scholarly journals Experimental study on the aeolian sands solidification via MICP technique

2021 ◽  
Author(s):  
Y.J. Zhou ◽  
Hongtao Wang
Keyword(s):  
Wave Speed ◽  
P Wave ◽  
Sand Sample ◽  
Carbonate Precipitation ◽  
Bender Element ◽  
S Wave ◽  
Compressive Test ◽  
Aeolian Sand ◽  
Sem Images ◽  
Aeolian Sands

Abstract This study solidifies the aeolian sand by microbial induced carbonate precipitation (MICP) technique. The effects of cementation solution with different concentrations, particle size, and grouting batches are examined via the bender element, unconfined compressive test and scanning electron microscope (SEM). The bender element results show that the wave speed of loose aeolian sand is 200m/s; however, after solidify the aeolian sand, the speed of P-wave is about 450-600m/s and S-wave is about 350-500m/s. Additionally, the unconfined compressive strength (UCS) results indicate that when the concentration of cementation solution is 0.75mol/L, the UCS of bio-solidified sand sample is the highest. Then, compared with the aeolian sand with original grade, the particles ranging from 0.1-0.4mm have a better cementation effect. Moreover, the UCS of bio-solidified sand samples increases along with the grouting batch. From the SEM images, it can be seen that when the grouting batch reaches to five times, the particles are almost completely covered by CaCO 3 crystals compared with the three batches and four batches.

EFFECT OF ALIGNMENT ON THE QUALITY OF BENDER ELEMENT PROCEDURE

2015 ◽  
Vol 76 (2) ◽  
Author(s):  
Badee Alshameri ◽  
Ismail Bakar ◽  
Aziman Madun ◽  
Edy Tonnizam Mohamad
Keyword(s):  
Vertical Axis ◽  
Poor Quality ◽  
P Wave ◽  
Secondary Wave ◽  
Horizontal Distance ◽  
Bender Element ◽  
S Wave ◽  
Testing Procedures ◽  
Wave Velocities

One of the main geophysical tools (seismic tools) in the laboratory is the bender element. This tool can be used to measure some dynamic soil properties (e.g. shear and Young’s modulus). However, even if it relatively simple to use the bender element, inconsistent testing procedures can cause poor quality in the bender element data. One of the bender element procedure that always neglected is the alignment (different positions of bender element receiver to the transmitter in the vertical axis). The alignment effect was evaluated via changing the horizontal distance between transmitter and receiver starting from 0 to 110 mm for two sizes of the sample's thickness (i.e. 63.17 mm and 91.51 mm). Five methods were applied to calculate the travel times. Those methods were as the following: visually, first-peak, maximum-peak, CCexcel and CCGDS. In general, the experiments indicated uncertain results for both of the P-wave (primary wave) and S-wave (secondary wave) velocities at zone of Dr:D above 0.5:1 (where Dr is the horizontal distance of the receiver from the vertical axis and D is the thickness of the sample). On the other hand, both the visual and first-peak methods show the wave velocities results are higher than obtained from other methods. However, the ratio between the amplitude of transmitter signals to receiver amplitude signal was taken to calculate the damping-slope of the P-wave and S-wave. Thus the results from damping slope show steeply slope when the ratio of  Dr:D is above 0.5:1 compare with gentle slope below ratio 0.5:1 at the sample with thickness equal to 91.51 mm, while there is no variation at a slope in sample with thickness equal to 63.17 mm.

Self-similar circular shear cracks lacking cohesion

1974 ◽  
Vol 64 (6) ◽  
pp. 1789-1808 ◽  
Author(s):  
Robert Burridge ◽  
Cesar Levy
Keyword(s):  
Wave Speed ◽  
Three Dimensional ◽  
Analytic Solutions ◽  
Two Dimensions ◽  
P Wave ◽  
Shear Cracks ◽  
Antiplane Strain ◽  
S Wave ◽  
Complete Evaluation ◽  
Crack Problems

abstract It has recently been shown (Burridge, 1973) that in two dimensions plane-strain shear cracks lacking cohesion may run at speeds ranging from the Rayleigh-wave to the S-wave speed or possibly at the P-wave speed. On the other hand, it has long been known that in antiplane strain, cracks lacking cohesion must run at least at the S-wave speed. Since locally at the edge of a three-dimensional crack there is a combination of plane and antiplane strain, we have sought and found solutions for circular shear cracks expanding at the S-wave speed and at the P-wave speed. These have finite shear tractions ahead of the crack and so may correspond to frictional sliding in the absence of cohesion. The analysis combines the method of Kostrov (1964b) with the results of Burridge (1973). We carry out a complete evaluation for the displacements and tractions on the fault plane, and far-field radiation for the S-wave-speed crack. The corresponding evaluations for the P-wave speed are not elementary and are not attempted here. As far as the authors are aware, these are the first analytic solutions of three-dimensional crack problems which satisfy a physically plausible fracture criterion for failure under shear.

EFFECT OF SENSOR ROTATION ON ASSESSMENT OF BENDER ELEMENT APPARATUS

2015 ◽  
Vol 77 (11) ◽  
Author(s):  
Badee Alshameri ◽  
Aziman Madun ◽  
Ismail Bakar ◽  
Edy Tonnizam Mohamad
Keyword(s):  
Cross Correlation ◽  
Rotation Angle ◽  
Sample Thickness ◽  
P Wave ◽  
Analysis Tool ◽  
Bender Element ◽  
S Wave ◽  
Testing Procedures ◽  
Maximum Peak ◽  
Correlation Methods

The bender element is one of the most useful geophysical tools used in the laboratory to measure soil dynamics properties in a non-destructive way. However, inconsistent testing procedures may produce unrepeatable test results. Therefore, understanding the effect of the sensor rotation between the source and receiver position is crucial. This effect was evaluated using polystyrene material, which was unchanged throughout the period of testing. With sensor rotation angle starting from 00 to 900, the P-wave and S-wave velocities were calculated using five methods (Visual, First-peak, Maximum-peak, CCexcel and CCGDS). The cross-correlation methods are used in two ways; by using normalized cross-correlation in Excel (knowned as CCexcel) and by using GDS (Geotechnical Digital Systems Company for supplying Geotechnical instrument) bender element analysis tool BEAT (knowned as CCGDS). The results show that the Visual and First-peak methods gave a consistent wave velocity compared to the three other methods. In addition, both calculation methods were not significantly affected by increasing the sensor rotation angles. However, the Maximum-peak showed significant effect when the sensor rotation angle was above 200. The same issue was recognized for both cross-correlation methods when the sensor rotation angle was above 500. Moreover, the results from damping-slope indicated low effects for increasing the sensor rotation at P-wave and S-wave with sample thickness of 62.58 mm and 88.97 mm respectively (with an average damping-slope of about 3.50). In addition, the effect of the sensor rotation became more obvious at P-wave and S-wave with sample thickness of 88.97 mm and 62.58 mm respectively (with variation in the damping-slope 0.40 to 41.20).

scholarly journals S-wave velocity in samples of calcareous waste

2018 ◽  
Vol 66 ◽  
pp. 02005 ◽  
Author(s):  
Elżbieta Pilecka ◽  
Jakub Zięba ◽  
Rafał Pilecki
Keyword(s):  
Wave Velocity ◽  
P Wave ◽  
Degree Of Saturation ◽  
Bender Element ◽  
S Wave ◽  
Waste Area ◽  
Velocity Increase ◽  
Triaxial Apparatus ◽  
Increase With Increase ◽  
Degree Of Consolidation

The studies have been carried out in the calcareous waste area “White Seas” of the closed factory Solvay Sodium Plant in Krakow in southern Poland. The study was conducted to determine the S-wave velocity of samples of the anthropogenic subsoil. It was aimed at the possibility of using post-production waste for construction purposes. Due to the high humidity of the analysed samples, the tests were carried out on samples taken using Shelby type probes, from the 12m borehole. The saturation level of soil samples was estimated based on Skempton’s law (B>0.95). The Swave velocity was determined depending on the different degree of saturation as well as the different degree of consolidation of the soil sample. Only S-wave velocity was analysed because properties of samples caused difficulties in determining of the first arrivals of P-wave. The measurements were carried out in the triaxial apparatus equipped with Bender element (BE). Finally, the shear modulus G of the samples were calculated. Results showed the effect of S-wave velocity increase with increase of degree of saturation and with the increase of effective stress in tested samples. The Swave velocity significant increased up to about 100 kPa, and then this increase was smaller.

scholarly journals Post-collisional mantle delamination in the Dinarides implied from staircases of Oligo-Miocene uplifted marine terraces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Philipp Balling ◽  
Christoph Grützner ◽  
Bruno Tomljenović ◽  
Wim Spakman ◽  
Kamil Ustaszewski
Keyword(s):  
Balkan Peninsula ◽  
Receiver Functions ◽  
P Wave ◽  
S Wave ◽  
Slab Geometry ◽  
Surface Uplift ◽  
River Incision ◽  
Marine Terraces ◽  
Convergence System ◽  
Internal Dinarides

AbstractThe Dinarides fold-thrust belt on the Balkan Peninsula resulted from convergence between the Adriatic and Eurasian plates since Mid-Jurassic times. Under the Dinarides, S-wave receiver functions, P-wave tomographic models, and shear-wave splitting data show anomalously thin lithosphere overlying a short down-flexed slab geometry. This geometry suggests a delamination of Adriatic lithosphere. Here, we link the evolution of this continental convergence system to hitherto unreported sets of extensively uplifted Oligocene–Miocene (28–17 Ma) marine terraces preserved at elevations of up to 600 m along the Dinaric coastal range. River incision on either side of the Mediterranean-Black Sea drainage divide is comparable to the amounts of terrace uplift. The preservation of the uplifted terraces implies that the most External Dinarides did not experience substantial deformation other than surface uplift in the Neogene. These observations and the contemporaneous emplacement of igneous rocks (33–22 Ma) in the internal Dinarides suggest that the Oligo-Miocene orogen-wide uplift was driven by post-break-off delamination of the Adriatic lithospheric mantle, this was followed by isostatic readjustment of the remaining crust. Our study details how lithospheric delamination exerts an important control on crustal deformation and that its crustal signature and geomorphic imprint can be preserved for millions of years.

scholarly journals S-wave experiments for the exploration of a deep geothermal carbonate reservoir in the German Molasse Basin

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Britta Wawerzinek ◽  
Hermann Buness ◽  
Hartwig von Hartmann ◽  
David C. Tanner
Keyword(s):  
Upper Jurassic ◽  
Carbonate Reservoir ◽  
P Wave ◽  
Seismic Survey ◽  
Seismic Exploration ◽  
Molasse Basin ◽  
S Wave ◽  
Induced Earthquakes ◽  
Conversion Point ◽  
Facies Classification

AbstractThere are many successful geothermal projects that exploit the Upper Jurassic aquifer at 2–3 km depth in the German Molasse Basin. However, up to now, only P-wave seismic exploration has been carried out. In an experiment in the Greater Munich area, we recorded S-waves that were generated by the conventional P-wave seismic survey, using 3C receivers. From this, we built a 3D volume of P- to S-converted (PS) waves using the asymptotic conversion point approach. By combining the P-volume and the resulting PS-seismic volume, we were able to derive the spatial distribution of the vp/vs ratio of both the Molasse overburden and the Upper Jurassic reservoir. We found that the vp/vs ratios for the Molasse units range from 2.0 to 2.3 with a median of 2.15, which is much higher than previously assumed. This raises the depth of hypocenters of induced earthquakes in surrounding geothermal wells. The vp/vs ratios found in the Upper Jurassic vary laterally between 1.5 and 2.2. Since no boreholes are available for verification, we test our results against an independently derived facies classification of the conventional 3D seismic volume and found it correlates well. Furthermore, we see that low vp/vs ratios correlate with high vp and vs velocities. We interpret the latter as dolomitized rocks, which are connected with enhanced permeability in the reservoir. We conclude that 3C registration of conventional P-wave surveys is worthwhile.

Inverse design of layered periodic wave barriers based on deep learning

2021 ◽  
pp. 146442072110168
Author(s):  
Chen-Xu Liu ◽  
Gui-Lan Yu
Keyword(s):  
Deep Learning ◽  
Activation Function ◽  
Periodic Wave ◽  
P Wave ◽  
Soil Parameters ◽  
S Wave ◽  
Output Frequency ◽  
Great Generality ◽  
Typical Range ◽  
Deep Learning Model

This study presents an approach based on deep learning to design layered periodic wave barriers with consideration of typical range of soil parameters. Three cases are considered where P wave and S wave exist separately or simultaneously. The deep learning model is composed of an autoencoder with a pretrained decoder which has three branches to output frequency attenuation domains for three different cases. A periodic activation function is used to improve the design accuracy, and condition variables are applied in the code layer of the autoencoder to meet the requirements of practical multi working conditions. Forty thousand sets of data are generated to train, validate, and test the model, and the designed results are highly consistent with the targets. The presented approach has great generality, feasibility, rapidity, and accuracy on designing layered periodic wave barriers which exhibit good performance in wave suppression in targeted frequency range.

P- and S-wave attenuation logs from monopole sonic data

Geophysics ◽  
2000 ◽  
Vol 65 (3) ◽  
pp. 755-765 ◽  
Author(s):  
Xinhua Sun ◽  
Xiaoming Tang ◽  
C. H. (Arthur) Cheng ◽  
L. Neil Frazer
Keyword(s):  
Wave Attenuation ◽  
Fluid Velocity ◽  
P Wave ◽  
Reservoir Rock ◽  
Rock Properties ◽  
S Wave ◽  
Intrinsic Attenuation ◽  
Modified Method ◽  
Receiver Array ◽  
Attenuation Profiles

In this paper, a modification of an existing method for estimating relative P-wave attenuation is proposed. By generating synthetic waveforms without attenuation, the variation of geometrical spreading related to changes in formation properties with depth can be accounted for. With the modified method, reliable P- and S-wave attenuation logs can be extracted from monopole array acoustic waveform log data. Synthetic tests show that the P- and S-wave attenuation values estimated from synthetic waveforms agree well with their respective model values. In‐situ P- and S-wave attenuation profiles provide valuable information about reservoir rock properties. Field data processing results show that this method gives robust estimates of intrinsic attenuation. The attenuation profiles calculated independently from each waveform of an eight‐receiver array are consistent with one another. In fast formations where S-wave velocity exceeds the borehole fluid velocity, both P-wave attenuation ([Formula: see text]) and S-wave attenuation ([Formula: see text]) profiles can be obtained. P- and S-wave attenuation profiles and their comparisons are presented for three reservoirs. Their correlations with formation lithology, permeability, and fractures are also presented.

Sign in / Sign up

Export Citation Format

Share Document