also difficult. In addition, sampling from historical sites, monuments and buildings for strength determinations in rock engineering studies is not allowed. To overcome these difficulties, a new and portable light-weight testing device, Needle Penetrometer (NP), has been developed in Japan. But there is no any standard or suggested method available for this test. It is a non-destructive test applicable both in the field and laboratory with minimum sample preparation. The use of NP was mainly concentrated on predicting the UCS of soft and weak-to-very weak rocks from the Needle Penetration Resistance (NPR) in Japan and more recently in Turkey by the authors, and a few empirical relationships between the UCS and NPR have been developed by some investigators. This most recent study aims to provide some new contributions to previous works on the NP test, to assess the performance of the test and to develop a more generalized empirical relationship for indirect estimation of the UCS from NPR based on the data obtained from a wider range of soft and weak-to-very weak rocks. In addition, the effect of penetration rate on test results was investigated and the possible uses of the NP test in geo-engineering with the recommendations of the authors were also briefly discussed. For these purposes, a database consisting of a total of 725 UCS–NPR data pairs from the previous studies of the authors and those from the investigators in Japan and additional new tests carried out in this most recent study was established. The experimental results suggested that the rate of penetration had no effect on the test results. This finding makes the use of NP advantageous both in the field and laboratory. Statistical analyses reveal that based on the database used, there is a significant relationship between UCS and NPR at the 95% confidence level and the UCS values predicted from the model recommended in this study show the best agreement with those experimentally determined when compared to those obtained from the existing models. Particularly 70% of the UCS predicted from this model fall into approximately ±7% scaled percent error. It was concluded that the NP tests can be applied to soft and weak-to-very weak rocks with UCS of up to 40MPa to predict the UCS from NPR, however, its use on rock types consisting of coarse grains embedded in a cementing material, such as conglomerate, should be avoided.

The effects of penetration rate and strain softening on the vertical penetration resistance of seabed pipelines

Offshore pipelines in deep water are generally laid directly on the seabed, without any additional stabilisation measures. Design parameters that determine the soil resistance to lateral and axial motion of the pipeline are a function of the amount of vertical embedment. However, this latter quantity is difficult to estimate, partly because of the effects of soil heave around the pipeline as it penetrates, and partly because the soil shear strength depends on the strain rate and the degree of softening as the soil is sheared and remoulded. In this paper, a large deformation finite-element approach was adopted to study pipe–soil interaction during vertical embedment of pipelines on the seabed. The simple Tresca soil model was modified to incorporate the combined effects of strain rate and softening. The present large deformation finite-element method was validated by comparing the results with data from centrifuge model tests. A parametric study was then performed, varying the strain rate and softening parameters to explore their effects on penetration resistance. Simple expressions for penetration resistance, incorporating the effects of strain rate and softening, have been developed. The effects of soil strength vertical heterogeneity and buoyancy have also been explored.

Thin-blade penetration resistance and snow strength

AbstractA thin-blade snow hardness gauge was developed that measures penetration resistance over a length scale (on the order of 10–100 grain contacts) relevant to the fracture of slab avalanches. A thin blade was chosen to measure the ruptures of bonds and grain structures and minimize the effects of snow compaction during penetration. The apparatus consists of a 10 cm wide, 0.6 mm thick stainless-steel blade attached to a digital push–pull gauge. Blade penetration measurements are easy to conduct in the field and laboratory and required no post-processing or subjective interpretation. Measurements were conducted in snow pits to test the effects of penetration rate, blade orientation and blade width. The blade hardness index, defined as the maximum force of penetration, is a highly repeatable measure across observers compared to the hand hardness test. The blade hardness index was a better variable than the density for correlating with tensile strength measurements in a cold laboratory and with a cohesive strength measure in the field. As strength is one of the most important parameters in the fracture mechanics of slab avalanches, the strong correlation between thin-blade penetration and strength should benefit future slope stability evaluations using this gauge.

Effect of Penetration Rate on Insertion Force in Trabecular Bone Biopsy

Bone biopsy is a common procedure in bone disease diagnoses, therapies and research. In this procedure, bone biopsy needles are inserted into bone tissues. Although needle insertion into bone is often essential for the diagnosis of bone diseases, the hard tissue-needle interactions are not quantitatively understood. In this paper, we describe a quantitative assessment of forces involved in insertion of healthy trabecular bone using clinically applied Jamshidi CrownTM bone biopsy needles of gauge 8 (4-mm diameter). The measured forces were related to the insertion depths up to 25 mm and insertion rates of 1 mm/s to 5 mm/s. At the initial insertion stage, a clear linear force-depth relation was measured. With the increase of the insertion depth, the forces increased nonlinearly. In the final stage of insertion, the forces increased much more quickly at the lower insertion rate than that at the higher insertion rate. The maximum insertion force reached approximately 1000 N when the insertion depth reached 25 mm at the insertion rate of 1 mm/s.

Penetration Rate Effect on Miniature Cone Tip Resistance for Different Cohesionless Materials

Abstract Cone penetrometer tests were carried out in a 140 mm diameter triaxial chamber by using a miniature cone of diameter 19.5 mm. The rate of cone penetration was varied from 0.01 mm/s to 0.1 mm/s. Tests were performed in (i) clean sand, (ii) silty sand, and (iii) sand added with fly ash. Two different effective vertical pressures (σv), 100 kPa and 300 kPa, were employed. It was noted that for clean and silty sand, the effect of penetration rate on the ultimate tip resistance (qcu) of the cone was found to remain only marginal. On the other hand, for sand added with 30 % fly ash, the variation in qcu values with penetration rate was found to become quite significant. The effect of penetration rate on qcu in all the cases was found to increase with a decrease in the rate of cone penetration. It was noted that with an increase in σv, the effect of penetration rate on qcu was found to become smaller. The effect of the cone penetration rate on qcu generally reduces with an increase in the relative density of the material.

Effect of Penetration Rate on Cone Penetration Resistance in Saturated Clayey Soils

In this paper, the effects of penetration rate on cone resistance in saturated clayey soils are investigated. Shear strength rate effects in clayey soils are related to two physical processes: the increase of shear strength with increasing rate of loading and the increase of shear strength as the process transitions from undrained to drained. Special focus is placed on this second effect. Cone penetration tests were performed at various penetration rates both in the field and in a calibration chamber, and the resulting data were analyzed. The field cone penetration tests were performed at two test sites with fairly homogeneous clayey silt and silty clay layers located below the groundwater table. Additionally, tests with both cone and flat-tip penetrometers in sand-clay mixtures were performed in a calibration chamber to investigate the change in drainage conditions from undrained to partially drained and from partially drained to fully drained. A series of flexible-wall permeameter tests were conducted in the laboratory for various clayey sand mixtures prepared at various mixing ratios in order to obtain values of the coefficient of consolidation, which is required to estimate the penetration rates below which penetration is drained and above which penetration is undrained. A correlation between cone resistance and drainage conditions was established based on the results of the calibration chamber and field penetration tests.

Discussion of “Effect of Penetration Rate on Penetrometer Resistance in Clay” by Shin Fun Chung, Mark F. Randolph, and James A. Schneider

Discussion of “Effect of Penetration Rate on Penetrometer Resistance in Clay” by Shin Fun Chung, Mark F. Randolph, and James A. Schneider

Closure to “Effect of Penetration Rate on Penetrometer Resistance in Clay” by Shin Fun Chung, Mark F. Randolph, and James A. Schneider

Closure to “Effect of Penetration Rate on Penetrometer Resistance in Clay” by Shin Fun Chung, Mark F. Randolph, and James A. Schneider